Evaluating the Effectiveness of Cancer Therapy

• The effectiveness of cancer therapy is usually evaluated by how well the therapy removes cancer cells. Some procedures--such as lumpectomy or mastectomy--are designed to remove all or most cancer cells at once by removing the breast where the cancer cells are. The effectiveness of these procedures is evaluated by how much of the cancer was removed. If the cancer has spread to the lymph nodes or other parts of the body, then the surgery will not be effective and other treatments might be used in conjunction with surgery. If the breast cancer was identified early and all of the cancer cells are removed, the surgery is effective at treating the cancer.
  
  Other types of therapy, such as radiation and chemotherapy, are not designed to remove all of the cancer cells at once. Instead, these therapies are designed to slowly kill cancer cells by preventing them from reproducing. If the tumor shrinks or the number of cancer cells in the body decreases, the treatments are said to be working.
  
  

Evaluating the Effectiveness of Treatment

• The effectiveness of treatments to cure a patient is measured by the American Cancer Society using five-year survival statistics. These statistics reflect the number of diagnosed patients alive at least five years from the date of diagnosis. They take into account death by unrelated causes. The published statistics in 2008 reported that patients diagnosed with Stage 0 breast cancer (the cancer is located in the duct of one breast only) have a 100 percent five-year survival rate. Stage I patients have a 100 percent survival rate. Stage II patients have an 86 percent survival rate. Stage III patients have a 57 percent survival rate. Stage IV patients have a 20 percent survival rate.
  
  

What This Means

• This data means that, for most women who have Stage 0, Stage I or Stage II breast cancer, the cancer treatments are effective. For women diagnosed with a more advanced stage of breast cancer, the treatments might not be effective. And for patients diagnosed with Stage IV breast cancer, in most cases the treatments are not effective.
  
  As the American Cancer Society cautions, these statistics are averages. The results of an individual patient might vary depending on many factors, including your general health and how your body responds to the cancer treatments.