Saturday, 4 December, 2021

Epidemiology Of Cancer

Prof. Dr. Shyam P Lohani


Human body has trillions of cells with specific functions and fixed lifespan. It is a natural phenomenon that old cells die and get replaced by new ones. This process is called ‘apoptosis’. Every cell gets instructions to die after their lifespan and the body will replace the old cells with the new ones which function better. However, even when a cell lacks such instructions, the cell division process continues. Such cells are called cancerous cells that rapidly grow utilising nutrients and oxygen which otherwise nourish other cells. Those cancerous cells can form tumors, impair the immune system and can cause other changes that prevent the body to function normally. There are more than 200 different types of cancer that may occur in almost every part of the human body. All of them are potentially life-threating. The cases of cancer are increasing rapidly throughout the world due to an unhealthy lifestyle and other environmental factors.

Global trend
Around 9.6 million people died due to cancer in 2018. This is the second leading cause of death worldwide. The disease is projected to increase by 70 per cent to 13.1 million annually by 2030. Globally, about 17 per cent of all deaths are attributed to cancer (WHO, 2018). Out of total deaths due to cancer, about 70 per cent occur in low and middle-income countries.
In Nepal, around 7.7 per cent of the total deaths were attributed to cancer in 2012 (WHO, 2014). The most common cancers that kill people worldwide are lungs, breast, colorectal, prostate, skin cancer (non-melanoma), and stomach. In Nepal, lungs, cervix, breast, and stomach cancers are most common. Most cancers form tumors but all tumors are not cancerous. Benign type of tumors does not spread to other parts of the body and do not cause new tumors. However, malignant tumors spread through lymph or blood to other parts of the body and form tumors.
There are many risk factors, which are associated with an increased incidence of cancer. These modifiable or avoidable risk factors are due to the use of cigarettes or smokeless tobacco, being obese or overweight, insufficient physical activities, unhealthy diets which include fewer vegetables and fruits and indoor air pollution. The harmful use of alcohol, urban air pollution, infection by Human Papilloma Virus (HPV) and hepatitis, ionising and ultraviolet radiation are other risk factors which are either avoidable or modifiable. Almost 9 out of 10 lung cancers are due to smoking or second-hand smoke. Tobacco use is the most common cause of cancer and almost 22 per cent of all deaths due to cancer are attributable to tobacco use (Lancet, 2016). Smoking causes 16 different types of cancer. Every time we smoke, some 7,000 different chemicals enter into lungs and spread to other parts of the body among which 69 are known carcinogens. Infections such as hepatitis and HPV are responsible for about 25 per cent of cancer cases in low and middle-income countries (WHO, 2018).
Almost up to half (30-50 per cent) of cancers can be prevented by lifestyle modifications and/or by avoiding preventable risk factors. The prevention of certain cancers is simple while others require a complex approach. The avoidance of exposure to a potential cause is the easiest approach. Quitting smoking (or better never start) tops the list of avoidable exposure. Avoiding excess sunlight or reducing exposure to sunlight by using sunscreen, avoiding asbestos exposure, arsenic exposure, and other known carcinogens such as certain pesticides can reduce the occurrence of cancer. Chemical workers, X-ray technicians and workers with ionising radiation should use protective equipment and also follow safety protocols. Although there has been no evidence that the use of cell phones has something to do with cancer, it is advised to use them with an earpiece or make as few cell phone calls as possible. There are vaccines available for Hepatitis B which is implicated for liver cancer and HPV which is responsible for about 70 per cent of cervical cancer (WebMD, 2018). The treatments of cancer include chemotherapy, radiotherapy or surgery and many times combination of the two. Immunotherapy has some promises in recent studies.

There are huge disparities in treatment facility available for cancer. More than 90 per cent of high-income countries have facilities for the treatment and management of cancer, whereas, only 30 per cent of low-income countries have such facilities. Another important aspect of cancer management is an early diagnosis. Cancer diagnosed early will have a high chance of cure. The vaccine against HPV and hepatitis can save at least a million cancer cases yearly (Plummer, 2016). The population-based screening of breast and cervical cancer will help detect those cancers early and treatment at the initial stage results in a better outcome.
The large percentages (77 per cent) of the Nepali family still rely on traditional fuels such as firewood and cow dung for cooking. Indoor air pollution from biomass causes a significant burden of cancers along with acute respiratory illnesses (ARIs) among children and chronic obstructive pulmonary diseases (COPD) in adults. Tackling outdoor as well as indoor pollution, although, challenging is possible by encouraging electrical vehicles and using smokeless stoves as well as using clean energy such as biogas. It has been estimated that within a few years, the country will have surplus hydroelectricity as well as almost complete electrification in households throughout the country. Every household should be encouraged to use electricity for cooking.
There are two specialised public cancer hospitals in Bhaktapur and Bharatpur. There are already two cancer hospitals in the private sector in Kathmandu and Bhaktapur. One new private cancer hospital is coming up in State 1. Few tertiary care centres and medical colleges have cancer treatment facilities. Currently, the government provides Rs. 100,000 to cancer patients from poor and impoverished families and working out plans to increase the amount to Rs. 500,000 and (Department of Health Services, 2018). The Nepal Health Research Council (NHRC) has launched a population-based cancer registry to collect data on the burden of cancers across the country which will help the government to formulate necessary policy. Lastly, effective preventive measures combined with better treatment facilities will help the country fight the burden of cancer in the coming days.

(Prof. Lohani is the Founder Academic Director of Nobel College/ Hospital and can be reached at