Overall survival and patterns of care for women with rare ovarian cancers: A prospective study from the Australian National Gynae-Oncology Registry (NGOR).

Abstract

e17554 Background: Ovarian cancer (OC) is a heterogenous group of malignancies, most of which are rare. Data on patterns of care and survival of the most-rare sub-groups of OC (incidence rates < 6 per 100,000) in the real-world setting is limited. This study aims to describe patterns of care and overall survival (OS) for women with rare ovarian cancers in Australia. Methods: Clinical data were sourced from the NGOR and assessed for accuracy and completeness. High grade serous and endometrioid OC subtypes were excluded. Due to incompleteness of survival follow-up data, 3-year OS was only calculated for the state of Victoria. Results: Data on 2812 women with newly diagnosed OC from 2017-2023 within NGOR were collected and 716 women were subsequently identified with rare subtypes of OC. The 5 sub-types with the highest incidences were clear cell (n = 168, 23.4%), mucinous (n=151, 21.1%), adult granulosa cell (n=111, 15.5%), low grade serous (n=98, 13.7%) and carcinosarcoma (n=59, 8.2%). A further 23 additional rare subtypes included germ cell tumours and sex cord stromal tumours. The median follow-up time was 2.6 years and median age at diagnosis was 55 years. Most women had an ECOG 0-1 performance status (n=551, 77.0%). The primary treatment modality was surgery only (n=360, 50%), followed by surgery and systemic therapy (n = 317, 44.2%), systemic therapy only (n=28, 3.9%) and no treatment (n=11, 1.5%). Most women were discussed at a multi-disciplinary meeting (n=701, 97.9%). The diagnosis was confirmed on histology for all women. The 30-day post-operative adverse events (Clavien-Dindo >III severity) was 3.6 % (n=26), with the highest rate of post-operative events in the carcinosarcoma group of 12% (n=6). Using Fisher’s exact test across the 5 most common sub-types described above, there were significant differences in treatment modalities (p<0.001), rates of 30-day post-operative events (p=0.002), age adjusted charlson comorbidity index (p<0.001) and metropolitan versus remote regional status (p=0.007) between the sub-types. Survival at 3 years for these five sub-types of rare OC within the state of Victoria are summarised in the table. The highest 3-year OS was in adult granulosa and low grade serous sub-types. Conclusions: This is a large, real-world analysis of patterns of care and survival for women with rare sub-types of OC. Combining data with international sites will likely further enhance research on patterns of care and outcomes for women with rare OC. [Table: see text]