There are numerous anti-cancer drugs on the market today, and the manner in which they attack cancer cells differs according to their classification. They may be administered orally, injected into a muscle, injected under the skin, or most commonly, into a vein. Patients may be given one drug, or a combination of two or more drugs, a method often recommended to increase effectiveness.
Antitumor drugs can be classified according to their effect on the mitotic cycle:
1. Cell cycle active, phase specific
2. Cell cycle active, non-phase specific
3. Non-cell cycle active
Following are some of the various classes of chemotherapy drugs based on their chemical structure and the mechanism they use to attack cancer cells:
Alkylating Agents
Alkylating agents are the oldest and most commonly used class of chemotherapy drugs, and work by directly damaging DNA and preventing cancer cells from reproducing. They are used to treat a wide variety of cancers, but have the greatest effect on those that are slow-growing. They are cell-cycle phase non-specific, meaning that they kill cancer cells in any phase of the cell cycle. Some examples of alkylating agents are carboplatin, cisplatin and oxaliplatin.
Antimetabolites
Antimetabolites are chemotherapy drugs that interfere with DNA and RNA growth. They are cell-cycle specific, meaning that they kill cancer cells in a specific phase of cell division. Some examples of antimetabolites are capecitabine, gemcitabine, and pemetrexed (Alimta).
Anthracyclines
Anthracyclines are anti-tumor antibiotics that interfere with enzymes necessary for DNA replication. They are cell-cycle non-specific, and are used to treat a variety of cancers. Some examples of anthracyclines are bleomycin, doxorubicin and mitomycin-C.
Plant Alkaloids
Plant alkaloids are derived from certain types of plants found in nature, and inhibit or prevent mitosis or inhibit enzymes from making proteins necessary for cell reproduction. Most plant alkaloids are cell-cycle specific, but can cause damage in all phases. Some examples of plant alkaloids are the taxanes, docetaxel and paclitaxel, and the vinca alkaloids, vinblastine, vincristine and vinorelbine.
All of these have been employed in the treatment of mesothelioma at some time. More on non-phase-specific chemotherapy agents.
Read about dose-dense chemotherapy, a method of administering the drugs.
