Chemo plus CRT vs SBRT: Which approach produces better outcomes in PDAC?

Multiagent chemotherapy (MAC) followed by conventionally fractionated radiotherapy (CRT) shows rates of margin-negative resection (R0) and pathologic complete response similar to those of MAC plus stereotactic body radiotherapy (SBRT) in patients with localized pancreatic ductal adenocarcinoma (PDAC), according to a study. However, MAC plus CRT is associated with less regional lymphatic disease.

The authors searched the National Cancer Database to identify patients diagnosed with nonmetastatic PDAC between 2012 and 2017 and who received preoperative MAC or MAC plus radiotherapy (RT). Logistic regression and Cox analyses were conducted to determine the variables associated with R0 and overall survival.

A total of 5,273 patients were identified, of whom 3,900 had MAC, 955 MAC plus CRT, and 418 MAC plus SBRT. The median RT dose/fraction (fx) was 50.4 Gy/28 fx in the MAC plus CRT cohort and 33 Gy/5 fx in the MAC plus SBRT cohort.

Patients who received MAC plus CRT, compared with MAC plus SBRT, showed similar rates of ypT3-T4 disease (54 percent vs 58 percent; p=0.187), R0 (87 percent vs 84 percent; p=0.168), and pathologic complete response (6 percent vs 4 percent; p=0.052). MAC plus CRT, however, resulted in less regional lymphatic disease (ypN+: 28 percent vs 41 percent; p<0.001).

The median overall survival was 24.6 months in patients receiving MAC plus CRT and 29.5 in those receiving MAC plus SBRT (p=0.045).

“Prospective evaluation of neoadjuvant RT regimens with attention to radiation therapy design is warranted,” the authors said.

“Chemotherapy followed by R0 is the treatment of choice for patients with localized PDAC. Neoadjuvant MAC or MAC then RT may optimize surgical candidacy,” they noted.