Fertility Concerns Trump Tamoxifen's Benefits for Many Young Women

Despite its known effectiveness in reducing breast cancer recurrence, many young women are bypassing taking tamoxifen because of fertility concerns.

Jacqueline Jeruss, MD, PhD

Despite its known effectiveness in reducing breast cancer recurrence, many young women are bypassing taking tamoxifen because of fertility concerns, according to a new study published in the Journal of National Cancer Institute.

The study followed 515 premenopausal women under age 45 with stage 0 to III hormone receptor-positive breast cancer who were treated at Northwestern Memorial Hospital’s Lynn Sage Comprehensive Breast Center and were recommended to take tamoxifen.

Fertility concerns kept a third of the premenopausal women in the study from taking the drug and led a quarter of the participants who started taking tamoxifen to discontinue taking it before the recommended 5-year treatment period ended.

“Our study points toward the importance of fertility to young breast cancer patients,” senior author Jacqueline Jeruss, MD, PhD, associate professor of surgery and biomedical engineering at the University of Michigan and breast cancer surgeon at the University of Michigan Comprehensive Cancer Center, said in a statement. “We need to find a way to bridge the gap between this patient survivorship goal and our concerns as physicians to facilitate the best treatment possible for our patients.”

Studies show that taking tamoxifen for 5 years can reduce recurrence risk by 47% and mortality by 26%, and recent data suggest 10 years of tamoxifen may be even more beneficial in preventing recurrence and death, but women taking the drug are advised to avoid pregnancy because of high potential for harm to the baby.

Using multivariable analysis, researchers found that desire for future fertility was significantly associated with both noninitiation and early discontinuation of tamoxifen.

Although fertility concerns were second to side effects in patients’ reasons for discontinuation, fertility was the only predictor for both noninitiation and early discontinuation.

Among 69 patients who declined treatment initiation, 24 (34%) cited fertility as their reason, and of 80 who discontinued taking tamoxifen before the 5-year period ended, 20 (25%) said they did so to attempt pregnancy.

Other independent predictors for noninitiation included diagnosis of ductal carcinoma in situ, declining radiation and not receiving chemotherapy. Smoking and not receiving radiation were also also significant predictors of early withdrawal from treatment.

“For those oncology patients who express a desire for future fertility or a concern about fertility preservation, appropriate counseling and referral to a fertility specialist should be offered at the outset as part of a multidisciplinary treatment plan,” Jeruss said.

“We should work toward a dialogue where patients can discuss with their physicians issues that are important to them. By creating such a dialogue, we may identify more patients who are willing to complete the recommended course of tamoxifen therapy, though this may involve a treatment delay or hiatus to allow for a pregnancy.”

A new international trial, POSITIVE, is being conducted by the International Breast Cancer Study Group to look at whether premenopausal women who stop tamoxifen to become pregnant and resume taking it after pregnancy have similar benefits as those who took tamoxifen for at least five years.

Jeruss and the other researchers concluded that treatment of young cancer patients should include access to fertility preservation options.

“These findings provide an avenue for intervention that may improve tamoxifen adherence and, thus, potentially survival in this patient subgroup,” the authors noted.

Llarena NC, Estevez SL, Tucker SL, et al. Impact of Fertility Concerns on Tamoxifen Initiation and Persistence [published online August 25, 2015]. J Natl Cancer Inst.