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Radiotherapy was non-inferior vs chemoradiotherapy in patients with nasopharyngeal carcinoma, and less toxicity was observed with radiotherapy alone.
Rui Guo, MD
Radiotherapy alone yielded non-inferior overall survival (OS) and failure-free survival (FFS) rates vs radiotherapy with concurrent chemoradiotherapy (CCRT) in patients with low-risk nasopharyngeal carcinoma, according to final OS data from a phase 3 trial (NCT02633202) presented at the 2024 ASCO Breakthrough Conference.1
At a median observation time of 44 months (IQR, 32-58), the HR for FFS, which represented the study's primary end point, was 1.36 (95% CI, 0.70-2.66; P = .85). Additionally, at a median follow-up of 70.1 months, the 5-year OS rate was 95.2% among patients who received intensity-modulated radiation therapy (IMRT) alone (n = 172) vs 98.2% among patients who received the current standard-of-care of CCRT (n = 169; HR, 2.27; 95% CI, 0.70-7.40; P = .16). The difference in 5-year FFS rates was not statistically significant, at 86.2% compared with 88.4%, respectively (HR, 1.16; 95% CI, 0.64-2.07; P = .63). Subgroup analysis data also showed that OS results were consistent across patient subgroups, including N categories and disease stages.1,2
“This low-risk nasopharyngeal carcinoma subgroup can be safely treated with IMRT alone instead of CCRT which provides non-inferior survival and disease control [and] reduces toxicities and improves quality of life. Our trial supports IMRT alone as a valid option for [patients with] low-risk T1-2N1 and T3N0 nasopharyngeal carcinoma,” Rui Guo, MD, of the Department of Radiation Oncology at Sun Yat-sen University Cancer Center in China, said during the presentation.
Late treatment-related toxicities in the safety populations of the IMRT alone arm (n = 165) vs the chemoradiation arm (n = 169) occurred at grade 1 (77.5% vs 81.0%), 2 (38.7% vs 51.4%), and 3 to 4 (4.84% vs 2.95%). Notably, hearing impairment according to the Hearing Handicap Inventory for Adult-Screening (HHIA-S) criteria showed that hearing impairment was more prevalent in the chemoradiation arm (39.4%) compared with the IMRT alone arm (29.6%). Patients treated with IMRT experienced mild (22.2%) and severe (7.4%) hearing impairment whereas those in the chemoradiation arm experienced increased rates of mild (28.9%) and severe (10.5%) hearing impairment. Mild impairment was defined as a total score of 8 to 24 and above 24 was defined as severe per HHIA-S criteria.1
“Our previous results showed that IMRT alone [demonstrated] non-inferior 3-year FFS compared with chemoradiotherapy—90.5% vs 91.9%, respectively—with a difference which matched the non-inferiority margin,” Guo said. “During the entire treatment course there was a significantly lower incidence of reported grade 3 or 4 adverse effects [AEs] in the IMRT alone group compared with chemoradiotherapy.”
Investigators conducted the randomized, open-label, non-inferiority trial at 5 hospitals in China to examine CCRT, the standard treatment for patients with stage II nasopharyngeal carcinoma, as cisplatin-based CCRT increases severe acute AEs and late occurring toxicities. Guo noted that “supportive evidence related to the roles of CCRT was based on 2D-CRT. High-level evidence regarding the role of chemotherapy for this population in the IMRT era is lacking.”
Patients enrolled in the study had low-risk nasopharyngeal carcinoma which was defined as stage II/T3N0M0 disease without adverse features including all nodes less than 3 cm, no level IV/Vb nodes, no extranodal extension, and Epstein-Barr virus DNA of less than 4000 copies/mL.1 CCRT consisted of IMRT given with cisplatin 100 mg/m2 every 3 weeks for 3 cycles. The recommended dose of IMRT was 69 to 70 Gy at 2.0-2.2 Gy per fraction administered once daily in 5 fractions every week.3
Baseline patient characteristics were well-balanced between the investigational and control arms; the median age was 48 years (range, 22-65) vs 48 years (range, 23-65), respectively. Most patients in the IMRT alone arm vs CCRT arm were male (68% vs 72%) and had parapharyngeal involvement (71% vs 68%). Disease stages included T2N0 (16% vs 12%), T3N0 (25% vs 26%), T1N1 (21% vs 20%), and T2N1 (38% vs 42%), respectively.3
Further data showed that the most common grade 1 late treatment-related AEs in the investigational and control arms included dry mouth (49.6% vs 43.1%), auditory/hearing (36.9% vs 41.4%), skin/neck tissue damage (24.2% vs 32.5%), hypothyroidism (14.5% vs 25.4%), and peripheral neuropathy (7.87% vs 15.3%), respectively. Grade 3 to 4 late treatment-related AEs occurring in the IMRT arm vs chemoradiation arm included hypothyroidism (2.42% vs 0.59%), dry mouth (1.21% vs 1.18%), auditory/hearing (0.60% vs 1.18%), and skin/neck tissue damage (0.60% vs 0.0%), respectively.1
Disclosures: This research was funded by the National Natural Science Foundation of China,Natural Science Foundation of Guangdong Province, Key-Area Research and Development Program of Guangdong Province, Overseas Expertise Introduction Project for Discipline Innovation, Sun Yat-Sen University Clinical Research 5010 Program, and the National Key Research and Development Program of China.