Comparison of involved-field intensity-modulated radiotherapy combined with S-1 vs radiotherapy alone for elderly patients with esophageal cancer

BACKGROUND It is estimated that about 30% of esophageal cancer (EC) patients are over 70 years old. Therefore, there is less evidence on the diagnosis and management of elderly EC patients. It is important to explore how elderly EC patients benefit from radical radiochemotherapy regimens, including the target area of radiotherapy (RT), radiation dose and fraction, and choice of chemotherapy drugs. AIM To compare the efficacy of involved-field intensity-modulated RT (IF-IMRT) combined with S-1 vs RT alone in the treatment of elderly EC patients in terms of safety, short-term response, and survival. METHODS Thirty-four EC patients aged > 70 years were prospectively enrolled between December 2017 and December 2019. Based on the random number table, they were divided into an IF-IMRT + S-1 group and an IF-IMRT alone group, with 17 patients in each group. All patients were treated with IF-IMRT at a dose of 50.4-56 Gy in 28-30 fractions (1.8-2 Gy/fraction, 5 fractions/wk). Oral S-1 was administered concomitantly in the IF-IMRT + S-1 group for 14 consecutive days, and a second cycle was started 7 d after drug withdrawal. After RT, 4 cycles of S-1 treatment were offered as the consolidation chemotherapy. The safety, short-term response, and survival were observed after the treatment. RESULTS As of April 2022, these 34 patients had been followed up for 15.2-32.5 mo, with a median follow-up period of 24.5 mo. Complete efficacy indicators were obtained from all the patients. The objective response rate was 88.2% vs 76.5%, respectively, in the IF-IMRT + S-1 group and the RT alone group, where as the disease control rate was 100% vs 82.4%, respectively. The incidence of adverse events including grade 1-2 fatigue, granulocytopenia, thrombocytopenia, anemia, radiation esophagitis, radiation-induced skin injury, and radiation-induced lung injury was not significantly different between these two groups, so was the incidence of the grade 3 radiation esophagitis (0% vs 5.7%). The rate of progressive disease (PD) was 52.9% (n = 9) in the IF-IMRT + S-1 group and 64.7% (n = 11) in the RT alone group. The median progression-free survival (PFS) was 23.4 mo vs 16.3 mo, and the 2-year PFS rate was 42% vs 41.2%. The median overall survival (OS) was 27.0 mo vs 23.0 mo, and the 2-year OS rate was 58.8% vs 47.1%. Multivariate analysis showed that age was a significant prognostic factor (P = 0.0019); patients aged < 75 years had a significant survival advantage over patients aged >= 75 years. The locations of EC also affected the prognosis. In the IF-IMRT + S-1 group, the number of chemotherapy cycles was a significant prognostic factor (P = 0.0125), and the risk of PD was significantly lower in EC patients who had received 6 cycles of chemotherapy than those who had received 2-5 cycles of chemotherapy. CONCLUSION Compared with IF-IMRT alone, IF-IMRT + S-1 shows the benefits of preventing PD and prolonging survival without increasing adverse reactions. Therefore, this concurrent radiochemotherapy deserves clinical application.