The impact of brachytherapy boost and radiotherapy treatment duration on survival in patients with vaginal cancer treated with definitive chemoradiation

Abstract

PURPOSE: Vaginal cancer is a rare tumor that is optimally treated with a combination of chemotherapy (CHT) and radiation therapy. Because of the rarity of this cancer, the benefit of a brachytherapy boost (BT) and the relevance of radiotherapy time to treatment completion (TTC) are unclear. METHODS: Patients diagnosed between 2004 and 2015 with non-metastatic vaginal cancer treated with definitive CHT and external beam radiotherapy with or without BT but with no surgery were identified in the National Cancer Database. Overall survival (OS) was assessed with Kaplan-Meier curves, and differences between groups were compared with the log-rank test. A Cox model was constructed to evaluate survival after controlling for confounders. A Cox model using a penalized spline function was constructed to evaluate how the length of radiation therapy correlated with OS among patients receiving BT. RESULTS: A total of 1094 patients who met the inclusion criteria were identified. The utilization of BT was associated with improved 5-year OS (62.9% vs. 49.3%, p 5 0.0126) on propensity scoreweighted analyses. TTC of 63 days or less was associated with improved 5-year OS (67.8% vs. 54.5%, p 5 0.0031) in patients who underwent BT. Other factors associated with improved OS in patients who received CHT, external beam radiotherapy, and BT were younger age, absent comorbidity score, and negative lymph nodes. CONCLUSIONS: A brachytherapy boost and shorter TTC were associated with a survival benefit in a cohort of patients with non-metastatic vaginal cancer treated with definitive chemoradiotherapy.

Development and validation of models for predicting the overall survival and cancer-specific survival of patients with primary vaginal cancer: A population-based retrospective cohort study

“…The radioactive implants and radioisotopes correspond to brachytherapy. We also found that beam plus implants or only implants had better effectiveness than beam radiation, similar to published studies ( 7 , 9 , 12 , 14 , 38 , 43 , 44 ). Some studies argued that image-guided brachytherapy might improve the effectiveness of brachytherapy ( 45 – 47 ).…”

Updates in the treatment of vaginal cancer

“…27 Another study looking at the NCDB database with patients treated with only CCRT for vaginal cancer also found that brachytherapy boost was associated with an improved 5 year overall survival (62.9% vs 49.3%, p=0.0126). 28 These findings are similar to results from large database studies in cervical cancer. [29][30][31] TECHNIQUES Brachytherapy techniques vary depending on the tumor's response and the site of the disease.…”

“…Patients with tumor size >5 cm had the most significant benefit from brachytherapy 27. Another study looking at the NCDB database with patients treated with only CCRT for vaginal cancer also found that brachytherapy boost was associated with an improved 5 year overall survival (62.9% vs 49.3%, p=0.0126) 28. These findings are similar to results from large database studies in cervical cancer 29–31…”

Clinical outcomes of distal vaginal and vulvar cancer treated with image-guided brachytherapy

“…As such, although the study by Yang et al reported similar outcomes with the use of primary surgery or radiation, definitive radiation, either with or without chemotherapy, is often pursued in an attempt to avoid the toxicity associated with surgery. Within radiation treatments available, the inclusion of BT has been associated with improved outcomes in several studies [15,[21][22][23].…”