Brain Metastases in Pancreatic Ductal Adenocarcinoma: Assessment of Molecular Genotype-Phenotype Features-An Entity With an Increasing Incidence?

PURPOSE: To assess clinical characteristics of patients with metastatic pancreas ductal adenocarcinoma (PDAC) and brain metastases (BM), and to assess somatic and germ-line molecular profiles where performed. PATIENTS AND METHODS: Patients with PDAC and BM between January 1990 and January 2016 were identified. Molecular characteristics of somatic and germ-line testing where performed in the subset of patients who had provided informed consent. Somatic alterations were assessed by either MSK-IMPACT testing (>340 key cancer genes) or Sequenom testing (8-gene panel). Overall survival was calculated from date of diagnosis to either date of last follow-up or death. Survival after BM was calculated from date of diagnosis of BM by radiology or pathology to either date of last follow-up or death.
RESULTS: From a total of 5824 patients with PDAC identified from January 2000 to January 2016, twenty-five patients (0.4%) had BM. Median age at PDAC diagnosis was 58 years. Median time to the development of BM from initial PDAC diagnosis was 17 months (range, 0-79 months). Median overall survival after BM diagnosis was 1.5 months (range, 1-31 months). Overall survival for patients who had craniotomy (n = 4) was 11 months (range, 1-31 months), with 2 long-term survivors at 21 and 31 months, respectively. Four patients had leptomeningeal disease. Six of 25 patients had germ-line testing, and 3 had BRCA mutations (2 BRCA1 and 1 BRCA2). Somatic profiling identified KRAS mutations in 100% (4 G12D, 2 G12V, and 1 Q61K).
CONCLUSION: BM from PDAC is a rare event. We identified a speculative association of germ-line BRCA1/2 alterations with BM in PDAC, which requires corroboration. Survival after BM development is poor; prolonged survival occurred in selected patients via a multidisciplinary approach.