By Alisdair Stirling
Researchers have cast doubt on a high profile analysis that showed a link between oral bisphosphonates and oesophageal cancer.
Findings published by researchers at the University of Oxford and the Medicines and Healthcare products Regulatory Agency in the BMJ earlier this month suggested the incidence of oesophageal cancer was 30% higher in patients with one or more previous prescriptions for the drug compared with those with no prescriptions.
The relative risk was 90% higher for patients with 10 prescriptions than for patients who had taken between one and nine prescriptions. But a separate analysis of the same data by a team from the Queen´s University in Belfast has suggested there may no such increased risk.
Both studies looked at data from the General Practice Research Database but the methodologies differed considerably.
The Belfast team excluded patients with a prior diagnosis of cancer as they have received bisphosphonates for treatment of osteoporosis/metastases associated with their cancer and they also have a higher risk of a second cancer, including oesophageal cancer. The other major difference was the new analysis looked at defined daily doses of bisphosphonates rather than number of prescriptions.
The results - published as a BMJ Rapid Response - showed no increased risk of cancer in patients who had ever prescribed oral bisphosphonates and no increased risk among those having received prescriptions equivalent to three years of use at standard doses. The researchers said their confidence intervals were higher than those of the earlier study because of the smaller number of incident cases they included.
Professor Liam Murray, head of the epidemiology research group at Queen's University Belfast concluded: 'The issue of whether use of oral bisphosphonates increases oesophageal cancer risk remains unresolved and further investigations using different data sources are required.'
Bisphosphonate link with oesophageal cancer 'unresolved'
