Treatment of cancer
Cancer can be treated by surgery, chemotherapy, radiation therapy, immunotherapy or other methods. The choice of therapy depends upon the location and grade of the tumor and the stage of the disease, as well as the general state of the patient (performance status). A number of experimental cancer treatments are also under development.
Complete removal of the cancer without damage to the rest of the body is the goal of treatment. Sometimes this can be accomplished by surgery, but the propensity of cancers to invade adjacent tissue or to spread to distant sites by microscopic metastasis often limits its effectiveness. The effectiveness of chemotherapy is often limited by toxicity to other tissues in the body. Radiation can also cause damage to normal tissue.
Because "cancer" refers to a class of diseases, it is unlikely that there will ever be a single "cure for cancer" any more than there will be a single treatment for all infectious diseases.
Surgery
If the tumor is localized, surgery is often the preferred treatment. Example procedures include mastectomy for breast cancer and prostatectomy for prostate cancer. The goal of the surgery can be either the removal of only the tumor, or the entire organ. Since a single cancer cell can grow into a sizable tumor, removing only the tumor leads to a greater chance of recurrence. A margin of healthy tissue is often resected to make sure all cancerous tissue is removed.
In addition to removal of the primary tumor, surgery is often necessary for staging, e.g. determining the extent of the disease and whether there has been metastasis to regional lymph nodes. Staging determines the prognosis and the need for adjuvant therapy.
Occasionally, surgery is necessary to control symptoms, such as spinal cord compression or bowel obstruction. This is referred to as palliative treatment.
Chemotherapy
Chemotherapy is the treatment of cancer with drugs ("anticancer drugs") that can destroy cancer cells. It interferes with cell division in various possible ways, e.g. with the duplication of DNA or the separation of newly formed chromosomes. Most forms of chemotherapy target all rapidly dividing cells and are not specific for cancer cells. Hence, chemotherapy has the potential to harm healthy tissue, especially those tissues that have a high replacement rate (e.g. intestinal lining). These cells usually repair themselves after chemotherapy.
Because some drugs work better together than alone, two or more drugs are often given at the same time. This is called "combination chemotherapy"; most chemotherapy regimens are given in a combination.
A novel technique involves taking samples of the patient's tissue before chemotherapy. These tissues samples are screened to ensure they do not contain cancerous cells. The samples are expanded using tissue engineering techniques, and are then re-implanted following high dose chemotherapy in order to recolonise the damaged and somewhat destroyed tissue. A variation upon this method uses allogenic samples (samples donated by a different donor) instead of the patient's own tissue4.
Immunotherapy
Immunotherapy is the use of immune mechanisms against tumors. These are used in various forms of cancer, such as breast cancer (trastuzumab/Herceptin®) but also in leukemia (gemtuzumab ozogamicin/Mylotarg®). The agents are monoclonal antibodies directed against proteins that are characteristic to the cells of the cancer in question, or cytokines that modulate the immune system's response.
Radiation therapy
Radiation therapy (also called radiotherapy, X-ray therapy, or irradiation) is the use of ionizing radiation to kill cancer cells and shrink tumors. Radiation therapy can be administered externally via external beam radiotherapy (EBRT) or internally via brachytherapy.