Long-term use of bone-strengthening drugs may increase oesophageal cancer risk
People who take bone-strengthening pills called bisphosphonates over a long period of time could be more likely to develop cancer of the oesophagus (gullet), new research suggests.
But Cancer Research UK said that any risk of oesophageal cancer is still small and should be balanced alongside the benefits of the drugs.
Scientists at the University of Oxford's Cancer Epidemiology Unit and the Medicines and Healthcare products Regulatory Agency (MHRA) analysed anonymous data from the UK General Practice Research Database.
They looked at information on 2,954 men and women with oesophageal cancer, 2,018 with stomach cancer and 10,641 with bowel cancer, each of whom was compared with five cancer-free controls.
Typically, oesophageal cancer develops in one per 1,000 people at age 60-79 over five years. Based on their findings, the authors estimate that in people who had received ten or more prescriptions for oral bisphosphonates, or had been taking the drug for about five years, this could increase to two cases per 1,000 people.
The researchers found no link between bisphosphonates and stomach or bowel cancer.
Dr Jane Green, lead author of the study in the British Medical Journal, said that oesophageal cancer is uncommon and that, even if the results are confirmed by further research, "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," she continued. "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."
Dr Laura Bell, science information officer at Cancer Research UK, commented: "This is an important study that will help doctors understand more about the risks and benefits of oral bisphosphonates but it's important to stress that, even if people take oral bisphosphonates for a long time, the risk of developing oesophageal cancer is still small. Anyone who is taking these drugs and is worried about their risk of cancer should talk to their doctor.
"Earlier this week Cancer Research UK reported that oesophageal cancer rates in men had increased by 50 per cent in the last 25 years, with obesity and increasing age believed to be major risk factors. Each year around 8,000 people are diagnosed with the disease, of whom 5,226 are men. Oesophageal cancer is the ninth most common cancer but affects very few people under 40."