Practice

Colorectal adenocarcinoma: risks, prevention and diagnosis

BMJ 2016; 354 doi: https://doi.org/10.1136/bmj.i3590 (Published 14 July 2016) Cite this as: BMJ 2016;354:i3590
  1. Sri G Thrumurthy, honorary research fellow1,
  2. Sasha S D Thrumurthy, medical officer2,
  3. Catherine E Gilbert, foundation year doctor3,
  4. Paul Ross, consultant medical oncologist4,
  5. Amyn Haji, consultant colorectal surgeon5
  1. 1Department of Surgery, University College Hospital, London, UK
  2. 2Department of General Medicine, Tan Tock Seng Hospital, Singapore
  3. 3Department of Surgery, Queen Elizabeth Hospital, London, UK
  4. 4Department of Medical Oncology, Guy's & St Thomas' Hospital, London, UK
  5. 5Department of Surgery, King's College Hospital, London, UK
  1. Corresponding author: A Haji amynhaji{at}nhs.net

What you need to know

  • Colorectal cancer is the third most common cancer in men and the second most common cancer in women worldwide

  • It is rare below 40 years of age

  • Increasing age, male gender, and a family history of colorectal cancer are the greatest risk factors for the disease

  • Patients presenting with suspicious symptoms and signs should be referred and investigated urgently in a specialised unit

Colorectal cancer is the fourth most common cause of cancer related mortality globally, with 1.4 million new cases and 700 000 deaths annually.1

What is colorectal cancer?

Colorectal cancer refers to tumours of the rectum or large bowel (including the appendix) that arise from the colorectal mucosa (fig 1). Adenocarcinoma is the most common form of colorectal cancer (>95%). Rarer subtypes include carcinoid tumour, sarcoma, and lymphoma; these present differently from adenocarcinoma1 and will not be discussed in this review.

Fig 1 Distribution of bowel cancer by anatomical site, UK (2007-09) (adapted from Cancer Research UK, bowel cancer incidence statistics, www.cancerresearchuk.org/health-professional/cancer-statistics/statistics-by-cancer-type/bowel-cancer/incidence)

How does colorectal adenocarcinoma develop?

Colorectal cancer typically develops from adenomatous polyps that undergo dysplastic changes to become cancerous (fig 2).2 Tumours can occur sporadically, but there are some inherited colorectal cancer syndromes (see table 1). Several risk factors are also recognised (see box 1).

Fig 2 Progression from colorectal polyp to cancer (adapted from Johns Hopkins Colon Cancer Center. Polyps 101. www.hopkinscoloncancercenter.org/CMS/CMS_Page.aspx?CurrentUDV=59&CMS_Page_ID=744568E4-291E-4276-97C4-FA7A4EE02235)

View this table:
Table 1

Inherited syndromes predisposing to colorectal cancer

Box 1: Risk factors for colorectal cancer

Sociodemographic factors
  • Older age

    • In the UK from 2009 to 2011, 43% of colorectal cancer was diagnosed in people aged ≥75 years, and 95% in those aged ≥50 years7

    • Age-specific incidence rates increase steeply after age 50, with the highest rates above age 85 years

  • Male sex

    • A meta-analysis of 17 studies comprising 924 932 patients showed men were at significantly greater risk than women (relative risk 1.83 …

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