How can we protect our daughters from breast cancer? - Childhood and puberty
Last updated: June 19, 2010
Daughters of women who have been diagnosed with breast cancer or who have a
BRCA1 or BRCA2 mutation are at higher risk for breast cancer than the general population. While there are some breast cancer risk factors such as height and age at first period over which parents have limited control, there are other sources of risk that they can minimize. These generally fall under diet and lifestyle factors, although minimizing exposure to certain pollutants and ionizing radiation are also important. We have divided this topic into three time periods:
prenatal period and infancy; childhood and puberty; and
teenage years and young adulthood. Below we summarize the findings of studies that have identified breast cancer risk factors during childhood and puberty.
Avoiding early puberty
Established risk factors for breast cancer include early age at menarche (first period), which increases premenopausal cumulative estrogen exposure. A diet rich in fruits and vegetables with high vitamin A content has been found to delay sexual maturation and carcinogen-induced mammary tumors in rats. On the other hand, consumption of high-carbohydrate drinks (i.e., soft drinks or soda), processed meats, and shellfish during childhood each have been found to be associated with early puberty in girls.
Some personal care products have been found to cause signs of sexual maturation in girls (and feminization, including breasts, in boys). These include shampoo and other hair products, body creams, body oils, and other personal care products with labels indicating that they contain
lavender or tea tree oil, placenta or placental extract, or hormones. Personal products containing parabens are also suspected of contributing to breast cancer incidence. These products are intended for external use, but are absorbed through the skin or scalp. In addition, there are a number of hair care and other products marketed to African-American women that contain placenta or "hormone" that should be avoided.
Childhood milk consumption and breast cancer
Although
milk consumption during adulthood has been found to be associated with higher risk of breast cancer, milk has previously been found to be somewhat protective against breast cancer when consumed in infancy and childhood. A partial explanation proposed for this finding is the fact that milk is a very good source of calcium and
vitamin D, both of which are known to protect against breast cancer. Exposure to estrogen during childhood also appears to be protective against subsequent breast cancer, although the mechanism of action is not understood. Milk consumption is also associated with higher bone mineral density and other measures of bone health.
Based on the available evidence, the point in time during which milk becomes a risk factor in U.S. girls appears to be late adolescence. We would recommend organic milk (from grass-fed cows, if possible), but not raw milk, for consumption by our children. Much of the milk we drink today is produced from pregnant cows, in which estrogen and progesterone levels are markedly elevated. Non-organic milk contains additional recombinant bovine growth hormone,
zeranol and other additives administered to cows; such additives are not likely to be protective against breast cancer at any age.
Childhood soy consumption and breast cancer
Numerous studies have found that soybean consumption in childhood is associated with lower risk of breast cancer in adulthood. The soybean products that are protective are not the highly processed forms of soy most often consumed in the U.S., namely
soy protein isolate and
soybean oil. Nor are they highly salty soy products such as miso soup,
soybean paste and soy sauce. Rather, they include less processed forms of soy, such as
tofu and
edamame, which are typically consumed as a protein or vegetable components of meals.
Childhood weight
Established risk factors for breast cancer also include tall stature, which is associated with higher levels of various growth hormones. Weight should not be confused with height. While obesity is associated with increased risk of postmenopausal breast cancer in adult women, being somewhat overweight appears to be protective against breast cancer before menopause. This is true also of childhood. Girls should not be deprived of needed calories in an effort to delay puberty. It is the tall, thin girls who go on to have the highest rates of premenopausal beast cancer. However, one study found that the associations of childhood height and weight with risk of breast cancer held only for women without a family history of breast cancer.
Childhood exercise
There is some evidence that vigorous exercise during childhood reduces the subsequent risk of breast cancer, although the evidence for the benefits of exercise in preventing breast cancer is strongest for teenagers and women. There is also evidence that vitamin D opposes breast cancer, although the effect is greatest in women who already have the disease. Exercise can also help prevent early puberty. Based on the available evidence, it makes sense for our high risk daughters to participate in outdoor sports and other regular physical activity during childhood. It is important to take steps to avoid sunburn, but girls should be allowed to develop a light tan outdoors (if possible for their skin type) and regularly expose the skin to sunlight. This includes African Americans and other girls of color.
Omega-3 vs. omega-6 fatty acids
Although numerous studies have found that a diet high in omega-3 and relatively low in omega-6 fatty acids is protective against breast cancer in adults, this topic has not been studied adequately with respect to the childhood years. Several studies have found that prepubertal rats fed diets very high in omega-3 fatty acids can have unwanted effects, including adverse effects on the prepubertal mammary gland and an increase in subsequent breast cancer risk. While it makes sense to introduce
fatty fish in the diets of children, fish oil supplementation does not appear warranted. Using
olive oil,
canola oil and
walnut oil in preparing meals instead of high omega-6 oils such as
corn oil,
sunflower oil and
soybean oil also appears logical given the available evidence, but there are no population studies that the support the hypothesis that childhood consumption of these oils influences breast cancer risk in adulthood.
Environmental carcinogens
Some plastics contain estrogenic and otherwise carcinogenic chemicals that can leach into food when the plastics are heated, microwaved, put under pressure or simply scuffed and worn. These chemicals include
bisphenol A (BPA), styrene, and phthalates. Plastics that may leach these substances include (1) polyvinyl chloride (PVC), which may be found in cling wrap, some plastic squeeze bottles, and cooking oil bottles; (2) polystyrene, which may be found in styrofoam food containers and disposable cups and bowls; and (3) polycarbonates, which may be found in plastic baby bottles, water bottles, and clear plastic sippy cups. Children and adults alike should avoid all but temporary, low temperature uses of these products. Plastic containers may be marked with a number in a triangle-like icon. Plastics marked 1, 2, 4 or 5 use less toxic additives in their manufacture. Products that use polyvinyl chloride should be marked with 3, polystyrene with a 6, and polycarbonate with a 7 - these are the ones to avoid.
Girls who are raised on or near farms, raised by farm workers, or who are themselves farm workers are especially vulnerable to the breast cancer-promoting effects of certain pesticides, hormones and other chemicals used in the production of food and other products. Girls should be kept out of harm's way when such chemicals are applied and should not be required to pick or process crops to which pesticides have been applied. Although not all crops are grown with the assistance of carcinogens, some crops are associated with particularly high rates of breast cancer among workers. For example, one study found that California mushroom workers had approximately six times the expected incidence of breast cancer. Parents of girls raised on or near farms should educate themselves on the risks of the specific chemicals used there and take appropriate precautions.
Household insecticides containing lambda-cyhalothrin should also be avoided, since this chemical has been found to have estrogenic properties, including promoting the growth of
hormone receptor positive breast cancer cells in the laboratory.
Childhood radiation
Whether used to treat or to diagnose illness, radiation to the chest or back (including x-rays, CT scans, and radiation treatment) during childhood can result in breast cancer in adulthood. While such radiation normally is administered for medically necessary reasons, parents of girls at high risk for later breast cancer should pay attention to the degree of exposure and try to limit it, where possible. Parents should also make sure that the chest is fully protected when radiation is administered to the head or neck or other areas close to the chest or back.
Foods and spices to include during childhood and puberty
The following foods and spices may reduce the subsequent risk of breast cancer in women when included in the diet during childhood and puberty:
Foods and products to limit or avoid during childhood and puberty
The following foods and products may increase the subsequent risk of breast cancer in women when consumed or used regularly during childhood and puberty:
- Butter
- French fries
- Processed meats (e.g., bacon, hot dogs, bologna, sandwich meats, pepperoni, beef jerky)
- Shellfish
- Soda and other high-carbohydrate drinks
Additional comments
Mothers who themselves have an elevated risk of breast cancer should eat a wide variety of the foods on our
recommended food list and limit or avoid those on our
avoid list, in addition to paying particular attention to the foods and other products on the lists above when feeding their children.
,
BRCA1BRCA2,
apricots,
asparagus,
bacon,
beanCurd,
beef,
bellPeppers,
blackPepper,
boneDevelopment,
butter,
calcium,
canolaOil,
carrots,
cauliflower,
cornOil,
eggs,
exercise,
fermentedBeanPaste,
fishOil,
greenBeans,
kale,
kiwifruit,
lavender,
mangoes,
melon,
milk,
mushrooms,
olive,
omega3,
omega6,
overweight,
peaches,
plantains,
plums,
potatoes,
processedMeat,
protectingOurChildren,
pumpkin,
rice,
saffron,
salt,
seaweed,
shellfish,
soyProteinIsolate,
soybeanOil,
soybeanPaste,
soybeans,
spinach,
sugar,
sunExposure,
sunflowerOil,
sweetPotatoes,
tofu,
vitaminA,
vitaminD,
walnuts
Selected studies
Effects of childhood body size on breast cancer tumour characteristics
Breast Cancer Research, April 2010
The present Swedish case-control study was designed to investigate the associations between childhood body size and risk of eventual postmenopausal breast cancer. The study included 2,818 breast cancer cases and 3,111 cancer-free controls. A nine-level somatotype (measurement of body shape type and size) scale was used to classify childhood body size. Unconditional logistic regression models were used to calculate relative risks by odds ratios (ORs) with 95% confidence intervals (CIs). Association between somatotype at age seven and tumor hormone receptor status were evaluated in a case-only analysis where P-values were calculated using one degree of freedom trend tests. A large body type at age seven was found to be associated with lower postmenopausal breast cancer risk than a slender body type. Although strongly associated with other factors known to increase risk of breast cancer such as young age of first period, high adult body mass index (BMI) and high mammographic breast density, large somatotype at age seven remained a significant protective factor (comparing large to lean somatotype at age seven, OR = 0.73; 95% confidence interval (CI) = 0.58 - 0.91, P trend = 0.004) after adjustment. The protective effect of a large body type was observed within all possible combinations of estrogen receptor (ER) and progesterone receptor (PR) status. However, a stronger effect was found for ER- (OR = 0.40; 95% CI = 0.21 - 0.75, P trend = 0.002), than for ER+ (OR =0.80; 95% CI = 0.62 - 1.05, P trend = 0.062) breast cancer (P heterogeneity = 0.046). Body type at age seven was not found to be associated with tumor size, histology, grade or lymph node status. The authors conclude that greater body size at age seven is associated with a decreased risk of postmenopausal breast cancer, and that the associated protective effect is stronger for the ER- breast cancer than for the ER+ breast cancer.
Prepubertal exposure to cow's milk reduces susceptibility to carcinogen-induced mammary tumorigenesis in rats
International Journal of Cancer, March 2010
The present study was designed to investigate whether prepubertal cow's milk exposure affects mammary gland development and carcinogenesis in rats. Milk contains high levels of estrogens, progesterone and insulin-like growth factor 1 (IGF-1), all of which have been reported to be associated with increased risk of breast cancer. In the study, Sprague-Dawley rats were given either whole milk or tap water to drink from day 14 to day 35 after birth; all of the rats received tap water thereafter. Mammary tumors were induced by administering the carcinogen 7,12-dimethylbenz[a]anthracene on day 50. Milk exposure was found to increase circulating estradiol (E2) levels 10-fold (p < 0.001) by day 25. Milk consumption also accelerated vaginal opening, which marks the onset of puberty in rats, by 2.5 days (p < 0.001). However, rats fed milk before puberty were found to have reduced mammary carcinogenesis: tumor latency was longer (p < 0.03) and incidence was lower (p < 0.05) than in the water-fed controls. Mammary glands of milk-exposed rats had significantly fewer terminal end buds than controls (p < 0.019) when sampled on days 25 and 50. Estrogen receptor protein levels were elevated in the terminal end buds and lobules of milk-fed rats, compared to controls (p < 0.019), but no changes in cyclin D1 expression, cell proliferation or apoptosis were observed. IGF-1 mRNA levels were found to be reduced on day 50 in the mammary glands of rats exposed to milk at puberty. The authors conclude that consuming milk before puberty reduces later risk of developing mammary cancer in rats. This reduced risk might be mediated by a reduction in the number of terminal end buds and lower expression of IGF-1 mRNA in the mammary glands of milk-exposed animals.
Radiation Dose and Breast Cancer Risk in the Childhood Cancer Survivor Study
Journal of Clinical Oncology, August 2009
The present case-control study was designed to quantify the risk of breast cancer in relation to radiation dose and chemotherapy among survivors of childhood cancer. The study included 6,647 women who were survivors of childhood cancer and who had been treated for cancer during the period 1970 to 1986. In this cohort, 120 breast cancer cases were identified and individually matched to four controls selected based on age at initial cancer and time since initial cancer. Medical records were used by medical physicists to estimate cumulative radiation dose to the breast tumor site and ovaries. The odds ratio for breast cancer was found to increase linearly with cumulative radiation dose, reaching 11 times the risk of controls who received no radiation for local breast doses of approximately 40 Gy (P for trend < .0001). The risk of breast cancer did not vary significantly by age at radiation exposure. The risk associated with breast irradiation was sharply reduced in women who received at least 5 Gy to the ovaries (P = .002). The excess odds ratio per Gy of radiation was 0.36 for girls who received ovarian doses less than 5 Gy and 0.06 for those who received higher doses. Borderline significantly elevated risks were also found for chemotherapy regimens containing doxorubicin, dactinomycin, dacarbazine, and carmustine. The authors conclude that breasts in girls aged 10 to 20 are vulnerable to radiation and that this sensitivity is not strongly related to age at exposure within this age range. Irradiation of the ovaries at doses greater than 5 Gy appears to lessen the carcinogenic effects of breast irradiation, probably by reducing exposure of radiation-damaged breast cells to the stimulating effects of ovarian hormones.
Childhood Soy Intake and Breast Cancer Risk in Asian American Women
Cancer Epidemiology Biomarkers & Prevention, April 2009
The present population-based case-control study was designed to investigate the association between childhood soy intake and breast cancer risk in U.S. women of Asian descent. Breast cancer rates are substantially higher in the U.S. than in Asia. When Asian women migrate to the U.S., their breast cancer rates rise over several generations and finally approach that of U.S. Caucasians. One explanation is that modifiable factors such as diet may be important. The study included women aged 20-55 years of Chinese, Japanese, and Filipino descent, living in San Francisco-Oakland, Los Angeles or Oahu (Hawaii). The 597 breast cancer cases and 966 controls were interviewed about adolescent and adult diet and cultural practices. For participants with mothers living in the U.S. (39% of participants), 99 mothers of cases and 156 mothers of controls were interviewed about their daughter's childhood diets and exposures. Comparing the highest with the lowest thirds, the multivariate relative risks (95% confidence interval) for childhood, adolescent, and adult soy intake were found to be 0.40 (95% CI = 0.18 - 0.83; Ptrend = 0.03), 0.80 (0.59-1.08; 0.12), and 0.76 (0.56-1.02; 0.04), respectively. Inverse associations with childhood intake were found in all three groups, all three study sites, and women born both in Asia and the U.S. Adjustment for measures of westernization lowered the associations with adolescent and adult soy intake but did not change the inverse relationship with childhood soy intake. The authors conclude that soy may be a hormonally related, early-life exposure that influences breast cancer incidence.
Growth Hormone and Insulin-Like Growth Factor-I in the Transition from Normal Mammary Development to Preneoplastic Mammary Lesions
Endocrine Reviews, February 2009
Adult female breast development begins at puberty and proceeds by means of tightly regulated cross-talk between hormones and growth factors. While estrogen and luteal phase progesterone are crucial, both of these hormones require growth hormone-induced insulin-like growth factor 1 (IGF-I) in the mammary gland in order to act. The same group of hormones, when experimentally manipulated, can lead to the development of hyperplastic lesions and increase the chances, or be precursors, of breast cancer. For example, systemic administration of growth hormone or IGF-I causes mammary hyperplasia, and overproduction of IGF-I in laboratory animals can initiate the development of usual or atypical hyperplasias and sometimes carcinoma. The theoretical model of progression from normal development to cancer through precursor lesions sensitive to hormones and growth factors described above is gaining support for humans as well. Indeed, elevation of estrogen receptor, growth hormone, IGF-I, and IGF-I receptor during breast cancer progression suggests a role for these pathways in this process. New substances targeting the growth hormone/IGF-I mechanism may provide a means to avert formation and progression of precursor lesions to overt breast cancer. For example, a novel somatostatin analog has been shown to prevent mammary development in rats via IGF-I action inhibition. In addition, the growth hormone antagonist pegvisomant and IGF-I antagonists such as IGF binding proteins 1 and 5 also block mammary gland development. The authors conclude that inhibition of IGF-I action, or perhaps growth hormone, in the mammary gland may eventually play a role in breast cancer chemoprevention by preventing actions of both estrogen and progesterone, especially in women at extremely high risk for developing breast cancer such as those with BRCA gene 1 or 2 mutations.
Milk, rather than other foods, is associated with vertebral bone mass and circulating IGF-1 in female adolescents
Osteoporosis International, August 2008
The present study was designed to examine the associations between dietary sources of calcium and vertebral mass in girls. Low calcium intake has been shown to hamper bone mineral acquisition in adolescent girls. On the other hand, milk consumption has been found to be positively associated with lumbar vertebrae mineral content and density, as well as serum IGF-1. Calcium sources and nutrients possibly associated with lumbar bone mineralization and calcium metabolism in adolescent girls were identified. The possible influence of a genetic polymorphic trait associated with adult-type hypolactasia was also evaluated. The study included 192 healthy adolescent girls for whom lumbar bone mineral content, bone mineral density and area, circulating IGF-1, markers of bone metabolism, and −13910 LCT (lactase gene) polymorphism were assessed. Intakes of milk, dairy products, calcium, phosphorus, magnesium, proteins, and energy were also evaluated. After menarche, lumbar bone mineral content, bone mineral density, serum IGF-1, and serum parathyroid hormone (PTH) were found to be strongly associated with milk consumption, but not with other calcium sources. All four of these factors were also found to be associated with phosphorus, magnesium, protein, and energy from milk, but not from other sources. Girls with milk intakes below 55 mL per day had significantly lower bone mineral density, lumbar bone mineral content, and IGF-1, as well as higher PTH than girls consuming at 260 mL or more of milk per day. Neither lumbar bone mineral content, bone mineral density, calcium intakes, nor milk consumption were associated with lactase gene polymorphism. The authors conclude that milk consumption, preferably to other calcium sources, is associated with lumbar bone mineral content and bone mineral density in postmenarcheal girls. In addition to being a major source of calcium, milk provides magnesium, phosphates, proteins, and as yet unidentified nutrients likely to favor bone health.
Whole-Food Sources of Vitamin A More Effectively Inhibit Female Rat Sexual Maturation, Mammary Gland Development, and Mammary Carcinogenesis than Retinyl Palmitate
Journal of Nutrition, June 2007
The current study examined the effects of vitamin A within a human food-based diet (i.e., whole food diet) on sexual maturation, mammary gland development, and sensitivity to carcinogenesis in laboratory rats. A prior study using an adolescent rat model for breast cancer found an increase in mammary tumor occurrence in animals fed a chemopreventive dose of vitamin A. Animal models for nutrient-cancer interactions using strictly defined diets do not replicate the complexity of the human diet and may not be adequate to investigate food patterns associated with cancer risk in humans. Starting at age 20 days, female rats were fed either a whole-food diet with adequate levels of vitamin A (control diet), a diet with a 5.5-fold increase in vitamin A from fruits and vegetables, or a diet with a 6.2-fold increase in vitamin A provided as retinyl palmitate. The dietary intervention period was from age 20 days to age 63 days in order to determine the effect of the diets on pubertal mammary gland development. On day 66, the rats were injected with the mammary carcinogen 1-methyl-1-nitrosourea. Compared with adolescent rats that consumed the control diet, consumption of the fruits and vegetables and vitamin A diets were found to reduce mammary tumor multiplicity (relative risk 0.7, P 0.002), which was associated with a decrease in alveolar gland development. The fruits and vegetables diet suppressed the onset of sexual maturation (P < 0.001) and inhibited markers of mammary alveologenesis more than the vitamin A diet. The authors conclude that the amount and source of vitamin A consumed by adolescent female rats can influence the onset of puberty, mammary gland alveolar development, and breast cancer risk. The study highlights the relevance of using whole-food diets to evaluate the impact of dietary factors in cancer prevention.
Vitamin D and Reduced Risk of Breast Cancer: A Population-Based Case-Control Study
Cancer Epidemiology, Biomarkers & Prevention, March 2007
The present case-control study was designed to investigate the possible relationship between sources of vitamin D and risk of breast cancer. The study included 972 breast cancer cases and 1,135 controls. The Ontario Cancer Registry was used to identify women with newly diagnosed invasive breast cancer. The controls were selected through randomly chosen residential telephone numbers. Telephone interviews were completed for all of the cases and controls. Unconditional logistic regression with adjustment for potential confounders was used to calculate odds ratios (ORs) and 95% confidence intervals (CIs) for vitamin D-related variables. Increasing sun exposure during ages 10 to 19 (for example, OR = 0.65; 95% CI = 0.50-0.85 for the highest quartile of outdoor activities versus the lowest) was found to be associated with lower subsequent risk of breast cancer. Reduced risk was also found for cod liver oil consumption (OR = 0.76; 95% CI = 0.62-0.92) and increasing milk intake (OR = 0.62; 95% CI = 0.45-0.86 for ≥10 glasses/week versus none). Weaker evidence was found for associations between ages 20 and 29 and none between ages 45 and 54. The authors conclude that the evidence strongly supports the hypothesis that vitamin D could help prevent breast cancer. However, the results suggest that exposure earlier in life, particularly during breast development, may be most relevant.
Effects of lifestyle on the onset of puberty as determinant for breast cancer
European Journal of Cancer Prevention, February 2007
The present study was designed to investigate the influence of nutrition and other lifestyle factors on physical development, puberty, menarche and breast growth in an attempt to understand the potential impact of these environmental and lifestyle factors on the breast cancer susceptibility. The study included 1,146 girls in 10 schools in Belgian Limburg with average age of 13 who completed a questionnaire during the 1999-2000 school year. Univariate and multivariate analyses of the most important variables of the period from birth to the age of menarche found clear evidence that lifestyle factors have an effect on breast development and menarche. In particular, body mass index, drinking high-carbohydrate drinks (i.e. soft drinks), height of the father and the mother, weight of the mother at the start of pregnancy, history of mononucleosis, origin and education of the parents, and physical activity were all found to be significantly associated with breast development and menarche. Lifestyle factors, including nutrition (i.e. soft drinks), influence the age of puberty and menarche. The same factors are known to be related to breast cancer risk. The authors conclude that better control of these variables during puberty might reduce breast cancer risk later in life.
Prepubertal Gynecomastia Linked to Lavender and Tea Tree Oils
New England Journal of Medicine, February 2007
Three cases of gynecomastia (enlarged breasts) in prepubertal boys who were otherwise healthy were found to be caused by the topical application of products containing lavender and tea tree oils. The boys were aged 4 years 5 months, 10 years 1 month, and 7 years 10 months. Each boy had normal serum concentrations of endogenous steroids. The products linked to the enlarged breasts were a healing balm containing lavender oil, a hair styling gel and a shampoo both listing Lavandula angustifolia (lavender) oil and Melaleuca alternifolia (tea tree) oil as ingredients, lavender-scented soap and lavender-scented commercial skin lotions. After discontinuing the use of these products, the gynecomastia resolved within several months in each of the patients. Testing using dose-response experiments in human breast cancer cell lines led the authors to conclude that the two oils have estrogenic and antiandrogenic properties.
Dietary patterns are associated with sexual maturation in Korean children
British Journal of Nutrition, April 2006
The present cross-sectional South Korean study was designed to investigate the association between dietary patterns and sexual maturation among children in Seoul. The study included 422 boys and 365 girls aged nine to 12 years old. Food records covering three days were obtained, pubertal stages were determined using Tanner stages, and body fat and bone mass were measured. Four distinct dietary patterns using twenty-four food groups were developed: (1) rice and Kimchi; (2) shellfish and processed meat; (3) pizza and drinks; and (4) milk and cereal. Twenty-six percent of the boys were found to have had genital development, and 79% of the girls were found to have breast development. Genital development was found to be weakly positively associated with "shellfish and processed meat" dietary factor scores (odds ratio (OR) = 1.65, CI 0.95 - 2.89, P for trend 0.07) among the boys after adjusting for confounders. On the other hand, breast development was found to be significantly positively associated with shellfish and processed meat consumption among the girls (OR = 1.88, CI 1.08 - 3.26, P for trend 0.05). The authors conclude that dietary patterns are related to body composition and sexual maturation among the Korean children.
Method of cooking and risk of breast cancer in the Philippines
Cancer Causes and Control, April 2006
The Philippines has the highest reported age-adjusted rates of breast cancer of all Asian countries. The present case-control study was designed to examine the possible contribution of method of cooking to these remarkable rates. Women were selected from a population undergoing evaluation for breast problems at the Philippine General Hospital in Manila. The women completed a risk factor questionnaire before being assigned to case (n = 240) or control (n = 240) study groups. Detailed information was collected regarding the women's current method of cooking, as well as the usual method of cooking in the household of the women when they were 12 years of age. The cooking method of boiling food in coconut milk was found to be associated with a strongly increased risk of breast cancer (odds ratio (OR) = 2.2; 95% confidence interval (CI) 1.3-3.8). A positive association also was found between frying food and breast cancer risk, however this was true only of women whose household fried food at 12 years of age (OR = 1.89; 95% CI 1.1-3.4).
Preschool diet and adult risk of breast cancer
International Journal of Cancer, August 2005
The current case-control study was designed to investigate the associations between preschool diet and risk of breast cancer later in life. The study included 582 women with breast cancer and 1,569 controls without breast cancer who participated in the Nurses' Health Study or the Nurses' Health Study II. Information concerning the diet of the participating nurses at ages 3 to 5 years was collected from the mothers of the study participants using a 30-item food-frequency questionnaire. Woman who had frequently consumed French fries at preschool age were found to have an increased risk of breast cancer. The analysis included adjustments for adult life breast cancer risk factors. For one additional serving of French fries per week, the adjusted odds ratio (OR) for breast cancer was 1.27 (95% confidence interval (CI) = 1.12-1.44). Whole milk intake was associated with a slightly decreased risk of breast cancer (adjusted OR for every additional glass of milk per day = 0.90, 95% CI = 0.82-0.99). None of the individual nutrients studied was found to be related to the risk of breast cancer. Imperfect or biased recall of preschool diet by the mothers has to be considered as a possible explanation for the observed associations. The authors comment that further studies are needed to evaluate whether the association between preschool diet and breast cancer is reproducible in prospective data not subject to recall bias.
Breast Cancer and the Brain: a Neurodevelopmental Hypothesis to Explain the Opposing Effects of Caloric Deprivation during the Dutch Famine of 1944–1945 on Breast Cancer and Its Risk Factors
Journal of Nutrition, December 2004
The current study was designed to investigate the impact of famine on risk of breast cancer. The study included the women of the DOM (diagnostic onderzoek mammacarcinoom) cohorts exposed to the Dutch Famine of 1944–1945 (World War II). Opposing effects were found on breast cancer risk factors. The famine caused shortening of leg length, later menarche, and earlier menopause, all of which would normally be associated with decreased risk of breast cancer. However, the famine also resulted in increased urinary estrogens and plasma insulin-like growth factor (IGF)-1 and IGF binding protein-3, and the incidence of breast cancer itself was increased. Exposure to famine between the ages of two and 10 was found to represent an unexpected window of vulnerability to the breast cancer promoting effects of calorie deprivation. The effects of exposure to famine were seen most clearly in women who never gave birth. The authors theorize that these observations can be explained by a neurodevelopmental model incorporating set-point shifts in the diencephalons/hypothalamus, either directly or from rebound effects. Such a mechanism reflects ancient evolutionary adaptive systems found in both lower and higher organisms to cope with periods of stress and famine by adjusting reproductive functions, among others. These effects in famine-exposed women may later affect their unexposed children. The authors conclude that the observations presented may have implications for popular preventive strategies such as promoting moderation of calorie intake to curb cancer risks.
Growth Patterns and the Risk of Breast Cancer in Women
New England Journal of Medicine, October 2004
The current Danish population study was designed to investigate the associations between growth during childhood and breast cancer risk. Adult height and body-mass index (BMI) are known to influence breast cancer risk. However, it has not been determined whether these associations reflect growth in the womb or growth during childhood and adolescence. The study included 117,415 Danish women for whom birth weight, age at first period, and annual measurements of height and weight were obtained from school health records. The data was used to model individual growth curves. Data concerning any deaths in the study cohort, age at first childbirth, number of children, and breast cancer diagnosis was obtained through linkages to national registries. During 3,333,359 person-years of follow-up, 3,340 cases of breast cancer occurred. High birth weight, tall stature as of age 14, low BMI at age 14, and peak growth at an early age all were found to be independent risk factors for breast cancer. Height at age eight and the increase in height during puberty (eight to 14 years of age) were also positively associated with breast cancer. The attributable risk of birth weight was 7%; it was 15% for height at age 14; 15% for BMI at age 14; and 9% for age at peak growth. Adjusting for age at menarche, age at first childbirth, and parity had no significant effects. The authors conclude that birth weight and growth during childhood and adolescence influence the risk of breast cancer.
Physical activity at age 12 and adult breast cancer risk
Cancer Causes and Control, July 1999
The present case-control study was designed to examine whether the level of physical activity at age 12 influences subsequent breast cancer risk. The study used data on physical activity at age 12 that had been obtained as part of the Carolina Breast Cancer Study. Included were 527 white and 337 African-American breast cancer cases and 790 controls, frequency-matched on both age and race. Respondents were asked whether, and to what degree, they engaged the following activities at age 12: walking to school; biking to school; competitive training; and performing vigorous household chores. Women who reported participation in any of the four activities were found to have a modest reduction in breast cancer risk (odds ratio (OR): 0.8, 95% confidence interval (CI) = 0.6–1.0). Further analysis using an index measuring approximate number of activity episodes per week demonstrated a modest inverse relationships for nearly all levels of activity relative to no activity and risk of breast cancer in adulthood. Weighting the index by metabolic equivalent scores produced similar results. The authors conclude that adolescent physical activity may protect against adult breast cancer, even at moderate levels.
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