Genetic Drivers of Pancreatic Cancer Are Identical Between the Primary Tumor and a Secondary Lesion in a Long-Term (>5 Years) Survivor After a Whipple Procedure

Abstract

Background: A new mass in the remnant pancreas of a patient with previously resected pancreatic ductal adenocarcinoma (PDA) typically represents either a recurrence of the initial primary tumor or a second primary tumor. Recent advances in next-generation sequencing (NGS) strategies allow us to compare the genetic makeup of primary and secondary lesions. Case presentation: A 50-year-old Caucasian female presented for a surgical evaluation of a new biopsy-proven PDA at the junction of the body and tail of the pancreas. Six years prior, in 2011, the patient was found to have a T3N0M0 PDA of the pancreatic head, which was surgically resected with a classic Whipple procedure and concurrent hemicolectomy. Pathology showed pancreatic intraepithelial neoplasia grade 2 and PDA with negative surgical margins, positive perineural spread, and negative lymphovascular spread, and the patient received adjuvant chemotherapy and local radiation. In 2017, she was diagnosed with a new PDA lesion in the remaining pancreatic body far from the previous anastomosis site and was taken to surgery for a completion pancreatectomy and revision of the gastrojejunostomy. NGS was performed on both specimens. Both lesions shared identical mutations in KRAS, TP53, and CDKN2A genes. Amplifications of MYC and mutant KRAS were identified in the 2017 tumor and an ACVR1B mutation was identified in the 2011 tumor, but was not found in the 2017 tumor. Conclusions: This case demonstrates the ability to evaluate similarities between key genetic drivers from a resected primary tumor and a PDA lesion that presented in the same patient 6 years later. Histological analysis and NGS can be used to understand potential differences and similarities between lesions and may be useful in future studies as predictive markers or to provide insight into resistance mechanisms (e.g., MYC amplification).

Keywords: KRAS; MYC; Whipple procedure; metachronous; pancreatic ductal adenocarcinoma; pancreaticoduodenectomy.

FIG. 1.

MRI (axial T1 weighted) of the 2017 pancreatic mass. The image was read to show interval development of a mass within the pancreatic body–tail junction with restricted diffusion and hypoenhancement. The mass was measured to be 2.3 × 2.2 cm (see arrow), and it was felt to focally encase the splenic artery and segmentally narrow the splenic vein.

FIG. 2.

Chronologic results of CA 19-9. Results are listed starting before the initial tumor resection in 2011 to identification of the new tumor in the pancreatic remnant in 2017.

FIG. 3.

Operative procedure summary; left depicting the patient's postclassic Whipple procedure anatomy (2011 surgery) and right depicting the patient's postrevision completion pancreatectomy anatomy (2017 surgery). Gastrojejunostomy was revised to address the patient's early satiety and cholangitis, which was thought to be due to a short afferent limb.