In this context, our present study is important because it provides valuable information on the safety of long-term administration of an LH-RH agonist plus tamoxifen for up to 5 years, which may help to make a decision on the indication for 5-year administration of an LH-RH agonist plus tamoxifen to Japanese breast cancer patients who were not studied in SOFT. This evidence concerns the gene GNRH1 and breast cancer.