Clinical FeaturesOncology

An Overview of Colorectal Cancer

Written by Professor Ronan Cahill, Professor of Surgery, School of Medicine, University College Dublin

Colorectal cancer is the commonest solid organ cancer that affects both genders. For context, there were 2,819 people diagnosed with this disease in 2020 versus 3,890 men with prostate cancer and 3,704 (mostly) women with breast cancer while 2,573 people were diagnosed with lung cancer. A recent seven country study in the Lancet using data from 21 population-based cancer registries in Australia, Canada, Denmark, New Zealand, Ireland and the UK showed overall declining or stable incidences for both colon and rectal cancer. Overall the risk of colon and rectal cancer has increased among more recent birth cohorts with higher numbers now presenting under the age of 50.

Interestingly and importantly improvements in treatments for patients in colorectal cancer means there were estimated to be over 17,000 people living with a history of colorectal cancer in 2014 focusing attention on survivorship programmes for this disease like those seen for other malignancies. Increasingly too patient advocacy groups along with a patientpublic engagement initiatives are enabling a greater degree of “patient voice” contribution into the care processes and pathways for this disease in Ireland.

While breast and prostate cancer have a strong hormonal component and so a potential hormonal therapy in addition to surgical and medical oncology therapies, care for colorectal cancer most often involves surgery. This is most especially for those with organ confined or regional only disease (i.e. Stage 1, 2 and 3) where surgery alone can often prove definitive therapy. Surgery is also increasingly a component of care of those with metastatic disease (stage IV) who either need palliation (including potentially a stoma) or who show response to chemo and immunotherapies especially with regard to liver metastases.

Indeed, such resection following systemic treatment at this stage of disease can provide cure for approximately 25% of such patients initially commenced on “palliative therapy”. Nonmetastatic rectal cancer patients may too receive pretreatment (neoadjuvant) with chemoradiotherapy ahead of surgery if there is any evidence on their staging investigations of disease involvement near the intended surgical resection planes as this helps improve disease free survival following surgery.

These patients as well as those with node positive either colon and rectal cancer undergoing primary surgery without any radiological evidence of any other metastases commonly also receive postoperative (adjuvant) chemotherapy too. To best guide patients through these treatment pathways, a multidisciplinary team is needed including regular meetings among these specialists where patient care can be planned, understood and updated/amended as needed.

Thanks to these types of treatments, alone or in combination, survival from colorectal cancer has improved over recent years, most especially rectal cancer thanks to personalized, sophisticated treatment plans alongside centralization of care among our eight designated cancer centres in Ireland.

It’s interesting to consider would similar efforts improve too the outcomes of colon cancers. Indeed in surgery there are efforts to develop a more radical resection standard safely following evidence in selected series regarding improved survival rates following such an operation.

This approach known as Complete Mesorectal Excision (matching as a corollary Complete Mesorectal Excision for rectal cancer) includes Central Vascular Ligation in its performance while still being completed laparoscopically. This may be something that selected patients can be offered nationally perhaps even initially at selected centres to try and better disease control and survival rates at a single (and indeed ideally index) procedure. At least the value of such a surgical approach could be better evaluated prospectively in such a way to understand its usefulness in real-world settings rather than research trials with outcome being measured perhaps by means of a registry used to show such operative care can be reliably and usefully performed for Irish patients at a regional or national basis.

Part of the improvement in colorectal cancer cure rates is doubtless due to the National Bowel Screening Programme (“Bowelscreen” launched in 2013) as the earlier the disease is detected the more likely treatment (and indeed surgery alone) is likely to cure the disease. Sadly however, generally, uptake of this service offered for free by the state is less then that seen with Breast cancer screening, especially among men within the age group being offered bowel screening.

Research published by National Cancer Registry researchers (and funded by the Irish Cancer Society) suggested that men who decided not to take part had overall a poor knowledge of bowel cancer were often rather fatalistic about cancer of any type while women who decide not to take part often held negative beliefs and emotions about the screening test itself.

This is a shame as premalignant and some earliest stage cancers in polyps can even be cured at colonoscopy by our accredited, expert gastroenterologists and other localized cancers (T1 and T2, N)) can be cured by minimally invasive surgery whether done by standard or robotic-assisted laparoscopy. Sadly too, the COVID-19 pandemic has impacted diagnostic services a lot in Ireland for both symptomatic and asymptomatic patients and as a result presentations with colorectal cancer have lately tended to be more advanced then previously.

This is awful for any such affected patients and others worrying regarding their symptoms as it often means that they will need more invasive therapies with less confidence of cure. While increasingly greater proportions of such patients can still be cured despite their later stage presentation, their disease will therefore present a much more daunting prospect for them and their families and comes at much higher cost for the health care system in terms of effort and expense.

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