Cancer chemotherapy has changed dramatically and advances in our understanding of cancer biology is facilitating development of drugs that produce cures.
Chemotherapy may be indicated as a primary treatment or as adjuvant or neoadjuvant therapy. The former is used when there are no other effective treatment approaches. Adjuvant therapy is used to eradicate micrometastatic disease following localized treatments such as surgery or radiation or both. Neoadjuvant chemotherapy is used to make other treatment modalities more effective by reducing tumor burden and to destroy micrometastases.
Despite the high cure rates of previously lethal cancers, the use of these drugs is associated with significant harmful effects. Thus, a thorough understanding of the pharmacology of the antineoplastics is important for their safe and effective use in clinical practice.
The compounds used in cancer chemotherapy are varied in structure and mechanism of action, including alkylating agents; antimetabolite analogs; natural products; hormones and hormone antagonists; and a variety of agents directed at specific molecular targets.

- Alkylating drugs and platinum compounds: These drugs are the classical cytotoxic drugs which chemically bind with macromolecules such as DNA and disrupt cell dynamics, growth and differentiation.
- Anthracyclines: These drugs disrupt DNA replication and transcription by DNA intercalation, a type of physical binding. Ultimately, they shift the balance in favor of cancer cell apoptosis.
- Antimetabolites: These drugs disrupt the metabolism inside the cells by inhibiting folate metabolism and/or DNA synthesis.
- Topoisomerase inhibitors: inhibit the release of supercoils during DNA replication and transcription and thus disrupt DNA dynamics.
- Antimitotic Drugs (Vinca alkaloids and Taxanes): Inhibit the dynamic instability of microtubules and thus arrests the cell cycle in mitosis.
- Protein kinase inhibitors and Antibodies: These are relatively new group of drugs which target specific growth receptors and thus help control cell growth and differentiation.
The biological targets of anticancer therapy are present throughout the cell, from cell membrane to nucleus. The cell cycle specificity is an important attribute and it determines the selection of drug regimen, among other factors. Likewise, ability to eradicate cancer cells can be judged with log-kill hypothesis.
Dr Nasir Afsar
This 42-minute video introduces the concept of chemotherapy for cancer. In addition to a short description of the log kill hypothesis, the mechanisms of action of the main classes of antineoplastic drugs are described. These include the cytotoxic drugs (e.g. alkylating agents), hormones, and immunoglobulins and tyrosine kinase inhibitors. The video concludes with a general overview of the general principles of chemotherapy and adverse effects. This video would be appropriate for learners as they begin their study of antineoplastic drugs. Presentation created and contributed by Dr Nasir Afsad, Alfaisal University College of Medicine, Riyadh, Saudi Arabia.