Proton therapy reirradiation confers survival benefits in head and neck cancer, with caveat

Treatment with proton therapy reirradiation (PT-ReRT) for head and neck cancer appears to improve survival outcomes in patients, but this benefit comes with substantial toxic effects, according to a study.

The retrospective cohort study included 242 patients (median age 63 years, 75.6 percent men) with head and neck squamous cell carcinoma who underwent PT-ReRT. Researchers looked at patient, clinical, and treatment characteristics and assessed survival outcomes including local control (LC), local-regional control, distant metastatic control, progression-free survival (PFS), and overall survival (OS).

Of the patients, 206 patients (85.1 percent) had recurrent disease, 231 (95.9 percent) had a Karnofsky performance status score of 70 or higher, and 145 (59.9 percent) had at least a 10–pack-year smoking history. Median follow-up was 12.0 months for all patients and 24.5 months for survivors.

Patients in the fractionated group received a median PT-ReRT dose of 70 cobalt gray equivalents (CGE), while those in the quad shot cohort received a median of 44.4 CGE. The median interval between radiation courses was 22 months.

The 1-year LC and OS rates were 71.8 percent (95 percent confidence interval [CI], 62.8–79.0) and 66.6 percent (95 percent CI, 58.1–73.8) in the fractionated group, respectively. The corresponding 1-year LC and OS rates in the quad shot group were 61.6 percent (95 percent CI, 46.4–73.6) and 28.5 percent (95 percent CI, 19.4–38.3).

Improved OS with PT-ReRT was predicted by Higher Karnofsky performance status scores (hazard ratio [HR], 0.50, 95 percent CI, 0.25–0.99; p=0.046) and receipt of salvage surgery prior to PT-ReRT (HR, 0.57, 95 percent CI, 0.39–0.84; p=0.005). On the other hand, receipt of quad shot was associated with worse OS (HR, 1.97, 95 percent CI, 1.36–2.86; p<0.001).

There were 73 cases of grade 3 and six cases of grade 4 early toxic effects. In addition, 79 potential grade 3, four grade 4, and five grade 5 late toxic effects were documented.