Tumour Regression Grade as a Predictor of Survival in Resectable and Borderline Resectable Pancreatic Ductal Adenocarcinoma: Limitations of a Post-Surgical Indicator of Prognosis.

INTRODUCTION

Treatment sequencing is a major focus in pancreatic ductal adenocarcinoma (PDAC) treatment in recent literature. A neoadjuvant chemotherapy (NAC) first approach has been suggested to improve tumour stage and, in some cases, produce a total neoadjuvant response. However, in resectable disease, there are concerns that non-response or delay to definitive surgical excision could allow disease progression during this time.

METHODS

This retrospective cohort analysis sampled cases (N = 152) of resectable and borderline resectable PDAC from a pancreatic cancer centre. Treatment demographics, chemotherapy and surgical outcomes, including tumour regression grade (TRG) and overall survival (OS), were compared.

RESULTS

Demographic and disease characteristics differed significantly in ECOG score and radiological tumour venous involvement between NAC and UFS groups. FOLFIRINOX (57.3%) was the most common chemotherapy agent, and overall NAC completion was 53.3%. Disease progression during NAC occurred in 33.3% of cases, with 20% of those initially classified as resectable. In this cohort, the UFS group had a significantly improved overall survival compared to the NAC group (25.2 vs. 18.2 months, p = 0.03), which was not influenced by initial disease classification (HR = 1.03, 95% CI [0.10-10.41], p = 0.98). A significant correlation was found between TRG and OS (rs = -0.53, p = 0.005).

DISCUSSION: Although TRG correlates with OS, this intention-to-treat analysis highlights the large proportion of cases, both resectable and borderline resectable, that do not complete NAC and do not receive surgical resection. This study did not identify any demographic or disease characteristics associated with favourable NAC tumour response.