Late Use of Aromatase Inhibitor Still Effective Against Breast Cancer

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In October of 2003 , the study was ended a year earlier than originally planned when preliminary data showed that women taking letrozole were significantly less likely to have a cancer recurrence. Study participants in the placebo arm were offered letrozole when the study was halted. According to Goss, that gave the researchers the opportunity to compare the recurrence rates in women from the placebo group who chose to take the AI with those who decided on no further treatment.

Based on the new findings, "we believe every patient who has previously taken tamoxifen should discuss the findings of this study with her oncologist. Our results suggest if you take anti-estrogen, aromatase inhibitor therapy at any point of diagnosis, it is going to impact your chances of not experiencing a recurrence," Goss said.

Another expert agreed that the findings are significant.

"This study shows that the hormonal driving pathways continue to be very active after the tamoxifen has ended. And, the fact you've got a 60 percent improvement in disease-free survival with the addition of letrozole is a very powerful argument for its inclusion in treatment," said Dr. Brian Leyland-Jones, executive director of the Winship Cancer Institute at Emory University in Atlanta.

"The only imperfection of this trial, in terms of its design, is that it was not randomized -- patients chose whether or not to continue on letrozole," Leyland-Jones said. "And the only negative note is the risk of osteoporosis and increased risk of fractures for those who switched to letrozole. So, the news is very good but not all perfect."

More information

For more on breast cancer, head to the National Cancer Institute.