Letrozole superior to Tamoxifen in adjuvant setting
Letrozole may be superior to tamoxifen for post-menopausal women who have breast cancer as per the results of a study presented at the Primary Therapy of Breast Cancer 9th International Conference. The study showed that the risk of recurrence of breast cancer would be reduced 19 percent further if women were treated with letrozole rather than with tamoxifen.
These results were presented by Beat Thurlimann PhD from Kantonsspital-St, Gallen and came out of a large phase III clinical trial involving 8,028 post menopausal women who had endocrine responsive tumors. The median age of patients who participated in the study was 61 years. Forty one percent of these patients had node positive breast cancer. The study compared 2.5 mg daily of letrozole against 20 mg daily of tamoxifen.
The study design comprised of four arms, tamoxifen for five years, letrozole for five years, two years of tamoxifen followed by three years of letrozole and two years of letrozole followed by three years of tamoxifen. Only the data from tamoxifen alone and letrozole alone were available at the time of presentation of the study. At the time of presentation the patients had a median follow up of 35.5 months, however more than 1,200 were followed more than 5 years.
A total of 4,003 patients received letrozole and 4,011 patients received tamoxifen. Letrozole was shown to significantly prolong progression free survival compared with tamoxifen (84% Vs 81.4%). There was no significant difference in overall survival between letrozole arm and tamoxifen arm.
Tamoxifen was associated with 62 percent higher incidence of grade-3 to grade-5 thromboembolic events. There were more vaginal bleeding and endometrial abnormalities in the tamoxifen arm compared to letrozole arm. On the other hand use of letrozole was associated with 44 percent higher incidence of bone fractures.