Many women with a common and aggressive form of breast cancer that is treated with Herceptin can get by with six months of the drug instead of the usual 12, greatly reducing the risk of heart damage it sometimes can cause, a study suggests.
It's good news, but it comes nearly two decades after the drug first went on the market and many patients have suffered that side effect.
The study was done in the United Kingdom and funded by UK government grants. Results were released Wednesday by the American Society of Clinical Oncology and will be presented at the group's meeting next month.
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Herceptin transformed care of a dreaded disease when it was approved in 1998 for women with advanced breast cancers whose growth is aided by a faulty HER2 gene, as 15 percent to 20 percent of cases are. It was later approved for treatment of those cancers in earlier stages, too, based on studies that had tested it in patients for 12 months. That guess, that the drug should be taken for a year, became the standard of care.
But the drug can hurt the heart's ability to pump. That often eases if treatment is stopped but the damage can be permanent and lead to heart failure.
Some studies tested shorter use, but results conflicted. The new study is the largest so far, and involved more than 4,000 women with early-stage cancers who were given usual chemotherapy plus Herceptin for either six or 12 months.
After four years, about 90 percent of both groups were alive without signs of the disease. Only 4 percent on the shorter treatment dropped out due to heart problems versus 8 percent of those treated for a year.
"It's great news" for patients, said the study leader, Dr. Helena Earl of the University of Cambridge in England. Earl has consulted for Herceptin's maker, Roche. The company had no role in the study.
"There's no reason to not immediately change practice. The findings are persuasive," said Dr. Richard Schilsky, chief medical officer for the oncology society. Most of Herceptin's cancer-fighting benefit seems to come in the early months of use, he said.
Others said that because so few women have died or relapsed after being treated with the drug, longer followup may be needed to make sure the findings hold up before guidelines should be changed. Doctors also want to see results published, and to study them to see if certain groups of women need longer treatment.
Herceptin is given through an IV every three weeks; a year of it costs $34,000 to $40,000 in England and about $70,000 in the U.S. In December, a copycat competitor known as a biosimilar was approved in the U.S. and already is used in some other countries.
Dr. Harold Burstein, a breast cancer expert at Dana-Farber Cancer Institute in Boston, said shorter treatment may increase access to the drug in countries where many women can't afford it now, but that in the U.S., "my guess is that people will continue to aim for a year of treatment" because of lingering concerns that longer use is better, as a smaller, previous study suggested.
Dr. Jennifer Litton, a breast specialist at MD Anderson Cancer Center in Houston, said Herceptin was a true breakthrough, but scaling back treatment whenever possible is just as important to patients. She said the results show how important it can be to study drugs already on the market, and that drug companies alone should not be relied on to do studies like this.
"It's really important that we continue to have public funding for trials so we can continue to ask all of these questions for our patients," she said.
Herceptin's developer, Genentech, now part of Roche, said in a statement that the new study must be viewed along with several smaller previous ones that found one year to be best. The goal of treatment "is to provide people with the best chance for a cure," so women need to talk with their doctors about how best to reach that goal, the statement says.
Earlier this year, the American Heart Association issued its first statement on the heart effects of cancer drugs, saying women should consider carefully the risks and benefits of any therapies that may hurt hearts.
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