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.

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.

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.

According to a report by the World Health Organization (WHO), which said that one in 10 Indians will develop, cancer during their lifetime and one in 15 will die of the disease.
In India, the six most common cancer types were

• Breast cancer (162,500 cases),
• Oral cancer (120,000 cases),
• Cervical cancer (97,000 cases),
• Lung cancer (68,000 cases),
• Stomach cancer (57,000 cases), and
• Colorectal cancer (57,000).

Together, these account for 49 per cent of all new cancer cases.

When identified early, cancer is more likely to respond to effective treatment and can result in a greater probability of surviving, less morbidity, and less expensive treatment. Significant improvements can be made in the lives of cancer patients by detecting cancer early and avoiding delays in care.
Early diagnosis consists of 3 steps that must be integrated and provided in a timely manner:

• Awareness and accessing care
• Clinical evaluation, diagnosis and staging
• Access to treatment.

Early diagnosis is relevant in all settings and the majority of cancers. In absence of early diagnosis, patients are diagnosed at late stages when curative treatment may no longer be an option. Programmes can be designed to reduce delays in, and barriers to, care, allowing patients to access treatment in a timely manner.

Screening aims to identify individuals with abnormalities suggestive of a specific cancer or pre-cancer who have not developed any symptoms and refer them promptly for diagnosis and treatment.
Screening programmes can be effective for select cancer types when appropriate tests are used, implemented effectively, linked to other steps in the screening process and when quality is assured. In general, a screening programme is a far more complex public health intervention compared to early diagnosis.
Examples of screening methods are:

• Visual inspection with acetic acid (VIA) for cervical cancer in low-income settings;
• HPV testing for cervical cancer;
• PAP cytology test for cervical cancer in middle- and high-income settings; and
• Mammography screening for breast cancer in settings with strong or relatively strong health systems.

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 globally.

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 year

Palliative care is treatment to relieve, rather than cure, symptoms caused by cancer and improve the quality of life of patients and their families. Palliative care can help people live more comfortably. It is an urgent humanitarian need for people worldwide with cancer and other chronic fatal diseases and particularly needed in places with a high proportion of patients in advanced stages of cancer where there is little chance of cure.
Relief from physical, psychosocial, and spiritual problems can be achieved in over 90% of advanced cancer patients through palliative care.

Although having a family history of cancer increases your risk of developing the disease, it is not a complete prediction of your future health. An estimated 4 out of 10 cancers can be prevented by making simple lifestyle changes, such as forming healthy eating habits, maintaining a healthy weight, exercising, limiting alcoholic beverages, practicing sun safety, and avoiding tobacco products. If you have inherited certain cancer genes that put you at high risk for cancer, your doctor may recommend surgery or medications to reduce the chance that cancer will develop.

Cancer is not contagious. However, some cancers are caused by viruses and bacteria that can be spread from person to person. Certain types of the human papillomavirus (HPV) have been known to cause cervical, anal, and some kinds of head and neck cancers. Hepatitis B and hepatitis C are viruses that increase the risk of developing liver cancer. Bacteria like H. pylori can cause stomach cancer. It is important to remember that while the viruses and bacteria that cause some cancers can be spread from person to person, the cancers they cause cannot be spread from person to person.

There is no conclusive evidence that proves eating sugar will make cancer grow and spread more quickly. All cells in the body, both healthy cells and cancer cells, depend on sugar to grow and function. However, there is no proof that eating sugar will speed up the growth of cancer or that cutting out sugar completely will slow down its growth. This doesn’t mean you should eat a high-sugar diet, though. Consuming too many calories from sugar has been linked to weight gain, obesity, and diabetes, which increase the risk of developing cancer and other health problems.

No one is with holding a cure for cancer. The fact is, there will not be a single cure for cancer. Hundreds of types of cancer exist, and they respond differently to various types of treatment. There is still much to learn, which is why clinical trials are essential for making progress in preventing, diagnosing, and treating cancer.

There is no scientific evidence that a positive attitude will prevent cancer, help people with cancer live longer, or keep cancer from coming back. However, things that promote positive thinking, such as relaxation techniques, support groups, and a support network of family and friends, may improve a person’s quality of life and outlook. It is important to remember that placing such an importance on attitude may lead to unnecessary guilt and disappointment if, for reasons beyond your control, your health does not improve.