UK Research Contradicts Earlier Study on Bisphosphonate (Fosamax) Cancer

Oxford, UKThe debate over Fosamax side effects took another turn earlier this month after a UK-based study found evidence of a link between bisphosphonates and esophageal cancer. The study appeared to contradict the findings of a US-based study published recently in the Journal of the American Medical Association (JAMA). The competing studies address the potential risk of esophageal cancer in relation to the use of bisphosphonates such as Fosamax, a drug used to treat osteoporosis.

Fosamax has been linked in the past to various side effects, including osteonecrosis of the jaw (ONJ), a debilitating condition characterized by the gradual breakdown of the jawbone. In the past, the debate centered on how a drug designed to slow bone loss can allegedly foster the weakening and breakdown of bone. The esophageal cancer link appears to be something new.

A study published on 9/2/10 in the British Medical Journal (BMJ) suggests a link between bisphosphonates and cancer of the esophagus. Tthe lead author of the study, epidemiologist Jane Green of the University of Oxford's Cancer Epidemiology Unit, cautioned that "the increased risks we found were in people who used oral bisphosphonates for about five years."

However, the overall risk of cancer is low. "Even if our results are confirmed, few people taking bisphosphonates are likely to develop cancer as a result of taking these drugs," Green said.

Fosamax side effects include nausea and heartburn, as well as inflammation of the esophagus. The quest to determine if such inflammation could lead to cancer with prolonged use began with an analysis of data from 15,000 cancer patients contained in that country's General Practice Research Database. The study followed the patients for a total of eight years and compared prescriptions with patient records.

The study found that at least one prescription for oral bisphosphonates increased the risk of esophageal cancer by 30 percent and 10 or more prescriptions almost doubled the risk.

These findings contradict those of an earlier study published last month in JAMA that found the rate of esophageal cancer in those who take oral bisphosphonates is not measurably different from that of the population as a whole.

Jane Green suggested the contradiction could be explained by the use of larger control groups and a longer period of follow-up. The US study also looked at more people—80,000—than the British study. Green noted that neither study interviewed patients or their doctors, validated diagnoses with medical records, or verified that bisphosphonates were taken according to prescribed directions.

The US study was conducted in response to a report by the US Food and Drug Administration (FDA) that the agency had received 24 reports of esophageal cancer in bisphosphonate patients—particularly Fosamax. Of those patients, eight are reported to have died. The link to Fosamax dead jaw was the subject of an earlier published study.