LONDON (Reuters) - Hormone replacement therapy, which is known to increase the risk of breast cancer, also appears to make it more likely a tumor will return in women who have had the disease, researchers said on Tuesday.

Women who had earlier had breast cancer were 14 percent more likely to get it again if they used hormone replacement therapy, or HRT, researchers said in the U.S. Journal of the National Cancer Institute.

"The results ... indicate a substantial risk for a new breast cancer event among breast cancer survivors using hormone-replacement therapy," wrote researcher Lars Holmberg and colleagues at Kings College London.

They followed for four years or longer 442 mostly Scandinavian women who had had breast cancer, half of whom had received HRT.

The women were part of a trial stopped in 2003 after concerns about the increased risk of breast cancer recurring for women on hormone therapy.

U.S. researchers have discovered a promising new drug for schistosomiasis -- a parasitic worm disease that affects more than 200 million people in 70 countries.

The compound killed worms in the lab, and cured mice infected with the disease, said David Williams of Illinois State University, who reported his findings on Sunday in the journal Nature Medicine.

The only existing drug that works against schistosomiasis, praziquantel, is more than 20 years old.

"There is nothing else you could go to if the parasite evolves resistance," Williams said in a telephone interview. He said about 100 million people will take the drug this year.

"When you treat as many people as are being treated, it is likely drug resistance will evolve," he said.

Schistosomiasis is caused by flatworms that live in snail-invested fresh water. Water becomes contaminated by worm eggs when infected people urinate or defecate in it.