Stage, treatment and survival of low‐grade serous ovarian carcinoma in the Netherlands: A nationwide study

INTRODUCTION: Serous ovarian carcinomas constitute the largest group of epithelial ovarian cancer (60%–75%) and are further classified into high‐ and low‐grade serous carcinoma. Low‐grade serous carcinoma (LGSC) is a relatively rare subtype (approximately 5% of serous carcinomas) and epidemiologic studies of large cohorts are scarce. With the present study we aimed to report trends in stage, primary treatment and relative survival of LGSC of the ovary in a large cohort of patients in an effort to identify opportunities to improve clinical practice and outcome of this relatively rare disease. MATERIAL AND METHODS: Patients diagnosed with LGSC between 2000 and 2019 were identified from the Netherlands Cancer Registry (n = 855). Trends in FIGO stages and primary treatment were analyzed with the Cochran–Armitage trend test, and differences in and trends of 5‐year relative survival were analyzed using multivariable Poisson regression. RESULTS: Over time, LGSC was increasingly diagnosed as stage III (39.9%–59.0%) and IV disease (5.7%–14.4%) and less often as stage I (34.6%–13.5%; p < 0.001). Primary debulking surgery was the most common strategy (76.2%), although interval debulking surgery was preferred more often over the years (10.6%–31.1%; p < 0.001). Following primary surgery, there was >1 cm residual disease in only 15/252 patients (6%), compared with 17/95 patients (17.9%) after interval surgery. Full cohort 5‐year survival was 61% and survival after primary debulking surgery was superior to the outcome following interval debulking surgery (60% vs 34%). Survival following primary debulking surgery without macroscopic residual disease (73%) was better compared with ≤1 cm (47%) and >1 cm residual disease (22%). Survival following interval debulking surgery without macroscopic residual disease (51%) was significantly higher than after >1 cm residual disease (24%). Except FIGO stage II (85%–92%), survival did not change significantly over time. CONCLUSIONS: Over the years, LGSC has been diagnosed as FIGO stage III and stage IV disease more often and interval debulking surgery has been increasingly preferred over primary debulking in these patients. Relative survival did not change over time (except for stage II) and worse survival outcomes after interval debulking surgery were observed. The results support the common recommendation to perform primary debulking surgery in patients eligible for primary surgery.