Colorectal cancer

Colorectal cancer is defined as a type of cancer that affects the colon (large intestine) or rectum (World Health Organization [WHO], 2023). It is the third most common cancer worldwide, and the second-highest cause of cancer deaths (Duan et al, 2022). In the UK, the disease is the fourth most frequently diagnosed cancer type and accounts for 11% of all new cancer cases with the highest occurrence found in those aged 85–89 (Vincent, 2024). Risk factors have been extensively studied and have been classified as non-modifiable and modifiable.

Non-modifiable risk factors include (Sawicki et al, 2021):

• Age: Advancing age is a key risk factor
• Family history: People with one affected first-degree relative have a two times greater risk, which is higher if the affected relative was diagnosed before the age of 60. Positive family history has a role in 15–20% of patients with colorectal cancer (Kuipers et al, 2015)
• Hereditary colorectal cancer: This accounts for 5–10% of all cases and the most common syndrome in this category is Lynch syndrome (a hereditary condition caused by genetic mutations). The second most common hereditary colorectal cancer syndrome is familial adenomatous polyposis, caused by genetic mutations in the adenomatous polyposis coli gene, and this type is associated with cancer at a young age (Kuipers et al, 2015)
• Genetic mutations: Genetic mutations are associated with a higher risk of colorectal cancer; however, these account for only 5% of cases (Roshandel et al,

Some patients may be asymptomatic, with no obvious symptoms, or diagnosed following screening. In some cases, symptoms may not become apparent until the cancer has reached an advanced stage. The presentation is also influenced by the site of the cancer as follows (Vincent, 2024):

• Right colon cancers: Patients may present with weight loss, anaemia, a mass in the right iliac fossa and occult bleeding (non-visible blood in the stool). The disease is more likely to be advanced at the time of diagnosis.
• Left colon cancers: These may present with symptoms of rectal bleeding, changes in bowel habit, colicky pain, bowel obstruction and tenesmus (a feeling of wanting to open the bowels but the bowels are empty). This type is less likely to be advanced at presentation.
• Jaundice and hepatomegaly are indicative of advanced disease with liver metastases. Approximately 20–25% of patients have metastases at the time of diagnosis and a

The underlying processes leading to the development of cancer are highly complex and involve several mechanisms. Most tumours arise from precancerous polyps and normal colorectal epithelium can transform into an adenoma, which can eventually become invasive and metastasise (Coulson, 2025). The transformation of normal colonic epithelium into adenomatous lesions, and ultimately into colon cancer, involves alterations in genes that regulate DNA repair and cell proliferation (Dragovich, 2025). These changes result in the disturbance of the process which controls the renewal of the epithelium, leading to a proliferation of abnormal cells. When an adenocarcinoma becomes invasive, it can spread to other body parts via blood and lymphatic arteries; however, up to 18 years may pass between developing a polyp and invasive cancer, and an average of around 9 years to form a metastasis (Hossain et al, 2022).

A thorough history is needed, which should include symptoms and their severity, past medical history, and family history as well as an assessment of risk factors, such as obesity, smoking history, and alcohol intake. Routine bloods should be requested and should include a full blood count (FBC) to assess anaemia as well as liver function tests (LFTs) to evaluate liver involvement. A quantitative faecal immunological test (FIT) is recommended by NICE for patients with the following symptoms to guide referrals (NICE, 2025):

• Altered bowel habit
• An abdominal mass on examination
• Anaemia on FBC result
• Aged 40 or above with abdominal pain and unexplained weight loss
• Aged 50 and over with any of the following unexplained symptoms: weight loss, rectal bleeding, or abdominal pain 
• Aged 60 or over with anaemia if iron deficiency is not present.
  An urgent referral on a 2-week wait is needed if the FIT test report identifies at
  

Treatment options are decided by the multidisciplinary team, comprised of doctors (an oncologist and a colorectal surgeon), specialist nurses, radiologists, and a pathologist. The treatment intensity is governed by the site of the cancer and the stage at diagnosis. Rectal cancer accounts for 49.66% of colorectal cancers and colon cancer accounts for 49.09% (Duan et al, 2022). See Table 2 for a further breakdown of sites of onset). Treatment is often given according to the cancer stage (Cancer Research UK, 2024).

Treatment of colon cancer by stage is as follows:

• Stage 1: Surgery is the first line for early cancer
• Stage 2: Chemotherapy may be given before surgery to shrink the cancer or after surgery if there is a risk of recurrence
• Stage 3: Treated the same as stage 2 cancers
• Stage 4: Treatment may involve surgery, chemotherapy, radiotherapy, and targeted immunotherapy drugs, needed for metastatic bowel cancer.

The treatment of rectal cancer is shown in Table 4.
The disease stage at initial diagnosis is the most important prognostic indicator and the reported 5-year survival rate of patients with localised cancer who can be surgically resected is about 90%, compared to a 5-year survival rate of around 10% in those with advanced cancer at the time of diagnosis (Duan et al, 2022). Over 50% of patients with colorectal cancer will develop liver metastases, and for these patients, liver resection with

Nursing and Midwifery Council: standards of proficiency for registered nurses

Part 1: Procedures for assessing people’s needs for person-centred care

2.1: Understand and apply the aims and principles of health promotion, protection and improvement and the prevention of ill health when engaging with people 

2.5: Promote and improve mental, physical, behavioural, and other health-related outcomes by understanding and explaining the principles, practice, and evidence base for health screening programmes 

3.11: Undertake routine investigations, interpreting and sharing findings as appropriate 

3.12: Interpret results from routine investigations, taking prompt action when required by implementing appropriate interventions, requesting additional investigations, or escalating to others 

Part 2: Procedures for the planning, provision and management of person-centred nursing care

4.2: Work in partnership with people to encourage shared decision making to support individuals, their families, and carers to manage their own care when appropriate

4.3: Demonstrate the knowledge, communication and relationship management skills required to

Cancer Research UK. Bowel Cancer. Available at: https://www.cancerresearchuk.org/about-cancer/bowel-cancer

Coulson M. Colorectal cancer. 2025. Available at: https://geekymedics.com/colorectal-cancer/

Dragovich T. Colon cancer. 2025. Available at: https://emedicine.medscape.com/article/277496-overview#a4

Duan B, Zhao Y, Bai J, Wang J, Duan X, Luo X, Zhang R, Pu Y, Kou M, Lei J, Yang S. Colorectal Cancer: An Overview. In: Morgado-Diaz JA, editor. Gastrointestinal Cancers. Brisbane (AU): Exon Publications. 2022. Doi: 10.36255​/exon-publications-gastrointestinal-cancers-colorectal-cancer

Geramizadeh B, Marzban M, Owen DA. Malignant colorectal polyps: Pathological consideration (A review). Iran J Pathol. 2017;12(1):1-8.

Hossain MS, Karuniawati H, Jairoun AA, Urbi Z, Ooi J, John A, Lim YC, Kibria KMK, Mohiuddin AKM, Ming LC, Goh KW, Hadi MA. Colorectal Cancer: A Review of Carcinogenesis, Global Epidemiology, Current Challenges, Risk Factors, Preventive and Treatment Strategies. Cancers (Basel). 2022;14(7):1732. Doi: 10.3390/cancers14071732

Jones RP, Kokudo N, Folprecht G, Mise Y, Unno M, Malik HZ, Fenwick SW, Poston GJ. Colorectal Liver Metastases: A Critical Review of State of the Art. Liver Cancer. 2016;6(1):66-71.