Cesar Rosa, DO1, Doug Taylor, DO1, Stalin R. Subramanian, MD2, John G. Quiles, MD3; 1Brooke Army Medical Center, San Antonio, TX; 2Brooke Army Medical Center, JBSA Fort Sam Houston, TX; 3San Antonio Military Medical Center, Ft Sam Houston, TX
Introduction: Metastatic pancreatic ductal adenocarcinoma (PDAC) carries a dismal prognosis. Although the colon is a known site of possible metastasis, near complete colonic malignant obstruction from a pancreatic primary is rare, with only a few case reports written to date. This case highlights the successful combination of palliative radiation and pembrolizumab therapy with a significant (66%) tumor reduction and subsequent improvement in partial colonic obstructive symptoms within 8 weeks.
Methods: The case presents an 82 year old Caucasian female with a history of obesity, rheumatoid arthritis presented to Emergency room for mild abdominal pain for 2 days. CT imaging revealed a 10.6cm cystic fluid collection in the peri-pancreatic area in addition to fat stranding and wall thickening of the colon at the splenic flexure thought to be reactive and pancreatitis was suspected. CEA was 67 ng/mL and CA 19-9 was 3366 U/mL. IgG4 was normal. A dedicated CT pancreas showed 10.1 x 9.6 cm cystic lesion arising from the pancreatic body. EGD demonstrated an extra-luminal compression along the posterior gastric body but was normal otherwise. EUS of the pancreas showed an irregular, hypoechoic and heterogeneous lesion with multiple cystic components and a centralized necrotic-appearing component in the tail of the pancreas. FNB was diagnostic of PDAC. EUS guided fiducial placement was performed to guide delivery of radiation therapy. A diagnostic colonoscopy showed a near obstructing mass at the splenic flexure, with biopsies consistent with a PDAC primary. Given symptoms of constipation, colonic stents were considered initially, but within 8 weeks of radiation and pembrolizumab therapy, the mass has significantly reduced in size and the partial colon obstructive symptoms were alleviated. Discussion: The Food and Drug Administration approved pembrolizumab in a fast-tracked review for advanced PDAC patients in 2019. Success in immunotherapy is urgently needed to address the side-effects, treating advanced disease and reducing metastasis for increasing the survival rate in pancreatic cancer patients. Pembrolizumab blocks the checkpoint protein, programmed cell death protein-1 (PD-1), on T cells to boost the response of the immune system against cancer cells, thus shrinking tumors. This case demonstrates immunotherapy’s benefit in the treatment of metastatic PDAC in reducing tumor size and alleviating the tumor burden of a near-obstructing colonic mass.
Pre-treatment pancreatic mass
Post-treatment pancreatic mass
Near-obstructing colonic mass
Disclosures: Cesar Rosa indicated no relevant financial relationships. Doug Taylor indicated no relevant financial relationships. Stalin Subramanian indicated no relevant financial relationships. John Quiles indicated no relevant financial relationships.