Adjuvant Hormonal Therapy for Low-Grade Endometrial Stromal Sarcoma.

To compare aromatase inhibitors (AIs) with progestins as adjuvant hormonal therapy(AHT) for low-grade endometrial stromal sarcomas (LGESSs). We reviewed cases with LGESS at our institution from 1984 to 2017. Disease recurrence and recurrence-free survival (RFS) were assessed among patients who received AI, progestins, or no AHT. Among 39 patients with LGESS, 18 received progestins, 13 received AI, and 8 received no AHT. Thirty patients had stage I disease, and 9 had stage II to IV disease. All underwent hysterectomies. Disease recurred in 70% (7/10) of stage I patients who received no AHT, compared to 14.3% (1/7) receiving AI, and 7.7% (1/13) receiving progestins ( P = .003). Among stage I patients taking AI, mean RFS was 153.1 months (95% confidence interval [CI]: 110-195.6) versus 306.2 months (95% CI: 259.7-352.6) for progestin patients and 90.8 months (95% CI: 56.8-124.9) for those who received no AHT. In stage II to IV patients, mean RFS was 148.5 months (95% CI: 148.5-148.5) and 120.8 months (95% CI: 55.8-185.9) for the AI and progestin groups, respectively. All stage II to IV patients received AHT. Among stage I patients, median follow-up time for RFS was 159.1 months for progestin patients, 52.6 months for AI, and 53.1 months for those who received no AHT. Of this, 69% of stage I patients taking progestins reduced/stopped treatment prematurely due to side effects. None of the patients taking AI discontinued treatment early. Aromatase inhibitor is associated with longer RFS in patients with advanced LGESS, is better tolerated than progestins, and can be primary AHT for LGESS.