Roisin Gowan is a senior oncology dietitian in the Nutrition and Dietetics Department at St Vincent's Private Hospital. She is a member of the Irish Nutrition and Dietetics Institute and currently works on the committee for the Oncology Special Interest Group. She also works with the Irish Cancer Society. Here she gives us an overview of the importance of diet after breast cancer.
With 2,600 new cases diagnosed every year, breast cancer is the most common cancer to affect women in Ireland. Incidences of breast cancer can occur before and after menopause and even (in smaller cases) among men. If you have been affected by this illness, you may be interested to know that diet and lifestyle choices may make a difference for breast cancer survival, as well as make you feel better. Studies on diet and lifestyle for breast cancer survivors were reviewed by a panel of experts from the World Cancer Research Fund (WCRF).
At present, there are extensive published studies that have investigated the relationship between diet after breast cancer diagnosis and survival. Although the results are promising, it is too early to tell if these results will be confirmed until after more research is done. One such study has examined dietary habits among breast cancer (survivors) in The Nurses Health Study that has followed participants over 20 years. The study showed that women who didn't have disease progression and ate higher amounts of poultry, omega 3 fatty acids from fish had statistically lower risks of death than those from the same group who ate less of these food and nutrients. In addition, women from the same group who ate more hydrogenated fats (trans fats) from processed baked goods were at significantly higher risk.
The study also looked at women whose cancer had metastasized. Those that had higher consumptions of dairy products, and high levels of calcium in their blood were at lower risk. For both groups of cancer survivors, there was no association between fruit, vegetables, grains or vitamin supplements and a worsening of conditions.
Whether diet can overall be a single agent in significantly reducing the risk of recurrence of breast cancer is yet to be confirmed, but if these results prove to be correct, they could be quite important. Diet after diagnosis is something that breast cancer survivors have some control over.
Although obesity has been identified as convincing risk for breast cancer, it is inconclusive if weight gain after diagnosis affects survival from breast cancer. Weight gain is common with breast cancer patients during treatment (e.g. hormonal chemotherapy such as tamoxifen). There is convincing evidence that obesity and being overweight does increase risk of primary breast cancer. Furthermore, weight gain can be stressful and affect the overall quality of life of breast cancer survivors.
Some studies have reported that soy foods can act like oestrogen and cause cell profileration in the breast. Phytoestrogens in soy have also been reported to interfere with the effects of tamoxifen in breast cancer cells. The WCRF has stated that eating soy foods in moderation (3-4 servings) does not show a negative effect on breast cancer during treatment, however soy supplements may best be avoided.
There is limited evidence on specific diet and lifestyle changes that women can make to improve their chances of preventing a recurrence of breast cancer, there are small positive changes that overall can help improve quality of life. ?The Irish Nutrition and Dietetics Institute (INDI) and the Irish Cancer Society (ICS) have published dietary advice for the secondary prevention of cancer. These recommendations are based on the research from The World Cancer Research Fund (WCRF) in 2007:
- Be as lean as possible within the normal range of body weight
- Be physically active as part of everyday life
- Limit the amount of high calorie food and drinks in your daily diet
- Limit red meat and avoid processed meats
- Eat foods mostly of plant origin
- Limit high salt, preserved and processed foods
- Limit your alcohol intake
- Do not smoke or chew tobacco
Having breast cancer can be a life-altering experience. After initial treatment of surgery, radiotherapy or/and chemotherapy has completed you may still feel the effects of your diagnosis and treatment for some time. Of course, each phase of treatment and the way you cope is unique. It is rare to feel the same as before diagnosis but breast cancer survivors can look forward to being healthy again.
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