Purpose: To provide a reference for clinicians, whether patients with advanced ovarian clear cell carcinoma (OCCC) require chemotherapy (CT) for more than 6 cycles after tumor debulking.
Patients and Methods: A retrospective review was performed on 85 women diagnosed and treated for advanced OCCC. Outcomes of patients who underwent > 6 vs ≤ 6 cycles of CT were analyzed based on clinicopathological factors.
Results: Among the 85 patients with advanced OCCC, 47 patients underwent ≤ 6 cycles of CT, and 38 patients underwent CT for over 6 cycles. Out of these, 49 patients had disease recurrence, and 35 died. The 2-year progression-free survival (PFS) for patients in the two groups was 51.5% and 42.2% (P＞0.05), respectively. The 2-year overall survival (OS) was 59.7% and 64.5%, respectively (P＞0.05), and the difference was not statistically significant. Multivariate analysis showed that residual tumor diameter was an independent risk factor for prognosis (PFS and OS). We divided the patients into three groups according to residual tumor diameter as 0 (R0), ≤ 1cm (R1), and > 1cm (R2). The prognosis of R0 was better than R1 and R2. Further studies found that patients who received postoperative adjuvant chemotherapy for over 6 cycles showed no difference in improved prognosis, regardless of residual tumor diameter.
Conclusion: Patients with advanced OCCC who received more than 6 courses of adjuvant chemotherapy after surgery did not show improved prognosis. The residual tumor diameter is an independent indicator of prognosis in patients with advanced OCCC. Complete staging improves the prognosis of patients compared to the ideal or non-ideal cytoreductive surgery.

Keywords: ovarian clear cell carcinoma, chemotherapy, residual tumor, prognosis, overall survival

INTRODUCTION

Epithelial ovarian cancer (EOC) is the most common cause of gynecological malignancy deaths. Each year, approximately 230,000 women are diagnosed with EOC globally, and 150,000 women die of the disease.¹ Ovarian clear cell carcinoma (OCCC) is a rare subtype of EOC, accounting for only 5–10% cases. However, it is of great concern because of its distinctive clinical features, such as concurrent endometriosis and poor prognosis.^2–5 The incidence of OCCC varies regionally and is significantly higher in Asia than in other regions. Reports show that OCCC accounts for approximately 4.8% of patients with EOC in whites, 3.1% in blacks, 11.1% in Asians, and 25% in Japanese patients.^6,7 A recent Japanese study reported that OCCC increased significantly, accounting for up to 30% of EOC.¹

In endometriosis patients, the risk of OCCC is significantly increased (relative risk = 12.4).^8,9 The majority of women (56.3%) who are diagnosed with OCCC are in the early stage. According to the Federation of Gynecology and Obstetrics (FIGO) staging criteria (2014), the 5-year survival rate of OCCC patients staged I–IV is 85.3%, 60.3%, 31.5%, and 17.5%, respectively, which is significantly lower than serous ovarian adenocarcinoma at corresponding stages.^10,11

Currently, the standard treatment for ovarian cancer is maximum tumor cell reduction combined with platinum-based CT.¹² However, compared with other subtypes, OCCC is less sensitive to platinum-based CT, and patients in the advanced stage of the disease are more likely to develop drug resistance to CT, which results in a high recurrence rate and poor prognosis.^13–16 The 2019 National Comprehensive Cancer Network (NCCN) guidelines recommended 6 cycles of CT after surgery for patients with advanced ovarian cancer (stages II–IV), and 3–6 cycles of intravenous chemotherapy for treating early-stage disease.^17,18 There is no evidence confirming the requirement of more than 6 cycles of combination chemotherapy as initial chemotherapy for ovarian cancer patients.¹⁹ For patients with OCCC, there is no consensus on the sufficient number of CT cycles, and whether over 6 cycles of CT are beneficial. We, therefore, retrospectively analyzed the clinicopathological data of 85 patients with advanced OCCC, evaluated the effect of different CT cycles on disease prognosis, and provided a reference for clinicians to select appropriate CT cycles.

Is There a Survival Benefit for Patients with Advanced Ovarian Clear Cell Carcinoma Who Complete More Than 6 Cycles of Postoperative Chemotherapy?

INTRODUCTION

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