Breast Cancer Medication Letrozole Reduces Risk of Recurrence of Disease in Certain Women by 43%, Study Finds

The cancer medication letrozole reduced by 43% the rate of breast cancer recurrence among postmenopausal women who had received standard treatment with tamoxifen, according to an international study that will appear in the New England Journal of Medicine next month, the Wall Street Journal reports (Naik, Wall Street Journal, 10/10). In the study, Dr. Paul Goss of Princess Margaret Hospital in Toronto and 18 colleagues from Canadian, European and U.S. hospitals tracked 5,197 women at 400 different locations who had estrogen-sensitive breast cancer and had completed five years of treatment with tamoxifen (Cohen, AP/Philadelphia Inquirer, 10/10). Past studies have found that tamoxifen, which blocks the production of estrogen, can prevent breast cancer recurrence for five years but has no additional benefit after five years (Kolata, New York Times, 10/10). Half of the women in the new study received letrozole once daily, and half received a placebo once daily. The study found that 132 of the women who received a placebo had breast cancer recurrence, compared with 75 who received letrozole. According to the study, the benefits of letrozole appeared the same for women whose breast cancer had spread to other areas of the body and women whose cancer had not (Stein, Washington Post, 10/10). Novartis, which markets letrozole under the brand name Femara; the National Cancer Institute; and the Canadian Cancer Society funded the study. Researchers had planned to track the women for five years, but they ended the study after they had tracked the women for an average of 2.4 years because of the effectiveness of letrozole. Researchers announced the results of the study Thursday at a press conference in Toronto. The results also appear on the NEJM Web site (Srikameswaran, Pittsburgh Post-Gazette, 10/10).

Additional Results

The study found that 17 women who received a placebo died, compared with nine who received letrozole, although the result does not have statistical significance (Maugh, Los Angeles Times, 10/10). In addition, about 4.5% of the women in the study who received letrozole ended their treatment because of side effects, compared with 3.6% who received a placebo (Los Angeles Times, 10/10). Side effects of letrozole include a higher risk of osteoporosis, hot flashes and night sweats (New York Times, 10/10). The FDA in 1997 approved Femara to treat late-stage breast cancer, and Novartis plans to seek fast-track approval for the medications as a treatment for early-stage breast cancer based on the results of the study; Novartis hopes to receive approval by early 2005.

Questions Remain

According to the Journal, because researchers ended the study early, "it didn't fully achieve one of its goals: to determine the disease-free survival and overall survival of patients" who take letrozole over five years. The study also did not determine the proper length of letrozole treatment (Wall Street Journal, 10/10). In addition, the study did not determine whether every woman with breast cancer who has completed five years of treatment with tamoxifen should begin to take letrozole or compare the effectiveness of letrozole with similar medications on the market -- such as anastrozole, marketed by AstraZeneca as Arimidex, and exemestane, marketed by Pfizer as Aromasin (New York Times, 10/10). However, Goss said that researchers ended the study early to allow women who received a placebo to receive letrozole (Pittsburgh Post-Gazette, 10/10). An abstract of the study is available online.

Reaction

Dr. James Doroshow of City of Hope in Duarte, Calif., said, "This is going to change the way we treat breast cancer. There are hundreds of thousands of women who could potentially benefit" (Los Angeles Times, 10/10). Dr. Jeffrey Abrams, associate chief of the clinical investigations branch of NCI, said that the study found a "treatment that could be used after tamoxifen" (New York Times, 10/10). In one of two editorials that accompanied the study, Dr. Harold Burstein, an oncologist at the Dana-Farber Cancer Institute, writes that researchers must conduct additional studies to determine "the optimal duration" of letrozole treatment, adding that physicians must educate women about the "realistic benefits and side effects" of such treatment (Bor, Baltimore Sun, 10/10). In the second editorial, Dr. Norman Wolmark of Allegheny General Hospital and Dr. John Bryant of the University of Pittsburgh write that the study will prompt "much debate" over whether researchers "made the best decision" when they ended the study, adding that women "must be given the opportunity to receive letrozole, with an understanding of the limitations of the data" (AP/Philadelphia Inquirer, 10/10).

Broadcast Coverage

Several broadcast programs reported on the study:

ABCNews' "World News Tonight": The segment includes comments from Dr. Clifford Hudis of the Memorial Sloan-Kettering Cancer Center, Mayo Clinic study investigator Dr. James Ingle and a woman who participated in the study ("World News Tonight," ABCNews, 10/7). The full segment is available online in RealPlayer.
CBS' "Evening News": The segment includes comments from Hudis, Ingle and a woman who participated in the study (Kaledin, "Evening News," CBS, 10/9). The full segment is available online in RealPlayer.
CNN's "Live Today": CNN medical correspondent Elizabeth Cohen discusses the study (Cohen, "Live Today," CNN, 10/9). The full transcript of the segment is available online.
NBC's "Nightly News": The segment includes comments from Goss and a woman who participated in the study (Bazell, "Nightly News," NBC, 10/9). The full segment is available online in Windows Media.
NPR's "All Things Considered": The segment includes comments from Burstein, Hudis and Ingle (Palca, "All Things Considered," NPR, 10/9). The full segment is available online in RealPlayer.
NPR's "All Things Considered": NPR's Michele Norris discusses the study with Dr. Mary Cianfrocca, an oncologist at Fox Chase Cancer Center (Norris, "All Things Considered," NPR, 10/9). The full segment is available online in RealPlayer.
PBS' "NewsHour with Jim Lehrer": PBS' Ray Suarez discusses the study with National Cancer Institute Director Andrew von Eschenbach (Suarez, "NewsHour with Jim Lehrer," PBS, 10/9). The full segment is available online in RealPlayer.

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