Leading diabetes drug metformin may have potential indications as a treatment for several types of cancer, including cancer of the prostate, liver and pancreas.
New studies have shown that metformin may slow down the growth of prostate cancer, prolong life expectancy in patients with early-stage pancreatic cancer, and help to prevent liver cancer.
If metformin is confirmed as an effective cancer therapy, it could help to reduce both the costs and the side-effects of cancer treatment.
Researchers have pointed to “strong signals of an anti-cancer effect” with metformin, but emphasised that further clinical studies are needed.
A Canadian study in 22 adult males with prostate cancer showed that high doses of metformin, given for an average of 41 days, slowed tumour growth by 32%.
Reasons for this effect could include direct impact on cancer cell metabolism and reduced bloodstream levels of insulin, which enhances tumour growth.
Nancy Dawson, prostate cancer specialist at a Georgetown cancer centre, commented: “It’s very early and the study is small. But it’s fascinating to see such a slowing of cancer cell growth in such a short period of time.”
A Texan study examined data on 302 people with pancreatic cancer and diabetes, of whom 117 took metformin. It found that 30% of those taking metformin were alive after two years, compared to 15% of those not taking it. The average survival was 15 months with metformin and 11 months without.
A Maryland study in mice showed that metformin was significantly effective in preventing primary liver cancer – a disease for which type 2 diabetes, obesity and hepatitis are risk factors in humans. Mice given metformin showed 57% fewer liver tumours, and their average tumour size was 37% smaller.
Study author Geoffrey D. Girnun said: “Based on these findings, we believe metformin should be evaluated as a preventive agent in people who are at high risk.”
Further studies are planned, but there is strong interest in the cancer-treating potential of this successful diabetes drug.
“These are still the early days,” noted Jose Baselga, Chief of Oncology at Massachusetts General Hospital. “But there are strong signals of an anti-cancer effect.”