Women with family history of breast cancer can cut their risk of developing it if they maintain a healthy lifestyle, according to an extensive study published in JAMA oncology.
The study found that if women keep a healthy weight, drink little alcohol, does not smoke, and does not use hormone therapy after menopause, they will have less risk of cancer.
The results were even more significant for women with relatively higher genetic risk of developing breast cancer, the research said.
If the high-risk women kept a healthy lifestyle, their chances of getting the disease was as low as an average white woman in the US with no genetic predisposition to it. For a 30-year-old white woman, the chances of developing breast cancer is about 11 percent before the age of 80.
"Those genetic risks are not set in stone," said Nilanjan Chatterjee, senior researcher and professor at Johns Hopkins Bloomberg School of Public Health in Baltimore.
This study did not involve women with BRCA 1 and BRCA 2 gene mutations which increase the risk of breast cancer by as much as five times. Generally BRCA genetic testing is recommended by the doctors in case suspicious signs appear in mammogram.
This research left out BRCA mutations, but scientists say that there are at least 92 genetic variations that are loosely associated with increased breast cancer risk, which are more common than BRCA variants. The effects of those common mutations on breast cancer risk are accumulated and needed to be studied, said Chatterjee.
Also, the causes and triggers of breast cancer from the 92 other mutations and lifestyle factors were not incorporated into the previous models, and their impact on increasing the disease risk remained vaguely accounted for.
The research team examined data from eight long-term studies conducted on more than 40,000 mostly white women, and controlled for factors such as family history of breast cancer, age of menstruation, and pregnancies. The scientists processed the findings to predict the chances of developing breast cancer in the presence and absence of these 92 genetic mutations, and how much lifestyle factors influenced cancer risk.
The study concluded that about 28.9 percent of all breast cancers can be prevented if women changed their lifestyles to rein in the risk factors that are under their control, namely to maintain a healthy weight, limit consumption of alcohol, quit smoking, and not use (or reduce the use of) hormone therapy after menopause.
"Such a model could also better inform therapeutic decisions regarding menopausal hormone replacement, particularly among those with greater nonmodifiable (including genetic) risk for breast cancer," the study editorial said.
The research was not done of women of non-white racial background, but scientists say that the same findings may be applicable to them also.
"Adoption of a healthy lifestyle is likely to be universally advocated by clinicians among all patients. Knowledge of personal risks could certainly alter the beneficial uptake of that advice," authors noted.