to Videolink arrow

Newton logo to print

Cancer Causes



Ninety percent of cancers develop because of complex interactions between our bodies, our lifestyles, our genetic makeup and our environment. Scientists have discovered different factors that cause cancer. Research shows that tobacco is estimated to cause 30 percent of all cancer deaths, poor diet 35 percent, reproductive and sexual behavior seven percent, work-related causes four percent and the environment itself causes three percent. Scientists believe that genetic changes, whether inherited or acquired, are the basic cause of cancer. Some scientific theories do suggest that cancer may be a hereditary disease because each individual's make-up may make them more susceptible to certain cancers. About 50 of the more than 120 different types of cancer occasionally run in families. Most of the current scientific evidence indicates that a normal cell can become transformed into a cancer cell when certain genes become activated. Recent work in cancer biology concerns the study of oncogenes, a specific gene that participates in changing a normal cell into a cancer cell. It is thought that an oncogene might be present in an inactive form in normal cells and is some way activated to create cancer cells. As mentioned, the nature of a person's work or the working environment can also be a factor in developing cancer. The chart below identifies several cancer-causing agents, occupations where this exposure occurs and the types of cancers that can develop.
Ultraviolet Farmers, Sailors, Lifeguards, Everyone Skin Light
Radon Underground Miners Lung (example- uranium)
Asbestos Asbestos workers, Insulation workers Lung
Benzene Workers who use glue, varnishes, etc. Marrow, Leukemia
X-rays, Radium Radiologists Skin


You will take a small sample of the epithelial cells that line the inside of your mouth. You'll get a glimpse of how scientists investigate inside cells. Materials
  • Microscope
  • Slide and cover slip
  • Flat toothpicks
  • Charts and models of cells
  • Medicine dropper
  • Jar
  • Iodine stain or methylene blue stain
1. Place a drop of stain on a microscope slide. 2. Gently scrape the inside of your cheek with the flat edge of a toothpick. 3. Dip this edge of the toothpick in the drop of stain on the slide. 4. Take another toothpick and once again scrape the inside of your cheek with the flat edge, and dip the second toothpick into the stain. 5. Spread the stain and cheek cells around in a small area with the toothpick and cover the slide with a cover slip. 6. First look at the slide under the low-power lens of the microscope. Focus carefully and record your observations. Now observe the slide under the high-power lens.


  • Goldfarb, Ronald H. Cancer Growth and Progression - Fundamental Aspects of Cancer. Norwell, MA: Kluwer Academic Publishers, 1989.
  • Lafond, Richard. Cancer: The Outlaw Cell. Washington, D.C.: American Chemical Society, 1988.
  • Oppenheimer, Steven B. "Advances in Cancer Biology." The American Biology Teacher, January, 1987, pp. 11-15.
  • Oppenheimer, Steven B. "Tumor Suppressor Genes: A Key to the Cancer Puzzle?" The American Biology Teacher, January, 1991. pp. 22-24.