Metastatic pancreatic acinar cell carcinoma with BRCA2 gene alternation resected after modified FORFIRINOX therapy: a case report and literature review.

Abstract

Background: Pancreatic acinar cell carcinoma (PACC) is a rare subtype of pancreatic cancer, and its clinicopathological behavior is not fully understood because of its rarity. The excision of the tumor is the best treatment, but PACC patients often have distant metastasis at the time of first diagnosis and sometimes have relapse after surgery. Thus, appropriate anti-tumor agents need to be administered; however, there is still no standard chemotherapy regimen for PACC. We report a case of PACC in a patient with breast cancer susceptibility gene (BRCA)2 gene alternation whose hepatic metastasis was shrunk by a treatment with a modified FORFIRINOX (mFFX) regimen. The patient also underwent conversion surgery after the mFFX treatment.

Case description: A 67-year-old man was treated for breast cancer in 2016. In 2022, he experienced a continuous left back pain, and abdominal computed tomography (CT) revealed a 47-mm hypo-dense mass in the pancreatic tail and a 100-mm slightly enhanced mass in the liver at segment 8. He was diagnosed with PACC with liver metastasis by liver and pancreatic tumor biopsies. He was started on mFFX and, at the same time, we performed an analysis of the BRCA gene alternation with blood and genetic screening using a liver biopsy specimen. Later, the germline BRCA2 gene alternation was identified, and mFFX was continued. He had considerable tumor shrinkage after 13 mFFX cycles and was then sent for surgery. An excised sample showed no tumor in the liver and a 900-µm residual tumor in the pancreatic tail. He had relapse in the liver at segment 6 at 12 months after surgery, which was then excised. He had a lymph node relapse at 3 months after the second surgery, and was receiving olaparib.

Conclusions: mFFX might be prioritized as the first-line chemotherapy for PACC patients, and an analysis of the BRCA gene alternation needs to be conducted.