The Importance of Colorectal Cancer Screening

Colorectal cancer (CRC) also termed Bowel Cancer is highly prevalent being the third most common cancer worldwide. This preventable diagnosis sadly accounts for 11% of all cancers and is the third leading cause of cancer-related deaths.1

Approximately 70% of CRC develops from traditional polyps along the adenoma-carcinoma sequence. This leaves 30% following the sessile serrated lesion (i.e. flat polyps) to carcinoma pathway which tend to be right sided, and more rapidly progressive.

The major risk factors for colorectal cancer are older age and having certain inherited conditions (e.g. Lynch Syndrome and Familial Adenomatous Polyposis). Several other factors are also been associated with increased risk, including:

• Family history of the disease
• Excessive alcohol use
• Obesity
• Being physically inactive
• Cigarette smoking
• Diet high in red meat intake

In addition, people with a history of Inflammatory Bowel (e.g. Ulcerative Colitis and Crohn’s Disease) have a higher risk of CRC than people without such conditions.

Although the incidence and mortality rates are declining in USA between 2007 and 2016 (by 2.4% and 2.2% each year, respectively), worryingly the incidence of colon cancer in younger populations is increasing. 2  This is termed Early onset colorectal cancer (eoCRC) and is not addressed by the current routine screening guidelines.

In USA recommendations have been made to screen from the age of 45. This is because though CRC incidence is decreasing in those 50 years of age and older, it is increasing substantially among those 20-49 years of age. Those born around 1990 have twice the risk for Colon cancer and four times the risk for rectal cancer compared with those born around 1950 3

The UK guidelines have currently not changed. Bowel Scope screening starts at age 55 years and the national bowel cancer screening programme is offered at age 60 years. It is now apparent that individuals with eoCRC have a lifetime risk of a second malignancy that is nearly 50% higher than the general population. This risk of a second malignancy is highest in the first 5 years after diagnosis and is increasing over time.

More now than ever, awareness of CRC is imperative. Young patients presenting with changes in bowel habit, rectal bleeding, anaemia, and weight loss should undergo colonoscopy. Rectal and anal symptoms should be reported urgently and prompt and careful physical and endoscopic examination undertaken.

Similarly, awareness of any bowel habit concerns that persist need to be brought to medical attention earlier rather than later. Strictly for screening non symptomatic individuals for example, multiple guidelines globally recommend that average-risk adults undergo CRC screening starting at the age of 50-75 years.

Available screening tools currently include stool-based screening tests which detect hidden blood. This is a 2-step process as positive cases need a colonoscopy thereafter.

The one step process is direct visualization methods, such as flexible sigmoidoscopy and colonoscopy.

The gold standard screening method is colonoscopy as it provides high sensitivity for cancers and all types of precancerous lesions and can deliver diagnostics and therapeutics in a single session. Colonoscopy also has longer procedure intervals (10 years) for normal results. One or two normal colonoscopy results may imply lifetime protection from CRC 4

That said, any screening test is better than none, and is worth discussing with your GP.

Gender is important in various aspects of CRC screening, especially attitudes towards colonoscopy, as well as anatomical factors and tumour behaviour.

Previous studies have shown that female sex is a risk factor for incomplete colonoscopy judged by a lower completion rate or Caecal Intubation Rate. This is not an issue amongst experienced colonoscopists, but it has been shown that endoscopist trainees are 1.5 times more likely to fail to fully complete the colonoscopy in female patients 5

Procedural difficulties encountered in women have been described since the 1990s. The difficulties are caused by the longer colonic length in women than in men (155 cm vs. 145 cm), especially the length of the middle portion or transverse colon (48 cm vs. 40 cm). This segment tends to be more redundant and lying deeper in the pelvis with women more than in men (62% vs. 26%). 6  Tumour location also differs according to patients’ sex. Females tend to have mostly proximal/right-sided-colon lesions, whilst males experience left-sided-colon tumours (55% and 44% respectively) 7

It is possible that hormonal factors play a role in the higher frequency of right-sided colon cancer (RCC) in women. RCC appears to be more advanced in stage upon diagnosis and to have more poorly differentiated tumours. Conversely, left-sided colon cancer (LCC) was associated with a reduced risk of death, independent of stage, race, adjuvant chemotherapy, and quality of study 8

As women tend to have lower rates of complete colonoscopy, it is possible that RCC can remain undetected during screening, and therefore present with an advanced stage when finally diagnosed. Moreover, a larger proportion of women develop flat and depressed type colorectal polyps which can remain undetected and lead to late diagnosis. This is in contrast to men, who tend to develop the traditional polypoid type of lesion that is more easily detected and resected 9

If you would like to speak to one of our specialists about bowel cancer, or any other concerns you might have regarding your digestive health, please do not hesitate to get in touch with us today.

You can easily book online, or simply contact us through our online form or via telephone.

1. Bray F, Ferlay J, Soerjomataram I, et al. Global Cancer Statistics 2018: GLOBOCAN Estimates of Incidence and Mortality Worldwide for 36 Cancers in 185 Countries. Ca Cancer J Clin. 2018;68:394-424.

2. Tiritilli, A., Ko, C. Patients with Early-Onset Colorectal Cancer Have an Increased Risk of Second Primary Malignancy. Dig Dis Sci (2021)

3. Vakil N, Ciezki K, Singh M. Colorectal cancer in 18- to 49-year-olds: rising rates, presentation, and outcome in a large integrated health system. Gastrointest Endosc. 2021 Mar 29:S0016-5107(21)00263-7.

4. Dekker E, Rex DK. Advances in CRC Prevention: Screening and Surveillance. Gastroenterology. 2018 May;154(7):1970-1984

5. Franco DL, Leighton JA, Gurudu SR. Approach to Incomplete Colonoscopy: New Techniques and Technologies. Gastroenterol Hepatol (N Y) 2017;13:476–83.

6. Saunders BP, Fukumoto M, Halligan S, et al. Why is colonoscopy more difficult in women? Gastrointest Endosc. 1996;43:124-6.

7. Quirt JS, Nanji S, Wei X, Flemming JA, Booth CM. Is there a sex effect in colon cancer? Disease characteristics, management, and outcomes in routine clinical practice. Curr Oncol. 2017;24:e15-e23.

8. Petrelli F, Tomasello G, Borgonovo K, et al. Prognostic Survival Associated With Left-Sided vs Right-Sided Colon Cancer: A Systematic Review and Meta- analysis. JAMA Oncol. 2017;3:211-9.

9. Kim S, Paik HY, Yoon H, et al. Sex- and gender- specific disparities in colorectal cancer risk. World J Gastroenterol. 2015;21:5167–75.