WEDNESDAY, Nov. 16 (HealthDay News) -- One in five male breast cancer patients stops taking the drug tamoxifen early due to side effects caused by the medicine and may be at increased risk for cancer recurrence, new research suggests.

Tamoxifen is the standard of care for the hormone treatment of male breast cancer patients, according to the authors of a new report published in the Nov. 16 issue of the Annals of Oncology.

In the study, researchers at the University of Texas M.D. Anderson Cancer Center in Houston examined the records of 64 male breast cancer patients who received tamoxifen for an average of four years and found that 34 of them (53 percent) experienced one or more tamoxifen-related side effects, such as weight gain and loss of sex drive.

Thirteen (20.3 percent) of the patients stopped taking tamoxifen due to the side effects. Nine of the patients died after they discontinued tamoxifen early, the study authors noted in a journal news release.

"This is the largest study to specifically assess tamoxifen-related side effects in men because in our institution we treated a relatively large number of male breast cancer patients," study author Dr. Naveen Pemmaraju said in the news release.

"We found that, after adjusting for patient age and stage of the disease, the prognosis for men with breast cancer is similar to that of women. Tamoxifen has been shown to improve survival rates for breast cancer patients, so early discontinuations may have the potential to increase the risk of the cancer recurring in this group of male breast cancer patients," he added.

"Male breast cancer is a very rare and unique cancer affecting approximately 2,000 men in the U.S.A. per year. As there are so few male breast cancer cases, clinical practice and optimal treatment strategies have been extrapolated from female breast cancer patients with very little published evidence to guide clinical decisions. In our institution, we noted that several of our male patients were having difficulty with taking tamoxifen therapy, and these side effects appeared to be a little bit different to those reported with women receiving the same drug," Pemmaraju continued.

"The results of this study should not change the recommendation for prescribing tamoxifen for male breast cancer patients. However, clinicians need to be aware of the possible side effects that men may experience when receiving tamoxifen so that the patients can be counseled appropriately," he added.

In the United States, about 2,140 new cases of invasive breast cancer in men will be diagnosed this year and about 450 men will die of the disease.

More information

The U.S. National Cancer Institute has more about male breast cancer.