Defenses against cancer

[Tracie Lynn]

After a cell becomes cancerous, the immune system is often able to recognize it as abnormal and destroy it before it replicates or spreads. The cancerous cells may be completely eliminated, in which case the cancer never appears. Certain cancers are more likely to progress in people whose immune system is altered or impaired, as in people with AIDS, people receiving immunosuppressive drugs, people with certain autoimmune disorders, and older people, in whom the immune system works less well than in younger people. Cancers that are more common with a weakened immune system include melanoma, kidney cancer, and lymphoma. Doctors are not sure why certain other cancers, such as cancers of the lung, breast, prostate and colon, are not more common in people with a weakened immune system.