 Many studies have been performed to examine cyclin levels in tumors, and it has been shown that levels of cyclin B is a strong indicator of prognosis in many types of cancer.Generally, elevated levels of cyclin B are indicative of more aggressive cancers and a poor prognosis.Immunohistologically assessed levels of cyclin B could determine if women with stage 1, node negative, hormone receptor positive breast cancer were likely to benefit from adjuvant therapy.