Definitive chemoradiotherapy with paclitaxel for locally advanced esophageal squamous cell carcinoma in older...

In older patients, esophageal squamous cell carcinoma (ESCC) is difficult to treat using standard therapies, including surgery and cisplatin-based chemoradiotherapy. Paclitaxel (PTX) has radiosensitizing activity. We conducted a phase I trial of PTX combined with radiotherapy to establish a standard therapy for locally advanced ESCC in older patients.

Enrollment was conducted at six centers in Japan from April 2016 to September 2019. The participants were aged ≥ 70 years, had locally advanced ESCC, and were intolerant to surgery or unwilling. A fixed 60-Gy radiation dose was administered in 30 fractions. PTX dosing levels started at 30 mg/m² weekly for 6 weeks. Depending on the number of DLTs, the dose was set to be increased by 10 mg/m² or switched to biweekly. A geriatric assessment was performed before treatment using the Geriatric-8 screening tool. The primary endpoint was dose-limiting toxicity (DLT).

We enrolled 24 patients (6 per group); DLT was observed in one (grade 4 hypokalemia), one (grade 3 aspiration), two (grade 3 radiodermatitis, grade 3 esophageal hemorrhage), and two (grade 3 anorexia, grade 5 pneumonitis) patients in the weekly PTX 30, 40, 50, and 60 mg/m² groups, respectively. All adverse events, except death in the 60 mg/m² group, showed reversible improvement, and the safety profile was considered acceptable. The 2-year survival and complete response rates were 40.0% and 54.2%, respectively. There was a significant difference in survival between favorable and unfavorable Geriatric-8 scores.

The recommended PTX dose with concomitant radiation was determined to be 50 mg/m² weekly. Phase II trials at this dose are underway.