Many breast cancer risk factors are well researched and late start of menopause, early 1st menstrual period, and a family breast cancer history are linked to an increased risk of breast cancer.
There are non-modifiable breast cancer risk factors like age at first and last menstrual period or family history. Researchers wanted to determine the percentage of cases where modifiable lifestyle risk factors were responsible for cases of breast cancer.
The focus of the study was on aspects like physical activity, hormone replacement therapy, consumption of alcohol and being overweight. Previous research has identified all these lifestyle factors as possible breast cancer risk factors.
6,386 control subjects and 3,074 individuals who had been diagnosed with breast cancer after the start of menopause were studied. Based on this data, the percentage of cancer cases that’s attributable to a specific risk factor or a specific combination of several risk factors was determined.
Of the modifiable lifestyle factors which increase a woman’s breast cancer risk, it’s primarily a lack of physical activity and hormone replacement therapy. Being overweight and alcohol consumption were found to have less influence on risk of breast cancer. Hormone replacement therapy is responsible for 19.4% cases of invasive postmenopausal breast cancer, and a lack of physical activity is responsible for 12.8% cases. 29.8% cases of breast cancer are due to the two factors together. An even higher value of 37.9% was determined for the group of individuals who had hormone receptor-positive breast tumors.
Of the non-modifiable risk factors like age at first and last menstrual period or family history are responsible for 37.2% of all malignant postmenopausal cases of breast cancer. The 2 modifiable factors are responsible for a similar number of cases of postmenopausal breast cancer as the non-modifiable factors. Nearly 30% cases of breast cancer after menopause could be prevented if women exercised more and refrained from hormone replacement therapy.