The researchers said that 28 percent of women who used the drug Herceptin for at least a year suffered cardiac problems. The affected women had to stop taking the cancer drug temporarily while their heart problems were treated.

    In previous clinical trials that tested Herceptin in combination with chemotherapy, between 10 and 26 percent of patients were found to experience cardiac problems.

    In the new study that 173 patients participated, who were with advanced stage breast cancer and used the drug for at least a year, 28 percent (49) of patients treated with Herceptin were found to have experienced a "cardiac event" after a follow-up of 32 months.

    But researchers said the risk was an "acceptable" one and that the majority of heart damage could be reversed with treatment.

    "The drug substantially prolongs survival ... If the cardiac side-effects of Herceptin treatment can be managed, the drug is safe to use." said lead researcher Francisco Esteva, professor of oncology at the University of Texas M.D. Anderson Cancer Center in Houston, U.S.

    Herceptin is already known to weaken the heart muscle and is therefore not recommended for those with heart trouble.

    A warning from the U.S. Food and Drug Administration last year said Herceptin could result in congestive heart failure, leading to inability to pump enough blood throughout the body, or a dysfunction in the heart's ventricle chamber.

    John Toy, Cancer Research UK's medical director, described the study as reassuring since it demonstrated for the first time that Herceptin could be restarted once the women affected had been treated.

    But in the UK, he added, the National Institute for Health and Clinical Excellence, which has authorized use of the drug for early and advanced breast cancer, stressed when approving the drug that heart function must be assessed beforehand. It also said the drug should not be given to those at risk of heart failure and patients should undergo regular assessments. Enditem

    (Agencies)