Cancer refers to a malignant neoplasm or new growth. Cancer cells manifest uncontrolled proliferation, loss of function due to loss of capacity to differentiate, invasiveness, and the ability to metastasize.
Cancer arises as a result of genetic changes in the cell, the main genetic changes being;
inactivation of tumor suppressor genes and activation of oncogenes.
There are three approaches for the management of cancer:
- Radiotherapy
- Surgery
- Chemotherapy
Most anticancer drugs are antiproliferative, and hence affect rapidly growing dividing normal cells. Anticancer drugs are broadly classified into two: cytotoxic drugs and hormones.
Cytotoxic drugs are further classified into:
- Alkylating agents and related compounds (e.g. cyclophosphamide, lomustine, thiotepa, cisplatin): These groups of drugs act by forming covalent bonds with DNA and thus impending DNA replication.
- Antimetabolites (e.g. methotrexate, fluorouracil, mercaptopurine): These drugs blocks or destabilize pathways in DNA synthesis.
- Cytotoxic antibiotics (e.g. Doxorubucin, bleomycin, dactinomycin): These drugs inhibit DNA or RNA synthesis or cause fragmentation to DNA chains or interfere with RNA polymerase and thus inhibit transcription.
- Plant derivatives (e.g. vincristine): Inhibits mitosis
Hormones and their antagonists are used in hormone sensitive tumors (eg. glucocorticoids for lymphomas, oestrogens for prostatic cancer, tamoxifen for breast tumors).
General toxic effects of anticancer drugs:
- Bone marrow toxicity.
- Impaired wound healing.
- Sterility.
- Loss of hair.
- Damage to gastrointestinal epithelium.
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