Oct. 26, 2000 BOSTON, MA – Doctors at Memorial Sloan-Kettering Cancer Center are developing new ways to more effectively treat lung cancer with radiation therapy by using enhanced imaging to better define tumors during treatment planning, and delivering higher doses with fewer side effects. Center researchers will present preliminary findings on these promising techniques at the American Society for Therapeutic Radiology and Oncology (ASTRO) meeting in Boston this week.
Approximately 175,000 people will be diagnosed with lung cancer in the US this year. It is the most common cause of cancer-related death among both men and women, accounting for 28 percent of all cancer deaths in the country. Because of limitations in diagnostic testing, the disease is often discovered at a more advanced stage when it is more difficult to treat. Radiation therapy has been shown to be the most effective treatment option for patients in whom the cancer is inoperable – when it has spread beyond the lung but is confined to the chest.
One study being presented highlights the use of Positron Emission Tomography (PET), which is a more sensitive imaging technique than Computed Tomography (CT), to identify lesions, determine the extent and spread of the cancer, and detect the presence of early disease in the lymph nodes. Cancer causes changes and obstructions in the lung tissue that make it difficult to clearly see the tumor when planning radiation treatment. PET improves the accuracy of radiation therapy by better contrasting and delineating the lung tumors and normal tissue during the planning done prior to treatment.
Memorial Sloan-Kettering researchers will report that each of the ten patients evaluated in the study have had changes made to their treatment plan as a result of PET data – the area intended to receive radiation was increased in six patients and decreased in four patients. “Using this sophisticated approach to accurately distinguish between cancerous and healthy tissue leads to more targeted radiation treatment and a better treatment outcome,” says Yusuf Erdi, DSc, a nuclear physicist at Memorial Sloan-Kettering and lead author of the study.
Researchers will also report on a new technique to reduce toxicity at the highest levels of radiation therapy. Because pulmonary tumors move when patients breathe, doctors have previously had to treat a wider area to hit this “moving target” in order to ensure that the lung tumors receive the ideal dose of radiation, increasing the side effects of treatment. However, physicians at Memorial Sloan-Kettering have discovered a way to immobilize the lung tumors during radiation treatment using a method called the “deep inspiration breath hold,” which decreases lung density and has allowed doctors to more safely treat patients at higher doses than ever.
The approach is used when free breathing with three-dimensional conformal radiation therapy does not allow for safe treatment at a high dose. It requires the patient to hold his or her breath for 10 seconds at a time to make sure the lung tumor stays still during treatment. This is repeated five or six times during each treatment episode. The individual must be at exactly the same breath level for each treatment, which is measured with a device called a spirometer. The therapy is only administered when the patient can maintain the same breath level as the last treatment.
“The deep inspiration breath hold allows for more targeted and thus safer treatment for large lung tumors that would otherwise not be eligible for dose escalation,” said Ken Rosenzweig, MD, a radiation oncologist with expertise in the treatment of lung cancer and who developed the technique at Memorial Sloan-Kettering. “Our findings show that high-dose radiation treatment can effectively control the rate of tumor growth with little toxicity despite locally advanced disease in the majority of patients,” said Dr. Rosenzweig. To date, 20 patients have completed high dose radiation treatment using the breath hold technique with positive results.
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