Is pancreatic adenosquamous carcinoma (PASC) a surgical disease? A large healthcare system review

<h2>Abstract</h2><h3>Introduction</h3> Pancreatic cancer represents an increasing cause of cancer-related deaths. Pancreatic adenosquamous carcinoma (PASC) is a rare subtype of pancreas cancer. Optimal treatment is not well-defined. This review aims to provide a detailed analysis of the natural history, management, and outcomes of the patients with PASC within a single large healthcare system. <h3>Materials and methods</h3> A large healthcare database was used to retrospectively identify all patients with histological diagnosis of PASC from 2010 to 2020. The cohort was evaluated as a whole and according to the following management modalities: operative, non-metastatic non-operative, and patients with metastatic disease. Abstracted data included patient characteristics, oncologic characteristics at presentation, and details of surgical and non-surgical treatment. <h3>Results</h3> In total, 60 patients with PASC were identified. All patients had confirmed histopathological diagnosis of PASC. Mean age at the time of diagnosis was 70.9 years, and 28 patients were male (46.7 %). Most patients presented with pancreas head tumors (60 %). Thirty-four patients presented with non-metastatic disease (56.6 %). The operative group consisted of 17 patients (28.3 %). Most patients received adjuvant systemic therapy (70.6 %). Majority of patients experienced recurrence (76.5 %), with median time to recurrence at 6.5 months. Median overall survival in the operative group was 19.1 months. Seventeen patients with non-metastatic disease (28.3 %) did not undergo resection. Median overall survival of this cohort was 3.3 months. Systemic chemotherapy was used in 8 patients. Approximately half of patients with non-metastatic disease (9/17) did not receive any treatment due to rapid physical deterioration or poor functional status at baseline. Median survival for the non-treatment group was 1.7 months. At presentation, 26 patients (43.3 %) had metastatic disease. Most common site of metastasis was the liver. Median survival for patients with metastatic disease was 3.1 months. <h3>Discussion</h3> PASC is a distinct entity from glandular PDAC, and it appears to be a more aggressive disease process. Complete resection confers survival benefit but is not curative. Furthermore, few patients undergo surgery, even with seemingly resectable disease. Systemic therapy administration is limited in many patients due to physiologic decline. Dismal clinical course and poor survival is universal among all patients who do not undergo any treatment modality, regardless of metastatic status. Globally grim prognosis appears to be due early systemic effects, disease progression and lack of effective systemic therapy. <h3>Conclusions</h3> PASC remains a poorly understood cancer and portends particularly poor prognosis. It is associated with a rapid clinical decline, poor response to systemic therapy, early recurrence, and poor overall survival. However, ability to treat with surgery and chemotherapy may best prolong survival. <h3>Synopsis</h3> Pancreatic adenosquamous carcinoma (PASC) is a rare subtype of pancreatic cancer. In this study, we evaluated 60 patients with PASC. PASC is a systemic disease characterized by rapid clinical decline, poor response to systemic therapy, early recurrence, and poor survival. Despite resection or systemic therapy, patients succumb rapidly.