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Introduction: Neoadjuvant chemoradiation given for locally advanced pancreatic cancer is recognized to improve respectability rates, and response to therapy has also been shown to be a prognostic factor. There is no data in the literature regarding time interval between chemoradiation and surgery, and response rates. We sought to evaluate the relationship between time interval from radiation therapy and pathologic response.
Methods: We retrospectively analyzed the records of 55 patients who underwent neoadjuvant chemoradiation for borderline resectable pancreatic cancers prior to definitive resection. Patients either proceeded directly to resection following chemoradiation or continued on chemotherapy depending on CA19-9 and pathologic response. We divided patients into three groups with respect to time interval between completion of chemoradiation and resection: A (0-10 weeks), B (10-20 weeks), and C (>20 weeks). Pathologic response was defined as major (>95% fibrosis), partial (50-94% fibrosis), or minor (<50% fibrosis).
Results: There were 32 patients in group A, 9 patients in group B, and 14 patients in groups C. There was no significant difference between the groups with respect to age or CA19-9 at diagnosis. The median post-chemoradiation CA19-9 was significantly higher for group C compared to group A, but there was no subsequent difference in the median pre-operative CA19-9. There was no difference with regards to R0 resection between all three groups. Patients in groups B and C were significantly more likely to have a major response than in group A (p<0.026).
Conclusion: There is no detriment in prolonged time interval between neoadjuvant chemoradiation and definitive resection provided there is ongoing chemotherapy. In our series, patients with a time interval greater than 20 weeks were more likely to have a major response to neoadjuvant therapy prior to surgery.