Cancer; Second-leading Cause of Death Globally
Since it was first discovered and documented 5 billion years ago, cancer has grown to be a major threat to human existence and is currently the second-leading cause of death worldwide. The deaths of a legendary footballer, Pele, and nearly 10 million others are a proof of the required urgency to keep cancer at bay. A report published by the World Health Organisation WHO in 2020 showed that Nigeria recorded over 124,000 new cases with over 78,000 deaths that year, recording one of the highest cancer mortality (death) rates in the world, with approximately four out of five cases resulting in death.
Cancer refers to a disease in which some human cells grow uncontrollably and spread to other parts of the body. The normal cells in the human body grow and multiply (through a process known as cell division) to form new cells as they become necessary for the human body to function optimally. When cells become old or damaged, they die and new cells take their place. When there is a compromise in this process, the abnormal or damaged cells grow and multiply when they should die. In most cases, they form cancerous tumours which spread into, or invade nearby and distant tissues in the human body (through a process called metastasis).
Different types of cancer exist, some of which include; lung cancer, prostate cancer, colorectal (colon and rectal) cancer, stomach cancer, liver cancer, breast cancer, cervical cancer and thyroid cancer. While prostate, stomach and liver cancer are common in men, breast, cervical and thyroid cancer are common in women.
What Causes Cancer?
Cancer is generally referred to as a genetic disease. This is because it causes changes (mutates) to the behaviour of genes that instructs the cells to function properly, especially during cell division. The DNA inside a cell is arranged into a large number of individual genes that contain instructions on how the cell should perform its functions, especially how to grow and divide. Errors in these instructions can make a cell stop its normal function and may become a cancerous cell.
A genetic mutation can instruct a healthy cell to grow and divide more rapidly, giving rise to many cells with the same mutations. A normal cell knows when to stop the cell division process so that the body has just the right number of cells, but a cancerous cell causes a change to the behaviour of the genes that instruct the cell to stop growing, thereby allowing the cancerous cells to continue growing.
Genetic mutations are caused by several factors. A small percentage of mutated genes are inherited from parents and they account for a very little percentage of cancer. Most gene mutations occur after birth, arising from different sources which may include; Carcinogens (any agent –chemical, physical or biological– that causes cancer). Carcinogens may be physical, such as ultraviolet and ionizing radiation; chemical, such as components of tobacco, asbestos, benzene and aflatoxins, certain nitrosamines can also lead to cancer if people are exposed to high quantities; and infections, such as certain viruses (e.g., HPV – Human Papilloma Virus, Hepatitis B & C, HIV, Epstein-Barr virus etc.), bacteria and parasites.
Are There Risk Factors for Cancer?
Yes, but while there are factors that may increase the chances of developing cancer, the majority of cancer cases were discovered in people who were not among those with known risk factors.
Some factors that may increase the risk of cancer include;
Age: The body normally eliminates cells with cancerous DNA but the ability to do so wanes as we grow old – this is why cancer tends to develop more in older persons.
Lifestyle: Certain choices of lifestyle could increase the risk of developing cancer. Tobacco or cigarette use is a risk factor for several cancer types and it accounts for about 25% of deaths caused by cancer. Excessive alcohol intake, excessive exposure to the sun, unsafe sex practices, unhealthy feeding habits and inadequate exercise or activity could increase the risk of cancer.
Environment: Second-hand inhalation of tobacco or cigarette smoke increases the risk of cancer. Contact with certain chemicals like asbestos or benzene at home or workplace, exposure to radiation such as radon (a naturally occurring radioactive gas) in unhealthy urban or working environments and air pollution, specifically from diesel engine exhaust are known to increase the risk of cancer.
Health Conditions: Some chronic health conditions can increase the risk of cancer. It is very important to always visit a professional healthcare practitioner each time you feel unwell.
Family History: This accounts for only a very little percentage of cancer cases. Most cancers are not caused by an inherited gene mutation. Belonging to a family with a history of cancer does not mean you would have cancer.
How Can Cancer be Prevented?
According to WHO, 30–50% of cancer cases could be prevented by modifying or avoiding key risk factors, especially those associated with lifestyle and environment. Modifying or avoiding the following key risk factors can help prevent cancer.
Avoid tobacco/cigarette use, maintain a healthy weight, eat healthily with plenty of fruits and vegetables, exercise regularly, avoid a sedentary lifestyle, limit alcohol use, practice safe sex, get vaccinated against hepatitis B and HPV, reduce exposure to ultraviolet and ionizing radiations (minimize exposure to the sun, ensure safe and appropriate medical use of radiation in diagnosis and treatment), avoid urban air pollution and indoor smoke from household use of solid fuels and always get regular medical care.
According to an American report published on the 12th of January 2023, high-intensity exercises like running, swimming, cycling, etc. can reduce the rate of metastatic cancer (cancer that spreads to other cells in the body). These aerobic exercises create a demand for glucose from internal organs, thereby starving cancerous cells which require glucose as their primary fuel to survive, grow and eventually divide.
What are the Available Treatments for Cancer?
Treatments that can be administered to cancer patients can involve surgery, systemic therapy (chemotherapy, immunotherapy, endocrine therapy) and radiotherapy. The different kinds of cancer treatments are administered based on the kind of cancer; each cancer requires a special mode of treatment.
