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Understanding Cancer and Cancer Therapy

Introduction

• cancer has afflicted humans throughout time
• it is observed in every geographic region and culture, in every age, sex and race

Cancer begins as a single cell that goes awry

• a cancer cell has lost control over its growth
• two kinds of genes regulate growth
  • oncogenes promote growth of cancer cells
  • cancer suppressor genes (anti-oncogenes) suppress growth of cancer cells
• when oncogenes are mutated by carcinogens, they induce malignant growth by "turning on" cell division
• it is now thought that most cancers result from a combination of genetic changes that cause both the absence of cancer-suppressor genes and the presence of oncogenes

Known and suspected carcinogens include:

• chemical factors - including tobacco, industrial chemicals, cancer chemotherapy agents
• physical factors - including ionizing radiation, ultraviolet radiation, asbestos, pollution
• dietary factors - including high fat intake, alcohol, vitamin deficiencies, low fiber diet

Familial cancers

• cancer clusters within families are sometimes due to common environmental exposures
• it may also be due to genetic inheritance
• earlier age at diagnosis is common in genetically linked cancers
• many cancer genes are being isolated and testing is being developed for these genes

Cancer cells continue to multiply without restraint at the expense of the host

• they compete for oxygen and nutrients
• they crowd out normal cells and prevent organ function

Cancer cells have the ability to spread to distant, nonadjacent sites, known as metastasis

• usually spread through the lymph channels
• spread to vital organs and prevent them from functioning normally

Cancer therapy is aimed at ridding the body of tumor cells that are in the process of multiplying

• surgery - primarily for patients with localized solid tumors
• radiation - the use of high energy radiation to treat disease
  • considered a local therapy
• chemotherapy - used to treat cancer systemically
  • over 50 drugs are available
  • usually used in multi-drug combination regimens
• biotherapy - produce anti-tumor effects primarily through the action of natural host defense mechanisms
• these modalities are often used in various combinations, e.g. chemotherapy + radiation
• cancer treatments have undergone tremendous change recently, including new modalities, new drugs, high dose therapies and combination therapies
• it is important to contact the health provider who is managing the treatment with questions and concerns about the treatment and its side effects

References

Groenwald, SL, Frogge, MH, Goodman, M, Yarbro, CH, Cancer Nursing: Principles and Practice, 4th ed. Boston: Jones and Bartlett, 1997.

Gross, J., Johnson, BL. Handbook of Oncology Nursing, 2nd ed. Boston: Jones and Bartlett, 1994.

McCorkle, R., Grant, M., Frank-Stromborg, M., Baird, S. Cancer Nursing: A Comprehensive Textbook, 2nd ed. Philadelphia: WB Saunders Company, 1996.

Varricchio, C. Ed. A Cancer Source Book for Nurses, 7th ed. Atlanta: The American Cancer Society, 1997.

The following patient resources are available from the National Cancer Institute for no charge (1-800-4CANCER):

• Chemotherapy and You: A guide for patients
• Radiation Therapy and You: A guide for patients
• What is Cancer?

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