The GITSG 91-73 trial 1st reported benefit to adj CRT for PCA in 1985. All pts had R0 resections.
Standard arm: postop observation
Experimental arm: adj CRT using split-course RT to 40 Gy (2-wk break after 20 Gy) with intermittent bolus 5-FU → 2 full yrs of adj 5-FU alone Improved MS (20 mos vs. 11 mos) and 2-yr OS (42% vs. 15%) in the adj CRT arm. (KalserMH et al., Arch Surg 1985)