VOA慢速英语:Brain cancer like Kennedy's is difficult to treat

This is the VOA Special English Health Report.

Last week doctors in Massachusetts announced that Senator Ted Kennedy has brain cancer.

The news came after he suffered a seizure. Doctors found a glioma, a growth in the supportive tissue of the brain. The glial tissue is where the largest percentage of brain tumors begin.

More than forty percent of growths in the brain are gliomas. But they make up almost eighty percent of cancerous growths, like the malignant glioma that Senator Kennedy has. Seizures and headaches are common first signs of a glioma.

Cancerous glial tumors generally spread in the brain the way roots spread from a plant. That makes removing the tumor more difficult. A clear border between the cancer and healthy tissue can be difficult to find.

The location of the glioma must also be considered when deciding treatment. Senator Kennedy’s tumor is in the left parietal lobe of the brain. This area is involved in some sensory understanding and spatial recognition, as well as language, reading and vision.

Removal of a glioma from this area can result in speech problems and other disabilities.

Some cancer experts believe that doctors are unlikely to operate on Senator Kennedy. They say the likely treatment is radiation and chemotherapy.

But chemical treatment for brain cancer is complex because of the protective blood-brain barrier. It stops some chemicals from entering the brain, including many chemo drugs.

Radiation treatments for brain cancer have improved a lot in recent years. New methods and equipment can permit extremely localized treatments that are less likely to damage healthy tissue.

Research into brain cancer treatment also includes drug therapy. In two thousand five, a drug called temozolomide was shown to add a few months to the lives of brain cancer patients.

And researchers are studying uses for the cancer drug Avastin. It is already used to treat breast, colon and lung cancer. It starves tumors by blocking blood flow to the growths.

The United States has about ten thousand new cancerous gliomas a year. Half of the people die within fifteen months. Malignant gliomas are more aggressive in older people.

Ted Kennedy is seventy-six years old. The senator competed Monday in the second half of a boat race in Massachusetts, finishing second in his five-boat division.

And that’s the VOA Special English Health report, written by Caty Weaver. Transcripts and MP3s of our reports are at www.hxen.net. I’m Bob Doughty.

glioma:神经胶质瘤（脑神经或脊神经束上产生的肿瘤）