ANN ARBOR, Mich. -- Concerns about fertility kept a third of young women with breast cancer from taking tamoxifen, despite its known benefit in reducing the risk of breast cancer coming back.
In addition, the study found fertility concerns led a quarter of women who started tamoxifen to stop taking it before the recommended treatment period ended.
"Our study points toward the importance of fertility to young breast cancer patients. 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," says senior study author Jacqueline Jeruss, M.D., Ph.D., associate professor of surgery and biomedical engineering at the University of Michigan and a breast cancer surgeon at the University of Michigan Comprehensive Cancer Center.
The study, published in the Journal of the National Cancer Institute, looked at the electronic medical records of 515 premenopausal women treated for breast cancer at Northwestern Memorial Hospital's Lynn Sage Comprehensive Breast Center. All patients who were included had estrogen receptor- or progesterone receptor-positive breast cancer and were recommended to take tamoxifen.
Previous studies have shown that five years of tamoxifen can reduce recurrence risk by 47 percent and mortality by 26 percent. More recent data suggests continuing tamoxifen for 10 years may be even more beneficial in preventing recurrence or death.
In the current study, researchers found that 13 percent of patients declined to take tamoxifen and 16 percent stopped before the five years of recommended treatment were up. Of those who declined, the most common factors were a diagnosis of ductal carcinoma in situ, declining radiation therapy, not receiving chemotherapy and expressing a desire for future fertility. A desire for future fertility was also significantly associated with the early discontinuation of tamoxifen.
The researchers also conducted phone interviews with 88 patients who did not initiate or discontinued tamoxifen to help confirm the findings obtained from patient records. Concerns about fertility and side effects were the primary factors patients mentioned as influencing their decisions about taking or staying on tamoxifen.
"This study shines a bright light on the fertility concerns of young cancer patients. Through the Oncofertility National Physicians Cooperative program, fertility concerns for young cancer patients can now be addressed. If provided at the time of diagnosis, this may ensure more young women with a cancer diagnosis adhere to their life-preserving tamoxifen treatments," said Teresa K. Woodruff, Ph.D., director of the Oncofertility Consortium, based at Northwestern University Feinberg School of Medicine.
Women taking tamoxifen are advised to avoid pregnancy because of the high potential for harm to the baby. The authors emphasize the need to provide additional counseling and education to patients who may be at higher risk for declining tamoxifen.
"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. 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," Jeruss says.
A new international trial is currently looking at whether premenopausal women who stop tamoxifen for a period of time to become pregnant and then resume tamoxifen after pregnancy have similar benefit as those who have a continuous course of tamoxifen. This trial, called POSITIVE, is being conducted by the International Breast Cancer Study Group. In addition, several options exist for preserving fertility before treatment begins, although these procedures may not be covered by insurance. For information, call the U-M Cancer AnswerLine at 800-865-1125.
Additional authors: Natalia C. Llarena and Samantha L. Estevez, from Northwestern University; Susan L. Tucker, from M.D. Anderson Cancer Center
Funding: National Institute of Child Health and Human Development grant P50 HD076188 and Northwestern University's Medical Student Summer Research Program
Reference: Journal of the National Cancer Institute, doi:10.1093/jnci/djv202, published online Aug. 24, 2015
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