Nowadays cancers are predominant cause of morbidity and mortality all over the world. Therefore, the greatest challenge for clinical oncology is to reduce the prevalence of these diseases. What gains rising interest are natural substances derived from plants, which have both chemopreventive and chemotherapeutic properties. The task is demanding since the mechanisms underlying antitumor activity of plants-derived natural substances are complex and diverse. Several natural substances are already the components of international protocols of multi-drug chemotherapy. Nevertheless, cooperation between botanists, pharmacologists and clinical oncologists is essential to achieve further improvement in this field
