Brittle bone drugs may double risk of cancer

People taking a drug to treat osteoporosis for more than five years may be doubling their risk of developing oesophageal cancer, a new study has found.

Oral bisphosphonates are a type of drug commonly used to treat osteoporosis and other bone diseases.

Researchers from Oxford University and the Medicines and Healthcare products Regulatory Agency analysed data stored on the UK General Practice Research database which has anonymised patient records for around six million people registered with a NHS GP.

They focused on men and women aged over 40 - 2,954 with oesophageal cancer, 2,018 with stomach cancer and 10,641 with colorectal (bowel) cancer diagnosed between 1995 and 2005.

The results showed that people with 10 or more prescriptions for oral biphosphonates, or with prescriptions over about five years, were twice as likely to develop oesophageal cancer compared with people with no biphosphate prescriptions.

But there was no increased risk for stomach or bowel cancer.

Based on the study findings, the researchers estimate that taking biphosphonates for five years would increase the risk of developing oesophageal cancer from one in 1,000 to two in 1,000 for men and women aged 60 to 79.

The study, published in today's British Medical Journal contradicts previous research using the same database which reported no increased risk of oesophageal cancer with oral bisphosphonate use. However, this study tracked patients for nearly twice as long, the researchers said.

Dr Jane Green, who led the study said: “Oesophageal cancer is uncommon. The increased risks we found were in people who used oral bisphosphonates for about five years, and even if our results are confirmed, few people taking bisphosphonates are likely to develop oesophageal cancer as a result of taking these drugs.

"Our findings are part of a wider picture. Bisphosphonates are being increasingly prescribed to prevent fractures, and what is lacking is reliable information on the benefits and risks of their use in the long term.”

This article was published on Fri 3 September 2010