Clinical Outcome of Immune Checkpoint Inhibitor Combination Chemotherapy for Unresectable Advanced Esophageal Squamous Cell Carcinoma in Elderly Patients

Background Until recently, elderly patients aged 75 years or older with unresectable advanced esophageal cancer were mainly treated with palliative therapies such as radiotherapy alone or esophageal stenting. In recent years, with the improvement of treatment results of unresectable advanced esophageal cancer with immune checkpoint inhibitors (ICIs), aggressive drug therapy is now being used for these patients. In the present study, we investigated the clinical outcomes of ICI combined chemotherapy (ICI + Ch) in elderly patients with unresectable advanced esophageal cancer at our hospital. Methods We compared the treatment details and outcomes of 9 elderly patients aged 75 years or older (group E) and 14 non-elderly patients (group C) out of 23 patients with unresectable advanced esophageal cancer who underwent ICI + Ch at our hospital. Results Seven patients (77.8%) in group E and 3 patients (21.4%) in group C received a reduced dose of chemotherapeutic agents. Regarding treatment outcomes, CR/PR/SD/PD were 1/4/4/0 in group E and 3/6/4/1 in group C. The 1-year progression-free rate was 15.8/50.7%, respectively, which were not significantly different but better in group C. Six patients (66.7%) in group E received aggressive subsequent treatment such as surgery or radical chemoradiotherapy, compared with 57.1% in group C. The resulting 1-year survival rate was 45.7/68.4%. Grade 3 or higher adverse events were similar in group C (88.9%) and group E (71.4%). Conclusion Elderly patients with unresectable advanced esophageal cancer have tended to avoid aggressive treatment because of the need to reduce the dose of chemotherapeutic agents, which is not expected to be effective. In the present study, ICI + Ch with reduced doses of chemotherapeutic agents was safe and comparable to standard chemotherapy, even in elderly patients. Prolonged prognosis can be expected with aggressive subsequent treatment, and ICI + Ch is useful for elderly patients with appropriate drug dosage adjustment.