Local Control and Survival after Induction Chemotherapy and Ablative Radiation Versus Resection for Pancreatic Ductal Adenocarcinoma with Vascular Involvement.

Objective

We sought to compare overall survival (OS) and disease control for patients with localized pancreatic adenocarcinoma (PDAC) treated with ablative dose radiotherapy (A-RT) vs. resection.

Summary background data

Locoregional treatment for PDAC includes resection when possible or palliative RT. A-RT may offer durable tumor control and encouraging survival.

Methods

This was a single-institution retrospective analysis of patients with PDAC treated with induction chemotherapy followed by A-RT (≥ 98Gy biologically effective dose (BED) using 15-25 fractions in 3-4.5 Gy/fraction) or pancreatectomy.

Results

One hundred and four patients received A-RT (49.8%) and 105 (50.2%) underwent resection. Patients receiving A-RT had larger median tumor size after induction chemotherapy [3.2 cm (undetectable-10.9) vs. 2.6 cm (undetectable-10.7), P < 0.001], and were more likely to have celiac or hepatic artery encasement (48.1% vs. 11.4%, P < 0.001), or superior mesenteric artery encasement (43.3% vs. 9.5%, P < 0.001); however, there was no difference in the degree of SMV/PV involvement (P = 0.123). There was no difference in locoregional recurrence/progression at 18-months between A-RT and resection; cumulative incidence was 16% (95% CI 10%-24%) vs. 21% (95% CI 14%-30%), respectively (P= 0.252). However, patients receiving A-RT had a 19% higher 18-month cumulative incidence of distant recurrence/progression (58% [95% CI 48%-67%] vs. 30% [95% CI 30%-49%], P= 0.004). Median OS from completion of chemotherapy was 20.1 months for A-RT patients (95% C.I. 16.4-23.1 mo.) vs. 32.9 months (95% C.I. 29.7-42.3 mo.) for resected patients (P < 0.001).

Conclusions

Ablative radiation is a promising new treatment option for PDAC, offering locoregional disease control similar to that associated with resection and encouraging survival.