Staging of esophageal cancer in patients treated with initial chemoradiation: Findings of the patterns of care study (PCS)

Abstract

Patients with esophageal cancer who do not have esophagectomy as initial treatment must undergo endoscopic ultrasound staging (EUS) to be staged by the current AJCC staging system. Since most patients do not undergo EUS prior to therapy, a modified 1983 AJCC staging system has been used by the PCS (Table 1). This study examines the merits of EUS (AJCC 1997) and PCS staging for patients with esophageal cancer treated initially with chemoradiation. PCS conducted nationwide process and outcome surveys in 1992–1994 and 1996–1999 on 818 patients with esophageal cancer who were treated with radiation as a component of their definitive management. Follow-up information was available for 802 of these patients, which represents a weighted sample size (wss) of 10,180 patients nationwide. Of these patients, 82 (wss=955) underwent pre-chemoradiation EUS staging and form the basis for this retrospective investigation. Statistical analysis was performed using the SUDAAN statistical software to allow the incorporation of the design elements and weights that reflect the relative contribution of each institution and each patient in this study. Kaplan-Meier estimates of the survivor function were obtained within defined stage levels. Multivariate and univariate comparisons of survival times were made using the Cox proportional hazards model. The clinical stage distribution for 82 patients per both PCS and EUS stage was: PCS I/II 29%, PCS III 71%; EUS I/II 48%, EUS III 52%. Of PCS I/II, 14% were EUS III and of PCS III, 32% were EUS I/II. The hazard ratios (HR) for death increased by PCS stage for all 802 patients (wss=10,180), (I=1.0, II=1.16,III=1.93) (III vs. I, p < 0.01).Three-year survival for all patients was 44%, 36% and 18% for PCS stage I, II,sIII respectively. The HR for death demonstrated a trend for the 82 patients (wss = 955) by EUS stage (EUS I/II = 1.0, III = 2.3; p = 0.12), as well by PCS stage (PCSI/II=1.0,III=2.5;p = 0.25). For patients staged by both PCS and EUS, significant survival differences were seen for patients with PCS III, EUS I/II (HR 0.46; p = 0.05) vs. PCS III, EUS III (HR 1.0). Three prognostic groups were identified: Group 1: PCS I/II, EUS any; Group 2: PCS III, EUS I/II and Group 3: PCS III, EUS III. Three-year survival was 83%, 61% and 29% for Groups 1, 2 and 3 respectively. Multivariate analysis of the components of each staging system indicated only tumor length ≤5 cm (HR 1.0) vs. >5 cm (HR 10.3; p = 0.03)to be statistically significant. For patients with esophageal cancer who were managed initially with chemoradiation, both the PCS staging system and EUS staging system (1997 AJCC)are of prognostic significance. EUS staging provides additional prognostic information for patients with PCS stage III esophageal cancer, and therefore should be strongly encouraged in addition to PCS staging.