Prognostic factors following curative resection for pancreatic adenocarcinoma: a population-based, linked database analysis of 396 patients

Abstract

Objective: To analyze prognostic factors influencing pancreatic cancer survival following curative resection, using prospectively collected, population-based data.

Summary background data: Several studies have analyzed the determinants of long-term survival in postresection pancreatic cancer patients, but the majority of these have been single-institutional chart reviews yielding inconsistent results.

Methods: This retrospective cohort study examined 396 Medicare-eligible patients over age 65 who were diagnosed with nonmetastatic pancreatic adenocarcinoma and who underwent surgical resection with curative intent while residing in one of the 11 Survival, Epidemiology, and End Results (SEER) registries between January 1991 and December 1996. Linked Medicare data provided information on treatment and comorbidity, while linked census tract data supplied sociodemographic characteristics.

Results: Median survival for the overall study population was 17.6 months, with 1- and 3-year survival rates of 60.1% and 34.3%, respectively. Survival appears to be gradually improving over time, concomitant with a rise in the proportion of patients undergoing surgery in teaching centers. Prognostic variables significantly diminishing survival on univariate analysis included African American race, treatment not in a teaching hospital, lack of adjuvant chemoradiation therapy, as well as histopathologic factors that included tumor size larger than 2 cm in diameter, moderate to poor histologic grade, and positive lymph node metastases. Higher socioeconomic status was associated both with an increased likelihood of receiving adjuvant therapy and improved overall survival. Multivariate analyses indicated the strongest predictors of survival were adjuvant combined chemoradiotherapy, small tumors (<2 cm in diameter), negative lymph nodes, well-differentiated histology, undergoing surgery in a teaching hospital, and high socioeconomic status.

Conclusions: Although biologic characteristics remain important predictors of survival for patients with resected pancreatic cancer, the most powerful determinant is postoperative adjuvant chemoradiation therapy. An interesting finding that warrants further investigation is the effect of socioeconomic status on both the likelihood of receiving adjuvant treatment and subsequent survival, indicating a possible relationship between the quality of care delivered and outcomes.

Figure 1. Overall survival (Kaplan-Meier) for study population of 396 patients who underwent curative surgical resection for nonmetastatic pancreatic adenocarcinoma.

Figure 2. Survival curves for patients undergoing curative resection for pancreatic adenocarcinoma, comparing patients with high SES (n = 196) to patients with low SES (n = 192). Survival was not significantly better for patients with high SES by the Kaplan-Meier method (P = .06), but was by multivariate analysis (P = .02).

Figure 3. Survival curves for patients undergoing curative resection for pancreatic adenocarcinoma, comparing patients undergoing surgery in a teaching hospital to patients undergoing surgery in a nonteaching hospital. Survival was significantly better for patients who were treated in a teaching hospital (P = .007).

Figure 4. Survival curves for patients undergoing curative resection for pancreatic adenocarcinoma, comparing patients who received adjuvant chemotherapy and/or radiation therapy (n = 185) to those who did not receive adjuvant therapy (n = 208). Survival was significantly better for patients who received adjuvant treatment (P = .0003).

Figure 5. Survival curves for patients undergoing curative resection for pancreatic adenocarcinoma, comparing patients with tumors 2 cm in diameter or smaller (n = 70) to those with tumors larger than 2 cm (n = 239). Survival was significantly better for patients with tumor diameter 2 cm or less (P = .002).

Figure 6. Survival curves for patients undergoing curative resection for pancreatic adenocarcinoma, comparing patients by histologic grade. Survival was significantly better for patients with well-differentiated tumors than those with moderately (P = .004) or poorly differentiated tumors (P = .002).

Figure 7. Survival curves for patients undergoing curative resection for pancreatic adenocarcinoma, comparing patients by lymph node status. Survival was significantly better for patients with negative lymph nodes (P = .05).

Figure 8. Survival curves for patients undergoing curative resection for pancreatic adenocarcinoma, comparing patients by AJCC stage. Stage I patients did not have significantly different survival from stage II or stage III patients. Stage II patients had significantly higher survival than stage III patients (P = .05).