Proton Beam Therapy Useful in Treating Sinonasal Cancers

Proton beam-radiation therapy shows encouraging results for patients with locally advanced sinonasal malignancies, according to a new study.

Researchers at Massachusetts General Hospital (MGH; Boston, USA) treated 99 patients with newly diagnosed sinonasal cancers with proton beam therapy between 1991 and 2003, with the median total dose of radiation to the primary tumor at 70 Gray. Most of the patients (67%), who usually presented with advanced stage tumors involving normal structures in the skull base such as eyes, optic nerves, brain, had undergone some type of surgery prior to their radiation. The researchers found that after a median follow-up of 8.5 years, the local control rates at five and eight years were 87% and 83%, respectively, and there was no statistically significant difference in local control per histological subtype, T stage, and surgery compared to biopsy. The study was presented at the Multidisciplinary Head and Neck Cancer Symposium, held during February 2010 in Chandler (AZ, USA).

"Due to the anatomical location of sinonasal cancers, conventional radiation therapy results in very poor local control and is associated with significant treatment-related toxicity,” said lead author radiation oncologist Annie Chan, M.D., of MGH and Harvard Medical School (Boston, MA, USA). "Proton beam radiation therapy, with its superior dose distribution, allows the delivery of higher doses of radiation to the tumor while sparing more or the healthy surrounding tissues. This study showed very encouraging results for these patients and now prospective multi-institutional studies are being planned to further study the use of proton therapy in the treatment of this rare but aggressive malignancy.”

Proton beam therapy is a form of particle therapy, which uses a stream of protons to irradiate diseased tissue, most often in the treatment of cancer. During treatment, a particle accelerator is used to target the tumor; these charged particles damage the DNA of cells, ultimately causing their death or interfering with their ability to reproduce. The chief advantage of proton therapy is increased precision by emphasizing the reduction of the integral dose to normal tissue, and thus a reduction of unwanted effects. The development of proton therapy began in the 1950s at accelerator laboratories, and in the last 20 years has expanded to hospital based facilities built specifically to perform this type of treatment. There are currently only 26 proton therapy centers worldwide, due to the size and cost of the cyclotron or synchrotron equipment needed.

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