Optimal cumulative dose of cisplatin for concurrent chemoradiotherapy among patients with non-metastatic nasopharyngeal carcinoma: a multicenter analysis in Thailand.

BACKGROUND: Chemoradiotherapy (CRT) with high cumulative doses (CDs) of cisplatin has been considered the standard of care for non-metastatic nasopharyngeal carcinoma (NPC). However, given most patients' inability to tolerate high CDs due to cisplatin-related toxicities, the optimal CD of cisplatin during CRT remains undetermined. METHODS: Patients with non-metastatic NPC who received CRT with cisplatin between 2007 and 2017 were identified through the Thai head and neck cancer multicenter database and then categorized according to cisplatin CD (mg/m2) received. All complications and cisplatin-related toxicities during CRT were recorded. RESULTS: We identified 779 non-metastatic NPC patients receiving low (≤150; n = 97), intermediate (151-250; n = 411), and high (> 250; n = 271) CDs of cisplatin. Low CD patients had significantly lower mean actual radiation dose (p < 0.001) and more radiotherapy delay (p = 0.010), while intermediate CD patients had the least hospitalization (p < 0.001). Overall, 39.3% of the patients experienced cisplatin-related toxicity, which was associated with poor overall survival (OS) (p = 0.001). Acute kidney injury was observed in 7% in all patients, which was highest among low CD patients (15.5%; p = 0.002). Intermediate CD patients had significantly longer median OS than the low and high groups (64 vs. 49.8 vs. 53.2, respectively; p = 0.015). Univariate, but not multivariate, analysis showed that CD of cisplatin was significantly associated with OS. CONCLUSION: CD of cisplatin during CRT was not an independent prognostic factor for OS. An intermediate CD induced minimal toxicity without compromising survival and should be considered the optimal CD. Nonetheless, a randomized phase 3 study evaluating the optimal CD of cisplatin is warranted.