This is Gwen Outen with the VOA Special English Health Report.

Dogs are known for their sense of smell. They can find missingpeople and things like bombs and illegal drugs. Now a study suggeststhat the animal known as man's best friend can even find bladdercancer.

Cancer cells are thought to produce chemicals with unusual odors.Researchers think dogs have the ability to smell these odors, evenin very small amounts, in urine. The sense of smell in dogs isthousands of times better than in humans.

The study follows reports of cases where, for example, a dogshowed great interest in a growth on the leg of its owner. The molewas later found to be skin cancer.

Carolyn Willis led a team of researchers at Amersham Hospital inEngland. They trained different kinds of dogs for the experiment.The study involved urine collected from bladder cancer patients,from people with other diseases and from healthy people.

Each dog was tested eight times. In each test there were sevensamples for the dogs to smell. The dog was supposed to signal theone from a bladder cancer patient by lying down next to it.

Two cocker spaniels were correct fifty-six percent of the time.But the scientists reported an average success rate of forty-onepercent.

As a group, the study found that the dogs chose the correctsample twenty-two out of fifty-four times. That is almost threetimes more often than would be expected by chance alone.

The British Medical Journal published the research. In all,thirty-six bladder cancer patients and one hundred eight otherpeople took part.

During training, all the dogs reportedly even identified a cancerin a person who had tested healthy before the study. Doctors found agrowth on the person's right kidney.

Carolyn Willis says dogs could help scientists identify thecompounds produced by bladder cancer. That information could then beused to develop machines to test for the chemicals. Now, doctorsmust remove tissue from the bladder to test for cancer. The teamalso plans to use dogs to help identify markers for other kinds ofcancer.

Bladder cancer is the ninth most common cancer worldwide. TheInternational Agency for Research on Cancer says this disease killsmore than one hundred thousand people each year. Doctors saycigarette smoking is the leading cause of bladder cancer.

This VOA Special English Health Report was written by CynthiaKirk. This is Gwen Outen.