• Colonoscopy: Examining the whole large bowel with a flexible camera; polyps found on the way are removed (polypectomy), which prevents most bowel cancers.
• Surveillance intervals after polypectomy: After polyps are removed, the date of your next colonoscopy is set by what was found, not by habit.
• Serrated pathway: The serrated pathway is the second route to bowel cancer, running not through the familiar mushroom-shaped polyp but through flat, pale, saw-toothed lesions that are easy to miss at colonoscopy and rarely bleed.
• MLH1 promoter methylation (sporadic versus Lynch mismatch repair loss): When a tumour has lost the MLH1 mismatch-repair protein, a methylation test on the tumour tells the two causes apart: methylation switching the gene off means a sporadic cancer, no methylation means an inherited Lynch syndrome mutation is likely and the whole family needs testing.
• Colectomy: Removing the part of the colon containing the cancer along with its blood supply and lymph nodes, then joining the ends.
• Lynch syndrome: Lynch syndrome is the most common inherited cancer syndrome: a faulty mismatch-repair gene raises lifetime bowel cancer risk to 40-80% and also endometrial and other cancers.
• Germline vs somatic mutations: Germline mutations are inherited and in every cell; somatic mutations arise in the tumour only.
• Microsatellite instability (MSI-H) / mismatch repair deficiency (dMMR): Microsatellite instability is the mark of a broken DNA spell-checker (loss of MLH1, MSH2, MSH6 or PMS2) that leaves thousands of mutations, so the tumour displays abnormal proteins that T cells can recognise.

Biomarker results to ask for: Mismatch repair protein loss on immunohistochemistry, or microsatellite instability, on every colorectal cancer at diagnosis, MLH1 promoter methylation and BRAF V600E testing to separate sporadic from inherited mismatch repair loss, Germline testing of MLH1, MSH2, MSH6, PMS2 and EPCAM to confirm the diagnosis and to test relatives.

Scans and tests linked to this cancer: Germline (hereditary) testing, Histopathology & immunohistochemistry, MSI and mismatch-repair testing.

Bring copies of scan reports, pathology and blood results, and a list of every medicine and supplement.

• Finding the syndrome: Mismatch repair immunohistochemistry or microsatellite instability testing on every colorectal cancer; MLH1 promoter methylation testing where MLH1 is lost, because most of those cancers are sporadic; germline testing when methylation is absent, then cascade testing of relatives. (MSI and mismatch-repair testing, Histopathology & immunohistochemistry, Germline (hereditary) testing, Lynch syndrome, MLH1 promoter methylation (sporadic versus Lynch mismatch repair loss))
• Risk reduction in carriers: Consider daily aspirin for more than two years (NICE NG151 1.1.1, from CAPP2); colonoscopic surveillance at intervals set by gene and age; discussion of the extent of colectomy when a cancer is found; gynaecological risk-reducing surgery after childbearing for women. (Aspirin for cancer prevention and adjuvant therapy, Colonoscopy, Surveillance intervals after polypectomy, Colectomy, Chemoprevention & risk-reducing surgery)

From the standard of care recorded for this cancer; which apply depends on your stage and biomarkers. Ask which the team recommends and why.