Breast cancer is a complex disease. Existing research tells us that obesity is clearly associated with an increased risk of breast cancer in general and, more specifically, in postmenopausal women. So, what is it about fat and fat cells that contribute to the growth of cancer? And, importantly, is this changeable? Could diet, exercise and supplements improve the health outcomes for obese, postmenopausal breast cancer patients?
Research led by Faculty of Health Professor Michael Connor asked these vital questions. He sought to look further into the connection between fat and cancer, and determine if obesity alters the micro-environment surrounding breast cancer cells. The research team specifically wanted to know if the supplement resveratrol, a natural antioxidant found in red grapes and cocoa, could counteract any obesity-dependent effects on the growth of a breast cancer tumour.
They were on the right track. Their findings, published in PLoS ONE (2017), suggest that the supplement resveratrol could improve breast cancer treatment in obese patients in a fashion similar to diet and exercise interventions.
Connor explained the significance of this result: “Targeting the stable components of a cancer patient’s physiology (e.g. the fat cells) as part of cancer therapy provides a strategy that will respond reliably and predictably over time, among patients and across cancer types.”
This work was funded by the Natural Sciences and Engineering Research Council of Canada and the Canada Foundation for Innovation.
Breast cancer rates and risk factors
Breast cancer will affect one in eight Canadian women in their lifetime, according to the Canadian Cancer Society. The society estimated that 26,300 women and 230 men in Canada would be diagnosed with breast cancer and almost 5,000 women and 43 men would die from the disease in 2017.
Some risk factors for breast cancer are impossible to control. The BRACA1 and BRACA2 genes, for example, may contain a mutation that increases the risk of developing breast cancer. Other risk factors, such as obesity, the level of physical exercise and alcohol consumption, can be modified.
Post-menopause and obesity pose added risk
The combination of age – or rather, being postmenopausal – and obesity poses an added risk. Many studies have shown that, in postmenopausal women, a higher body mass index (BMI) is associated with a modest increase in risk of breast cancer. Obese postmenopausal women are 50 per cent more likely to develop breast cancer and respond poorer to therapy compared to their lean counterparts, Connor noted.
Supplement alters breast cancer proliferation
The researchers discovered that “obese” fat cells created a growth environment that induced breast cancer cell cycle entry [proliferation], while “lean” fat cells inhibited cell growth in these same cells.
After this was established, the team then examined the cases where the supplement was added. “We wanted to establish that the supplementation could alter the effects of obese tissue hormone profile, which would elicit altered cell cycle effects in proliferating MCF7 breast cancer cells,” Connor explained.
They discovered that the supplement resveratrol overcame the effects of obesity by altering the cancer cell growth environment.
Findings could have wider application
These findings could be applicable to different cancers, as the link between obesity and cancer is found in other cancer types, such as liver, kidney and endometrial, as illustrated in the diagram above.
Connor presses for more research in this area.
By Megan Mueller, manager, research communications, Office of the Vice-President Research and Innovation, York University, firstname.lastname@example.org