Power Over Breast Cancer
Letrozole seen as alternative to gold standard tamoxifen, says noted oncologist
 The advent of specific aromatase inhibitors has given physicians an alternative to the gold standard tamoxifen in the treatment of post-menaopausal estrogen-positive breast cancer patients.
Breast cancer is the second most common malignancy worldwide with about 1,053,000 recorded cases in 2000. In estrogen receptor-positive cases, aromatase inhibitors have been shown to work well as a hormonal intervention. These drugs inhibit aromatase, a cytochrome p-450 enzyme that converts androgens in the peripheral tissue to estrogen, which stimulate proliferation of breast cancer cells.
One such aromatase inhibitor is letrozole (Femara), which Prof. Yan Sun, chief of the department of medical oncology at the Cancer Institute and Hospital in Beijing, said has been shown in the 025 clinical trial to work better than tamoxifen as first-line therapy in advanced breast cancer.
The extension phase of the study showed that the time to progression was longer with Femara (9.4 months) than tamoxifen (six months). Prof. Yan also noted that 79 percent of the patients in the Femara group progressed over nine months vis-à-vis 85 percent in the tamoxifen group.
The time to treatment failure was also superior at 89 percent in nine months with Femara compared to 94 percent in six months with tamoxifen. He also noted increased objective tumor response and clinical benefit rate with a 78 percent increased chance of response (p= 0.0002), as well as significant early survival benefit (up to two years, p < 0.02).
Declared the widely experienced oncologist and council member of the International Society of Chemotherapy: "We finally have one drug better than the gold standard tamoxifen for postmenopausal advanced hormone-sensitive breast cancer patients."
He added that Femara was noted to be more effective as neoadjuvant treatment of early breast cancer than tamoxifen as shown in the double-blind 024 protocol that involved 337 postmenopausal women with primary invasive ER- or PgR-positive breast cancer, > T2 tumors, and who were not eligible for breast conserving surgery (BCS) were randomized to Femara (162) and to tamoxifen (175).
He said the results showed that Femara significantly improved clinical response and breast-conserving surgery rates, and that patients given Femara were almost twice as likely to respond than those given tamoxifen.
Tumor size had no significant effect on clinical response rate. He explained that T2 tumors were over four times more likely to undergo breast conserving surgery compared with tumors over T2. Prof. Yan said that the objective response rate determined through clinical palpation was 55 percent with Femara and 36 percent with tamoxifen; by ultrasound 35 percent with Femara and 25 percent with tamoxifen; by mammography 34 percent with Femara and 17 percent with tamoxifen. Prof. Yan said these results showed that a four month therapy using Femara was consistently superior to tamoxifen use.
There was also 45-percent breast-conserving surgery with Femara as against 35-percent with tamoxifen. Prof. Yan said "this makes Femara better than tamoxifen in terms of objective response rate and clinical benefit."
Femara has also been shown better than another aromatase inhibitor (anastrozole) in terms of objective response rate.
On a head-to-head trial involving postmenopausal women with advanced breast cancer who had progression on tamoxifen, the median time to progression and median survival were comparable (24.7 for Femara and 24.6 for anastrozole). However, objective response rate was significantly better with Femara (19 percent) than with anastrozole (12 percent). In another double-blind, randomized, crossover comparison of patients, Prof. Yan noted that those who took Femara first and then crossed over to anastrozole had a lower inhibition rate.
Prof. Yan said Femara is the new alternative drug to gain power over breast cancer.
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