Colorectal Cancer - What are the Risk Factors

Ramsay Health Care Consultant Colorectal and General Surgeon, Mr Triantafyllos Doulias, has been discussing colorectal cancer and the risk factors associated with it.

Colorectal cancer is found in the large bowel (colon and rectum), where abnormal cells in your large bowel divide uncontrollably and form a cancerous tumour. 

In the UK, colorectal cancer is the 4th most common cancer with around 43,000 cases being diagnosed annually, according to the national statistics, 1 in 15 males and 1 in 18 females will be diagnosed with bowel cancer in their lifetime and colonic cancer is the 2nd leading cause of cancer related deaths globally (1,2).

However, bowel cancer mortality rates are projected to fall by 10% in the UK between 2023 - 2025, mainly due to the effective screening programme we have in place (1). The prognosis for colorectal cancer varies depending on the stage at diagnosis, with early-stage cancers having a higher life expectancy and better quality of life than advanced-stage cancers.

Timely diagnosis, appropriate oncological and surgical treatment, and regular follow-up care are important for improving survival rates.

What are the risk factors? 

Factors that may increase the risk of developing colorectal cancer can include certain lifestyle factors and others such as:

Lifestyle factors - 

  • Diet; high in red and processed meats raises the colorectal cancer risk
  • Low vitamin D may also increase the risk
  • Smoking; Long term cigarette smoking is well linked to lung cancer but there is evidence to support that people who smoke are more likely to develop and die from colorectal cancer.
  • Alcohol use; Colorectal cancer has been linked to moderate to heavy alcohol use. Even light-to-moderate alcohol intake has been associated with some risk.

Other Factors -

  • Age; the risk of developing colorectal cancer increases with age, with most cases occurring in individuals over 50 years old although there are several studies reporting increased incidence of colorectal cancer in patients over 40 years old
  • History of colonic polyps; individuals who have had adenomatous polyps especially if the polyps shown evidence of dysplasia have a higher risk for colorectal cancer. Individuals who had colorectal cancer even if completely removed have higher chances of developing colonic or rectal cancer in other parts of the colon/ rectum. The risk increases if the initial cancer was diagnosed at a young age.
  • Inflammatory Bowel Disease; Individuals with inflammatory disease (Ulcerative Colitis or Crohns disease) have higher risks of developing colorectal cancer since they tend to develop dysplastic changes in the colon and rectum
  • Family history: About 5% of people who develop colorectal cancer have inherited genes (mutations) that can lead to developing colorectal cancer. The most common inherited syndromes linked with colorectal cancers are Lynch syndrome (hereditary non-polyposis colorectal cancer, or HNPCC) and familial adenomatous polyposis (FAP), but other rarer syndromes can increase colorectal cancer risk
  • Diabetes type II; Patients with type 2 diabetes have an increased risk of colorectal cancer. The link could potentially lay on the fact that both type 2 diabetes and colorectal cancer share some of the same risk factors (such as being overweight with reduced physical inactivity).


Risk can also be affected by genetics; an American study shows having a close relative such as a parent, child or sibling who was diagnosed with a colorectal cancer, particularly before the age of 50, can cause an increased risk. It’s advised anyone with this increased risk should start their screening at around 40 years old, or 10 years before the age at diagnosis of the youngest affected relative (whichever is earlier) (4).

For more information on Consultant Colorectal and General Surgeon, Mr Triantafyllos Doulias visit his profile on our website. 


Bowel cancer incidence statistics | Cancer Research UK

April – Bowel Cancer Awareness Month (

Colorectal cancer (

Issaka et al, Gastroenterology 2023;165:1280–1291. AGA Clinical Practice Update on Risk Stratification for Colorectal Cancer Screening and Post-Polypectomy Surveillance: Expert Review

Northern Cancer Alliance Colorectal Stratified Follow Up Clinical Review and Surveillance Guidelines

G. Argilés et al, Localised colon cancer: ESMO Clinical Practice Guidelines for diagnosis, treatment and follow-up. Annals of Oncology, 2020

American Gastroenterological Association (AGA) Clinical Practice Update on Colorectal Screening and Post-Polypectomy Surveillance

Register your interest to hear from us