Endometriosis Associated Ovarian Cancer: A Single Gynecologic Oncology Practice [25H]

INTRODUCTION: There is increasing evidence of the association between endometriosis and ovarian cancer. Data is limited regarding stage, subtype, and recurrence for this specific subset of patients. We report and analyze findings from cases with histologically confirmed ovarian cancer associated with endometriosis at time of surgery. METHODS: Retrospective review surgical cases from a single gynecologic oncology practice between 2003-2019. Selection criteria of surgical cases included final pathology reports showing endometriosis and ovarian malignancy with adequate follow up. RESULTS: 31 cases were diagnosed. Average patient age was 52.4 (29-83). Histologic subtypes diagnosed were high grade serous 9/31 patients (29%), clear cell 12/31 patients (39%), endometrioid 8/31 (26%), and mucinous 2/31 (6%). Surgical staging ranged from 1A-IIIC. 18/31 patients (58%) were diagnosed with Stage I (A: 6, B: 1, C: 11), 5/31 patients (16%) with Stage II, 8/31 patients (26%) with Stage III. All patients underwent surgical staging/debulking with 5 patients (15%) receiving neoadjuvant chemotherapy. 28/31 patients (90%) received adjuvant chemotherapy with Carboplatin/Taxol while 3/31 patients (10%) did not require further treatment. Surgical staging/debulking was performed by Laparotomy 6/31 patients (19%) or Laparoscopy/Robotic 24/31 patients (78%) with 1 case converted to Laparotomy (3%). Recurrence noted with clear cell histology 6/10 (60%) all stage I, high grade serous 3/10 (30%) all stage IIIC, and mucinous 1/10 (10%) stage I. CONCLUSION: The most common endometriosis associated ovarian cancers were early stage clear cell and endometrioid subtypes. Clear cell histology in spite of early stage was the most significant factor for recurrence.