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Aim: To estimate the frequency of extra-pancreatic benign and malignant neoplasms in patients with intraductal papillary mucinous neoplasm (IPMN) of the pancreas and compare the derived frequency to two, matched, control groups.
Methods: We identified all cases of IPMN diagnosed from 1994-2006 using 4 institutional registries. For matched groups, we used control Group 1 consisting of patients diagnosed with pancreatic adenocarcinoma during the same time period matched for sex and age at diagnosis (±2 years). Control Group 2 was a random selection of referral patients seen at our institution during the time period matched 3:1 for sex, birth date (±5 years), year of registration at our clinic (±5 years), and geographic location of primary address. We compared the proportions of patients with any extra-pancreatic benign or malignant neoplasm diagnosed before and/or coincident with the diagnosis of IPMN or pancreatic adenocarcinoma between the IPMN cases and each control group separately using the Chi-square test. We calculated the risk of new benign or malignant neoplasms diagnosed after the diagnosis of IPMN or adenocarcinoma between groups using Cox proportional hazards regression.
Results: The IPMN group consisted of 477 patients, pancreatic adenocarcinoma group 471, and general referral group 1431. The proportion of patients in the IPMN group having any extra-pancreatic neoplasm (benign or malignant) diagnosed before or coincident to the index date was 52% (95% CI 47-56%), compared with 36% (95% CI 32-41%) in Group 1 (p<0.001), and 43% (95% CI 41-46%) in Group 2 (p=0.002). The most common benign neoplasms in the IPMN group were adenomatous colon polyps (n=116), Barrett’s neoplasia (n=18), and carcinoid neoplasms (n=6). The most common malignant neoplasms were non-melanoma skin (n=36), breast (n=24), prostate (n=24), and colorectal cancers (n=19). The hazard ratio of diagnosis of any neoplasm after the index date was 3.8 (95% CI 2.0-7.3, p<0.001) for the IPMN group compared to Group 1, and 1.4 (95% CI 0.9-2.1, p=0.09) for the IPMN group compared to the Group 2. In the IPMN group, 47 patients had a new neoplasm diagnosed after the index date.
Conclusions: Patients with IPMN are at greater risk of benign or malignant extra-pancreatic neoplasms compared to both control groups. The majority of neoplasms were diagnosed prior to or coincident with the IPMN diagnosis; however, the risk of developing neoplasms after the diagnosis of IPMN remains increased. Based on the frequency of colonic polyps, screening colonoscopy should be considered in all patients with IPMN.

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