The parasites that cause malaria may be helpful in treating patients with terminal cancers, Chinese researchers speculate, although more work is needed before the idea can be adopted for clinical use.

In their study, malaria parasites were injected into the bodies of patients in a precisely controlled manner designed to minimize risks. The parasites stimulated the immune system, which in turn fought off cancerous cells, according to the Guangzhou Institute of Biomedicine and Health.

Zhong Nanshan, a member of the Chinese Academy of Engineering and a leading member of the research team, said nearly 30 patients have been involved in trials over the past four years. Of the 10 cases that were under observation in the past year, five have shown progress against cancers.

All the patients are at terminal stages of cancers such as lung and rectal cancer. All had tried other means of treatment before the trial but nothing was effective, he said.

Chen Xiaoping, a researcher at the institute in Guangzhou, said that of the five whose conditions improved with the therapy, two may have been cured.

In one case, a patient with lung cancer, all the tumors on his neck vanished after a month of receiving injections of one milliliter of blood with malaria parasites, he said. The anti-malaria drug artemisinin was given to the patient at the same time to minimize side effects, he said.

Later, surgeons removed the original tumor in the patient's lung and found the tumor had been wrapped by a membrane, and most of the cancer cells had disappeared and been replaced by immune cells, as was shown in previous experiments with mice, he said.

The patient has lived for about two years after receiving the therapy and no recurrence of the cancer has appeared, he said.

Chen said before the study, researchers at the institute had done more than 10 years of research, which revealed that infection with malaria can greatly extend the life of mice with cancer.

Zhong said that although the new treatment shows positive signs, it has been applied to only a few individual cases, and there's not enough evidence to prove the therapy is broadly effective. More research is needed before any firm conclusions can be drawn, Zhong said.

Zhou Shuisen, a malaria researcher at the Chinese Center for Disease Control and Prevention, said the use of malaria parasites as a cancer treatment is limited to research and exploration, and more study is needed before moving to clinical application.

"It is still too early to reach the conclusion that malaria parasites can cure cancer," he said.