The prognostic impact of daytime and seasonality of radiotherapy on head and neck cancer.

BACKGROUND: The potential impact of daytime and season of radiotherapy application on prognosis is unclear. This was analyzed in a retrospective cohort of patients who were diagnosed with non-metastatic head and neck squamous cell carcinoma (HNSCC) and treated with definitive radiotherapy with or without chemotherapy. MATERIALS AND METHODS: Patient and tumor characteristics, treatment parameters and outcome until last follow-up or death were obtained. Median radiotherapy delivery daytime of each patient was categorized as morning (AM) and afternoon (PM). Treatment season was defined by median date of treatment course. Each year was divided into DARK and LIGHT according to equinoxes. Time-to-event endpoints were defined by first biopsy confirming the HNSCC. RESULTS: Six hundred fifty-five cases were identified who were treated with (chemo)radiotherapy between 2002 and 2015. Median follow-up was 47 months. No significant heterogeneity in patient, tumor and treatment characteristics were observed between DARK and LIGHT or regarding median daily fraction time (X2 p > 0.05). Five-year loco-regional control (73% vs. 61%; p = 0.0108) and progression-free survival (51% vs. 43%; p = 0.0374) were superior when radiotherapy was administered in DARK. Neither the daytime nor any other treatment time-related parameter affected prognosis. CONCLUSION: This is the first study investigating and presenting the prognostic impact of seasonality regarding the treatment course on loco-regional control and progression-free survival (DARK > LIGHT). The biological mechanism of action is unclear. These results should be interpreted with caution and our findings have to be validated externally.

The impact of delivery daytime and seasonality of radiotherapy for head and neck cancer on toxicity burden.

AIM: The potential impact of the daytime and season of radiotherapy application on acute and late toxicity burden was analyzed on a cohort of curatively treated head and neck squamous cell carcinoma patients. METHODS: Through a retrospective chart review, patient and tumor characteristics, treatment parameters and outcome were obtained. Patients treated with definitive or adjuvant radiotherapy with and without chemotherapy receiving ≥60 Gy between 2002 and 2015 were included (n = 617). Daily fraction times and dates were extracted. Median radiotherapy delivery time of each patient was categorized as morning (AM) and afternoon (PM). Treatment season was defined by the median day of the treatment course. Each year was divided into DARK and LIGHT by the March and September equinoxes. Acute (T) and late (A) toxicity were defined by TAME methodology. RESULTS: Median follow-up was 51 months. Mean T and A scores during and after radiotherapy in DARK vs. LIGHT were 1.98 vs. 1.61 (p = 0.0127) and 0.41 vs. 0.30 (p = 0.1699), respectively. Mean T and A scores during and after AM vs. PM radiotherapy were 1.71 vs. 1.88 (p = 0.0387) and 0.31 vs. 0.41 (p = 0.2638), respectively. Multivariate analyses indicated DARK vs. LIGHT as the only independent treatment time-related factor among other factors such as tumor subsite, UICC stage, radiotherapy technique, and chemotherapy for T. CONCLUSION: This is the first study investigating the impact of seasonality on toxicity burden, showing higher acute toxicity with radiotherapy in DARK. The daytime did not predict the toxicity. The hypothesis-generating findings of this retrospective study should be further investigated.

Incidence of second primary cancers after radiotherapy combined with platinum and/or cetuximab in head and neck cancer patients.

PURPOSE: The second primary cancer (SPC) incidence after treatment with platinum-based chemotherapy and cetuximab in combination with radiotherapy has not been previously reported. Our aim was to compare SPC risk following radiotherapy in combination with these agents for the treatment of head and neck squamous cell carcinoma (HNSCC). METHODS: The charts of 296 cases treated for loco-regionally advanced HNSCC between 2009 and 2015 were retrospectively reviewed for patient, tumor, and procedural characteristics. All patients were planned to undergo radiotherapy either with platinum compounds (group: Platinum) or monoclonal antibody cetuximab (group: Cetuximab). A third group of patients switched from platinum compounds to cetuximab due to toxicity (group: Switch). Treatment groups were evaluated for the incidence of SPC with log-rank test. Possible confounders were investigated with multivariate Cox's proportional hazards model. All tests were two-sided, and a p < 0.05 was set to indicate statistical significance. RESULTS: Median follow-up was 36 months. Platinum, Cetuximab, and Switch groups consisted of 158, 101, and 37 patients, respectively. Three-year overall survival in the whole cohort was 70%. The rate of SPC was comparable between Platinum (9.2%) and Cetuximab (11.5%) groups (p = 0.98), whereas the patients in the Switch group were exposed to a significantly higher incidence of SPC (23.3%) in 3 years (p = 0.01). The multivariate model indicated Switch to be the only variable correlating with an increased risk for SPC. CONCLUSIONS: The Switch strategy may expose the patients to an increased risk of developing SPC. The use of switch should be advocated with caution until robust pre-clinical and clinical data are available.