Sometimes, radiation oncologists face a vexing dilemma. That is, should they irradiate a tumor at a dose high enough to eradicate the tumor, but, at the same time, run the risk of damaging the surrounding healthy tissue so that the patient faces life-long side effects? Or, should they try to spare the healthy tissue and hope that the dose will be high enough to shrink the tumor? This all-too-common dilemma may be relegated to the past with the advent of Intensity Modulated Radiation Therapy (IMRT).

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IMRT is a form of 3D conformal radiation therapy that delivers a highly specific, individualized treatment plan for each patient. The essence of IMRT is quite simple; by varying the intensity of radiation beams, it allows clinicians to ‘paint’ the tumor with radiation and, at the same time, shape the beam to avoid surrounding tissue. In some cases, the increased precision enables physicians to escalate the dose directed at the tumor. This means there is a greater chance of complete eradication of the tumor, rather than a temporary regression.

Although IMRT is a fairly new cancer treatment tool, it is making a considerable impact in how certain cancers are treated. Michael J. Greenberg, M.D., radiation oncologist at Pocono Health System (East Stroudsburg, Pa.) explains the significance of IMRT. “In prostate cancer, where the final outcome is dependent on the dose, it is almost necessary to use IMRT for patients with anything other than early prostate cancer.” Researchers at Memorial Sloan-Kettering Cancer Center (New York, N.Y.) have shown that higher radiation doses made possible by IMRT improve local control of prostate tumors from 55 to 94 percent than with lower doses. At the same time, the rate of normal tissue complications is reduced from 10 percent to 2 percent.

Please refer to the October 2001 issue for the complete story. For information on article reprints, contact Martin St. Denis