Recursive Partitioning Analysis Identifies Pretreatment Risk Groups for the Utility of Induction Chemotherapy Before Definitive Chemoradiation Therapy in Esophageal Cancer

Purpose To assess the contribution of induction chemotherapy (IC) before definitive chemoradiation therapy (dCRT) in patients with esophageal cancer (EC) based on recursive partitioning analysis (RPA). Methods and Materials A total of 496 eligible patients with EC staged by positron emission tomography (PET) who received dCRT from 1998 to 2015 were included, 162 (32.7%) of whom underwent IC before dCRT. RPA was used to risk-stratify patients on the basis of independent prognostic factors to predict progression-free survival (PFS). Outcomes were compared between treatment groups. Results The median follow-up time was 49.1 months (range, 7.0-155.9 months) for survivors. Compared with the non-IC group, the IC group had a comparable 5-year PFS rate (21.0% vs 23.4%; P=.726) in the whole cohort. Multivariate analysis identified age, performance status, primary tumor length, baseline PET maximum standard uptake value (SUV_max), and maximum lymph node diameter as independent prognostic factors for PFS. RPA segregated patients into 3 prognostic groups: low-risk group (PET SUV_max <9.7 and tumor length ≤5 cm), intermediate-risk group (PET SUV_max ≥9.7 and age ≥67), and high-risk group (PET SUV_max <9.7 and tumor length >5 cm, or PET SUV_max ≥9.7 and age <67). Significant improvements in PFS (P=.006) and locoregional failure–free survival (P=.028) in the IC group in comparison with the non-IC group were observed in high-risk patients, whereas no differences in survival were found between the 2 treatment groups in low-risk or intermediate-risk patients. After propensity score matching, the high-risk group still demonstrated a significantly improved PFS with IC (P=.009). Conclusions The RPA prognostic grouping provides a useful method of selecting high-risk EC patients who may benefit from IC before receiving dCRT. Prospective validation is warranted.