Of 199 women asked to eat lots of fruit, vegetables, fish, and olive oil in an Italian trial, none relapsed within three years
According to a study presented at a major international cancer conference, a Mediterranean diet rich in fruits, vegetables, fish and olive oil may help prevent breast cancer from recurring.
Lifestyle - whether people are physically active or not - and obesity are known risk factors for breast cancer, but there is increasing interest in whether certain eating habits play a role in its occurrence and recurrence.
The study, presented at the American Society of Clinical Oncology (ASCO) meeting in Chicago, is a study in Italy that compared the outcomes of 307 women who had been treated for early-stage breast cancer. A group of 199 women was asked to eat a Mediterranean diet consisting of four servings of vegetables, three pieces of fruit, and one serving of grains per day, along with four or more servings of fish per week, some red and processed meat, and plenty of olive oil. They were allowed up to one alcoholic drink per day.
Cancer researchers at Piacenza Hospital, Italy, found that 11 women in the group eating a normal diet had breast cancer recurrence after three years, while none of the women eating a Mediterranean diet were affected.
Experts say the study is small and has limitations but raises questions of great interest. “The whole issue of lifestyle interventions for breast cancer survivors is very important. There is a lot of research going on as to what we should recommend," said Dr. Erica Mayer, ASCO Breast Cancer Expert, Assistant Professor at Harvard Medical School, and Director of Clinical Research at the Dana-Farber Cancer Institute in the US.
However, the results of previous studies are contradictory. "It's not clear if there's a specific diet or foods that one should or shouldn't eat to prevent a recurrence," she said. Physical activity, on the other hand, is very beneficial and helps prevent the occurrence and recurrence of cancer.
The signals so far from research into women's eating habits and breast cancer "are more likely to reflect weight loss than diet," she said. This particular study had problems with the methodology. “They don't say if this is randomized. People were asked to participate in one diet or another. There's no information about activity level or weight change that you need to know for most lifestyle research," she said.
Cancer charities said more research was needed. "The preliminary results of this small study suggest that a Mediterranean diet may reduce the risk of breast cancer coming back, but we would need much more than three years of follow-up to confirm the effect of the diet," said Prof. Arnie Purushotham, Sr from Cancer Research UK Clinical Advisor. "Further studies involving more women are needed to understand more about the impact diet can have on breast cancer survival and the biological reasons for this."
Lady Delyth Morgan, Executive Director of Breast Cancer Now, said: "This study adds to an increasingly interesting discussion of how lifestyle factors might influence breast cancer recurrence. However, we still don't have enough evidence to show a strong link between any particular type of food and breast cancer recurrence.
“We need to see results from longer-term studies before we can provide specific nutritional advice to breast cancer patients. We now know that a varied, balanced diet can be beneficial for overall health and well-being, and physical activity can be beneficial for breast cancer patients.”