Genomic landscape and clinical features of rare subtypes of pancreatic cancer: analysis with the national database of Japan

BACKGROUND

Special subtypes of pancreatic cancer, such as acinar cell carcinoma (ACC), adenosquamous carcinoma (ASC), and anaplastic carcinoma of the pancreas (ACP), are rare, and so data on them are limited. Using the C-CAT database, we analyzed clinical and genomic characteristics of patients with these and evaluated differences on comparison with pancreatic ductal adenocarcinoma (PDAC) patients.

METHODS

We retrospectively reviewed data on 2691 patients with unresectable pancreatic cancer: ACC, ASC, ACP, and PDAC, entered into C-CAT from June 2019 to December 2021. The clinical features, MSI/TMB status, genomic alterations, overall response rate (ORR), disease control rate (DCR), and time to treatment failure (TTF) on receiving FOLFIRINOX (FFX) or GEM + nab-PTX (GnP) therapy as first-line treatment were evaluated.

RESULTS

Numbers of patients with ACC, ASC, ACP, and PDAC were 44 (1.6%), 54 (2.0%), 25 (0.9%), and 2,568 (95.4%), respectively. KRAS and TP53 mutations were prevalent in ASC, ACP, and PDAC (90.7/85.2, 76.0/68.0, and 85.1/69.1%, respectively), while their rates were both significantly lower in ACC (13.6/15.9%, respectively). Conversely, the rate of homologous recombination-related (HRR) genes, including ATM and BRCA1/2, was significantly higher in ACC (11.4/15.9%) than PDAC (2.5/3.7%). In ASC and ACP, no significant differences in ORR, DCR, or TTF between FFX and GnP were noted, while ACC patients showed a trend toward higher ORR with FFX than GnP (61.5 vs. 23.5%, p = 0.06) and significantly more favorable TTF (median 42.3 vs. 21.0 weeks, respectively, p = 0.004).

CONCLUSIONS

ACC clearly harbors different genomics compared with PDAC, possibly accounting for differences in treatment efficacy.

Anaplastic carcinoma of the pancreas diagnosed by endoscopic ultrasound-guided fine-needle aspiration: a case report and review of the literature

Background

Anaplastic carcinoma of the pancreas is a rare pancreatic neoplasm with a poor prognosis. It is classified as a variant of ductal adenocarcinoma, but the clinical features and treatment of it remain unknown because of its rarity and aggressiveness. Endoscopic ultrasonography and endoscopic ultrasound-guided fine-needle aspiration are useful techniques for the diagnosis of pancreatic tumors with high sensitivity and specificity.

Case presentation

A 72-year-old Japanese woman presented with a diagnosis of acute pancreatitis, and a cystic lesion with slightly high density area was observed by computed tomography in her pancreatic head. In addition, endoscopic ultrasound revealed a heterogeneous lesion. Endoscopic ultrasound-guided fine-needle aspiration showed pleomorphic atypical cells. We diagnosed anaplastic carcinoma of the pancreas. We resected the lesion, and she has shown no sign of recurrence for > 6 months. There are few reports of anaplastic carcinoma of the pancreas diagnosed by endoscopic ultrasound-guided fine-needle aspiration and treated by surgery. Our analysis indicates that anaplastic carcinoma of the pancreas is more likely than typical ductal carcinomas to have cystic lesions with the tumor.

Conclusions

We report a case of anaplastic carcinoma of the pancreas diagnosed by endoscopic ultrasound-guided fine-needle aspiration and subsequently resected with a clear margin. We speculate that anaplastic carcinoma of the pancreas is more likely to have cystic changes than pancreatic ductal adenocarcinoma. When we diagnose pancreas tumor as having cystic changes, anaplastic carcinoma of the pancreas should be considered one of the differential diagnoses.