Does the Planning Target Volume Correlate with Toxicity for Head and Neck Cancer Patients Undergoing Radiation? A Prospective Observational Study.

Tolerance to radiation depends on the tumor volume; the greater the volume, the higher the toxicities. In this study, we aimed to study the impact of planning target volume (PTV) on toxicities in head and neck cancer (HNC) patients assigned to receive radiation with or without chemotherapy. Planning target volume (PTV) of 35 histologically proven non-nasopharyngeal head and neck cancer patients undergoing radiation with or without chemotherapy was recorded in cubic centimeters (cc). Their PTV high risk (PTVH) and PTV low risk (PTVL) were correlated with mucositis and dermatitis assessed weekly during treatment and at 2 weeks and 6 weeks post treatment. Thirty-five patients were treated with chemoradiation. Their mean PTVH was 278.08 cc (83-812 cc). The mean PTVL was 505.5 (44-1173 cc). Grade II and above mucositis was seen around fourth week and dermatitis and dysphagia by the end of fifth week which persisted till 2 weeks post follow-up in majority of patients. A cutoff of PTVH > 220 cc and PTVL > 550 cc correlated with grade 2 and above toxicities. Head and neck cancer patients with PTV 66 Gy > 220 cc need to be monitored closely during chemoradiation as they are likely to develop severe grades of toxicities.