Assessment of survival advantage in ampullary carcinoma in relation to tumour biology and morphology.

Introduction: Carcinoma of the ampulla of Vater is said to carry a significantly better prognosis than pancreatic ductal adenocarcinomas arising in the pancreatic head. However, it is uncertain as to whether this is due to the fact that they have differing oncological characteristics or simply an earlier presentation as a result of the exophytic morphology of ampullary lesions causing obstruction of the bile ducts.

Methods: All patients undergoing pancreaticoduodenectomy between January 1998 and December 2004 were identified from a prospectively maintained database. Patients with a pathologically confirmed ampullary (AMP) tumour were compared to those with a carcinoma of the head of the pancreas (HOP). Tumour characteristics including size, stage and degree of differentiation were analysed as were survival data.

Results: 71 AMP and 144 HOP tumours were resected during the period studied and had full histology reports available for assessment. The median diameter of the AMP tumours was significantly less than those of the HOP (2 cm vs. 3 cm; p = 0.04). The T stage distribution differed significantly between the AMP and HOP tumours in favour of the former (Stages I--10 vs. 0 (p = 0.03); II--29 vs. 13 (p = 0.04); III--25 vs. 121 (p = 0.01); IV--7 vs. 10). The number of resection specimens with positive lymph nodes was lower in the AMP group (31 vs. 121; p = 0.03) as was the prevalence of vascular invasion (33 vs. 114; p = 0.006) and neural invasion (23 vs. 134; p = 0.009). There was no difference in the degree of differentiation of the AMP and HOP tumours. The 5-year survival rates were significantly better in the AMP group at 60% vs. 20% (p = 0.008). Subdivision of AMP carcinoma into polypoid (60%) and ulcerating (40%) lesions revealed a non-significant survival advantage in favour of polypoid tumours at (64% vs. 60%; p = 0.07) at 5 years.

Conclusions: The outcome of resection for AMP is significantly better than for pancreatic ductal adenocarcinomas arising in the periampullary region. Although the anatomical position of AMP tumours may contribute to this survival advantage, the HOP tumours exhibit more adverse histological features suggesting that they are different diseases and hence the difference in survival.