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).
Highlights
Pancreatic ductal adenocarcinoma (PDA) accounts for45,000 cancer diagnoses in the United States per year and 90–95% of all pancreatic cancers.[1,2,3] pancreatic ductal adenocarcinoma (PDA) has historically high rates of recurrence and the lowest 5-year survival of any cancer.[2]
Mortality, such as positive surgical margins, positive lymph node metastasis, large tumor size (>3 cm), and poor histological differentiation[5,8]; in resections that achieve R0 status, it seems that the presence of synchronously adjacent pancreatic intraepithelial neoplasia (PanIN) lesions in the surgical specimen does not influence outcomes.[14,15]
Since our patient had a followup MRI of the abdomen and pelvis and CT of the chest that showed no metastatic disease, a completion pancreatectomy was planned, a PET scan could have been utilized to rule out metastatic disease as well
Summary
45,000 cancer diagnoses in the United States per year and 90–95% of all pancreatic cancers.[1,2,3] PDA has historically high rates of recurrence and the lowest 5-year survival of any cancer.[2]. To fully understand this disease, it is important to understand PDA’s biology, including key driver mutations leading to the progression of normal pancreatic tissue to PDA. Upon histological analysis, staining for MLH1, MSH2, MSH6, PMS2, pAKT, and HER2 was similar in both samples, but in the 2017 tumor, there was 60% increased staining for RRM1 and 20% increased staining for ERCC1, which changed the classification from low to high staining for ERCC1
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