Prevention and Treatment of Cancer

Reducing the risk of certain cancers may be possible through dietary and other lifestyle changes. How risk can be reduced depends on the specific cancer. For example, not smoking and avoiding exposure to tobacco smoke can greatly reduce the risk of lung, kidney, bladder, and head and neck cancer.
Avoiding the use of smokeless tobacco (snuff, chew) decreases the risk of cancer of the mouth and tongue. Avoiding sun exposure (especially during the middle of the day) can reduce the risk of skin cancer. Covering exposed skin and using sunblock lotion with a high sun protection factor (SPF) against ultraviolet light also helps reduce the risk of skin cancer.
Other lifestyle changes reduce the risk of several types of cancer. A reduced intake of fat in the diet appears to decrease the risk of breast and colon cancer. Use of aspirin and other nonsteroidal anti-inflammatory drugs (NSAIDs) reduces the risk of colon cancer.
Treating cancer is one of the most complex aspects of medical care. It involves a team that encompasses many types of doctors working together (for example, primary care doctors, gynecologists, oncologists, surgeons, radiotherapists, and pathologists) and many other types of health care workers (for example, nurses, physiotherapists, social workers, and pharmacists) . Treatment decisions take into account many factors, including the likelihood of cure or of prolonging life when cure is not possible, the effect of treatment on symptoms, the side effects of treatment, and the person's wishes regarding all of these issues. People undergoing cancer treatment hope for the best outcome and the longest survival with the highest quality of life. However, people who are candidates for radiation therapy or anti-cancer drugs must understand the risks involved with treatment. People with cancer should discuss their wishes regarding medical care with all of their doctors, including the level of treatment desired when no cure is possible.
When the diagnosis of cancer is first made, the main goals of treatment are to remove the cancer if possible (through a single treatment or a combination of surgery, radiation therapy, or chemotherapy) and reduce the chance of spread (metastases) . Chemotherapy is usually the only way to treat the cancer cells that have spread beyond the original (primary) site. Using
combinations of chemotherapy drugs may help eradicate the original cancer and kill cancer cells elsewhere in the body.
Even when a cure is impossible, symptoms resulting from the cancer can often be relieved with treatment that improves the quality and length of life (palliative therapy). For example, if a tumor cannot be removed surgically, radiation of the tumor may shrink it, temporarily reducing pain and symptoms in the immediate vicinity of the tumor (local symptoms).
As treatments become more complex, specific approaches to care, called treatment protocols, have been developed for many types of cancer to ensure that people receive the most effective care with the fewest side effects.
Thus, the use of treatment protocols assures that people with the same type and stage of cancer are treated with some standard sequence and dose of therapies. Such protocols are derived from careful scientific experiments. Protocols are constantly being refined to improve their effectiveness.

Response to Treatment
While being treated for cancer, the person is assessed to see how the cancer is responding to therapy. When a cancer disappears for any length of time after treatment, a person is said to have had a complete response (remission). The most successful treatment produces a cure. A cure means that all evidence of cancer disappears and never recurs. Doctors sometimes consider cures in terms of the 5-year or 10-year disease-free survival rates, in which the cancer completely disappears and does not recur within these (or some other usually long) time periods. With a partial response, the size of one or more tumors is reduced by more than half; this response can reduce symptoms and may prolong life, although the cancer eventually grows back. The least successful treatment produces no response. Sometimes a cancer completely disappears but returns later (relapse); the interval between these two events is called the disease-free interval. The interval from diagnosis of cancer to the time of death is the total survival time. In people who have a partial response, the duration of response is measured from the time of the partial response to the time when the cancer begins to enlarge or spread again.
Some cancers respond well to chemotherapy or radiation therapy and are termed responsive. Some cancers respond poorly to chemotherapy or radiation therapy and are termed resistant. Other cancers may have excellent initial responses but may develop resistance after repeated treatment.
Some cancers produce substances that are termed tumor markers. Most of these tumor markers are not specific enough to be useful in screening-a number of disorders other than cancer can cause many of these substances to appear in the blood. However, they can often be useful to assess response to treatment. If the tumor marker was present before treatment but no longer appears in a blood sample after treatment, the treatment has probably been successful. If the tumor marker disappears after treatment then later reappears, the cancer has probably returned.

Preventing Cancer
According to the American Cancer Society, the risk of developing certain cancers may be reduced by making lifestyle changes.

• Measures known to reduce the risk of cancer:
• Avoiding smoking or exposure to tobacco smoke
• Avoiding occupational carcinogens (for example, asbestos)
• Avoiding prolonged exposure to sunlight without sunscreen protection
• Measures that possibly reduce the risk of cancer:
• Limiting intake of high-fat foods, particularly from animal sources (for example, high-fat meats, whole-fat dairy products)
• Increasing intake of fruits and vegetables
• Being physically active
• Achieving and maintaining a healthy weight

(Merck)