Tailoring Adjuvant Chemotherapy to Biologic Response Following Neoadjuvant Chemotherapy Impacts Overall Survival in Pancreatic Cancer

BACKGROUND

The role of postoperative chemotherapy in patients with resected pancreatic cancer who receive neoadjuvant treatment is unknown. Clinicians use changes in CA19-9 and histopathologic scores to assess treatment response. We sought to investigate if CA19-9 normalization in response to NAT can help guide the need for postoperative treatment.

METHODS

Patients with elevated baseline CA19-9 (CA19-9 > 37U/mL) who received NAT followed by surgery between 2011 and 2019 were retrospectively reviewed. Treatment response was determined by CA19-9 normalization following NAT and histopathologic scoring. The role of postoperative chemotherapy was analyzed in light of CA19-9 normalization and histopathologic response.

RESULTS

We identified and included 345 patients. Following NAT, CA19-9 normalization was observed in 125 patients (36.2%). CA19-9 normalization was associated with a favorable histopathologic response (41.6% vs 23.2%, p < 0.001) and a lower ypT (p < 0.001) and ypN stage (p = 0.003). Receipt of adjuvant chemotherapy was associated with improved overall survival in patients in whom CA19-9 did not normalize following NAT (26.8 vs 16.4 months, p = 0.008). In patients who received 5FU-based NAT and in whom CA19-9 did not normalize, receipt of 5FU-based adjuvant chemotherapy was associated with improved OS (p = 0.014).

CONCLUSION

CA19-9 normalization in response to NAT was associated with favorable outcomes and can serve as a biomarker for treatment response. In patients where CA19-9 did not normalize, receipt of postoperative chemotherapy was associated with improved OS. These patients also benefited from additional 5FU-based postoperative chemotherapy following 5FU-based NAT.

Neoadjuvant Chemotherapy in Pancreatic Cancer: An Appraisal of the Current High-Level Evidence

At the time of diagnosis, only about 20% of patients with pancreatic ductal adenocarcinoma (PDAC) have resectable disease. PDAC treatment necessitates a multidisciplinary approach, and adjuvant chemotherapy after upfront resection is an established means of preventing recurrence. Neoadjuvant chemotherapy (NAT), originally introduced to downstage tumor size, is nowadays more frequently used for selection of patients with favorable tumor biology and to control potential micrometastases. While NAT is routinely applied in locally advanced (LA) PDAC, there is increasing evidence demonstrating benefits of NAT in borderline resectable (BR) PDAC. The concept of NAT has recently been tested in resectable PDAC, but to date NAT has been restricted to clinical trials, as the data are limited and no clear benefits have yet been shown in this patient group. This review summarizes the current evidence for NAT in resectable, BR, and LA PDAC, with a focus on high-level evidence and randomized controlled trials.