The relationship between observation interval and prognosis in pancreatic cancer concomitant with intraductal papillary mucinous neoplasia.

Background: Intraductal papillary mucinous neoplasia (IPMN) is a risk factor for pancreatic cancer (PC). PC concomitant with IPMN shows rapid progression similar to de novo PC, therefore, the appropriate observation interval (OI) is not yet clear.

Patients And Method: This was a multicenter retrospective observational study, and patients with PC concomitant with IPMN were analyzed. OI was defined as the interval between the date of imaging at PC diagnosis and just before the diagnosis. Clinical factors of PC and prognosis were assessed according to OI.

Results: From January 2010 to December 2018, 73 patients from 11 institutions were enrolled. The images performed just before PC diagnosis were contrast-enhanced CT/magnetic resonance imaging/endoscopic ultrasonography in 44/27/2 patients, respectively. The median cyst size was 14.0 mm, and the median main pancreatic duct diameter was 3.0 mm. The median OI was 6.8 months. In OI 6 months or less (OI ≤ 6 M)/OI more than 6 months (OI > 6 M), the mean tumor size, the frequencies of metastatic PC, resectable PC and early-stage PC were 20.1/21.5 mm (P = 0.91), 12.1 %/32.5 % (P = 0.05), 72.7 %/52.5 % (P = 0.09) and 27.3 %/25.0 % (P = 1.00), respectively. The median overall survival was 35.5 months in OI ≤ 6 M and 16.2 months in OI > 6 M (P = 0.05).

Conclusion: In OI 6 months or less, the rate of resectable PC was high, however, the rate of early PC was almost the same as that of OI more than 6 months. Approximately 10 % of cases found in the advanced stage with metastasis even if OI 6 months or less.