Cancer Overview – Causes of Cancer

Every year, more than 560,000 people die of cancer in the United States. It is only second to cardiovascular or heart disease as the leading cause of death. Cancer is predominantly a disease of older adults – about 70% of those who die of cancer are 65 years or older.

Carcinogenesis or Development of Cancer

Cancer results when normal cell transforms into a malignant growth in a process called carcinogenesis. Cancer cells proliferate or grow uncontrollably, and can spread to nearby tissue and even to tissues far away from the original site through the blood or lymphatic vessels in a process called metastatis. It can also spread by unintentional transplantation during surgery.

Cancer develops because of mutations in the genes of the cells. There are two types of genetic susceptibility to cancer:

  • Oncogenes
    These are genes that activate cell division and are involved in embryo development.

  • Tumor suppressor genes
    Genes that stop cell division.

These genes are found in all normal cells. Mutations in these cells, either inherited (or also called genetic mutation) or caused by exposure to cancer-causing chemicals or carcinogens (called acquired mutations) can cause normal cells to become malignant, cancerous cells. The exact mechanism of cancer development or carcinogenesis is complicated. Current medical understanding is that interaction of carcinogens and accumulated mutations in several genes are involved.


Exposure of the following carcinogens can cause cancer:

  • Tobacco
    Smoking is the leading cause of preventable deaths in the Untied States, and is responsible for about 85% of deaths due to lung cancer. Tobacco is also linked to increased risk for cancers of the mouth, larynx (respiratory tract), esophagus (food tract), kidney, pancreas, bladder, and cervix.

    A word on tobacco: there are many cancer-causing hazards that we may not have control over, but smoking is not one of them. Do not continue to jeopardize your health by smoking, and to jeopardize the health of those around you (through second-hand smoke). While quitting smoking is difficult, it is undoubtedly the best health decision you can make.

  • Radiation
    High-energy or ionizing radiations can cause damage to the cell’s DNA, leading to cancer-causing mutations.

    Controlled radiation can actually be used to treat cancer – by concentrating the dosage only to the cancer cells, radiation can be used to selectively kill rapidly dividing, cancerous cells.

    X-rays, a valuable medical tool for diagnosing diseases, does contain ionizing radiation. However, its does is about 1,000th of that used in cancer treatment, and does not pose a significant risk for cancer.

  • Ultraviolet Radiation
    Prolonged exposure to sunlight and ultraviolet radiation (through tanning lamps) can cause damage to skin cells that lead to skin cancers, such as basal cell and squamous cell carcinomas and the deadly melanomas.

    To minimize the risk of skin cancer, it is recommended that you wear long sleeves and hats while outdoors in addition to using sunscreens (with protective factor or SPF of 15 or higher).

  • Chemicals
    Various environmental pollutants and chemicals can pose risk to workers who are regularly subjected to them. These chemicals include asbestos, industrial dyes, heavy metals such as nickels, acids such as chromic acid or chromate, vinyl chloride, a class of organic compounds called benzene and benzopyrene.

  • Viruses
    Several viruses have been linked to increased risk of cancer.
Virus Disease Cancer
Human Immunodeficiency Virus (HIV) Acquired Immunodeficiency Syndrome (AIDS) Hepatoma (Liver Cancer), Lymphoma
Hepatitis B Virus (HBV) Hepatitis B Hepatoma
Epstein-Barr Virus (EBV) Mononucleosis Burkitt's Lymphoma,
Nasopharyngeal cancer
Human papilloma virus Genital wart Cervical cancer
Herpes Simplex Virus 2 (HSV-2) Genital herpes Cervical cancer


In addition to the factors above, food and diet may also play a big role in cancer. For example, high animal fat diet has been linked to gastrointestinal cancer. Food additives containing nitrates as well as charbroiling may also be a factor.

Hormones and Cancer

The role of hormones in carcinogenesis or the development of cancer is still controversial. However, laboratory studies have shown that excessive use of hormones, such as estrogen, in animals can lead to cancer.

In rare cases, synthetic estrogen (diethylstilbestrol) has been linked to vaginal cancer in daughters of women taking this hormone.

Hereditary Factors

Genetics play a significant role in many forms of cancer, such as breast and ovarian cancers, retinoblastoma, hereditary nonpolyposis colorectal cancer, and colon cancer. In these cases, common characteristics of cancers caused by genetic factors include:

  • Early onset of the disease
  • Cancer occurring in both paired organs (for example, cancer in both breasts, adrenal glands, and kidneys)
  • Multiple growths
  • Abnormal chromosomes sets or complement in tumor cells

Main Menu
Health Articles
Health News
Health Research
Site Map

Health Conditions
Cardiovascular Health
Digestive Health
Infectous Diseases
Musculoskeletal Health
Pregnancy & Childbirth
Skin Health

Misc. Health Articles
Presidential Diseases

All Cancers

Brain Tumor
Breast Cancer
Prostate Cancer

©copyright 2004 - Health In Plain English. All Rights Reserved.

Health Articles Health News Health Research Explained in Plain English