Oncologic outcomes and prognostic factors of colloid carcinoma of the pancreas – a retrospective real-world data analysis from the German cancer registry group of the society of German tumor centers

Background Colloid carcinoma (CC) is a rare subtype of pancreatic ductal adenocarcinoma (PDAC) characterized by mucin pools in over 80% of the tumor. This study compares the histopathology and outcomes of CC and not-otherwise specified PDAC (PDAC-NOS, referring to “classical” PDAC) using pooled data retrieved from regional cancer registries participating in the Clinical Cancer Registry Group of the Association of German Tumor Centers (GCRG/ADT). Materials and methods Data from patients within the pooled dataset of the GCRG/ADT with pancreatic cancer (diagnosed between 2000 and 2023) were analyzed. Histological subtypes were identified by ICD-O3 histology code. Epidemiology, histopathology and survival rates were compared between surgically resected CC and PDAC-NOS. Prognostic impacts were assessed using uni- and multivariable regression analyses in R. Results The study included 474 CC and 21,360 PDAC-NOS patients. CC patients presented more often without lymph node metastases (pN0: 44.0 vs. 31.5%, p < 0.001), lower grading and less lymphatic and blood vessel invasion (each p < 0.001). The R0 resection rate was similar in both groups. CC patients had superior OS compared to PDAC-NOS (median OS: 24.8 vs. 17.3 months, p < 0.001). Importantly, CC histology was an independent positive prognostic factor for OS. Grading, lymph- and blood-vessel invasion were independent prognostic factors for CC patients. Adjuvant therapy was associated with improved survival in UICC IIB CC patients. Conclusion CC patients showed better oncological outcomes after surgical resection compared to PDAC-NOS. Thereby, CC-subtype is an independent positive prognostic factor for OS, associated with lower tumor stages, fewer lymph node metastases, and less vascular invasion.