The CHAMPS questionnaire includes 41 questions that measures frequency and duration of activities. The primary endpoint is the estimated Caloric Expenditure Per Week measure from the CHAMPS, which is calculated by weighting the duration variable of the 28 exercise-related activities using the corresponding metabolic equivalents (METs) value, then multiplying by 60 to convert METs/minute to METs/hour, then multiplying by participant weight in kg/200 to calculate the caloric expenditure/week score, and then summing the individual item caloric expenditure scores across all 28 items. This scale score was transformed into the unit of kcal. The minimum possible value of the scale is 0 and there is not a defined maximum possible value. Higher scores equate to more kilocalories burned per week, which is a better outcome in the context of this trial.

All eligible participants who undergo major cancer surgery, consent to complete CHAMPS questionnaires, have a baseline CHAMPS score and have a CHAMPS score at 8 weeks post-surgery +/- 2 weeks.

Postoperative complications were assessed at 12 weeks following surgery using the Clavien-Dindo classification:

Grade I: Any deviation from the normal postoperative course w/out the need for pharmacological treatment or surgical, endoscopic, and radiological interventions Grade II: Requiring pharmacological treatment w/ drug other than such allowed for Grade I complications Grade III: Requiring surgical, endoscopic or radiological intervention Grade IIIa: Intervention not under general anesthesia Grade IIIb: Intervention under general anesthesia Grave IV: Life-threatening complication Grade IVa: Single organ dysfunction Grade IVb: Multiorgan dysfunction Grave V: Death A generalized linear mixed model (with logit link function) with random practice effect to account for clustering within practice will be used to compare postoperative complications within 12 weeks of surgery between the combined OPTI-Surg no-coach & coach arms vs usual care followed by pairwise comparisons

All eligible participants who undergo major cancer surgery (no documentation of postoperative complications will be considered as not having any postoperative complications).

EFS is a validated measure of frailty that identifies distinct frailty domains that are potential targets for additional pre-operative optimization. For frailty domains that score 1 or 2 points, optimization referrals will be recommended. Clinic or research staff at sites randomized to OPTI-Surg intervention arms will screen and identify eligible patients for administration of the EFS and provide printed surgery preparation materials. A generalized linear mixed model (with logit link function) with a random practice effect to account for clustering within practice will be used to compare compliance rate for screening between the no-coach and coach arms.

All eligible participants from Arm II (OPTI-Surg) and Arm III (OPTI-Surg plus Coach) who undergo major cancer surgery who are evaluable for postoperative complications outcome. Notes: Generalized linear mixed model analysis not performed.