Intact SMAD-4 is a predictor of increased locoregional recurrence in upfront resected pancreas cancer receiving adjuvant therapy.

Background: Previous reports suggest that intact SMAD4 expression is associated with a locally aggressive pancreas cancer phenotype. The objectives of this work were to determine the frequency of intact SMAD4 and its association with patterns of recurrence in patients with upfront resected pancreas cancer receiving adjuvant therapy.

Methods: A tissue microarray was constructed using resected specimens from patients who underwent upfront surgery and adjuvant gemcitabine with no neoadjuvant treatment for pancreas cancer. SMAD4 expression was determined by immunohistochemical staining. Associations of SMAD4 expression and clinicopathologic parameters with clinical outcomes were evaluated using Cox proportional hazard models.

Results: One hundred twenty-seven patients were included with a median follow up of 5.7 years. Most patients had stage ≥ pT3 tumors (75%) and pN1 (68%). All patients received adjuvant gemcitabine, and 79% of patients received adjuvant chemoradiotherapy. Ten (8%) patients had intact SMAD4 expression. Grade was the only clinicopathologic parameter statistically associated with SMAD4 expression (P=0.05). Median overall survival was 2.1 years. On univariate analysis, SMAD4 expression was associated with increased locoregional recurrence (hazard ratio 7.0, P<0.01, 95% confidence interval: 2.8-18.0) but not distant recurrence (P=0.06) or overall survival (P=0.73). On multivariable analysis, SMAD4 expression (hazard ratio 9.6, P<0.01, 95% confidence interval: 3.7-24.8) and adjuvant chemoradiotherapy (hazard ratio 0.3, P=0.01, 95% confidence interval: 0.1-0.8) were associated with higher and lower locoregional recurrence, respectively.

Conclusions: In patients with upfront resected pancreas cancer, SMAD4 expression was associated with an increased risk of locoregional recurrence. Prospective evaluation of the frequency of SMAD4 expression and validation of its predictive utility is warranted.