Regardless of whether or not you have a family history of breast cancer, your risk of developing the disease can be reduced considerably if you do exercise regularly, keep your body weight as near as possible to the ideal for your height and age, and consume less alcohol, say researchers from the University of Rochester Medical Center, New York, USA, who carried out a study involving over 85,000 postmenopausal women. The study has been published in the peer-reviewed medical journal Breast Cancer Research.

Lead author, Robert E. Gramling, M.D., D.Sc., said:

It's important to note that a family history of breast cancer can arise in part due to shared unhealthy behaviors that have been passed down for generations. Untangling the degree to which genes, environments, and behaviors contribute to the disease is difficult. But our study shows that engaging in a healthy lifestyle can help women, even when familial predisposition is involved.

Gramling and colleagues examined data from a study that started in 1993, the Women's Health Initiative Observational Study, which included females aged 50 to 79. Women with a personal history of breast cancer, or those with a close relative who developed breast cancer before the age of 45 years were not included - the investigators explain that these women were excluded because they wanted to determine whether diet, exercise and alcohol consumption had an impact on disease rates. Women who have a close relative with early-onset breast cancer (before age 45) have a more dominant genetic pattern.

They divided the women into those with a family history of breast cancer that developed after the age of 45 and those who did not. They then categorized the data further, based on how much the women reported adherence (compliance) to recommendations for exercise, good diet and body weight control.

The researchers' definition of Complete Adherence included:
  • At least 20 minutes of vigorous exercise for five or more days each week
  • A normal body weight
  • Consumption of 1 alcoholic drink per day or less
They also assessed invasive breast cancer cases that occurred during a mean follow-up of 5.4 years. They examined possible associations between invasive breast cancer cases and family history (later onset), and whether the women had veered from their healthy lifestyle recommendations.

The investigators found that:
  • Women with a family history - those with complete adherence to healthy lifestyle recommendations had an invasive breast cancer rate of 5.94 per 1,000 woman years
  • Women with a family history - those who did not adhere to any of the healthy lifestyle recommendations had an invasive breast cancer rate of 6.97% per 1,000 woman years
  • Women with no family history - those with complete adherence to healthy lifestyle recommendations had an invasive breast cancer rate of 3.51 per 1,000 woman years
  • Women with no family history - those who did not adhere to any of the healthy lifestyle recommendations had an invasive breast cancer rate of 4.67% per 1,000 woman years
Women who adhered completely to healthy lifestyle recommendations had the same comparable percentage lowered risk of breast cancer in both groups (with or without family history).

Breast cancer is the second most common cancer diagnosed in females, after non-melanoma skin cancer, the researchers inform. Approximately 15 in every 100 postmenopausal females have a genetic predisposition to breast cancer.

Doctors and scientists must understand what women can do to lower their risk, Gramlin said, given the heightened awareness of the disease and distress regarding risk, especially among those with a family history.

The authors concluded:

Participating in breast healthy behaviors was beneficial to postmenopausal women and the degree of this benefit was the same for women with and without an FHLBC (family history of later-onset breast cáncer).

"Family history of later-onset breast cancer, breast healthy behavior and invasive breast cancer among postmenopausal women: a cohort study"
Robert Gramling, Timothy L Lash, Kenneth J Rothman, Howard J Cabral, Rebecca Silliman, Mary Roberts, Marcia L Stefanick, Rosanne Harrigan, Monica L Bertoia and Charles B Eaton
Breast Cancer Research 2010, 12:R82doi:10.1186/bcr2727

Written by Christian Nordqvist