[1440] Histologic Description of Pancreatectomy Specimens after Current Neoadjuvant Therapies

NJ Nolan, JB Stokes, TW Bauer, RB Adams, EB Stelow. University of Virginia, Charlottesville, VA

Background: Most patients who develop pancreatic ductal adenocarcinoma (PDA) are considered to be unresectable at the time of their diagnosis. For those who are considered to be resectable, surgery allows for their only possible cure. Occasionally patients will be considered borderline resectable usually based on anatomic criteria. They receive neoadjuvant chemoradiation therapy and can then be considered for resection if they show no evidence of progressive disease throughout their treatment. Most information regarding this method of treatment has been published in the surgical literature and we are not aware of a detailed description of the associated histologic changes. Here, we describe our experience with these specimens.
Design: Sixteen patients with borderline resectable PDA underwent resection (pancreaticoduodenectomy=14) following neoadjuvant chemoradiation therapy (capecitabine and 50 Gy of radiation). Histology was reviewed. The tumor response was determined based on the percentage of viable tumor. Grade 1 was defined as >90% viable tumor, Grade 2a had 50-89% viable tumor, Grade 2b had 10-49% viable tumor, Grade 3 had < 10% viable tumor and Grade 4 showed complete response. Specific histologic findings and staging information were noted. Follow-up data were pursued.
Results: Three cases (18.75%) demonstrated grade 1 response, 5 cases (31.25%) grade 2a response, 2 cases (12.5%) grade 2b response, and 6 cases (36.5%) grade 3 response. Eight of sixteen (50%) cases were pathologically down-staged. Histologic response was variable and non-specific. Most cases (15) showed prominent dense fibrosis throughout sections of tumor. Coagulative necrosis (8 cases), prominent hemorrhage, cholesterol material and mucin pools (sometimes perineural) were less commonly seen. Viable perineural invasion was seen in 8 cases. Viable tumor was present at margin in 4 cases. At a mean follow-up of 10 months, degree of response did not correlate with recurrence or death.
Conclusions: The histologic response to neoadjuvant chemoradiation is nonspecific. Fibrosis is the most frequent histologic finding while a minority of cases had other features including coagulative necrosis and mucous pools. Neoadjuvant therapy results in pathologic downstaging of tumor in half of borderline resectable patients. More than one-third of cases show more than 90% tumor death using today's chemoradiation regimens. Further follow-up is needed to evaluate the relationship between response and survival.
Category: Liver & Pancreas

Monday, March 9, 2009 9:30 AM

Poster Session I Stowell-Orbison/Autopsy Award # 210, Monday Morning