Cancer is a complex and difficult topic. In this write-up, we are merely imparting our knowledge on this subject from a layperson's standpoint. You are encouraged to learn more about cancer from other textbooks.

Cancer is a disease in which healthy cells stop functioning and maturing properly. As the normal cycle of cell creation and death is interrupted, these newly mutated cancer cells multiply uncontrollably, no longer operating as an integrated and harmonious part of the body. They also act parasitically, developing their own network of blood vessels to siphon nourishment away from the body's supply. This process allows a tumor to grow, free from the restraints to which other cells are subject. Cancer cells split off from the tumor and enter the bloodstream, and in this way spread to other parts of the body. The result is the formation of additional tumors, which further sap the body's energy supply, weakening and perhaps even killing the patient.

There are more than one hundred different types of cancer, affecting virtually every part of the body. Broadly, cancer can be classified into the following five basic categories:

• Carcinomas, the most common cancers, originate in tissues that cover a surface, or line internal organs. Lung, breast, prostate, skin and intestinal cancers are all carcinomas.
  
  
• Sarcomas originate in connective tissues and muscles, attacking bones, muscles, cartilage, or the lymph system. They are the rarest malignant tumors, and also the most deadly.
  
  
• Myelomas are also rare tumors; they start in plasma cells found in the bone marrow.
  
  
• Lymphomas are cancers of the lymph system, a series of glands that act as a filter for the body's impurities. Lymph glands (nodes), are found in the neck, the groin, the armpits, and the spleen.
  
  
• Leukemias are cancers originating in the tissues of the bone marrow, spleen and the lymph nodes. Leukemias are not solid tumors and result in an overproduction of white blood cells.

In his book, Natural Compounds in Cancer Therapy, John Boik describes seven strategies for cancer inhibition:

1. Reduce genetic instability
   
   Each cancer cell carries within itself genetic instability that is aggravated by oxidative stress, or stress caused by free radicals.
   
   
   
2. Inhibit abnormal expression of genes
   
   The function of genes is to make proteins, a process known as gene expression. In cancer cells, abnormal expression of genes occurs, resulting in too few proteins that inhibit cancer and too many that facilitate it.
   
   
   
3. Inhibit abnormal signal transduction
   
   Signal transduction is the movement of a signal from the outer cell surface toward the cell's nucleus. It is a normal process used by healthy cells, but in cancer cells the volume of signal transduction is excessive and the signals that flow favour proliferation and spread.
   
   
   
4. Encourage normal cell-to-cell communication
   
   Cancer cells detach from their neighbors, thereby losing gap junction communication and becoming free to act independently. It is important to foster normal cell-to-cell communication by improving gap junction communication and by normalizing cell adhesion molecule (CAM) activity.
   
   
   
5. Inhibit tumor angiogenesis
   
   Angiogenesis is the growth of new blood vessels toward and within a tumor (or other tissues). It is most successful if certain chemicals called angiogenic factors are present, as well as certain environmental conditions, such as hypoxic (low-oxygen) ones. Cancer can be inhibited by blocking the release or action of angiogenic factors or by otherwise altering the local environment to inhibit tumor angiogenesis.
   
   
   
6. Inhibit invasion and metastasis
   
   Tumors can spread both locally, via invasion of adjacent tissues, and distantly, via metastasis through the blood and lymph circulation.
   
   
   
7. Increase the immune response
   
   The immune system must recognize a cancer cell as foreign before it can be destroyed. However, cancer cells can hide from immune cells by employing various camouflaging techniques or can produce immunosuppressive compounds that impair the ability of immune cells to function.

By understanding of the above seven strategies for cancer inhibition, cancer patients and their caregivers will be in a better position to assess the efficacy of each type of complementary and alternative cancer methods by judging its ability to carry out these strategies.