Metastatic breast cancer patients who take a new chemotherapy drug made from a sea sponge may live about two and a half months longer, a new research shows.

The drug, known as eribulin, is more effective than other chemotherapies, according to a study presented on Sunday by a group of British researchers to the annual meeting of the American Society of Clinical Oncology in Chicago.

The study involved more than 750 female patients who were randomized to receive either eribulin or a "treatment of physician's choice." All of them had already been treated extensively for cancer and had undergone four chemotherapies on the average.

The researchers reported a 23-percent improvement in median survival for those who took eribulin, with the median survival for those in the eribulin group at slightly over 13 months compared to 10.7 months in the treatment-of-choice group.

"These results potentially establish eribulin as a new and effective treatment for women with heavily pretreated breast cancer," said Dr. Christopher Twelves, author of the study and a professor at the Clinical Cancer Research Groups at the Leeds Institute of Molecular Medicine and St. James' Institute of Oncology in Leeds, Britain.

"We see a statistically significant benefit in overall survival in a situation where we rarely see this sort of improvement," he added.

"Eribulin targets the ...mechanisms by which the cells divide, which is different from previous agents," explained Twelves.

"These results potentially establish eribulin as a new and effective treatment for women with heavily pretreated breast cancer, "he said.