• 3/4/2002
  • New York, NY
  • St. Vincent’s Comprehensive Cancer Center

New SmartBeam IMRT technology from Varian Medical Systems zeroes in on tumors while sparing healthy tissue.

When the CFO of a New York company was diagnosed with a cancerous tumor at the base of his tongue last March, he learned that conventional radiation therapy could potentially cure him, but might also cause serious side effects. The tumor was near his salivary glands and his brain stem. If not targeted precisely, radiation could affect one or both.

He and his wife had been going over their treatment options with his doctor at St. Vincent’s Comprehensive Cancer Center here when his wife asked about intensity modulated radiation therapy, or IMRT, a new and more precise radiation therapy technique that enables doctors to escalate the radiation dose to tumor cells while protecting nearby healthy tissues. By coincidence, St. Vincent’s had just commissioned a SmartBeam® IMRT system from Varian Medical Systems, and after reviewing the case, doctors decided that the man was an ideal candidate to be their first IMRT patient.

“In cases like this, conventional radiotherapy can damage one or both parotid glands, causing xerostomia, a severe, chronic, and irreversible dry mouth condition that makes it difficult for patients to chew, swallow, or speak,” said Dr. Anthony Berson, Chief Radiation Oncologist at St. Vincent’s. “With IMRT we increase the chances of eradicating the cancer while preventing dry mouth and other serious side effects. IMRT enables us to concentrate more of the dose on the tumor, and that gives us a much greater chance of completely eradicating the tumor,” he said. “Because the technique is so precise, we can treat areas that would have been considered much too risky before IMRT, too close to important critical structures.”

The St. Vincent’s radiotherapy team, led by Dr. Berson and medical physicist Richard Emery, began treating their first IMRT patient in April 2001. The patient completed the entire course of treatment without any breaks and continued to work full time. One month after treatment was over, the patient’s salivary function was essentially normal and a diagnostic PET scan showed that glucose metabolism at the tumor site had decreased significantly. “This is what you want to see at this point in time post-treatment,” said Dr. Berson. “It will take a little longer before we can know whether we’ve eliminated the cancer but these are encouraging results.”

According to Emery, in addition to head and neck cancers, St. Vincent’s will also use SmartBeam IMRT to treat prostate, breast, lung, pancreatic, and other cancers. SmartBeam IMRT treatments are delivered using a sophisticated computer-controlled medical linear accelerator that generates high-energy X-rays beams through a beam-shaping accessory called a multi-leaf collimator. St. Vincent’s has two linear accelerators. Each has a multi-leaf collimator with 120 computer-controlled mechanical “leaves” or “fingers” that shape and size the beam to as small as 2.5 mm by 5 mm to deliver an exact dose directly to the tumor.

St. Vincent’s also uses sophisticated multimodality imaging to create their complex IMRT treatment plans. They combine computed tomography (CT) and magnetic resonance (MR) scanning to locate tumors and to develop intricate treatment plans that enable them to deliver precise radiation doses of varying intensities to different areas of a tumor while sparing nearby healthy tissues. This improved precision makes it possible for physicians to safely escalate doses and thus improve the chances of eradicating tumors.

“In the past, we were often very restricted as to the amount of radiation we could give to a tumor, because we needed to protect critical structures nearby,” Dr. Berson said. “With IMRT, we are doing things we couldn’t do before.”

In the State of New York, there will be 83,200 new cancer cases and 36,300 cancer related deaths in 2001, according to statistics published by the American Cancer Society. St. Vincent’s Comprehensive Cancer Center, with its new IMRT capabilities, will be able to help many of them.

OCF Note: While this article showcases St.Vincents in NY, many cancer centers around the country are involved in the use and further testing of IMRT technologies.