The efficacy of adjuvant therapy for pancreatic invasive intraductal papillary mucinous neoplasm (IPMN).

BACKGROUND

The literature investigating pancreatic invasive intraductal papillary mucinous neoplasm (IPMN) has largely come from small institutional studies, preventing adequately powered comparisons of adjuvant therapy versus surgery alone (SA) within specific patient subgroups.

METHODS

Patients with resected, stage I through IV, invasive IPMN and conventional pancreatic ductal adenocarcinoma (PDAC) were identified in the National Cancer Data Base (1998-2010). Cox modeling of patients with invasive IPMN was used to compare overall survival (OS) between patients who received adjuvant therapy and those who underwent SA. A second model was used to compare OS between patients with invasive IPMN and those with PDAC.

RESULTS

For the 1220 patients with invasive IPMN, the median OS was 28.9 months; the 1-year and 5-year actuarial survival rates were 76% and 17%, respectively; and 47% received adjuvant therapy. Cox modeling associated SA with worse OS (hazard ratio, 1.36; 95% confidence interval, 1.17-1.58; P = .00005) as well as American Joint Committee on Cancer (AJCC) TNM stage III/IV disease, positive lymph node status, positive margins, and poor tumor differentiation (all P ≤ .05). In addition, Cox modeling stratified by the following characteristics demonstrated improved OS with adjuvant therapy: AJCC TNM stage II or III/IV, positive lymph node status, positive margins, and poorly differentiated tumors. There was no survival advantage from adjuvant therapy for patients who had AJCC TNM stage I or lymph node-negative disease. Patients who had invasive IPMN had improved risk-adjusted OS compared with those who had PDAC (hazard ratio, 0.73; 95% confidence interval, 0.68-0.78; P < .00001).

CONCLUSIONS

Invasive IPMN appears to be more indolent than conventional PDAC. Adjuvant therapy is associated with improved OS compared with SA in patients with invasive IPMN, especially for those with higher stage disease, positive lymph nodes, positive margins, or poorly differentiated tumors. Conversely, this benefit does not extend to patients with stage I or lymph node-negative disease.