SARAH LONG:You are listening to the Special English program SCIENCE IN THE NEWS on VOA.
This is Sarah Long with Bob Doughty in Washington.
Chemotherapy is a common way to fight cancer.
Doctors give patients powerful drugs to kill cancer cells.
However,chemotherapy drugs often are poisonous to healthy cells as well.
Patients often suffer unwanted side effects.
Among the most common side effects are a sick feeling in the stomach and the uncontrolled expulsion of food from the mouth.
Other side effects are hair loss,a feeling of weakness and infection.
In addition,patients who have traditional chemotherapy often say they suffer from temporary memory loss and reduced thinking ability.
Tim Ahles of Dartmouth Medical School in Hanover,New Hampshire,organized a study of the problem
BOB DOUGHTY:Doctor Ahles compared cancer patients who had traditional chemotherapy to patients who had limited treatments.
The two groups were tested for memory,reading ability,and the ability to think clearly.
Doctor Ahles says his study showed that patients who had traditional chemotherapy were two times as likely as the other patients to do poorly in the intelligence tests.
Doctor Ahles presented the findings to a group of cancer patients who had chemotherapy.
He says those patients felt better knowing that the study found evidence of what many of them already knew.
Doctor Ahles says almost everyone who has chemotherapy experiences problems with memory and thinking.
He says the problems are most common from the middle of treatment until up to four months after the chemotherapy stops.
He says the ability to think clearly begins to improve later.
SARAH LONG:Recently,research scientists in Canada reported similar findings about chemotherapy.
The findings were reported in the Journal of Clinical Oncology.
Researchers from Princess Margaret Hospital in Toronto studied breast cancer patients who were given chemotherapy.
They compared the patients to other women who were not receiving the treatment.
The Canadian researchers found the women taking the anticancer drugs did worse in tests of memory and language than the other women.
The researchers say doctors and patients should understand the problem when making treatment decisions.
However,they say this possible problem should not be used as an argument against chemotherapy treatment.