Contributed by the LUTHER G. SPEARE MEMORIAL SCHOLARSHIP TRUST FUND (LGSMS)
The LGSMS was established in memory of Luther G. Speare to assist in funding postgraduate research on Gastrointestinal, Cervical, Breast and Prostate cancers at the Mona Campus of the University of the West Indies. Luther G. Speare would have celebrated his birthday on 14 September. September is also Gynecologic & Prostate Cancers awareness month.
Cancer is a leading cause of death worldwide and is estimated to have caused 9.6 million deaths in 2018. In Jamaica, cancer accounted for 3,538 deaths in 2016 or 19.3% of all deaths.
Prevention of cancer, if possible, would be one of mankind’s greatest achievements.
Cancer is a disease caused by cells that have lost control over growth and/or replication. Key risk factors are exposure to infectious agents, toxins, ultraviolet radiation as well as the genetic background of the individual. All these risk factors are influenced by diet and lifestyle. Two main interrelated systems mediate this process: the immune system and gut bacteria
Healthy cells grow, proliferate and have a definite lifespan; cancer cells have a much faster proliferation rate and have an indefinite lifespan. In normal cells tumour suppressive genes are activated to regulate cell growth, cancer occurs where certain genes promote unregulated cell growth.
The immune system plays a role in counteracting the formation of tumours. However, some of the substances produced as a result of the inflammatory reaction of the body’s immune system also play a tumour promoting role. In addition, tumour cells may themselves produce immunosuppression and proangigenic molecules. In brief, the actions of our immune system can produce inflammation which in turn can have the effect of suppressing the body’s immune response or produce molecules which promote the growth of tumours.
The body’s inflammatory response gives rise to the development of cancer where it does the following:
- Stimulates the survival and proliferation of abnormal cells which are predisposed to become cancerous
- Activates oncogenes transcriptase (switching on cell proliferation)
- Suppresses the cell’s normal anti-tumour response
- Stimulates the production of molecules which promote the growth of tumours
- Stimulates the penetration of cancer cells into neighbouring tissue and the spread of cancer cells to more distant areas of the body through the circulatory system or the lymphatic system
An examples of chronic inflammation leading to cancer is helicobacter pylori. The helicobacter pylori bacteria can enter your body and live in your digestive tract, leading to ulcers. The ulcers cause severe inflammation, (or gastritis), which eventually leads to stomach or liver cancers. Another common example occurs when tobacco smoke triggers chronic lung inflammation and hence vastly increases the risk of developing lung cancer.
Gut bacteria play a significant role in preventing or promoting the chronic inflammatory process. Further, certain gut bacteria produce substances that promote the development of cancer cells.
At birth the newborn has a bacteria free gastrointestinal system but by the time adulthood is reached there are ten times more bacterial cells in the gastrointestinal system than there are cells in the human body. This is a huge amount of genetic material which can interact with the host’s (that is person’s) immune system directly or indirectly.
The composition of the gut bacteria will determine the person’s immune response and also the level of chronic inflammation in the individual. “Good” bacteria may produce chemicals that reduce inflammatory response, for example, having the Lachnospiraceae family of bacteria in the gut decreased the inflammatory reaction in mice leading to decreased obesity and its resulting conditions, including the possible reduction in cancer. The absence of “bad” bacteria also reduced risk. Bad bacteria increase the inflammatory response and thus the risk of cancer formation as set out above.
Since we have all have our gut colonized by bacteria what are the measures which we can employ to reduce our cancer risk? Here are the suggestions:
- Reduce sugar. Diets that cause spikes in blood sugar levels are associated with increase risk of stomach, breast and colorectal cancers. It must be acknowledged that because of the gut bacteria (microbiome) the glycemic response varies in individuals.
- Increase the intake of high fiber fruit and vegetables (preferably organically grown). This reduces the load of disease-causing bacteria in the gut which in turn reduces the inflammatory substances linked to tumour progression. The bacteria that help to digest the fibre produce short chain fatty acids which assists in maintaining gut health.
- Increase the intake of foods that contain probiotics, e.g. yogurt or tempeh.
- Ingest high fibre carbohydrates (such as fruits); these act like prebiotics promoting the growth of beneficial bacteria in the large intestine.
- Breast feed for six months – this significantly promotes the balance of good bacteria in the gut of the infant reducing the risk of cardiovascular disease and cancer in later life.
- Increase the intake of polyphenols (e.g. red wine, dark chocolate, onions, broccoli, coffee) these act directly on tumour cells, influences gut bacteria composition and also optimizing the immune system function.
- Reduce exposure to known toxins such as smoking, ultraviolet radiation, infectious agents (e.g. HPV).
No measure so far has been 100% effective in preventing cancer, however, following these measures may reduce risk by over 30% and lead to a better quality longer life.