Patients suffering from osteoporosis who take formulations containing ibandronate, alendronate or risedronate to strengthen their bones could be at an increased risk of cancer in the esophagus, a new research has suggested.

The report, published in the online edition of the BMJ, suggests that drugs commonly used to treat bone diseases in the oral bisphosphonates category, could increase the risk of esophageal cancer though there is still only limited scientific evidence of this link.

The research team used data from the General Practice Research Database of the UK believes that the analysis still does not provide a full picture of the benefits versus risks of the drugs that are prescribed by doctors.

The study team at the Oxford University's Cancer Epidemiology Unit believes that there should be no immediate implication on treatment and suggests that since esophageal cancer is quite uncommon, the risk would still be relatively low at a per person level.

Dr. Jane Green, a clinical epidemiologist at the Unit who lead the study team believes that the results may not reflect the true effect of drugs like Boniva, Fosamax and Actonel on cancer symptoms. "It could be that people more likely to get cancer are prescribed the drugs more often," Green says while seeking additional research on the topic.

The study collected data from 3,000 men and women with esophageal cancer, 2,000 with stomach cancer and 10,000 with colorectal cancer. All the patients were diagnosed in the decade between 1995 and 2005. Analysis of the data revealed that people who had ten or more prescriptions of the drug over a five year period had almost double the risk of esophageal cancer compared to those who hadn't taken the drugs.

Esophageal cancer is usually seen among one in every 1,000 people aged between 60 and 79 years. If the research results were to be accepted, the rate of esophageal cancer will rise to about two per 1,000 people, the researchers say.

They believe that the possibility of adverse effects on the esophagus may result in doctors actually asking about digestive disorders in patients before prescribing oral bisphosphonates.