Bisphosphonates May Protect Against Endometrial Cancer

By Will Boggs MD

NEW YORK (Reuters Health) - Bisphosphonates may protect against endometrial cancer, according to results from the Prostate, Lung, Colorectal and Ovarian (PLCO) Cancer Screening Trial.

"I think clinicians could consider bisphosphonates for the treatment of low bone density and potential reduction of endometrial cancer risk (and maybe recurrence, although my paper could not address this)," Dr. Sharon Hensley Alford from Henry Ford Hospital System, Detroit, Michigan told Reuters Health by email.

Dr. Alford's team used data from 23,485 women in the PLCO Cancer Screening Trial to explore the impact of nitrogenous bisphosphonate use on the risk of developing endometrial cancer.

Women who had ever used bisphosphonates were 51.1% less likely than other women to develop endometrial cancer, according to the December 22nd Cancer online report.

Results were similar when the risks of developing Type I and Type II endometrial cancer were considered separately and when all hormone-related variables were factored in.

"The results of the current study suggest that nitrogen-containing bisphosphonates may reduce the risk of endometrial cancer," the researchers conclude. "However, additional studies are needed that include other potential confounders and a larger sample so that Type II endometrial cancer could be assessed more confidently."

"There are risks to bisphosphonates, so the potential benefit versus risk must be discussed (by the) patient with her clinician," Dr. Alford said.

"We reached similar results for breast, colon, ovary, lung and also endometrium and each of these findings has since been replicated numerous times," Dr. Gad Rennert from B. Rappaport Faculty of Medicine, Technion, Haifa, Israel told Reuters Health by email. "Further to this, we have very good evidence that bisphosphonates are also beneficial if taken after diagnosis (survival benefit), but the big journals are still reluctant to send these papers for review, and I assume that I will have to publish it in a lesser impact journal."

"Because of the very low profile of side effects for bisphosphonates, I do not see it a problem to provide it to cancer patients, but still think that women at high risk for endometrial cancer (usually with high BMI and therefore low risk of osteoporosis and hence low use of bisphosphonates) should await results of randomized trials," Dr. Rennert concluded. "This is mainly because the lifetime risk of endometrial cancer is quite low (i.e., I think it is of much more relevance in the prevention of common cancers such as breast and colon)."

But Dr. Aju Mathew from University of Pittsburgh Cancer Institute, Pittsburgh, Pennsylvania wonders if the findings simply reflect an indication bias. He told Reuters Health, "Type I cancers are more hormonally dependent. They are more common in this dataset and hence may have influenced the results entirely. Patients with low estrogen levels have low bone mass and more osteoporosis. Therefore, they are on bisphosphonates. It is this group that has been found to have fewer endometrial cancers. And, we know that endometrial cancer risk is lower in low estrogen state."

"Similar observational studies were done in breast cancer, and those found a protective effect for the medication," he said. "But when similar analysis was performed in a randomized fashion, the effect dissipated."

"Practicing physicians should be aware that bisphosphonates may have an anti-tumor role, but it awaits confirmation in large clinical trials," Dr. Mathew concluded. "Until then, the results of this study cannot be translated to clinical practice."

SOURCE: https://bit.ly/16K7Y83

Cancer 2014.

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