Evaluation of the efficacy of adjuvant radiotherapy versus chemoradiotherapy in patients with salivary gland tumors

Aims: The aim of this study was to compare the efficacy of adjuvant radiotherapy (RT) versus adjuvant chemoradiotherapy (CRT) in patients with salivary gland tumors (SGTs).

Materials and methods: Data from patients who underwent adjuvant RT for a diagnosis of SG cancer at Ankara Atatürk Education and Research Hospital, Ankara Numune Education and Research Hospital and Ankara Bilkent City Hospital between September 01, 2009 and September 01, 2022 were analysed retrospectively. We evaluated the efficacy of RT alone versus CRT in these patients in terms of acute response, treatment tolerance, overall survival (OS), and disease-free survival (DFS).

Results: Fifty-five patients who underwent RT between September 14, 2009 and August 04, 2022 at Ankara Atatürk Education and Research Hospital, Ankara Numune Education and Research Hospital and Ankara Bilkent City Hospital were included in this study. Eight patients who did not meet the study criteria were excluded; thus, the analysis was performed for 47 patients. The median follow-up period was 60 months (range: 6-160 months). The median patient age was 53 years (range: 18-86 years). Thirty-nine patients (83%) had parotid tumors and eight patients (17%) had submandibular cancer. The time from surgery to RT was 48 days (range: 20-126 days). Intensity-modulated radiotherapy was administered to all patients and the median RT dose was 66 Gy (range: 52-70 Gy). Concomitant chemotherapy (CCT) (40 mg/m 2 of cisplatin weekly) was administered to 13 patients (27.7%). Acute adverse events were observed in 17 patients (36.2%). Interruption of RT was noted for only six patients (12.8%), and this proportion did not differ significantly between the CRT and RT-only arms ( P = 0.538). Acute side effects were observed in 17 patients (36.2%), and there were no significant relationships between acute side effects and the administration of CCT ( P = 0.112). Recurrence was observed in 10 patients (21.3%). All recurrences were locoregional and no distant metastases were observed during the follow-up period. The median DFS of the patients was 48 months (range: 4-160 months), 1-year DFS was 86%, 2-year DFS was 83.5%, and 5-year DFS was 77.9%. There was no statistically significant difference in DFS between the adjuvant CRT and RT-alone arms ( P = 0.114). At the date of last follow-up, 14 patients (29.8%) had died. The median OS of the patients was 58.5 months (range: 6-160 months), 1-year OS was 91.4%, 2-year OS was 86.8%, and 5-year OS was 78%. There was no statistically significant difference in OS between the adjuvant CRT and RT-only arms ( P = 0.453).

Conclusion: Stage was identified as the most important prognostic factor for DFS and OS. No significant differences in OS, DFS, or acute side effects were observed between the CRT and RT-only arms. Additional studies are needed to identify the subgroup of SGT patients for which CRT is most warranted.