Statistical analysis in cancer clinical trials

Evidence suggests that over the long term (>5 years), tamoxifen should be replaced with an agent such as an aromatase inhibitor. Recent decisions to terminate several large clinical trials, in view of emerging efficacy data with the aromatase inhibitors, indicate that there is a need for guidelines that determine when trials should be discontinued. As a result of the interim efficacy analysis and subsequent discontinuation of the NCIC MA.17 trial, the National Surgical Adjuvant Breast and Bowel Project B-33 study was unblinded after a median of 10 months of treatment. The B-33 trial, nevertheless, demonstrated a statistically significant improvement in relapse-free survival indicating that exemestane is likely to be a valuable treatment option in postmenopausal women with early breast cancer who remain disease-free following 5 years of tamoxifen therapy.