• Home
  • Colon Cancer: ADVANCED INFORMATION

Colon Cancer: ADVANCED INFORMATION

Condition

ADVANCED INFORMATION:

New Zealand has one of the highest rates of colorectal cancer (CRC) in the world, and New Zealand women have the highest age-standardised rate of colon and rectal cancer worldwide. With over eight patients diagnosed per day, it is the second most common cancer diagnosed in New Zealand, and the second most common cause of cancer death – more than prostate cancer and breast cancer combined. This is despite recent improvements in treatment and subsequent survival.

In addition, absolute rates continue to rise in the face of an ageing and increasing population. New Zealanders have a 6 per cent risk of developing CRC in their lifetime.1,2

These frankly sobering statistics are juxtaposed against the fact that at first presentation, over 25 per cent of patients already have metastatic disease. We have the lowest percentage of surgically curable localised disease (28 per cent) when compared with Australia (34 per cent), the US (40 per cent) and the UK (42 per cent).3 The highest proportion of these late-stage diagnoses are in Māori and Pacific patients.

Overall, current rates of CRC for Māori are lower than for the European patients. However, Māori have had consistently increasing incidence since 1996. If current trends continue, within the next five years, Māori are projected to have a higher incidence of CRC than non-Maori.4

In addition, Māori patients present at a younger age – 58 per cent of bowel cancers in Māori females and 52 per cent in males present before the age of 60, compared with 27 per cent and 29 per cent in non-Māori, respectively. Some of this may also be explained by Māori having a younger population age structure.5

Compounding this is increased mortality, with the five-year risk of death from CRC at 47 per cent, compared with 38 per cent for non-Māori, non-Pacific.6 The lower survival rate of CRC among Māori may reflect diagnosis at a later stage, as they are 37 per cent more likely to present with obstruction or perforation and 35 per cent more likely to undergo emergency surgery compared with non-Māori.7

Comorbidity and difficulties accessing health services, such as colonoscopy, are estimated to account for 30 per cent of this excess mortality. Some of the barriers contributing to low rates of colonoscopy in Māori have been identified, and recommendations around how to address them have been made. Barriers include Māori living with a low socioeconomic status, which includes poverty and a proportionately higher burden of medical fees. Further, intergenerational racial injustice and discrimination contributes to mistrust and a lack of communication, preventing Māori from presenting to medical care.8,9

Pacific patients have even worse outcomes, with a five-year cumulative incidence of death from CRC of 59 per cent, which represents a twofold higher risk than for non-Pacific patients. This increased risk is not completely explained by differences in stage at diagnosis. In the New Zealand bowel screening pilot in Waitematā, Auckland, Pacific participation rates were half that of the European group.

In 2022, the Government announced it would lower the age for screening commencement for Māori and Pacific people to 50 years, instead of 60 as per the general population (see screening later in this article). This started in December 2022 in Waikato and is expected to be rolled out to other hospitals in mid-2023.

Diagnosis based on symptoms and signs is challenging

Why is does New Zealand have high rates of CRC yet low rates of early diagnosis? How are patients with this disease presenting? How can we identify them, and do so earlier? What are we doing, and what more can we do? And where does primary care fit into this picture?

Symptoms

Early CRC is often asymptomatic. Patients may initially present with mild changes, and overt symptom development is often a reflection of an advanced lesion. The challenge of diagnosis is that patients may present with a heterogenous and diverse spectrum of symptoms, often mimicking more benign gastrointestinal pathology.

Large international analyses report poor predictive probabilities of common symptoms, such as change in bowel habit, constipation, diarrhoea, abdominal pain and weight loss, with many traditional alarm features demonstrating poor sensitivity and specificity for the diagnosis of CRC. A meta-analysis including 15 studies of nearly 20,000 patients showed the sensitivity to be as low as 5–64 per cent, and even lower in patients under age 55.10

In a case–control trial of symptomatic patients suspected to have CRC and referred for colonoscopy in south Auckland, the only significant discriminatory symptom was haematochezia. This was only 1.7 times more likely to be CRC as opposed to a benign cause, such as haemorrhoids or diverticulosis. Change in bowel habit was the predominant presenting complaint in 44 per cent of those ultimately diagnosed with CRC, but also in 51 per cent of those with benign diagnoses at colonoscopy. Patients with CRC reported their symptoms for an average of 115 days prior to the first GP presentation, compared with 128 days for those with a benign diagnosis.11

Currently, there is an attempt to encapsulate these difficulties within grading criteria, with prioritisation of symptoms, signs and risk factors based on UK National Institute for Health and Care Excellence referral guidelines for suspected CRC.12 Local retrospective review of these grading criteria demonstrated that they may miss one-quarter of patients with CRC in the referral population.13 This leads to convoluted and delayed presentations, diagnostics and treatments.14

This frustration is reflected in patient complaints about perceived delays in diagnosis in primary care, where 27 per cent of the 197 complaints regarding a delay of cancer diagnosis between 2004 and 2013 were related to CRC.15 The report confirms that the most common issue for CRC complaints related to non-specific or atypical symptom presentation.

When it comes to patients without red flag symptoms, my personal practice is to ask patients to keep a written record of symptoms and return after six to eight weeks for further review. I suggest that even if their symptoms have completely resolved, they call the practice to let us know. This adds a layer of formal documentation without increasing workload or generating a recall task. If symptoms persist or are progressive despite intervention, this would be an indication for further investigation.

Symptoms of CRC may depend on the location of the lesion. Lesions in the right colon (caecum, ascending) may be larger at diagnosis, manifesting only when they grow large enough to block off the lumen or grow into adjacent organs or metastasise.

Left-sided lesions may be smaller before they cause an obstruction as the colon is narrower in calibre. This may result in variable bowel habit with harder stools and overflow diarrhoea from liquid stools passing the compressed area. Pain and cramping may result from the bowel peristalsis to overcome the narrowing.

Some bleeding occurs in most lesions, but overt visible blood loss (haematochezia) is more common in distal lesions, such as the sigmoid colon and rectum.

Slower occult blood loss from an oozing mass may only present with anaemia-related symptoms, such as shortness of breath or fatigue. Younger patients may compensate for this slow loss and not demonstrate any abnormality on blood tests.

Bleeding from a right-sided lesion may present with melaena (dark, tarry black stools), usually attributed to upper gastrointestinal bleeding. If a gastroscopy is requested and no cause found, usually a colonoscopy is the next investigation requested.

Rectal lesions may also present with tenesmus, or the sensation of incomplete emptying following a bowel motion. Perineal or sacral pain may indicate a rectal lesion that has invaded adjacent organs.

Weight loss due to CRC may be related to abdominal pain and cramping that reduces appetite, or cancer-related cachexia in advanced malignancy. This causes loss in both adipose tissue and skeletal muscle, as opposed to predominant adipose tissue loss in non-cancer-related weight loss.

Metastatic spread to the liver may cause right upper quadrant pain and jaundice. This is the most common location for metastasis as the colon venous system drains via the portal vein into the liver. Rectal veins drain via the inferior vena cava into the pulmonary circulation, so rectal cancer may present with additional shortness of breath or haemoptysis from pulmonary metastasis.

Summary

Diagnosing CRC is difficult. Symptoms of CRC are non-specific and may already represent advanced disease when they manifest. Haematochezia is the most discriminatory symptom. If an alternate or benign aetiology for symptoms is suspected, clinical follow-up of intervention in an agreed-upon time frame, to assess for improvement and response, is crucial to prevent missed or delayed diagnoses of CRC.

Signs

Clinical signs such as palpable mass (rectal or abdominal) and iron-deficiency anaemia are thought to be robust and consistent markers of CRC that are well understood and subsequently integrated into rapid referral pathways.

Local data demonstrate you are seven times more likely to have CRC as opposed to benign pathology if you have a palpable mass, and nearly two times more likely if you have iron-deficiency anaemia.11 However, the proportion of patients with CRC with a palpable mass may only be about 4 per cent, while 10 per cent of patients with CRC have iron-deficiency anaemia.

The carcinoembryonic antigen (CEA) tumour biomarker blood test is non-discriminatory and non-specific for assessment of patients with symptoms and should not be requested. It is used as a prognostic and monitoring test once CRC is diagnosed.

Ideally, a rectal examination should always be performed. Although specific, a normal rectal examination does not exclude rectal malignancy. Rectal cancers are said to be palpable in 25 per cent of cases, with an estimated sensitivity of 76 per cent.16

The average length of the index finger is approximately 8.25cm, so lesions higher in the rectum will not be palpable. False positives also occur, as alternate causes for masses include a palpable cervix, retroverted uterus, enlarged prostate, angulated coccyx and faecal loading.

It is important to also examine the anterior prostate and circumference of the rectum, not just the posterior wall of the rectum which is most accessible in the left lateral position.

Summary

Signs of CRC are more specific but not as common to detect. You should maintain an index of suspicion in symptomatic patients despite normal physical signs or blood tests.

Young patients

The rate of CRC in young patients under the age of 50 in New Zealand is increasing. This concerning trend is also seen in Australia, the UK, US and Asia. From 1995 to 2012 in New Zealand, distal colon cancer increased by 14 per cent per decade in men under 50, and rectal cancer by 18 per cent.21 CRC is now the second most common cause of cancer among men in this age category. Women’s rectal cancer also increased by 13 per cent per decade.

Recent estimates suggest that by 2030, the incidence of CRC in this age group will increase by 90 per cent, and the incidence of rectal cancer will increase by 124.2 per cent.22 Internationally, these patients are more likely to be Caucasian females. In New Zealand, 30 per cent of the CRC seen in Māori and Pacific females, and 25 per cent of that in Māori and Pacific males, occurs before age 50.5

The reason for this phenomenon is not known. Although some cases are familial (23–39 per cent have a family history of CRC), many are not. It may be due to a birth cohort effect, with a significant change in exposure to risk factors – in particular, lifestyle, diet and obesity.23

Younger patients may compensate for disease symptoms such as occult bleeding or weight loss, increasing the diagnostic challenge. Additional confounders, such as delayed patient presentation and fewer financial resources, have also been demonstrated to be contributory.

Younger patients have a three to fourfold longer delay in diagnosis, whereby alternate benign causes, such as haemorrhoids or menorrhagia, may be assumed causes of haematochezia and iron-deficiency anaemia. Young patients with these symptoms have 10 times the risk of CRC.24

Prompt evaluation and follow-up is crucial. If a clinically confirmed alternate source is not identified, or if treatment for the proposed cause does not improve symptoms, specialist review or endoscopy should be strongly considered.

Younger patients with CRC often present with more aggressive disease, both histologically and clinically. However, stage for stage, they often have a better prognosis with treatment, which may be aggressive and with curative intent.

 

Summary

Given the increasing incidence, young patients deserve a higher index of suspicion and inclusion of CRC in a differential diagnosis. Follow-up of symptoms to assess for resolution, and referral for additional assessment, are warranted if symptoms are not improving as expected.

 

REFERENCES:

  1. New Registrations and Deaths 2006 [Internet]. [cited 2020 Feb 29]. Available from: http://www.moh.govt.nz/moh.nsf/indexmh/cancer-reg-deaths-2006
  2. Cancer Projections: Incidence 2004-08 to 2014-18 | Ministry of Health NZ [Internet]. [cited 2020 Feb 29]. Available from: https://www.health.govt.nz/publication/cancer-projections-incidence-2004-08-2014-18
  3. Samson P, O’Grady G, Keating J. An international comparison study of stage of colorectal cancer at diagnosis: how does New Zealand compare? N Z Med J [Internet]. 2009 May 8 [cited 2020 Mar 5];122(1294):74–83. Available from: http://www.ncbi.nlm.nih.gov/pubmed/19465950
  4. Te Aho o Te Kahu CCA. Te Aho o Te Kahu. He Pūrongo Mate Pukupuku o Aotearoa. The State of Cancer in New Zealand 2020. [Internet]. Wellington; 2021 [cited 2023 Mar 6]. Available from: https://teaho.govt.nz/reports/cancer-state
  5. McLeod M, Robson B. Bowel cancer screening age range for Māori: what is all the fuss about? - PubMed. N Z Med J [Internet]. 2021 May 21 [cited 2023 Mar 4];134:71–7. Available from: https://pubmed.ncbi.nlm.nih.gov/34012141/
  6. Sharples K, Firth M, Hinder V. The New Zealand PIPER Project: colorectal cancer survival according to rurality, ethnicity and socioeconomic deprivation-results from a retrospective cohort study. N Z Med J. 2018;131(1476):24–39.
  7. Swart EM, Sarfati D, Cunningham R, Dennett E, Signal V, Gurney J, et al. THE NEW ZEALAND MEDICAL JOURNAL Ethnicity and rectal cancer management in New Zealand. J New Zeal Med Assoc NZMJ. 2013;126:8716.
  8. Pitama S, Cave T, Huria T, Lacey C, Cuddy J, Frizelle F. Exploring Maori health worker perspectives on colorectal screening. N Z Med J. 2012 Jun 8;125(1356):75–84.
  9. Pitama S, Huria T, Lacey C. Improving Māori health through clinical assessment: Waikare o te Waka o Meihana. N Z Med J. 2014;127(1393).
  10. Vega P, Valentín F, Cubiella J. Colorectal cancer diagnosis: Pitfalls and opportunities. World J Gastrointest Oncol [Internet]. 2015 Dec 12 [cited 2023 Mar 10];7(12):422. Available from: /pmc/articles/PMC4678389/
  11. Improving efficiency of current diagnostic pathways for investigation of colorectal cancer in symptomatic patients - PubMed [Internet]. [cited 2023 Feb 24]. Available from: https://pubmed.ncbi.nlm.nih.gov/33651784/
  12. Clinical Governance Research and Development Unit, University of Leicester. Referral Guidelines for Suspected Cancer in Adults and Children. (NICE Clinical Guidelines, No. 27.) London, UK: Royal College of General Practitioners; 2005. https://www.ncbi.nlm.nih.gov/books/NBK45764/
  13. Hsiang JC, Bai W, Lal D. Symptom presentations and other characteristics of colorectal cancer patients and the diagnostic performance of the Auckland Regional Grading Criteria for Suspected Colorectal Cancer in the South Auckland population. N Z Med J. 2013;126(1382):95–107.
  14. Murray M, Brown J, Hinder V, Merrrie A, Hill A, Hulme-Moir M, et al. The colorectal cancer patients’ journey: the Auckland region - New Zealand Medical Journal. N Z Med J [Internet]. 2011 [cited 2020 Mar 5];124(1331):1–11. Available from: http://www.nzma.org.nz/journal/read-the-journal/all-issues/2010-2019/2011/vol-124-no-1331/article-murray
  15. The Health and Disability Commissioner. Delayed Diagnosis of Cancer in Primary Care: Complaints to the Health and Disability Commissioner: 2004–2013 [Internet]. Auckland; 2015 [cited 2023 Mar 10]. Available from: https://www.hdc.org.nz/media/2698/delayed-diagnosis-of-cancer-in-primary-care_april-2015.pdf
  16. Ang CW, Dawson R, Hall C, Farmer M. The diagnostic value of digital rectal examination in primary care for palpable rectal tumour. Colorectal Dis [Internet]. 2008 [cited 2023 Mar 4];10(8):789–92. Available from: https://pubmed.ncbi.nlm.nih.gov/17868406/

21. Gandhi J, Davidson C, Hall C, Pearson J, Eglinton T, Wakeman C, et al. Population-based study demonstrating an increase in colorectal cancer in young patients. Br J Surg [Internet]. 2017 Jul 1 [cited 2023 Mar 4];104(8):1063–8. Available from: https://onlinelibrary.wiley.com/doi/full/10.1002/bjs.10518 

22. Bailey CE, Hu CY, You YN, Bednarski BK, Rodriguez-Bigas MA, Skibber JM, et al. Increasing disparities in the age-related incidences of colon and rectal cancers in the United States, 1975-2010. JAMA Surg [Internet]. 2015 Jan 1 [cited 2023 Mar 4];150(1):17–22. Available from: https://pubmed.ncbi.nlm.nih.gov/25372703/

23. Done JZ, Fang SH. Young-onset colorectal cancer: A review. World J Gastrointest Oncol [Internet]. 2021 Aug 15 [cited 2023 Mar 4];13(8):856–66. Available from: http://www.ncbi.nlm.nih.gov/pubmed/34457191

24. Demb J, Liu L, Murphy CC, Doubeni CA, Martínez ME, Gupta S. Young-onset colorectal cancer risk among individuals with iron-deficiency anaemia and haematochezia. Gut [Internet]. 2020 Aug 1 [cited 2023 Feb 24];70(8):1529–37. Available from: https://pubmed.ncbi.nlm.nih.gov/33443020/