Impact of the G8 Score on Treatment Strategies and Outcome in Definitive Radiotherapy for the Elderly Esophageal Cancer Patients

Abstract

Although chemoradiotherapy (CRT) is widely used as a curative treatment for esophageal cancer, it is often difficult to perform standard CRT for the elderly in the real world. This study aimed to investigate the impact of the Geriatric 8 (G8) score on treatment strategies and outcome in definitive radiotherapy (RT) for elderly esophageal cancer patients. We analyzed 81 esophageal cancer patients aged ≥65 years who received definitive RT between 2018 and 2021. The G8 score was acquired at the first visit to the radiation oncology department. The treatment strategy was decided by a multi-disciplinary conference, and the G8 score was not used to determine the treatment strategy. Standard treatment (standard CRT) was defined as RT with elective nodal irradiation and a total dose ≥50 Gy, and chemotherapy with two cycles of platinum (70 mg/m2) and 5FU (700 mg/m2 for 4 days) concurrently. The Kaplan-Meier method was used to generate actual survival curves. The Common Terminology Criteria for Adverse Events (CTCAE) version 5.0 was used to assess toxicities. The Mann-Whitney U test was used to compare the two groups, and statistical significance was set at p<0.05. The Receiver Operating Characteristic (ROC) curve was used to calculate the cutoff value. The Median follow-up time was 30 months (range: 8-51) for survivors. The mean G8 scores by treatment strategy were 13.9 (range: 9-17) for standard CRT group (n = 26), 12.1 (range: 7-16) for reduced CRT group (n = 30), and 9.7 (range: 4.5-14) for RT alone group (n = 25). G8 score was significantly higher for standard CRT (p = 0.017) and significantly lower for RT alone (p<0.01). The cut-off value of the G8 score for standard treatment, calculated by the ROC curve, was 12.5 points. In the non-standard treatment group, the cut-off value of the G8 score for RT alone, calculated by the ROC curve, was 10.5 points. The 2-year overall survival (OS) rates for standard CRT, reduced CRT and RT alone were 74%, 71% and 35%, respectively, and significantly lower in RT alone (p<0.001). The 2-years OS rates for G8 score >10.5 points and ≤10.5 points were 69% and 48%, respectively (p = 0.039). Grade 3 or higher acute toxicities were observed in 33 patients (41%); 14 (54%) in standard CRT, 17 (57%) in reduced CRT and 2 (8%) in RT alone. Grade 5 acute toxicity was not observed. G8 scores tended to be higher in the patients with grade 3 or higher acute toxicities, but the difference was not statistically significant (p = 0.057). Grade 3 or higher late toxicities were observed in 7 patients. Our results suggest that there is an association between the G8 score and clinicians' treatment decisions. Although RT alone could be safely performed even in patients with low G8 scores, administration of chemotherapy strongly affected prognosis. These results suggest the importance of developing less toxic systemic therapy regimens for patients with low G8 scores.