Lifestyle, nutrition and breast cancer: facts and presumptions for consideration

http://www.eurekalert.org/pub_releases/2015-07/e-rtc072315.php

http://ecancer.org/journal/9/full/557-lifestyle-nutrition-and-breast-cancer-facts-and-presumptions-for-consideration.php

Abstract

Breast cancer is the most common cancer in women worldwide, and the high incidence of this cancer coupled with improvements in initial treatments has led to an ever-increasing number of breast cancer survivors. Among the prospective epidemiological studies on diet and breast cancer incidence and recurrence, to date, there is no association that is strong, reproducible and statistically significant, with the exception of alcohol intake, overweight, and weight gain. Nevertheless, many beliefs about food and breast cancer persist in the absence of supporting scientific evidence.

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Evidence of body weight and breast cancer

Increased body mass index (BMI) is associated with a significant increase in the risk of breast cancer, although with some differences in age and menopausal status. The association between being overweight (defined as a BMI of 25 to 29.9 kg/m2) or obese (BMI of 30 kg/m2 or greater) and breast cancer incidence has been found in many studies.

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Evidence of alcohol consumption and breast cancer

A number of epidemiological studies have provided convincing evidence that alcohol consumption is an important risk factor for the incidence and mortality of breast cancer

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the Million Women Study showed that the relative risk of developing breast cancer increases by 7.1% for each 10 g/day of alcohol [24]. The relationship between breast cancer and alcohol was confirmed by the reanalysis of 53 epidemiological studies performed by Hamajima et al

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Evidence of lifestyle and breast cancer

Many behavioural choices during life are likely to enhance the risk of developing breast cancer. There is strong scientific evidence that not having children or having them after 30 years, avoiding breast feeding, prolonged use of the contraceptive pill, and having hormone replacement therapy after menopause all increase the incidence of mammary tumours. Other aspects of lifestyle have also been investigated. Among these, physical activity is associated with lower risk of invasive breast cancer

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These results were confirmed in the recent European Prospective Investigation into Cancer and Nutrition (EPIC) study which demonstrated that moderate and high physical activity are associated with modest reduction in breast cancer risk [30]. According to these results, the Breast Cancer Report of WCRF and American Institute for Cancer Research (AICR) states that the evidence for reduction in cancer incidence in physically active women is probable

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Pierce et al have also shown that patients that consume a healthy diet and are physically active may increase their years of survival after diagnosis of breast cancer and those who reported eating a minimum of 5 vegetable and fruit servings daily and performing weekly physical activity equivalent to 30 minutes of walking at a moderate pace for 6 days a week had a higher 10-year survival rate than those who did not adhere to these lifestyle practices

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Presumptions of a plant-based diet and the risk of breast cancer

Substances contained in vegetable foods are studied as possible ways to prevent cancer, since a number of studies have suggested that people who eat more fruit and vegetables are less likely develop cancer.

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However, a more recent meta-analysis, which reviewed fifteen prospective studies, revealed a lower risk of breast cancer for the highest versus the lowest intake of fruit and vegetables combined, but when fruit and vegetable were separated, data were significant only for fruit consumption

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the Pooling Project of Prospective Studies of Diet and Cancer analysed 20 studies and reported that only for oestrogen receptor-negative (ER−) breast cancer, there was a statistically significant inverse trend for total fruit and vegetable consumption; in this case, when intakes of fruit and vegetables were examined separately, statistically inverse associations were observed only for vegetable intake
[i.e., there was less cancer for those who ate more vegetables.]

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