About one in three newly diagnosed cancer patients in the United States receives radiation treatment, which is being used increasingly as the first line of cancer therapy, according to Dr. Steven Leibel, president of the American Society for Therapeutic Radiology and Oncology (ASTRO).
About one in three newly diagnosed cancer patients in the UnitedStates receives radiation treatment, which is being used increasinglyas the first line of cancer therapy, according to Dr. Steven Leibel,president of the American Society for Therapeutic Radiology andOncology (ASTRO).
He spoke at ASTRO's annual meeting, attended by several thousandworldwide cancer experts. ASTRO is the largest international organizationof radiation oncologists.
Dr. Leibel, vice chairman and attending physician, Departmentof Radiation Oncology, New York's Memorial Sloan-Kettering CancerCenter, said that the use of radiotherapy translates into 450,000patients this year.
Recent improvements in the precision of radiation therapy planningand delivery have demonstrated that higher doses of radiationare more effective in treating cancer with less toxic effect onhealthy tissue, Dr. Leibel said. "This experience provideshope for immediate improvement in controlling local tumors,"he added.
Long-term survival statistics compiled by the National CancerInstitute "indicate that approximately 65% of radiotherapypatients with a curative potential are indeed cured," Dr.Leibel noted. "Of those who fail, more than half initiallyrelapse at local or local-regional sites." Evidence of apossible cause-and-effect association between local failure andan increased incidence of distant metastases underscores the importanceof maximizing efforts to control cancer locally, he said.
Dr. Leibel also said, "Recent technological advances in computerizedradiation treatment planning and delivery have produced new high-precisiontechniques to improve the likelihood of successful local treatment."
Computer technology and software design advances have provided"tools to aid in the ability to delineate the target andnormal structures and to define more precisely the dose absorbedat each point within the irradiated tissues," Dr. Leibelexplained.
Three-Dimensional Conformal Systems
Three-dimensional (3D) conformal systems generate treatment plansthat focus the prescribed radiation dose at the tumor, conformingits distribution to the 3D configuration of the target. This reducesdoses to normal tissues and enhances safety, Dr. Leibel said."If 3D treatment planning and delivery are implemented attheir technical feasibility and carried to the highest tolerabledose, the rates of local control hypothetically should increase,albeit up to a ceiling dictated by the inherent radiation resistanceof each tumor type," he said.
Clinical use of 3D conformal radiation therapy (3D-CRT) is expandingrapidly worldwide, with systems in use at many institutions forroutine patient management. Artificial intelligence and new imageprocessing techniques are under development to address some ofthe limitations of 3D conformal systems. As for cost concerns,Dr. Leibel said many components of 3D-CRT are add-on costs tobasic conventional radiation techniques, most of which are computer-drivenand automated.
"Cost-benefit studies should include not only immediate costparameters, but also the medical and socioeconomic impact of improvedcure and the cost saving associated with decreased short- andlong-term toxicity," he said.
Dr. Leibel added, "While significant advances have alreadyimproved the precision of radiation treatment and permitted closeescalation, it remains for 'new biology' to match 'new physics'in this quest of local control ... As we turn into a new century,3D in radiotherapy coupled with 'new biology' may indeed leadus into as yet unexplored dimensions in the ability to cure localizedtumors."