11 March2024
Commentary by Dr. Donald Greig
10 minute read
March marks an important observance for global health – Colorectal Cancer Awareness Month. This condition represents one of the foremost healthcare challenges worldwide. It is with this in mind that we bring you the most recent colorectal cancer statistics and vital information to enhance awareness and encourage proactive health measures.
Take Home Messages
Colonoscopy screening to prevent the development of colorectal cancer
Proactive life style changes to reduce your personal risk of developing colorectal cancer
Awareness of the signs and symptoms of colorectal cancer is critical for early detection and effective treatment
Global Incidence of Colorectal Cancer
Colorectal cancer is a serious health concern around the world. According to the World Health Organization (WHO), colon cancer is the second leading cause of cancer-related deaths worldwide. In 2020, more than 1.9 million new cases of colorectal cancer and more than 930,000 deaths due to colorectal cancer were estimated to have occurred worldwide. Large geographical variations in incidence and mortality rates were observed. The incidence rates were highest in Europe, Australia, New Zealand, Central and South America, and the mortality rates were highest in Eastern Europe. The lowest rates are seen in parts of Africa and South-Central Asia. By 2040, the burden of colorectal cancer will increase to 3.2 million new cases per year (an increase of 63%) and 1.6 million deaths per year (an increase of 73%).
Mortality Associated with Colorectal Cancer
Despite advancements in detection and treatment, colorectal cancer is the second leading cause of cancer death worldwide when both sexes are combined but it is notable that mortality is higher in men. However, when detected early, survival rates improve significantly, which underscores the critical importance of prevention, early detection and screening.
Incidence rates of colorectal cancer have been decreasing in high-income countries, largely as a result of effective screening programmes. The prognosis for colorectal cancer varies depending on the stage at diagnosis. Early-stage cancers have higher survival rates than advanced-stage cancers. Timely diagnosis, appropriate treatment, and regular follow-up care are important for improving survival rates and quality of life.
Both men and women are impacted by colorectal cancer, although there exists a slightly higher incidence in men. It is essential for all adults, regardless of gender, to recognize the risk and engage in prevention strategies. Overall, the lifetime risk of developing colorectal cancer is about 1 in 23 for men and 1 in 25 for women. However, each person's risk might be higher or lower than this, depending on their risk factors for colorectal cancer.
Arguably, colorectal cancer can be considered a preventable disease to a significant extent. Understanding the biological progression of this disease is crucial; by doing so, individuals can take proactive steps to mitigate their risk. Lifestyle modifications play a vital role in reducing the likelihood of developing colorectal cancer. Furthermore, by engaging in established early detection and treatment strategies, individuals can substantially improve their chances of survival.
Is colorectal cancer a preventable disease?
Colorectal cancer is indeed a preventable disease, in my opinion. This conviction is solidly grounded in 26 years of empirical data from running the colonoscopy screening program at HKSS. This platform targets individuals over 40-years old, including those with a family history of colorectal cancer. A testament to the program's effectiveness is noteworthy: Out of the all the participants who have consistently followed the regimen and remained on the program, not one has developed colorectal cancer. Furthermore, a comprehensive dataset from 2002 to 2015, which includes over 2,500 patients, reveals a median age of 49 at the time of screening. The data indicated a significant detection rate (27%) of precancerous lesions, where 44% of the precancerous polyps occurred less than 49 years.
But is this personal experience translatable to country wide populations? Probably not, for many reasons. However, there are other strategies to be considered and utilized for the detection of earlier colorectal cancers and reduction in personal risk.
Causes and Associations
Colorectal cancer arises from a confluence of genetic, environmental, and lifestyle factors. Diet plays a significant role; high consumption of red and processed meats is associated with an increased risk while fibre-rich foods like fruits, vegetables, and whole grains are protective. Obesity, smoking, and heavy alcohol use are also notable risk factors. Conversely, regular physical activity is shown to reduce the risk. In recent newsletters I have highlighted many of the health benefits associated with the plant, Atlantic and Mediterranean based diets. Genetic predisposition may contribute to 10-15% of all colorectal cancers. A family history of colorectal cancer or precancerous polyps in first degree relatives may enhance your own individual risk. There is an increasing body of evidence that relative Vitamin D deficiency may enhance an individual’s risk, similar to that found in a predisposition to breast and prostate cancer. Ongoing research will provide more definitive conclusions.
What symptoms and signs should I be looking for to be proactive in my body’s health?
· Passage of blood or mucus (slime) in the stool or on the paper
· The presence of tarry black coloured stools
· Altered bowel habit such as alternating constipation or diarrhoea, loose stools, or
increasing constipation
· Urgency and the feeling of incomplete defaecation
· Abdominal bloating or distension
· Lower abdominal pain, colic or cramps
· Unexplained weight loss or loss of appetite
· Feeling constantly tired and lacking energy, even with enough rest
· Iron deficiency anaemia due to chronic bleeding, causing fatigue, weakness and
paleness
If you become aware of any of these symptoms or signs, please consult your doctor as soon as possible.
How does colorectal cancer arise in the bowel?
The development of colorectal cancer follows a defined sequence from normal colon cells to pre-cancerous adenomas to invasive cancer as certain genetic mutations accumulate. Key mutations include those involving the APC, KRAS and TP53 genes. Finding and removing adenomas interrupts this sequence and prevents cancer from developing. Continued research seeks more effective screening strategies and treatments to further reduce colorectal cancer incidence and mortality worldwide.
The normal bowel lining to precancerous polyp to cancer is a well-established sequence. Identification and removal of precancerous adenomas, breaks the sequence to prevent colorectal cancer.
Prevention and Diagnosis
There are three aspects to this: prevention, screening for the detection of early colorectal cancers and diagnosis once lower gastrointestinal symptoms manifest themselves.
Prevention:
Identification, removal and pathological examination of all colorectal polyps found at colonoscopy before significant symptoms first appear.
This is a typical set up for a colonoscopy room
During a colonoscopy procedure, which is also referred to as a lower GI endoscopy, patients are usually sedated to ensure their comfort and relaxation. Sedation can be achieved with various types of drugs, such as benzodiazepines (e.g vallium or midazolam) or with an intravenous anaesthetic, propofol. Propofol is administered by an anaesthetist, providing what is known as "monitored anaesthesia care" (MAC). MAC is my preferred method to make patients feel relaxed and comfortable as it is safer than sedative type procedures as propofol is short acting, your conscious level and vital signs are monitored continuously by the anaesthetist.
The actual procedure involves gently inserting a thin, flexible instrument called a colonoscope into the patient's colon (large intestine). The colonoscope is equipped with a light and a camera that allows the physician to examine the lining of the colon in detail. If during the examination any polyps (abnormal growths that may potentially become cancerous) are detected, they can be removed then and there. Removal is frequently performed using specialized instruments such as cold or hot biopsy forceps, or a snare loop, which cuts the polyp off with a wire that can also cauterize to prevent bleeding.
Enhancing the detection of polyps, some colonoscopy procedures might utilize advanced imaging techniques such as chromoendoscopy (where a dye is used to stain the tissue), narrow band imaging (NBI), or other light-filtering technologies. These methods can make the polyps stand out more against the surrounding tissue, making it easier for the physician to identify and remove them.
Colonic polyp with and without NBI
Polypectomy has been shown to reduce the incidence of colorectal cancer when performed for adenomas.
Polyps that are identified and removed during a colonoscopy are indeed typically sent to a laboratory for histological examination, also known as a biopsy. This step is crucial because it helps determine the nature of the polyps.
Most polyps are benign, but they generally fall into two main categories:
1. Hyperplastic (or non-neoplastic) polyps: These are usually not precancerous and have a very low risk of turning into cancer. They are quite common and are often found in the left colon and rectum.
2. Adenomatous polyps: These are considered precancerous because they have the potential to develop into colorectal cancer, especially if they grow larger. Included in this category are tubular adenomas, tubulovillous adenomas, and villous adenomas, with the risk increasing from tubular to villous types.
It is primarily the adenomatous polyps that clinicians are concerned with as they may progress to cancer if left untreated. When such polyps are removed, the immediate risk is mitigated, and depending on the biopsy results, a schedule for future surveillance colonoscopies can be determined.
Screening:
Many countries have organized screening programs to increase early detection. For example, the National Health Service Bowel Cancer Screening Program in the UK offers home FIT kits to men and women aged 60-74. Completion and positive test results have improved outcomes.
· Faecal Occult Blood Test (FOBT) or Faecal Immunochemical Test (FIT): Non-invasive tests that check for hidden blood in the stool, or genetic markers of bowel cancer.
· Colonoscopy: An examination that allows doctors to look inside the entire rectum and colon for polyps or cancer.
· Sigmoidoscopy: Similar to a colonoscopy, but it only examines the rectum and the lower part of the colon. That is only approximately 30% of the bowel is examined.
· CT colonography, also known as virtual colonoscopy, is a non-invasive medical imaging procedure that uses computed tomography (CT) scans to obtain an interior view of the colon and rectum. The goal is to screen for polyps, cancer, and other abnormalities. However, one should consider radiation exposure. CT colonography exposes patients to ionizing radiation, which is a risk factor for cancer. The dose is roughly equivalent to that of 40 to 120 chest X-rays, which is a relevant factor for patients and healthcare providers to take into account when choosing screening methods. The sensitivity of CT colonography for detecting colorectal cancer and large adenomas is high, approaching that of traditional colonoscopy for polyps larger than 1 cm in size. However, sensitivity for the detection of diminutive polyps (≤ 5 mm) is 10–67%.
Diagnosis:
The mainstay of investigation once significant symptoms have appeared is colonoscopy and in geographical regions where endoscopic access may be limited, then barium enema examination.
The WHO is actively involved in addressing the global burden of colorectal cancer and implementing strategies to reduce its impact. The WHO's approach involves raising awareness, cancer prevention and control, early detection and screening, strengthening health systems, capacity building, research and surveillance, as well as collaboration and partnerships. These comprehensive efforts contribute to reducing the burden of colorectal cancer by promoting prevention, early detection, equitable access to quality care, and improving overall cancer control globally.
To summarize
Taking personal control to reduce your risk of developing colorectal cancer involves making certain lifestyle changes, being aware of your health, and undergoing recommended screenings. Here are some key take-home messages for anyone looking to minimize their risk of colorectal cancer:
Get Screened Regularly: Compliance with screening protocols, such as colonoscopies, is vital. Polyps can be identified and removed before they become cancerous. The recommended age to start regular screenings has recently been adjusted to 45 years old for most adults, but could be earlier based on family history or other risk factors. In my practice, based on the empirical data I have collected prospectively over 26 years, I recommend screening starts at 40 years old and earlier, if there is a significant family history of colorectal cancer.
Know Your Family History: Genetics can play a significant role in your risk for colorectal cancer. If you have a family history of the disease, you might need to be screened more frequently and earlier in life.
Eat a Healthy Diet: Diets high in fruits, vegetables, and fibre have been associated with a reduced risk of colorectal cancer. Conversely, diets high in red and processed meats have been linked to an increased risk.
Maintain a Healthy Weight: Obesity is a known risk factor for developing many forms of cancer, including colorectal cancer. Striving for a healthy weight through diet and exercise can reduce your risk.
Limit Alcohol and Avoid Smoking: Alcohol consumption and smoking are both linked to an increased risk of colorectal cancer. Limiting alcohol and avoiding smoking can be beneficial in risk reduction.
Stay Physically Active: Regular physical activity is not only good for overall health but also helps to lower the risk of developing colorectal cancer.
Understand Symptoms and Signs: Be vigilant about changes in your bowel habit, such as persistent diarrhoea or constipation, blood in the stool, unexplained anaemia, or abdominal discomfort. Promptly discuss any changes with your doctor.
Consider Genetic Counselling: If there is a significant family history or early onset of colorectal cancer, genetic counselling can provide information about your risk and guide you in decision-making about screening and prevention strategies.
Know the Guidelines: Stay informed about current guidelines for colorectal cancer screening and discuss them with your doctor to ensure that you’re following a screening regimen appropriate for your level of risk.
Use Preventive Medication Cautiously: Some medications like aspirin or other non-steroidal anti-inflammatory drugs (NSAIDs) have been shown to reduce polyp formation but come with their own risks. Due to these risks, I am of the opinion that colonoscopy is a safer option and more effective option.
By taking these steps, individuals can actively participate in reducing their risk of developing colorectal cancer and take control of their overall gut health. Remember that early detection is key, and many cases of colorectal cancer are preventable with proper screening and lifestyle modifications.
If you or anyone you know need a consultation to discuss having a colonoscopy and risk factor assessment, please make an appointment with Dr. Greig at Hong Kong Surgical Specialists.
Contact us
Tel: +852 2715 4577
Email: info@hkss.info