Forest plot for the propensity-matched patient subgroup analysis showing multivariable (adjusted) hazard ratios; a subgroup analysis was undertaken to assess the association of total IV anesthesia and volatile inhalational (INHA) anesthesia with outcome depending on specific cancer types and severity of surgery. This analysis demonstrated a significantly worse outcome in the INHA group for all severities of surgery except 3 (which demonstrated a trend), for patients scored American Society of Anesthesiologists (ASA) I to III and for patients with or without metastasis at the time of surgery. Surgical severity was graded from 1 (least) to 4 (most) according to a scale derived by the National Institute for Health and Care Excellence. E = events; GI = tumors of gastrointestinal origin; METno = metastasis not present at time of surgery; METyes = metastasis present at time of surgery; SEV = severity of surgery.