Women with ovarian cancer who are also receiving metformin for diabetes have significantly improved survival rates compared with their counterparts without diabetes, study findings show.
Furthermore, the researchers found improved survival rates among ovarian cancer patients on metformin compared with their peers with diabetes who received other forms of therapy.
While a causative link cannot be established by these findings, "metformin nevertheless is a strong contender for further clinical studies in ovarian cancer," write Viji Shridhar (Mayo Clinic, Rochester, Minnesota, USA) and colleagues in Cancer.
The team identified 72 women with ovarian cancer from their institution's 1995 to 2010 data, all of whom received metformin for a mean 2.3 years. These women (cases) were compared with 143 randomly selected women with ovarian cancer who did not receive metformin (controls).
The entire cohort had a mean disease-specific survival rate of 5.5 years, with higher 5-year survival rates for cases than controls, at 73% versus 44%.
Indeed, after adjusting data for age, year of cancer diagnosis, body mass index, disease stage, histology, and whether patients had received chemotherapy, only disease grade (3 and 4 vs 1 and 2, using International Federation of Gynecology and Obstetrics criteria) and receiving metformin predicted survival independently, with hazard ratios (HRs) of 8.6 and 2.7, respectively.
The association between receipt of metformin and prolonged survival also emerged in a subanalysis of 61 women with epithelial ovarian cancer who received the drug, matched with 178 nonmetformin-treated controls, giving a hazard ratio of 2.2.
The team then conducted a comparison using data for 103 women who had both diabetes and epithelial ovarian cancer, but who were treated with insulin or other treatments other than metformin, and the 61 women with epithelial disease who did receive metformin.
Receipt of metformin was associated with a significantly higher 5-year disease-specific survival, at 67%, compared with receipt of insulin at 43%, and other antidiabetic medications at 34%, report Shridhar et al.
"This study opens the door for using metformin in large-scale randomized trials in ovarian cancer which can ultimately lead to metformin being one option for treatment of patients with the disease," said co-author Sanjeev Kumar, also from the Mayo Clinic, Rochester, in a press release.
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