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“Our data support the use of tamoxifen as an effective option that offers the benefit of a shorter duration of treatment than other approaches such as combined oral contraceptives,” wrote Alison B. Edelman, MD, MPH, of Oregon Health & Science University, Portland, and coauthors. The report is in Obstetrics & Gynecology.
To determine if a short course of tamoxifen – typically used to treat breast cancer – could prove beneficial in reducing bothersome bleeding, the researchers launched a 90-day, double-blind randomized trial of women between the ages of 15 and 45 years who had been using the etonogestrel 68-mg subdermal contraceptive implant for at least 30 days. All participants suffered from frequent or prolonged bleeding or spotting during the previous month; their mean age was 24, and most (n = 62) identified as White.
Of the initial 112 participants, 107 began treatment and were split into two groups: 10 mg of tamoxifen twice a day for 7 days (n = 55) or placebo (n = 52). One hundred and four patients completed treatment one, and 88 completed 90 days. After the first treatment, women in the tamoxifen group experienced 9.8 more consecutive days of amenorrhea (95% confidence interval, 4.6-15.0) compared with the placebo group, as well as more total days of no bleeding in the first 90 days (median 73.5 [24-89] versus 68 [11-81], P = .001).
Afterward, both groups underwent a 90-day, open-label study where all participants took tamoxifen. The differences between the groups mostly disappeared, as they both experienced more amenorrhea days (median 56 [6-81] for tamoxifen and 67.5 [7-83] for placebo) and fewer bleeding days (median 12 [0-63] for tamoxifen and 12 [0-82] for placebo) compared with the placebo group during the initial 90 days. Although no serious adverse events occurred, more women taking tamoxifen reported fluid retention (12 versus 1), headache (19 versus 1), and mood changes (13 versus 2).
“This is a very promising drug for this purpose,” Catherine Cansino, MD, MPH, of the University of California, Davis, said in an interview, adding that it is “a bit unconventional because tamoxifen is traditionally used for cancer or precancer.”
Dr. Catherine Cansino
As such, she recognized that young people of reproductive age might be a little wary of the drug. That said, having an effective treatment for troublesome bleeding beyond estrogen-based products should ultimately prove beneficial for clinicians and patients alike.
“Unfortunately, we don’t have long-term data so it’s unclear what the safety outcomes are,” she said, “but having another option to address bothersome bleeding can help women stay on birth control longer. The alternative would be pregnancy, with its own associated risks.”
The authors acknowledged their study’s limitations, including a lack of Black patients and the likelihood that their volunteer cohort “may not reflect the general population of implant users who present for discontinuation owing to bleeding problems.” They also enrolled a small but notable number of women who had been using the implant for less than 3 months, noting that bleeding patterns often change from the first 90 days and so “some of these women would likely experience better (or worse) bleeding irrespective of treatment.”
The study was supported by a Merck Women’s Health Investigator Initiated Studies Program and the Oregon Clinical and Translational Research Institute. Four of the authors acknowledged receiving consulting fees and research support from various organizations and pharmaceutical companies. The remaining three had no relevant financial disclosures. Dr. Cansino is a member of the Ob.Gyn. News editorial advisory board. She said she had no relevant financial disclosures.
SOURCE: Edelman AB et al. Obstet Gynecol. 2020 Jul 9. doi: 10.1097/AOG.0000000000003896.