The Washington University School of Medicine in St. Louis Researchers says that highly targeted radiation therapy improves survival and lessens treatment-related complications in cervical cancer patients.

The technique, called intensity-modulated radiation therapy (IMRT), is widely accepted for treating many cancers of the pelvic region, head and neck, and central nervous system, but the use of IMRT for cervical cancer is not as common. This is the first large study to show its effectiveness as a primary therapy for cervical cancer.

"Previous studies of IMRT for cervical cancer have been small with limited follow-up and some used IMRT as a post-operative treatment instead of as primary therapy, but this evidence did suggest that IMRT could be an effective treatment choice," says lead author Elizabeth Kidd, M.D., a Barnes-Jewish Hospital resident in Washington University's Department of Radiation Oncology. "So we undertook a larger study involving IMRT treatment of advanced cervical cancer, and the positive results we saw will likely encourage more medical facilities to use IMRT for these patients."

Kidd and her colleagues, including researchers with the Siteman Cancer Center at Washington University and Barnes-Jewish Hospital, report their findings in an upcoming issue of the International Journal of Radiation Oncology, Biology, Physics.

IMRT is an advanced mode of radiotherapy that allows the radiation dose to conform more precisely to the three-dimensional shape of the tumor. IMRT minimizes the dose to surrounding normal tissues and organs, reducing possible damage to the bowels, bladder, rectum, vagina and pelvic bones.

The study included 452 patients with newly diagnosed cervical cancer who were treated with external-beam radiation therapy at Washington University in St. Louis. More than 80 percent of the patients received concurrent cisplatin, a chemotherapy drug commonly used for cervical cancer. The patients also received brachytherapy, in which a radioactive source is placed close to the cervical tumor.

"Our IMRT protocol was designed to replicate the traditional approach in terms of the amount of radiation going to the tumor and pelvic lymph nodes, which is the first area where the cancer spreads," Kidd says. "In the IMRT group, we expected to see a reduction of radiation-induced side effects in adjacent normal tissues, but we expected that both approaches would result in equivalent control of the cancer. We did see fewer treatment-related complications in the IMRT group, but we were surprised that the IMRT group also had better overall survival."

Kidd says that one reason IMRT has not been more widely adopted for cervical cancer treatment is that cervical tumors are hard to distinguish from surrounding normal tissue with standard computed tomography ( CT ) scans, which are used to create a detailed three-dimensional simulation of patients' anatomy during treatment planning. The uncertainty concerning tumor location made a whole-pelvic approach more appropriate.

The Washington University researchers used PET imaging that allowed them to clearly delineate the extent and position of the cervical tumors as well as whether the cancer had spread to any lymph nodes. PET is particularly useful for imaging cervical cancer because the commonly used glucose tracer is highly absorbed by both the primary tumor and those that have spread, making them easy to locate. The use of PET and CT helped ensure that the IMRT fields were precisely contoured for each patient.

Source: Washington University in St. Louis

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