Omission of concurrent chemotherapy in and out of a phase III randomized controlled trial for stage II nasopharyngeal carcinoma.

6085 Background: In the era of intensity-modulated radiotherapy (IMRT), the precision of radiotherapy has been greatly enhanced, allowing for more precise targeting of tumor tissue while minimizing damage to surrounding normal tissues. Therefore, whether radiotherapy alone can replace the traditional chemoradiotherapy regimen, which may cause substantial side effects, particularly hematologic toxicity, gastrointestinal adverse reactions, and immune suppression, has become a key focus of current clinical research. This investigation explores the potential benefits of IMRT as a standalone treatment, particularly its ability to offer similar efficacy in terms of overall survival and disease control while sparing patients from the added toxicities associated with chemotherapy. Methods: In a parallel-group, multicenter, randomized, controlled phase III trial, we compared cisplatin-based concurrent chemoradiotherapy with radiotherapy alone. Stage II NPC patients (2010 UICC staging) were randomly assigned in a 1:1 ratio to receive concurrent chemoradiotherapy (IMRT combined with cisplatin, 100 mg/m² every 3 weeks for 3 cycles) or IMRT alone. The primary endpoint was overall survival in the intention-to-treat population. Secondary endpoints included progression-free survival, locoregional relapse-free survival, distant metastasis-free survival, and safety. Results: A total of 211 patients were enrolled (106 in the IMRT alone group, 105 in the concurrent chemoradiotherapy group). The median follow-up time was 37 months. The 3-year overall survival rate was 96.3% for the IMRT alone group and 98.2% for the concurrent chemoradiotherapy group (HR = 0.650, 95% CI: 0.109-3.889; p-value = 0.637). No significant differences were observed between the groups in progression-free survival, locoregional recurrence, or distant metastasis (all p-values > 0.05). The incidence of grade 3-4 adverse events was significantly lower in the IMRT alone group (p-value < 0.05), including hematologic toxicity (leukopenia) and non-hematologic toxicity (hypokalemia). Conclusions: In stage II NPC patients, IMRT alone can achieve comparable 3-year overall survival to concurrent chemoradiotherapy, while significantly reducing side effects, which may provide a feasible treatment option for these patients, particularly for those with early-stage II nasopharyngeal carcinoma, where radiotherapy alone offers high therapeutic potential and lower treatment risks. Clinical trial information: NCT02610010 .