Comparison Of Patient-Reported Outcomes And Acute Toxicities In Oropharyngeal Cancer Patients Treated With Vmat Vs Impt

IMPT offers superior normal tissue sparing compared to VMAT for the treatment of oropharyngeal cancer (OPC). Our aim was to determine if these dosimetric differences translate into clinical gains. Inclusion criteria were OPC patients receipt of IMPT or VMAT to 70 Gy for definitive RT or >60 Gy for adjuvant RT from 2013 to 2018. All patients underwent prospective assessment using patient-reported (EORTC QLQ-H&N35) and physician-reported outcomes. PEG tube, hospitalization, and narcotic use data were retrospectively collected. Differences at the end of treatment were compared with pretreatment baseline. A priori stratification was performed for definitive vs. adjuvant RT, concurrent chemotherapy (CRT), and RT laterality. Statistical analysis used the Wilcoxon Rank Sum Test for PROs/physician-reported toxicities with propensity matching, and unpaired t tests for other clinical outcomes. Propensity scores were applied to a linear regression model using inverse probability weighting. 46 IMPT and 259 VMAT patients were included. Baseline patient and tumor characteristics were similar except for greater tobacco use in the VMAT group. More IMPT patients completed PRO assessments (93.5% vs. 44%). In the overall cohort, PROs showed reduced cough (p=0.019), need for nutritional supplements (p=0.039), and a trend to less change in taste (p=0.054) with IMPT. Patients treated definitively with IMPT also reported feeling less ill (p=0.037), and showed trends for reduced need for feeding tube (p=0.06) and better swallow (p=0.12). Patients treated with unilateral RT using IMPT had less dry mouth (p=0.039), sticky saliva (p=0.044), and change in taste (p=0.048). Physician-reported toxicities demonstrated less pain (p<0.001), mucositis (p<0.001), and anorexia (p=0.102 overall cohort, p=0.028 for adjuvant RT) with IMPT, but more dermatitis (p=0.013) and mucosal infection (p=0.002). The IMPT group had a lower likelihood of PEG tube placement (OR=0.44, p=0.006), hospitalization within 60 days (OR=0.28, p=0.009), and a relative risk reduction of 22.3% for end of treatment narcotic use. Subgroup analysis showed that differences attributable to IMPT in PEG placement rates were most evident in patients treated definitively (26% vs. 63%, p=0.001) or with CRT (25% vs. 56%, p<0.001). The difference approached significance for adjuvant RT patients (10.5% vs. 32%, p=0.069). With hospitalization, subgroup analysis showed that IMPT offered significant benefits only in patients receiving CRT (8% vs. 40%, p<0.001) or definitive RT (3.7% vs. 43%, p<0.001). IMPT was associated with improvements in PROs compared with VMAT for OPC. Among physician-reported toxicities, mucositis and pain were decreased with IMPT at the expense of increased dermatitis and mucosal infection. IMPT offered lower rates of PEG tube placement, hospitalizations, and narcotic pain medicine requirements. Benefits were predominantly seen in those treated definitively or with CRT.