Induction Radiation Therapy for Esophageal Cancer: Does Dose Affect Outcomes?

Abstract

Background: Wide variation is seen in the dosage of preoperative induction radiation therapy for esophageal cancer. We investigated associations between outcomes after esophagectomy and dosage of induction radiation therapy.

Methods: Patients undergoing induction radiation therapy (30 to 70 Gy), followed by esophagectomy, were identified from the National Cancer Database and classified as low (<40 Gy), standard (40 to 50.4 Gy), and high dose (>50.4 Gy). Perioperative outcomes and overall survival were compared. Subgroup analysis compared two common dosages: 45 Gy and 50.4 Gy.

Results: From 2004 to 2014, 10,738 patients (84.7%) received standard-dose radiation, increasing from 69.7% in 2004 to 93.6% in 2014 (p < 0.001), 1,329 (10.5%) received low-dose radiation, and 608 (4.8%) received high-dose radiation. Higher rates of pathologic complete response (pCR; low: 11.7%, standard: 16.2%, high: 21.0%; p < 0.001) and downstaging (low: 52.0%, standard: 56.4%, high: 63.1%, p = 0.001) were observed as the dosage increased. On multivariable analysis, compared with standard-dose, high-dose radiation was associated with higher 30-day mortality (odds ratio [OR], 2.11; p < 0.001) without a higher likelihood of downstaging or pCR. Low-dose radiation was associated with lower likelihood of downstaging (OR, 0.85; p = 0.04) and pCR (OR, 0.67; p < 0.001) without lowering the risk of 30-day mortality. The dose of 50.4 Gy was associated with higher likelihood of pCR (OR, 1.12; p = 0.04), without affecting 30-day mortality, compared with 45 Gy.

Conclusions: High-dose induction radiation (>50.4 Gy) is associated with increased perioperative death after esophagectomy, without a significant improvement in tumor response. Low-dose radiation (<30 Gy) is associated with worse tumor response without a lower risk of perioperative death. Within standard dosages, 50.4 Gy is associated with higher likelihood of pCR without adversely affecting perioperative mortality compared with 45 Gy.