SAN ANTONIO – Metabolic syndrome is a potent independent risk factor for breast cancer recurrence in patients who are otherwise at low risk, based on a widely used 21-gene recurrence score assay.
This novel finding in an observational study underscores how much is riding on the outcome of ongoing randomized clinical trials of metformin and aggressive lifestyle modification through weight loss and exercise for secondary prevention of breast cancer, Dr. Arti Lakhani reported at the annual San Antonio Breast Cancer Symposium. If those interventions ultimately prove effective in reducing the risk of breast cancer recurrence, their success may in part be attributed to their ability to reduce the prevalence of metabolic syndrome.
Dr. Lakhani, of Loyola University Medical Center in Maywood, Ill., presented a single-center study of 322 consecutive women newly diagnosed in 2006-2011 with estrogen receptor–positive/lymph node–negative early-stage breast cancer. All patients’ tumors were analyzed using the Oncotype DX assay, which is used to estimate the risk of recurrence based on the expression of 21 genes.
Of the 322 patients, 89 (27%) met World Health Organization criteria for metabolic syndrome. So far, breast cancer has recurred in 21 patients; 13 (62%) of them had metabolic syndrome.
In a multivariate analysis, patients with a low-risk Oncotype DX score of 0-17 had a 24-fold greater risk of recurrence if they had metabolic syndrome. In intermediate-risk patients having a score of 18-30, metabolic syndrome was independently associated with a fourfold increased risk of recurrence. In patients with higher scores, metabolic syndrome didn’t significantly add to the predictive value of the test result, said Dr. Lakhani.
The impact of metabolic syndrome on recurrence score was independent of tumor grade, size, HER2/neu status, and Ki67, as well as patient age and menopausal status.
During a discussion after the presentation, one physician remarked that if the findings are confirmed in an independent data set with larger numbers, he would feel compelled to recommend chemotherapy in all patients with hormone receptor–positive/lymph node–negative breast cancer and metabolic syndrome.
Another oncologist observed that breast cancer treatment seems to inherently promote metabolic syndrome, with its pear-shaped body habitus. "If my breast cancer patients don’t have metabolic syndrome before they start treatment, they often seem to afterwards."
Dr. Lakhani reported having no financial conflicts.