Inclusion Criteria:  Able to provide written informed consent Age greater than 18 years Elective surgery scheduled greater than 1 week from preoperative assessment and date of pharmacogenomic testing Major cancer surgery expecting to last two or more hours with anticipated admission of at least 1 night including: breast, melanoma, colorectal (laparoscopic or open), prostate, or other major cancer surgery (e.g. oesophagectomy, head and neck cancer, retroperitoneal sarcoma, etc.)  Exclusion Criteria:  Day case surgery Expected surgery duration of < 2 hours Urgent surgery expected within 1 week of pre-operative assessment Emergency surgery