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Hepato-pancreato-biliary

P37: CA 19-9 Normalization Following Neoadjuvant Therapy and Yield of Laparoscopy for Pancreatic Ductal Adenocarcinoma

Introduction: Despite modern high-resolution imaging, occult metastases can be discovered during pre-resection laparoscopy for pancreatic ductal adenocarcinoma (PDAC). The purpose of this study was to determine the yield of laparoscopy based on serum carbohydrate antigen (CA) 19-9 response to assess the utility of universal versus selective laparoscopy prior to planned resection. 

Methods:

A prospective institutional database was reviewed for PDAC treated with NT followed by laparoscopy prior to or on the date of planned resection (Feb. 2009 – Mar. 2023). Those who underwent laparoscopy to biopsy radiographically suspicious lesions were excluded. Clinicopathologic data, treatment details, and CA 19-9 from pre-NT (CA-PRE), mid-therapy (CA-MID) and post-NT (CA-POST) were analyzed.


Results: Of 612 patients who underwent laparoscopy, 16.7% (102/612) had laparoscopy prior to planned resection, 79.1% (484/612) on the date of planned resection, and 4.2% (26/612) had laparoscopy both prior to and on the date of planned resection. Only 5.2% (32/612) of all laparoscopies found metastatic disease. Of 68.8% (421/612) patients with an elevated CA-PRE and an available CA-POST, CA 19-9 normalization (decrease to less than 37 U/mL) was observed in 42.3% (178/421). CA 19-9 normalization was associated with negative laparoscopy (OR 0.44, 95% CI 0.21-0.91, p=0.028). The rate of positive laparoscopy was 2.8% (5/178) with CA 19-9 normalization, compared to 8.2% (20/243) with non-normalized CA19-9 (91.8%; 223/243). Laparoscopy on the resection date had higher odds of a positive finding with non-normalized vs. normalized CA 19-9 (10.1%, 19/187 vs. 2.1%, 3/144; OR 2.94, 95% CI 0.13-0.86, p=0.023). Late rising CA 19-9 (CA-POST > CA-MID) was observed in 23.4% (107/457) of patients with available values and was also associated with positive laparoscopy (OR 2.15, 95% CI 1.00-4.62, p=0.050).

Conclusions: Following NT, occult metastases are rarely found during routine laparoscopy. With CA 19-9 normalization after NT, the number needed to laparoscope to yield one positive finding was 35. With high-quality imaging, routine laparoscopy after induction chemotherapy has low sensitivity for identifying occult metastases. Instead, selective use of laparoscopy based on CA 19-9 trend would improve operating room resource utilization and be more cost-effective.

Learning Objectives:

  • To determine number of laparoscopies needed to yield one positive finding in patients with CA19-9 normalization after neoadjuvant therapy.
  • To describe how trends in CA 19-9 predict positivity of laparoscopy before intended resection for pancreatic ductal adenocarcinoma.
  • To describe the association between laparoscopy findings and CA 19-9 increase between the midpoint of neoadjuvant therapy and resection.