6. Conclusions
Single phytochemicals and enriched natural extracts able to interfere with self-renewal and drug resistance pathways in CSCs have been identified. This is a milestone in the improvement of cancer treatment because the synthetic anticancer drugs that are currently used are often highly toxic for healthy organs and weakens the patient’s immune system.
These phytochemical compounds or extracts, which show low levels of toxicity for normal cells can be used against cancers in combination with other phytochemicals, yielding powerful synergistic effects.
The main obstacle to overcome consists in finding a way to combine the single drugs or extracts into very active cocktails of phytochemicals able to cope with molecular targets in the signaling network of CSCs sustained cancerogenesis in several tumors. Moreover, it is necessary to compare the anticancer effects of natural phytochemicals extracted from vegetables with synthetic products that may be less efficient than the natural forms due to different mixtures of stereoisomers.
Finally, it is imperative to gain a better understanding of the signaling pathways that govern the self-renewal and survival of CSCs. Current findings on phytochemicals warrant further investigation in order to better define the role played by these molecules in human cancer therapy.