ASCO 2016-HORMONE MAINTENACE THERAPY HELPFUL FOR LOW GRADE OVARIAN CANCER

CHICAGO—Hormone maintenance therapy (HMT) is associated with better survival than post-treatment surveillance for women with low-grade serous carcinoma of the ovary or peritoneum, according to a retrospective study presented at the 2016 American Society of Clinical Oncology (ASCO) Annual Meeting, held June 3–7 in Chicago (abstract 5502).

“Women with stage II–IV low-grade serous carcinoma who received HMT following primary treatment had significantly better outcome compared to women who underwent surveillance,” reported lead study author David Marc Gershenson, MD, of the University of Texas MD Anderson Cancer Center in Houston.

Low-grade serous carcinoma is a rare subtype representing approximately 10% of serous carcinomas of the ovary or peritoneum. “It may arise de novo or following diagnosis of a serous borderline tumor,” Gershenson noted. Compared with high-grade serous carcinoma, these tumors tend to occur in younger patients, and exhibit aberrations in the MAP kinase pathway, as well as a high frequency of estrogen receptor and progesterone receptor expression.

No prospective clinical trials have been undertaken for frontline treatments, but data from MD Anderson’s Low-Grade Serous Tumor Database suggest that relative to high-grade serous carcinomas, low-grade tumors exhibit chemoresistance in the frontline chemotherapy setting (with more than 40% of patients experiencing persistent disease) and platinum-sensitive or platinum-resistant salvage chemotherapy settings.

“Low-grade serous carcinoma is not as responsive to platinum/taxane chemotherapy as is high-grade serous carcinoma,” Gershenson said.

In order to compare patient outcomes associated with HMT and surveillance following primary cytoreductive surgery and platinum-based chemotherapy in women with pathologically confirmed stage II–IV low-grade serous carcinoma of the ovary or peritoneum, the researchers conducted a retrospective cohort study using the MD Anderson Low-Grade Serous Tumor Database. They identified 240 eligible patients diagnosed between 1981 and 2013; 134 had undergone post-treatment surveillance and 70 had received HMT. Patients whose disease had progressed during primary chemotherapy were not included in the study.

Median progression-free survival (PFS), the primary study endpoint, was 27.3 months for women in the surveillance group (95% CI, 22.7–31.9 months) and 64.9 months in the HMT group (95% CI, 43.5–86.3 months; P < .001). Forty percent (28/70) of HMT patients had not had disease recurrence, compared with 12% (16/134) in the surveillance group.

For overall survival (OS), the difference was not significant (median OS, surveillance group: 98.8 vs 115.7 months; P = .36).

The study was retrospective, covering a long period of time during which there were heterogenous treatments and varying follow-up practice patterns, Gershenson cautioned.

However, in a subset analysis of the 148 women in the cohort who had no evidence of disease following primary chemotherapy, HMT was associated with superior median PFS (81.1 vs 29.9 months; P < .001) and superior OS (191.3 vs 106.8 months; P = .04) compared with surveillance.

In multivariate analysis, HMT was also associated with a reduced risk of relapse (hazard ratio, 0.23 [95% CI, 0.11–0.51]).

Gershenson called the findings “potentially practice-changing,” and called for a prospective clinical trial.