Survival Outcomes and Genetic Characteristics of Resected Pancreatic Acinar Cell Carcinoma

Abstract

Background: Pancreatic acinar cell carcinoma (pACC) is a rare neoplasm of the exocrine pancreas. There is a dearth of information about tumor characteristics and patient outcomes. This study describes the clinical characteristics, genetic alterations, and survival outcomes of resected pACC.

Patients and methods: Consecutive patients undergoing pancreatectomy for pathologically confirmed pACC from 1999 to 2022 across three high-volume pancreas surgery centers were analyzed. Patient demographics, tumor characteristics, treatment data, and genetic sequencing were obtained through retrospective abstraction.

Results: A total of 61 patients with resected pACC were identified. Median overall survival (OS) was 73 months and median recurrence free survival was 22 months. Nine patients underwent resection for oligometastatic disease; median OS was not reached after a median follow-up of 31 months from date of metastasectomy. Adjuvant chemotherapy was administered in 67% of patients with FOLFOX/FOLFIRINOX (5-fluorouracil, leucovorin, oxaliplatin, ± irinotecan) the most common regimen (58%). Sequencing data were obtained in 47 (77%) patients. A mutation in at least one of three core genes associated with the homologous recombination repair (HRR) pathway (BRCA1, BRCA2, or PALB2) occurred in 26% (n = 12) with BRCA2 the most frequently identified. A mutation in any other "non-core" gene associated with DNA damage repair or the HRR pathway was identified in 45% (n = 21) with a high tumor mutational burden of > 10 mutations per megabase in 13%.

Conclusions: Resection of pACC is associated with favorable survival outcomes, even in the setting of oligometastatic disease. Mutations in the HRR pathway are common, providing opportunities for potential targeted therapeutic options.

Keywords: Acinar cell carcinoma; Homologous repair deficiency; Pancreatic exocrine cancer; Survival; Whole exome sequencing.

FIG. 1

Kaplan–Meier survival estimates of resected pACC disease from the time of surgery: A overall survival, B recurrence free survival, C overall survival from time of oligometastatic disease resection

FIG. 2

Kaplan–Meier survival estimates of resected pACC disease comparing A patients with pACC with a deleterious core and noncore mutation in the HRR pathway versus pACC patients with no mutation B with a deleterious mutation in the core HRR pathway whom received adjuvant platinum therapy versus all other sequenced patients

FIG. 3

Distribution of documented recurrence patterns after resection of pACC