Inflammation increases breast cancer risk and reduces survival. Breast cancer growth, invasion and metastasis all are promoted by inflammation. Plasma C-reactive protein (CRP) is a measure of inflammation that can be measured with a routine blood test. Elevated CRP levels both before and after diagnosis have been shown to be associated with reduced overall and disease-free survival, especially among women with HER2/neu overexpressing (HER2+) disease.
Inflammation involves chronic activation of the immune system
Acute inflammation, which occurs after an injury, infection or exposure to certain irritants, results in temporary symptoms such as redness, pain, swelling and heat.
Systemic inflammation, which is the "inflammation" discussed in the remainder of this article, is a persistent state of inflammation that involves the chronic activation of the immune system. This immune system activation results in the release of pro-inflammatory cytokines (small signaling molecules used in intercellular communication) from immune system-related cells. CRP is produced in the liver in response to infection or injury.
Inflammation increases breast cancer risk
Laboratory studies have demonstrated that pro-inflammatory cytokines can facilitate tumor growth and metastasis by altering tumor cell biology and activating cells in the tumor microenvironment. In addition, inflammation has been shown to be important to the growth and activity of cancer stem cells. Studies of human populations have also found a link between inflammation and breast cancer. For example, one prospective UK study of 223,393 initially cancer-free people who had a blood sample taken between 2000 and 2008 compared the inflammation status of the 22,715 who subsequently developed cancer with that of those who did not. Cancer patients, including those with breast cancer, were found to have had higher CRP levels and other markers of inflammation at baseline.
Periodontal disease, which qualifies as a chronic inflammatory disorder, has also been shown to be associated with increased risk of postmenopausal breast cancer.
Inflammation promotes breast cancer recurrence
Growing evidence links inflammation to breast cancer progression. One Danish prospective study was designed to investigate whether circulating CRP levels are associated with breast cancer prognosis. The study included 2,910 women whose CRP levels were measured at the time of diagnosis. A total of 383 women died during up to seven years of follow-up, of whom 225 died from breast cancer, and another 118 women had a recurrence (without dying during the study period). Elevated CRP levels at the time of diagnosis were found to be associated with reduced overall survival and with increased risk of breast cancer-specific death. Five-year breast cancer-free survival was 87% among women with low CRP levels compared to 74% for those with high CRP. Among women with HER2+ tumors, those with the highest compared to the lowest third of CRP levels were 8.6 times more likely to die from any cause.
Another study evaluated the relationship between circulating markers of inflammation and breast cancer survival in 734 disease-free breast cancer survivors in the Health, Eating, Activity, and Lifestyle (HEAL) Study. Circulating CRP protein and serum amyloid A (SAA, another marker of inflammation) were determined approximately 31 months after breast cancer diagnosis. Elevated CRP and SAA were both found to be associated with reduced survival.
Anti-inflammation lifestyle and diet
Inflammation is influenced by both lifestyle and nutrition. Regular exercise can reduce inflammation whereas obesity increases it, as does metabolic syndrome (which is characterized by abdominal obesity, high blood sugar levels, impaired glucose tolerance, dyslipidemia, and hypertension). Cigarette smoking also increases inflammation. High consumption of dietary fiber has been shown to be associated with low levels of inflammation in breast cancer survivors.
Numerous studies have also documented the influence of individual foods and food groups on inflammation. Most deeply colored fruits and vegetables have anti-inflammatory properties. Below are anti-inflammatory foods that have also been associated with reduced risk of breast cancer:
Foods that increase inflammation
Inflammation has been found to increase as a result of consuming the following foods:
- Bacon and other processed meats
- Cheese, full fat
- High fructose corn syrup
- Lard (shortening)
- Milk, full fat, and cream
- Omega-6 fats such as corn oil, soybean oil, sunflower oil and safflower oil
- Partially hydrogenated oil
- Red meat such as beef, pork and lamb
- White bread and other highly refined wheat flour products
- Well done or fried meat or fish of any type
Please see our article on how to optimize your breast cancer diet for information on what to eat during all stages of treatment and recovery. Below are links to recent studies on inflammation and breast cancer. For a more complete list of studies, please click on the tag inflammation.