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Introduction: Several pathologic features of periampullary tumors (of the pancreas, ampulla, distal common bile duct, and duodenum) have been shown to be correlated with survival following resection. We aim to evaluate the association between survival and both perineural invasion and the lymph node ratio at multiple time-points.
Methods: A retrospective chart review identified 147 patients with periampullary adenocarcinoma tumors who underwent attempted curative resection (pancreaticoduodenectomy) between 1/1/2003 and 12/31/2008. The Social Security Death Index was utilized to determine current living status. Clinical and pathologic features were assessed from the medical record, and the data were analyzed using univariate and multivariate analyses.
Results: Of the 141 patients identified, there were 71 males and 70 females with an average age of 67 years. The median follow-up was 1.7 years (vs. 5.4 years for survivors alone), and the crude overall survival was 33% at the end of the follow-up period. Most tumors were pancreatic in origin (57% vs. 26% ampullary, 8.5% distal common bile duct, and 8.5% duodenum). The average tumor size was 2.9cm, and an R0 resection was achieved in 70% of patients. On average, 20 lymph nodes were identified in a surgical specimen, and at least one lymph node was positive in 66% of patients. The median lymph node ratio was 18%, while 70% of tumors demonstrated perineural invasion. At 1 year follow-up, 25% of patients had expired, which increased to 60% by 3 years. Using univariate analyses, 1 year mortality was independently associated with age, tumor size, margin status, lymph node status, lymph node ratio, and perineural invasion. Multivariate analysis also revealed a significant association between 1 year mortality and the lymph node ratio (OR 1.4, p=0.037), after adjusting for age, tumor size, and margin status. Perineural invasion and lymph node status were no longer significant in similar analyses at 1 year. However, there was a significant association between 3 year mortality and both lymph node ratio (OR 2.6, p<0.001) and perineural invasion (OR 4.9, p<0.001), after controlling for age, tumor size, and margin status. Notably, perineural invasion had a stronger association with overall mortality (HR 2.56, p=0.001) than the lymph node ratio (HR 1.35, p<0.001), after adjusting for age, tumor size, and margin status. Stepwise selection modeling of overall mortality again revealed a stronger association with perineural invasion than the lymph node ratio (HR 2.42 vs. 1.34), which also included age and tumor size.
Conclusions: Survival appears to be more closely related to lymph node ratio within the first year following surgery, while longer follow-up periods demonstrated a stronger association between survival and perineural invasion at both 3 years follow-up and in overall survival.