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Patients who are treated with proton therapy (a specialized type of external beam radiation therapy using protons rather than X-rays to treat cancer) decreases the risk of patients developing a secondary cancer by two-fold, compared to being treated with standard photon radiation treatment, according to a first-of-its-kind study presented September 22, 2008, at the American Society for Therapeutic Radiology and Oncology's 50th Annual Meeting in Boston
This study contradicts recent theories that have suggested that proton radiation might actually increase - instead of decrease - the incidence of secondary cancers because of what is called scatter radiation. When proton radiation is delivered, neutrons are produced by nuclear interactions and are therefore scattered as a result.
"This study could have a substantial impact on the care of patients," Nancy Tarbell, M.D., senior author of the study and a radiation oncologist at the Massachusetts General Hospital in Boston, said. "Since cancer patients are surviving for longer periods of time, side effects of therapy are becoming increasingly important for doctors to consider when developing treatment plans. Since this is a retrospective study, however, we will need additional studies to further prove this hypothesis."
Photon radiation is the standard external beam radiation therapy treatment, while proton radiation is a more targeted form of external beam radiation which delivers less radiation to bordering normal structures. During external beam radiation therapy, a beam of radiation is directed through the skin to the cancer and the immediate surrounding area in order to destroy the main tumor and any nearby cancer cells.
The retrospective cohort study matched 503 patients who underwent Harvard Cyclotron proton radiation treatment with 1,591 patients treated with photon radiation therapy from the Surveillance, Epidemiology, and End Results (SEER) cancer registry from 1974 to 2001. According to the study, 6.4 percent of patients who underwent proton therapy developed a secondary cancer while 12.8 percent of patients who had photon treatment developed another type of cancer.
For more information on radiation therapy for cancer, visit http://newswise.com/articles/view/544328/www.rtanswers.org.
About Cancer
Cancer (medical term: malignant neoplasm) is the general name for a group of more than 100 diseases in which a group of cells display uncontrolled growth (division beyond the normal limits), invasion (intrusion on and destruction of adjacent tissues), and sometimes metastasis (spread to other locations in the body via lymph or blood). These three malignant properties of cancers differentiate them from benign tumors, which are self-limited, do not invade or metastasize. Most cancers form a tumor but some, like leukemia, do not. The branch of medicine concerned with the study, diagnosis, treatment, and prevention of cancer is oncology.
Cancer cells can spread to other parts of the body through the blood and lymph systems. Most cancers are named for the organ or type of cell in which they start - for example, cancer that begins in the colon is called colon cancer; cancer that begins in basal cells of the skin is called basal cell carcinoma.
Cancer types can be grouped into broader categories. The main categories of cancer include:
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Carcinoma - a cancer which is derived from the lining cells, or epithelium, of an organ. There are 4 major types of epithelium in the body (Glandular, squamous, transitional, and pseudostratified). Some types are only found in a few select organs such as the lung (pseudostratified) or urinary bladder (transitional). Carcinomas can arise from any of these epithelial types. For example, breast carcinoma is most commonly derived from the lining cells of the milk producing glands. A carcinoma with a glandular growth pattern is an adenocarcinoma. Common adenocarcinomas include prostate, colon, and breast. A carcinoma with a growth pattern resembling the squamous lining cells is termed a squamous cell carcinoma. Common squamous cell carcinomas are found in the esophagus and skin. However, any of these organs may have either type of carcinoma arising from it, although these latter diagnoses are exceedingly rare.
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Central nervous system cancers - cancers that begin in the tissues of the brain and spinal cord.
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Leukemia - cancer that starts in blood-forming tissue such as the bone marrow and causes large numbers of abnormal blood cells to be produced and enter the blood.
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Lymphoma - a cancer derived from the white blood cells that are present in the lymphoid tissues of the body. These sites most commonly include the lymph nodes and spleen. However, lymphomas may arise from any organ and body site.
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Sarcoma - cancer that begins in bone, cartilage, fat, muscle, blood vessels, or other connective or supportive tissue.
Today, millions of people are living with cancer or have had cancer. The risk of developing most types of cancer can be reduced by changes in a person's lifestyle, for example, by quitting smoking, limiting time in the sun, being physically active, and eating a better diet. Half of all men and one-third of all women in the US will develop cancer during their lifetimes.
Although doctors often cannot explain why one person develops cancer and another does not, research shows that certain risk factors increase the chance that a person will develop cancer. Nearly all cancers are caused by abnormalities in the genetic material of the transformed cells. These abnormalities may be due to the effects of carcinogens, such as tobacco smoke, radiation, chemicals, or viruses, bacteria, and certain hormones. Other cancer-promoting genetic abnormalities may be randomly acquired through errors in DNA replication, or are inherited, and thus present in all cells from birth. Other common risk factors for cancer include:
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