Time to completion of radiation treatment in locally advanced squamous cell carcinoma of the vulva and the impact on survival.

Objective: To assess whether radiation completion within a planned timeframe in locally advanced squamous cell vulvar cancer impacts overall survival (OS).

Methods: The National Cancer Database from 2004 to 2017 was used to identify women ≥18 years old with stage II-IVA squamous cell vulvar cancer. We included women who received radiation alone (RT) or concurrent chemoradiation (CRT) for initial vulvar cancer treatment. Primary outcome was overall survival associated with time of delay in radiation completion.

Results: There were 2378 women identified (n = 856 RT and n = 1522 CRT). Median age was 67 (IQR 56-78), majority (88.35%) were white with advanced stage III or IVA (72.29%) disease. Median radiation dose was 5720 c-Gray (IQR 5040-6300). Radiation completion with delay ≥7 days resulted in reduction in survival compared to delay of <7 days (unadjusted HR 1.183 [95%CI: 1.066-1.313], p = 0.0016). When delays extended to ≥14 days compared to <14 days there was increased hazard of death (unadjusted HR: 1.263 [95%CI:1.126-1.416], p < 0.0001). Survival improved for patients with <7 versus ≥7 days delay whether treatment was with RT (median OS: 34.9 months versus 21.6 months, p < 0.01) or CRT (Median OS:58 months versus 41.3 months, p < 0.01). Stage IVA disease was associated with the greatest increase in hazard of death (HR 1.759 [95%CI 1.517-2.039], p < 0.0001) compared to stage II.

Conclusion: Radiation completion with <7 days delay is associated with improved overall survival, independent of concurrent chemotherapy. This suggest that strategies to minimize delays in radiation are crucial in locally advanced vulvar cancer.