Dose and Volume De-Escalation for HPV-Positive Oropharyngeal Cancer is Associated with Favorable Post-Treatment Functional Outcomes

Abstract

To report functional outcomes for patients with HPV+ oropharyngeal cancer treated on a phase II protocol of risk- and induction chemotherapy response-adapted dose and volume de-escalated radiation (RT)/chemoradiation (CRT). Patients were stratified as low-risk (LR) or high-risk (HR) according to T/N-stage and smoking history. Induction chemotherapy was followed by radiographic response assessment. LR patients with ≥50% response received 50Gy RT (RT50) whereas LR patients with 30-50% response or HR patients with ≥50% response received 45Gy CRT (CRT45). All other patients received 75Gy CRT (CRT75) with RT limited to the first echelon of uninvolved nodes. Pre- and post-RT/CRT oropharyngeal motility studies were performed. Percutaneous endoscopic gastrostomy (PEG) tube placement, body mass indices (BMI), and narcotic use were recorded. Statistical comparisons used logistic regression, the Mann-Whitney U test, the chi square test, or Fisher’s exact test as appropriate. Twenty-eight LR and 34 HR patients were enrolled, and 49 completed RT50/CRT45 while 11 completed CRT75. PEG-tube dependency at the end of RT/CRT and 3 months post-RT/CRT significantly differed according to risk- and treatment groups (all p<0.05, see table). Treatment intensity independently associated with 3-month PEG status while adjusting for risk group (p=0.002). The CRT75 group had a median -8.42% change from baseline BMI one year post-RT/CRT vs. -2.54% for the RT50/CRT45 group (p=0.01). At the end of RT/CRT, CRT75 patients were less likely to tolerate a normal diet, more likely to have Swallowing Performance Status Scale (SPS) scores ≥4 corresponding to at least mild-moderate dysphagia, more likely to have Rosenbek’s penetration-aspiration scores ≥6, more likely to have developed trismus, and more likely to require narcotics >2 months (all p<0.05, see table). Induction chemotherapy followed by risk- and response-adapted dose and volume de-escalated RT/CRT is associated with clinically meaningful functional outcomes including (1) improved swallowing function, (2) higher BMI, and (3) lower narcotic use for patients receiving de-escalation.Abstract 2959; Table 1Post-RT/CRT Swallowing Outcomes by Risk- and Treatment Group*Low RiskHigh RiskP-valueRT50/CRT45CRT75P-valueNo. (%)No. (%)No. (%)No. (%)PEG-Tube DependenceEnd of RT/CRT2 (7)16 (50)0.00059 (18)9 (82)0.00013-months post-RT/CRT1 (4)11 (34)0.0035 (10)7 (64)0.0005Regular Diet/Thin Liquids19 (86)20 (74)0.4835 (88)4 (44)0.01SPS Score ≥46 (27)8 (31)0.798 (21)6 (67)0.01Rosenbek’s Penetration-Aspiration Scale ≥64 (18)7 (27)0.515 (13)6 (67)0.002Developed Trismus2 (11)3 (15)1.002 (6)3 (43)0.03Narcotic Use > 2 Months13 (48)17 (59)0.4323 (48)7 (88)0.04***Denominator for percentages includes patients with available data for each outcome**One-sided Fisher's exact test Open table in a new tab