Prognostic value of the CRM-status in pancreatic ductal adenocarcinoma - data from a regional cancer registry

Background: Ductal pancreatic adenocarcinoma (PDAC) still has a dismal prognosis even when deemed resectable. A cancer free resection margin (R0) is associated with a more favourable prognosis than the presence of tumour cells at resection margin (R1). However, the precise definition of the R0 status is still a matter of debate in PDAC. For a more accurate determination of R0 in PDAC the concept of circumferential resection margins (CRM) has been established and has been incorporated into the German national S3 guideline on exocrine pancreatic cancer. However, an international standardized nomenclature of CRM is still missing, and the clinical value of the CRM concept is not yet fully established. Here we evaluate whether the CRM status as defined in the national German S3 guideline corresponds with overall and progression free survival in PDAC using data from the regional cancer registry of the State of Baden Württemberg in Germany.

Methods: Data from the cancer registry of the State of Baden-Württemberg, Germany, were used to assess the relationship between CRM-status and progression free survival (PFS) as well as 3-year overall survival (OS) using documented patients diagnosed with resectable ductal adenocarcinoma of the pancreas between 2015 and 2020. Patients were residents of the State of Baden-Württemberg and underwent surgery for PDAC. The R-status was assessed according to the national German S3 guideline with R0 wide/CRM- when CRM is > 1 mm from the tumour, R0 narrow/CRM + when CRM is ≤ 1 mm from the tumour and R1 when tumour cells are found at the resection margin.

Results: In total we identified 1098 cases surgically treated for pancreatic cancer and fulfilling the inclusion criteria. 340 patients had an R0 wide/CRM- resection, 410 patients an R0 narrow/CRM + resection, and 348 patients an R1 resection. The R0 wide/CRM- status was associated with a significantly increased median OS rate compared to the other two groups (51,5%, 37,4% and 26,7% for R0 wide/CRM-, R0 narrow/CRM + and R1, respectively). mPFS was also longer in the R0 wide/CRM- group. These findings were robust with regards to grading and tumour location.

Conclusions: CRM is prognostic for patients with resectable PDAC making the pathological assessment of the R-status according to the CRM concept worthwhile.