Young women who have survived breast cancer may be in a position to reduce their odds of a recurrence through nutrition and lifestyle strategies. This also includes those who have been diagnosed with DCIS or LCIS, which can progress to invasive breast cancer. We define "young women" as those under 45 years of age at diagnosis. These are women in their twenties, thirties, and early forties who had no overt signs of perimenopause when diagnosed (although the process may in fact have been underway). Breast cancer in young women is not as rare as it once was. Approximately 7% of U.S. breast cancers are diagnosed before age 40, 2.4% are diagnosed before 35, and 1% are diagnosed before 30. Some of these women have BRCA1 or BRCA2 mutations, but most do not.

Generally speaking, breast cancer in young women is the result of a combination of genetic, environmental and lifestyle factors. Breast cancer in young women tends to have aggressive characteristics even if standard prognostic characteristics do not appear to be particularly unfavorable. Preventing recurrence involves supporting the body's defenses, avoiding sources of estrogen and environmental carcinogens, and changing diet and lifestyle to provide the best possible support for continued health and well being. Please also see our article on the latest research concerning breast cancer in very young women.

Young women have not been exposed to endogenous estrogen long enough to develop breast cancer

Generally speaking, the most common forms of breast cancer in postmenopausal women are thought to be the result of exposure to endogenous estrogen (i.e., estrogen produced in the body by the ovaries and other tissues), which promotes breast cancer growth. This explains why breast cancer risk increases with age (i.e., with more years of exposure to estrogen) and is lower for women who have had children, start their periods after age 12, or experience an early menopause (all of which reduce the length of exposure to relatively high levels of estrogen). Under this theory, young women have not experienced a long enough period of endogenous estrogen exposure to develop hormone receptor positive breast cancer. This means that there are other important contributing factors for these women. These variables are thought to include a genetic susceptibility to breast cancer, increased exposure to various growth hormones, exposure to estrogens and other carcinogens from environmental, food and personal care products, and radiation to the chest area. Some of these factors also contribute to the risk of triple negative (ER-/PR-/HER2-) breast cancer, which is not hormone receptor positive.

Although BRCA1 and BRCA2 mutations are the most well known, there are other genetic mutations and variants that make breast cancer more likely to develop or progress for which tests are not generally available. Some types of breast cancer, for example lobular breast cancer, are more likely to have a familial component, although the mechanism is not well understood. Sources of exposure to growth hormones, additional estrogen, and radiation to the chest area are discussed after the sections directly below, which summarize our recommendations with respect to food for young women with breast cancer.

Foods that reduce the risk of breast cancer recurrence in young women

Adequate calcium and vitamin D levels both are associated with reduced risk of premenopausal breast cancer. However, we do not recommend high-fat dairy products as sources of these nutrients. Coffee also appears to be protective against premenopausal cancer, except for women with fibrocystic breast disease or other benign breast disease. In addition to emphasizing food sources of calcium and vitamin D, we encourage young women with breast cancer to eat a wide variety of the foods on our recommended list and limit or avoid those on our avoid list. Women taking tamoxifen or Herceptin should also review the relevant web pages.

Food sources of calcium

The following are good sources of calcium while also preventing or at least not promoting breast cancer:

Broccoli
Brussels sprouts
Cheese, lowfat
Collard greens
Garlic
Green beans
Kale

Kefir
Mustard greens
Oats
Sardines
Seaweed
Tofu
Yogurt, lowfat

Sources of vitamin D

In addition to exposing the skin to sunlight, the following foods and supplements are sources of vitamin D while also having been found to protect against breast cancer:

Arctic char
Herring
Lake trout
Mackerel
Salmon, wild
Sardines
Vitamin D3 supplements

Foods and supplements that should not be used by young breast cancer survivors

The following foods and supplements may increase the risk of recurrence and should be limited or avoided by young breast cancer survivors:

Alcohol
Bacon
Beef
Butter
Cheese
Iron supplements (unless medically necessary)
Lamb

Multivitamins or other antioxidant supplements
Lard
Liver, any type
Milk, whole
Pork
Processed meats
Shellfish

Breast cancer survivors should also limit the other foods on the foods to avoid list.

Foods with a high glycemic index

The following foods (as well as other foods with a high glycemic index) can increase the risk of breast cancer recurrence for young women:

Bread, white
Cookies, candy and cake
Sweetened breakfast cereals
Granola
Plantains, fried ripe
Potatoes, white
Rice, white
Sugar
Sweet desserts

Calcium

High dietary intake of calcium has been found to be associated with lower risk of breast cancer, particularly among premenopausal women. This is in part because diets with higher vitamin D and calcium are associated with lower mammographic breast density in premenopausal women. Women with very dense breasts have a four- to six-fold higher risk for breast cancer compared to women with little or no dense breast tissue. However, high dose supplementation with calcium is not advisable.

Vitamin D

Low levels of vitamin D are associated with increased risk of breast cancer. Vitamin D deficiency is common among young breast cancer patients, even those taking vitamin D supplements. It appears to be very difficult to obtain enough vitamin D through exposure to sunlight and by consuming vitamin D-rich foods. We suggest that breast cancer patients and those at high risk have their vitamin D levels evaluated (through a simple blood test) and increased through vitamin D supplementation, if indicated.

Red meat

Exposure to relatively high levels of endogenous growth hormones has been shown to be associated with higher risk of breast cancer. This is the explanation given for the fact that tall women are more likely to develop breast cancer than short women. Red meat is an important dietary source of growth hormones, which are added to the feed of the animals to promote their growth. Most population studies that have examined the relationship have found that consumption of red meat (especially beef) is associated with higher risk of premenopausal breast cancer. The use of various growth promoters in raising cattle has been proposed as one explanation for this association.

Red meat is also an abundant dietary source of iron, which is also suspected to promote breast cancer. However, note that iron deficiency anemia is also associated with breast cancer risk in premenopausal women. Therefore, based on the available evidence to date, adequate but not high or dangerously low levels of iron appear to be best.

Whole milk, butter and cheese

While some studies indicate that childhood intake of milk may be protective against breast cancer (due to its calcium and vitamin D content, among other factors), exposure to milk after a diagnosis of breast cancer has been shown to promote malignant growth. The fact that much of the milk we drink today is produced from pregnant cows (in which estrogen and progesterone levels are markedly elevated) may contribute to this increased risk. Cheese incorporates saturated fat, recombinant bovine growth hormone, and various environmental contaminants. Recombinant bovine growth hormone (a synthetic version of the bovine growth hormone that occurs naturally in cows) is administered to cows to increase milk production and has been suggested to increase breast cancer risk. Recombinant bovine growth hormone itself is thought to be biologically inactive in humans. However, it causes the cow liver to produce insulin-like growth factor 1 (IGF-1), which enters the blood and milk as well. The bovine form of IGF-1 is identical to the human form. IGF-1 is required for mammary development at puberty and has been implicated in increased risk of breast cancer. Several studies have found a modest positive association between circulating IGF-I levels and breast cancer risk among premenopausal women.

Personal care products

Some personal care products can be important sources of estrogen and ongoing use of them may present a very serious risk for breast cancer survivors. Such products are intended for external use, but are absorbed through the skin or scalp. These include shampoo and other hair products, face and body creams, body oils, and other products containing lavender, tea tree oil, or parabens. Sunscreens and other UVF-rated personal care products containing benzophenones, octylmethoxycinnamate, 4-methylbenzilidenecamphor or homosalate should also be avoided. In addition, estrogen face creams, and creams designed to reduce the signs of "hormonal" aging should be avoided (these typically contain estrogenic ingredients such as soy, red clover, wild yam or wild Mexican yam). There are also a number of hair care and other products marketed to African-American women that contain "placenta" or placental extract, or "hormone" or hormones that should be avoided.

There is evidence that using hair dye can increase breast cancer risk. Long-term use of antiperspirants or deodorants containing aluminum salts such as aluminum chlorohydrate could also increase the risk of breast cancer, especially sprays or solids and if applied after shaving or when the armpits are irritated.

Birth control and fertility

Birth control pills and other hormonal contraception use started at a young age increases the subsequent risk of breast cancer. For example, one study found that oral contraceptive use was associated with an almost three-fold increase in the risk of triple negative (ER-/PR-/HER2-) breast cancer among women 45 to 64 years of age who had begun to use oral contraceptives before age 18. While the use of contraceptive injections and implants have not been widely studied, implants appear to have the greatest potential to increase breast cancer risk, whereas injections appear comparable to birth control pills. Use of birth control pills after a diagnosis of breast cancer appears to be unwise.

Some studies have reported that fertility treatments (assisted reproductive technology) could increase the risk of breast cancer. However, one 2015 study reported that while in vitro fertilization (IVF) was associated with substantially increased risks of ovarian and endometrial cancers, it did not appear to increase breast cancer risk.

Hormone replacement therapy (HRT)

Use of hormone replacement therapy (HRT) during or after menopause is also not advisable for survivors. Some of the benefits once thought to be associated with combined HRT, such as reductions in heart disease and dementia, have turned out to be non-existent. In addition, combined HRT (estrogen plus progestin) has been found to be associated with increased risk of breast cancer, especially estrogen receptor positive (ER+/PR+ and ER+/PR-) and lobular breast cancer.

Strong evidence that combined HRT use could increase the risk of breast cancer was first published in 2002, when it was reported that participants in the Women’s Health Initiative trial who were taking combined HRT had higher rates of breast cancer than those who did not. Subsequent studies have confirmed the finding that combined HRT promotes breast cancer. The picture is less clear for estrogen-only HRT; some but not all studies have concluded that estrogen-only HRT is also associated with increased breast cancer risk, although lower than that of combined HRT. Bioidentical hormone formulations are not necessarily safer than conventional HRT.

Breast implants and breast enlargement products

Cosmetic breast implants do not appear to increase the risk of breast cancer. However, breast cancer patients with cosmetic breast implants tend to be diagnosed at a later stage and have poorer survival than those without implants. Preliminary evidence suggests that silicone breast implants may cause anaplastic large cell lymphoma, a rare type of non-Hodgkin lymphoma. On the other hand, breast reduction surgery has been shown to reduce the risk of breast cancer by reducing the volume of breast tissue that could develop cancer.

Pills and creams designed to increase breast size should be avoided. These products typically contain a variety of ingredients, for example wild yam, hops, saw palmetto, dong quai, chaste-tree berry, fennel, kava, black cohosh, and fenugreek. To the extent that some breast enlargement products work temporarily, it is because some of the component herbs are estrogenic.

Coffee and tea

Coffee consumption is associated with reduced risk premenopausal breast cancer. Several studies have also found that heavy consumption of coffee is associated with significantly reduced breast cancer risk among women with BRCA1 and BRCA2 gene mutations. However, women with benign breast disease (e.g., fibrocystic breast disease) should not drink coffee.

Alcohol

One study found that alcohol consumption promoted premenopausal tumor development in a mouse model of HER2 overexpressing breast cancer. While the evidence is inconsistent as to whether young women who consume alcohol before a diagnosis of breast cancer have improved survival, it is clear that consuming alcohol (including wine) after diagnosis is associated with decreased survival.

Weight and glycemic index/load

Obesity is associated with increased risk for postmenopausal, but not premenopausal breast cancer. In fact, being somewhat overweight appears to protect young women from breast cancer. However, breast cancer survival has been found to be lower among young women with general or abdominal obesity. In addition, weight gain during treatment has been found to be associated with less favorable prognosis. Human growth hormone (HGH) should not be used for weight loss or any other purpose that is not medically necessary.

Regular exercise has been shown to reduce the risk of breast cancer in premenopausal women who are overweight. In addition, a diet with a high glycemic load may be associated with breast cancer risk in young women, especially those who are not overweight. On the other hand, underweight breast cancer survivors have been shown to have a higher risk of recurrence. Therefore, young breast cancer survivors who are overweight or underweight at diagnosis might reduce their risk of recurrence by achieving normal weight. In addition, all young breast cancer survivors should probably limit consumption of high glycemic index foods such as potatoes, white bread, cakes and sugar, as well as refraining from eating meals with a high overall glycemic load, regardless of their body mass index.

Cigarette smoking

Cigarette smoke contains numerous carcinogens that can damage DNA, and cigarette smoking has been found to be associated with increased risk of breast cancer in young women. Smoking-related DNA damage might extend to breast cancer-related genes. It makes sense for young breast cancer survivors not to smoke.

Radiation exposure

Women who were treated with chest radiation, or who were subjected to repeated diagnostic x-rays (e.g., for scoliosis) as children or during puberty have been found to have higher subsequent risk of breast cancer, including at a young age. Such women are recommended to have an annual screening mammogram starting at age 25 years or eight years after radiation, whichever occurs last. They should also attempt to minimize their exposure to additional radiation, including from CT scans as well as x-rays, as well as avoiding occupations such as pilot or flight attendant that involve heightened exposure to ionizing radiation.

Chemicals in plastics

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, 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. Breast cancer survivors 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.

Exposure to agricultural and industrial carcinogens

Women living on or near farms, or who are themselves farm workers, are vulnerable to the breast cancer-promoting effects of certain pesticides, hormones and other chemicals used in the production of food and other products. Breast cancer survivors should keep out of harm's way when such chemicals are applied and should not pick or process crops to which pesticides have been applied. This includes greenhouse crops. Not all crops are grown with the assistance of carcinogens, so women 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.

Breast cancer survivors would also be better off not working in or near auto repair shops, gas stations, printers, chemical plants, recycling or waste disposal facilities, jewelry makers or other operations involving soldering, and military bases with any such facilities.

Exposure to light at night

Sleeping in the presence of light (including night lights, light entering through windows, and light from television screens) and night shift work both have been found to increase breast cancer risk, apparently by inhibiting melatonin production.

Additional comments

Unlike most other cancers, breast cancer cannot be considered cured after five years without a recurrence. Although it is not common, breast cancer can metastasize 25 years after initial diagnosis and treatment. For young women with breast cancer, this means an extended period of vigilance and a long-term commitment to a customized breast cancer diet and life-style.

Below are links to recent studies on breast cancer in young women. For a more complete list of studies, please click on the tag young age.