Jones, Monica B.

PURPOSE To compare mortality risk among long-term survivors of high-grade serous ovarian cancer (HGSOC) with that of the general US population and to examine how mortality and recurrence trends have evolved under changing treatment approaches. MATERIALS AND METHODS This is a retrospective cohort study including patients with histologically confirmed HGSOC treated at a single referral cancer center from 1991 to 2022. Mortality risk, expressed as standardized mortality ratios (SMRs, ratio of observed deaths in the study population to expected deaths in an age-matched US population), was assessed at diagnosis and yearly on patients without events (disease persistence, recurrence, or death from any cause). RESULTS A total of 2,074 consecutive patients were included. The median follow-up was 12.5 years (IQR, 11.7-13.8). Most patients were stage III (1,396, 69.2%), 1,299 (62.8%) underwent primary cytoreductive surgery, and 1,688 (87.4%) received platinum-taxane as first-line therapy. At diagnosis, the mortality rate was 7.40 times higher than that in the general population (95% CI, 7.04 to 7.77). By 7 event-free years, the 95% CI for the SMR included 1 for the first time, and at 10 years, the SMR was 1.05 (95% CI, 0.72 to 1.49), indicating no statistically significant excess mortality compared with the general population. In those event-free at 10 years, the 5-year cumulative incidence of ovarian cancer–related deaths (8.2% [95% CI, 4.2 to 16.0]) was comparable with that of non–ovarian cancer–related deaths (6.3% [95% CI, 2.9 to 13.8]). CONCLUSION In this cohort, mortality risk steadily declined for patients who remained event-free, approaching that of the general population by 7 years after diagnosis. These results emphasize the importance of individualized, long-term follow-up to address both recurrence risk and survivorship needs.

5565 Background: The goal of this study was to determine the recurrence rates (R) of patients with grade 1 and 2 stage 1A and IB ovarian tumors treated with and without chemotherapy. Methods: We conducted a five-center retrospective study of patients with Stage 1A/B grade 1 and 2 ovarian carcinoma. All women underwent comprehensive staging including a minimum of unilateral salpingo-ophorectomy, unilateral pelvic and para-aortic lymphadenectomy, and omentectomy. Clear cell histologies were classified as grade 3 and excluded. The minimum cancer-free survivor follow-up was 3 years. Results: We identified 82 patients with Stage 1A/B grade 1 and 2 who met criteria for the study. The median age was 58 yrs (range 29 to 83) and the median follow-up was 5.3 yrs (range 3 to 11 yrs). The majority were of endometrioid histology (51), followed by mucinous (19), papillary serous (11), and mixed (1). Recurrences were of endometrioid (4), mucinous (1), or papillary serous (1) histology. For Stage 1A, overall recurrence rate was 9% (6/67). The overall recurrence rates for Stage 1A, grade1 tumors was 6% and among grade 2 tumors 12% (p=0.40). Among Stage 1A patients not treated with chemotherapy, there was a 7% (2/29) and 9.5% (2/21) recurrence rate for grade 1 and grade 2 tumors, respectively. For the grade 1 tumors, both patients are alive with disease at 3 and 5 yrs. For the grade 2 tumors, one is alive without evidence of disease at 7 yrs and the other died from disease at 4 yrs. Time to recurrence (TTR) was 2.3 yrs for grade 1 tumors and 2.6 yrs for grade 2 tumors. For Stage 1A patients treated with a platinum chemotherapy regimen, there were no recurrences (0/5) for grade 1 tumors and a 16% (2/12) recurrence rate for grade 2 tumors. Of the recurrences, one patient died from disease at 1.4 yrs and the other is alive with stable disease at 6 yrs. Time to recurrence was 2.85 yrs for grade 2 tumors. For grade 1 or 2, Stage 1A tumors, recurrence rates and time to recurrence were not effected by chemotherapy administration (R, p=0.55 and p=0.54, respectively; TTR, grade 2, p=0.85). No recurrences were observed in the 15 patients with Stage IB, grade 1 and 2 tumors. Conclusions: In comprehensively staged patients with Stage 1A/B, grade 1 and 2, low recurrence rates suggest adjuvant chemotherapy may not be indicated. No significant financial relationships to disclose.