Bowel cancer: Aspirin to the rescue

 It affects mainly older adults above the age of 50, peaking at 70 years of age. The good news is that colon cancer can be cured if detected early enough and even avoided through regular screening. Even better, a valuable preventive effect should soon be established with aspirin, which has been shown to be a versatile anti-tumoural agent for CRC. 

CRC often starts from small benign growths known as polyps that develop in the inner lining of the colon. Although the majority of these tumours do not evolve into malignancies, some become pre-cancerous and then advance into full-blown colon cancer. As a result, polyps that are discovered during a routine check-up are systematically removed and analysed under the microscope. 

Polyps and early bowel cancer rarely have symptoms. If manifestations are present, it is likely that the polyp is quite large or the cancer has already progressed. Symptoms may include abdominal discomfort or pain in one precise location, blood in the stool and abnormal bowel movements with intermittent episodes of constipation and diarrhoea. There may also be unexplained weight loss, lack of energy and poor appetite. 

The best way to lower the risk of bowel cancer is to undergo a colonoscopy from the age of 50 up as part of a routine check-up to catch possible polyps at an early stage. After a colon-cleansing preparation, the exam allows for visualisation of the polyps (or the cancer) and these are then removed or a biopsy is performed. When cancer is found, a thorough analysis of its evolution known as cancer staging is carried out to determine the optimal course of treatment, which include surgery, radiotherapy and chemotherapy, and newer more specific medications called targeted therapy.

Aspirin (acetylsalicylic acid) has been extensively studied for its multiple pharmacological effects: one of the oldest (it was first synthesized in the late 19th century) and cheapest medicines, aspirin possesses an antipyretic effect (reduces fever), has a pain killer effect (for minor pain) as well as an anti-inflammatory effect. 

In the early ’70s, its blood thinning effect was discovered and its efficacy in preventing blood clots in people who suffered a heart attack was subsequently recognised. Now aspirin is routinely used for lowering the risk of heart attack and stroke. When a large number of heart attack patients started taking daily aspirin, its added anti-cancer properties were incidentally observed especially on tumours in the gastrointestinal tract. This has led to the development of many studies in the field of cancer treatment. 

Evidence of aspirin’s anti-tumour effects has been consistently demonstrated in large and long-term trials involving hundreds of thousand patients on various aspects of the CRC development. Aspirin reduces the risk of polyps incidence, lowers the risk of CRC occurrence by about 20 to 40 per cent depending of the patient’s risk level, and limits the spread of secondary tumors (metastasis) in patients with existing CRC. In hereditary bowel cancer, known as Lynch syndrome, aspirin significantly reduces the frequency of malignant colon tumours and is now considered standard therapy for these high-risk patients. 

The optimal dosage to use – likely around 300 mg per day – for CRC prevention is still being debated but more importantly, the duration should exceed at least 5 years to provide significant benefits. The concern for prolonged usage of aspirin is the risk of bleeding and ulcer in some sensitive individuals but most researchers and medical experts believe that in the majority of cases, the benefits of aspirin on CRC prevention and treatment outweigh its potential risks. Some biomarkers (enzymes, gene mutations) have been identified and will allow for selecting the patients who will best benefit from aspirin treatment.

With the current state of the evidence, should aspirin come to the rescue of CRC now? A positive response is highly probable for many people and the forthcoming review from Cochrane, one of the most reliable scientific organisations, should confirm the CRC indication and clarify its usage. 

In the meantime, prevention of bowel cancer relies on adhering to the proven healthy lifestyle behaviour, that is, no smoking, moderate alcohol consumption, maintenance of healthy body weight and regular exercise. For those above or approaching 50 years of age, it is worth asking the opinion of your GI specialist when you undergo your next colonoscopy.

 

 

Dr Gerard Lalande is managing director of CEO-Health, which provides medical referrals for expatriates and customised executive medical check-ups in Thailand. He can be contacted at [email protected].