Osteoporosis drug may double risk of oesophageal cancer

Oral bisphosphonates are frequently given to treat or prevent bone disease and can have gastrointestinal side-effects such as nausea and abdominal pain.

Recent studies have suggested no link between the drugs and oesophageal cancer, but it is thought the drugs do protect against breast cancer in post-menopausal women.

Now, a study published online today in the British Medical Journal has found that long-term use of the drugs may double risk of oesophageal cancer.

Experts from the University of Oxford's cancer epidemiology unit and the Medicines and Healthcare products Regulatory Agency analysed data from a UK GP practice database on around six million people.

Among those aged 40 and over, 2,954 had oesophageal cancer, 2,018 had gastric cancer and 10,641 had bowel cancer, all diagnosed between 1995 and 2005.

The experts looked at the use of oral bisphosphonates and cancers of the oesophagus, stomach and bowel, taking into account factors such as smoking, alcohol and body mass index.

The results showed that the chance of oesophageal cancer was 30 per cent higher in people with one or more previous prescriptions for oral bisphosphonates compared to people who had never taken the drugs.

The risk was almost double for those who had 10 or more prescriptions compared with those who had had between one and nine.

For those taking the drugs for at least three years (five years on average), the risk was more than double compared with those who had never had a prescription for the drugs.

There were no links between the drugs and stomach or bowel cancer.

Typically, oesophageal cancer develops in one per 1,000 people aged 60 to 79 over five years.

Use of oral bisphosphonates over five years would push this up to two cases per 1,000 people, the authors said.

They said that while a study published just a few weeks ago using the same database showed no link between the drugs and risk of cancer, the latest research tracked patients for almost twice as long.

Lead author Dr Jane Green, said oesophageal cancer is uncommon. "Even if our results are confirmed, few people taking bisphosphonates are likely to develop oesophageal cancer as a result of taking these drugs."