Adjuvant Treatment of Early Ovarian Clear Cell Carcinoma: A Population-Based Study of Whole Abdominal Versus Pelvic Nodal Radiotherapy

Abstract

Background: Adjuvant treatment in early ovarian clear cell carcinoma (OCCC) is not yet standardized. The objective of this population-based study was to compare the outcome of patients with early OCCC treated with adjuvant chemotherapy versus chemoradiotherapy (chemoRT) and evaluate the association of adjuvant radiotherapy regimens (whole abdominal radiotherapy [WART] versus pelvic nodal radiotherapy [PRT]) with outcome. Patients and Methods: Chart review was conducted to identify patients with stage I and II OCCC with complete information on staging. Patients with stage IA, IB, or IC OCCC purely resulting from capsular rupture were excluded because the provincial protocol does not recommend adjuvant treatment. Results: Overall, 403 patients were identified and 343 received adjuvant treatment, of whom 255 had stage IC or II OCCC and 153 were eligible for final analysis. On Cox multivariable regression, receipt of chemoRT (n=90) was associated with an improvement in failure-free survival (FFS) (hazard ratio [HR], 0.57; 95% CI, 0.34–0.94) compared with chemotherapy alone (n=63). Use of chemoRT also resulted in 54% reduction in the cumulative incidence of cancer-specific mortality (subdistribution HR, 0.46; 95% CI, 0.24–0.89). However, there was no significant difference in the HR for overall survival (OS) between the chemoRT (HR, 0.70; 95% CI, 0.43–1.13) and chemotherapy group. Relative to chemotherapy + WART (chemo-WART), chemotherapy + PRT (chemo-PRT) was not associated with any significant difference in HR for FFS (HR, 1.34; 95% CI, 0.40–4.44) or OS (HR, 1.13; 95% CI, 0.37–3.46). Conclusions: Adjuvant chemoRT was associated with a lower risk of failure compared with chemotherapy alone. However, there was no difference in OS between the adjuvant chemotherapy and chemoRT regimens. Additionally, no significant difference in terms of FFS or OS was found between the chemo-WART and chemo-PRT groups.

Treatment for clear cell carcinoma of the abdominal wall at a tertiary cancer center

“…This may be due to the unknown tumor margin. Adjuvant chemo-radiotherapy was associated with a lower risk of disease failure compared with chemotherapy alone in early stage ovarian CCC treatment 18 . Regarding the similar origin of ovarian CCC, radiotherapy could help for regional disease control.…”

The role of radiotherapy in ovarian cancer

“…The difference between the two radiotherapy techniques was non-significant for peritoneal recurrence and local failure rates although, as might be expected, there were a higher number of para-aortic node relapses in the pelvic nodal radiotherapy group. There were three treatment-related deaths in the whole abdominal radiotherapy group including small bowel obstruction, radiotherapy-induced liver disease, and a thromboembolic event 25…”

“…There were three treatment-related deaths in the whole abdominal radiotherapy group including small bowel obstruction, radiotherapy-induced liver disease, and a thromboembolic event. 25 Despite the studies demonstrating that there is unlikely to be a significant overall survival benefit from adjuvant whole abdominal radiotherapy in localized ovarian clear cell carcinoma, there is a suggestion that pelvic radiotherapy, which is less toxic than whole abdominal radiotherapy, may be considered to improve local disease control.…”

Ovarian Cancer Radiosensitivity: What Have We Understood So Far?

“…Nowadays, adjuvant whole abdominal radiotherapy (WART), commonly delivered in the past years for ovarian tumors, is no longer considered standard practice due to the high rate of toxicity (gastrointestinal, hematological, and bone) [ 1 ]; radical cytoreductive surgery and chemotherapy are the cornerstones of the treatment. WART showed good results in terms of a lower risk of failures [ 2 ] and also for the most uncommon histologies such as ovarian clear cell carcinoma [ 3 ], which is characterized by unique genotypic and phenotypic signatures and platinum resistance. Although resistance is usually crossed between chemotherapy and radiotherapy (RT), this seems not to be the case for clear-cell ovarian cancers.…”