Across 15 mutation categories (see Additional file 1 ), there was a highly significant trend for users to have fewer mutations (SNVs and indels) than non-users (sign test p < 9.8 × 10 −04 ; Additional file 2 : Tables S5 and S7).
NSAID users had a lower median combined mutation load (SNVs and indels) with 2.95 mut/Mb (range = 0.15–10.28 mut/Mb) compared to 3.46 mut/Mb (range = 0.08–19.55 mut/Mb) for non-users, but the overall difference in median total mutation load per biopsy between users and non-users did not reach statistical significance ( p = 0.104, Kruskal–Wallis).