CCNA2 and breast cancer: Huuhtanen et al. (1999) reported association between higher cyclin A score and good chemotherapy response in soft tissue sarcoma patients but no such association was found in breast cancer patients (Poikonen et al., 2005). On the other hand, cyclin A overexpression should also be considered in terms of chemotherapy resistance (Cybulski et al., 2015; Huang et al., 2016).