Individualized treatment of head neck squamous cell carcinoma patients aged 70 or older with radiotherapy alone or associated to cisplatin or cetuximab: impact of weekly radiation dose on loco-regional control

The purpose of this study is to evaluate if, in elderly HNC patients, loco-regional control (LRC) is influenced by average weekly radiation dose (AWD). From 2009 to 2017, 150 consecutive HNC elderly patients were analyzed. AWD was calculated by dividing total dose in Gray by overall treatment time in weeks. Patients were divided in 2 groups: Group 1 (70-75years) and Group 2 (>75years). Primary endpoint was LRC; secondary endpoints were overall survival (OS) and compliance to treatment. The median age was 76years (range 70-92), the distribution of patients by age was 72 and 78 patients in Group 1 and in Group 2, respectively; overall median follow-up was 23months. Optimal cut-off of AWD for LRC was 9.236 (p=0.018). Median OS was 73months. In univariate survival analysis low PS (p=0.005), T3-T4 (p=0.021), Stage III-IV (p=0.046) and AWD(Low) (<9.236) (p=0.018) were significantly associated with lower LRC; low PS (p<0.001) and Group 2 (p=0.006) were also associated with lower OS. Considering patients treated with radiotherapy alone AWD(Low) was significantly associated with lower LRC (p=0.04) whereas among patient treated with chemoradiotherapy AWD did not affected LRC (p=0.18). The multivariate analysis confirmed the significant value of PS for the prediction of LRC and OS (p=0.035 and p<0.001, respectively). In elderly patients an AWD of>9.236Gy was found to be beneficial for RT alone regimen. When radiotherapy alone is indicated in elderly patients an effort should be made to maintain an increased AWD in order to improve LRC.