CANCER :Causes & Treatment .
Dr ANSHUL MAHAJAN
Cancer is a generic term for a large group of diseases that can affect any part of the body. Other terms used are malignant tumours and neoplasms. One defining feature of cancer is the rapid creation of abnormal cells that grow beyond their usual boundaries, and which can then invade adjoining parts of the body and spread to other organs, the latter process is referred to as metastasizing. Metastases are a major cause of death from cancer.
What causes cancer?
Cancer arises from the transformation of normal cells into tumour cells in a multistage process that generally progresses from a pre-cancerous lesion to a malignant tumour. These changes are the result of the interaction between a person's genetic factors and 3 categories of external agents, including:
physical carcinogens, such as ultraviolet and ionizing radiation;
chemical carcinogens, such as asbestos, components of tobacco smoke, aflatoxin (a food contaminant), and arsenic (a drinking water contaminant); and
biological carcinogens, such as infections from certain viruses, bacteria, or parasites.
WHO, through its cancer research agency, International Agency for Research on Cancer (IARC), maintains a classification of cancer-causing agents.
Ageing is another fundamental factor for the development of cancer. The incidence of cancer rises dramatically with age, most likely due to a build-up of risks for specific cancers that increase with age. The overall risk accumulation is combined with the tendency for cellular repair mechanisms to be less effective as a person grows older.
Risk factors for cancers
Tobacco use, alcohol use, unhealthy diet, and physical inactivity are major cancer risk factors worldwide and are also the 4 shared risk factors for other noncommunicable diseases.
Some chronic infections are risk factors for cancer and have major relevance in low- and middle-income countries. Approximately 15% of cancers diagnosed in 2012 were attributed to carcinogenic infections, including Helicobacter pylori, Human papillomavirus (HPV), Hepatitis B virus, Hepatitis C virus, and Epstein-Barr virus3.
Hepatitis B and C virus and some types of HPV increase the risk for liver and cervical cancer, respectively. Infection with HIV substantially increases the risk of cancers such as cervical cancer.
Reducing the cancer burden
Between 30–50% of cancers can currently be prevented by avoiding risk factors and implementing existing evidence-based prevention strategies. The cancer burden can also be reduced through early detection of cancer and management of patients who develop cancer. Many cancers have a high chance of cure if diagnosed early and treated adequately.
Modify and avoid risk factors
Modifying or avoiding key risk factors can significantly reduce the burden of cancer. These risk factors include:
tobacco use including cigarettes and smokeless tobacco
being overweight or obese
unhealthy diet with low fruit and vegetable intake
lack of physical activity
alcohol use
sexually transmitted HPV-infection
infection by hepatitis or other carcinogenic infections
ionizing and ultraviolet radiation
urban air pollution
indoor smoke from household use of solid fuels.
Tobacco use is the single most important risk factor for cancer and is responsible for approximately 22% of cancer-related deaths globally2.
Pursue prevention strategies
To prevent cancer, people may:
increase avoidance of the risk factors listed above;
vaccinate against HPV and hepatitis B virus;
control occupational hazards;
reduce exposure to ultraviolet radiation;
reduce exposure to ionizing radiation (occupational or medical diagnostic imaging).
Vaccination against these HPV and hepatitis B viruses could prevent 1 million cancer cases each year3.
Treatment
A correct cancer diagnosis is essential for adequate and effective treatment because every cancer type requires a specific treatment regimen that encompasses one or more modalities such as surgery, radiotherapy, and chemotherapy. Determining the goals of treatment and palliative care is an important first step, and health services should be integrated and people-centred. The primary goal is generally to cure cancer or to considerably prolong life. Improving the patient's quality of life is also an important goal. This can be achieved by supportive or palliative care and psychosocial support.