MONDAY, June 4, 2007 (HealthDay News) -- After almost a decade of use, Herceptin continues to prolong the lives of women with a particularly aggressive form of breast cancer.
An analysis of two clinical trials showed that breast cancer patients receiving Herceptin along with chemotherapy have better survival and fewer recurrences after four years, compared to patients receiving chemotherapy alone. Previous data had shown improved outcomes only over two years.
"When we presented the original data in 2005, people wondered if the benefits were going to be maintained or were we just seeing acute, short-term benefits in this aggressive type of breast cancer," said Dr. Edith Perez, director of the Multidisciplinary Breast Clinic at the Mayo Clinic in Jacksonville, Fla., and the primary investigator of one of the trials. "The data now states that the benefit is completely maintained over time, maybe even increasing, without any increase in toxicity."
Perez presented the results of the joint analysis Monday at the American Society of Clinical Oncology's annual meeting in Chicago.
"The prediction that women would continue to do well appears to be accurate," added Dr. Len Lichtenfeld, deputy chief medical officer of the American Cancer Society. "This seems to confirm another substantial advance in treating cancer with molecular therapies. There's a lasting benefit, and that's important."
"This is great news for women," added Dr. Ramona Swaby, a medical oncologist specializing in breast cancer at Fox Chase Cancer Center in Philadelphia. "It's reassuring because we're so used to using Herceptin in a non-curative [ie preventive] setting."
Herceptin, which was approved to treat advanced breast cancer in 1998, is effective in the 20 percent to 25 percent of breast cancer cases that test positive for the HER2/neu receptor.
This paper was an analysis of two trials that had already shown a benefit with Herceptin. Participants in both trials underwent chemotherapy and were then randomized to receive Herceptin or a placebo.
After four years, 85.9 percent of the women in the Herceptin arm remain cancer-free and 92.6 percent are still alive, compared with 73.1 percent and 89.4 percent respectively, of those not treated with Herceptin.
Overall, 397 patients in the chemotherapy-alone group have developed a recurrence or died, compared to only 222 in the Herceptin group.
The addition of Herceptin to therapy decreased the chances of the cancer returning by 52 percent and the risk of death by 35 percent.
"The benefit is not short-term, it's long-lasting, which impacts many, many lives," Perez said.
The first joint analysis of these two trials appeared in the Oct. 20., 2005, issue of the New England Journal of Medicine and found that disease-free survival and overall survival were improved by 52 percent and 33 percent, respectively, after two years of follow-up.
The good news follows another longer-term study of the drug, released Sunday at the cancer meeting, which showed that the risk of heart failure in women taking Herceptin was not any higher at five years than it was at two years.
Among the other findings of the joint analysis: the highest risk of relapse for HER2-positive breast cancer occurs within the first two years, although additional recurrences occur later and the cancer is more likely to recur in patients who initially had larger tumors, who had lymph node involvement or whose tumors were also estrogen-receptor-negative.
"The peak of relapse is still within the first three years, but relapses still continue occurring," Perez said.
Interestingly, Perez also found that estrogen-receptor-positive tumors experienced a 15 percent improvement, even though many physicians had believed these tumors did not respond well to Herceptin.
"That's going to be news to a lot of people," Perez said.
More information
The National Cancer Institute has more on Herceptin.
