The progression-free survival (PFS) was statistically similar in patients with oligo or generalized-progression to erlotinib. However, all four cases with solitary-progression did benefit from continued erlotinib maintenance and salvage radiation with 41-140 % prolongation of PFS. It was reflected in an improved overall survival when they were compared with patients with generalized-progression (76.4 vs. 19.9 months; p = 0.018).