Elective upper-neck irradiation an option in N0–N1 NPC

Elective upper-neck irradiation provides similar regional control, with a lower incidence of late toxicity, compared with standard whole-neck irradiation in patients with N0–N1 nasopharyngeal carcinoma (NPC), a phase III trial in China has shown.

After a median follow-up of 53 months, 3-year regional relapse-free survival (the trial’s primary endpoint) was comparable between patients randomized to receive elective upper-neck irradiation of the uninvolved neck (n=224) and those who received standard whole-neck irradiation of the uninvolved neck (n=222) (97.7 percent vs 96.3 percent; difference, -1.4 percent; 95 percent confidence interval [CI], -4.6 to 1.8; p_{noninferiority}<0.0001). [Lancet Oncol 2022;doi:10.1016/S1470-2045(22)00058-4]

Rates of acute radiation-related toxic effects were similar between the upper-neck and whole-neck irradiation groups. However, patients treated with upper-neck irradiation had lower incidence rates of late toxicity, including any-grade hypothyroidism (30 percent vs 39 percent), skin toxicity (14 percent vs 25 percent), dysphagia (17 percent vs 32 percent), and neck tissue damage (23 percent vs 40 percent), than those treated with whole-neck irradiation.

“No patients died during treatment. After treatment, one patient in the whole-neck irradiation group died from a non–cancer-related cause [dermatomyositis],” the investigators reported.

The open-label, noninferiority, randomized controlled trial included 446 patients with

untreated, nonkeratinizing, nondistant metastatic (M0), N0–N1 NPC with a Karnofsky performance status score of ≥70, who were recruited from three Chinese medical centres.

The patients were randomized between 22 January 2016 and 23 May 2018 to receive elective upper-neck irradiation or standard whole-neck irradiation of the uninvolved neck at total radiation doses of 70 Gy for the primary tumour volume and enlarged retropharyngeal nodes, 66–70 Gy for the involved cervical lymph nodes, 60–62 Gy for the high-risk target volume, and 54–56 Gy for the low-risk target volume, administered in 30–33 fractions, five fractions per week. Additionally, patients with stage II–IVA disease were recommended to receive combined intravenous cisplatin-based chemotherapy, either as induction chemotherapy followed by concurrent chemoradiotherapy, or as concurrent chemoradiotherapy alone.

“Elective upper-neck irradiation of the uninvolved neck provides similar regional control and results in less radiation toxicity compared with standard whole-neck irradiation in patients with N0–N1 NPC,” the investigators concluded.