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Prescribir medicamentos para prevenir el cáncer
Una cantidad estable de medicamentos están siendo probados para saber si tienen efectos anti-cáncerigenos importantes. Algunos grupos de personas pueden considerar tomar dichos fármacos "Quimio-preventivos" para fines profilácticos, incluso si no están enfermos. Algunos de estos fármacos han producido resultados prometedores, pero todos tienen efectos secundarios añadidos. El concepto de "Quimio-prevención" es mejor conocido en el caso de prevención de ataques cardiacos, por ejemplo fármacos para reducir los niveles de colesterol o la presión sanguínea.
Up to now, the emphasis in cancer research has been on curing the condition. While these efforts continue, an increasing number of researchers are searching for drugs or other supplements that will prevent or delay the onset of cancer in the first place. Because of the side-effects, this is not recommended for everybody; but two developments now make the preventive approach using drugs more attractive. It is now recognised that many cancers start out years earlier as pre-malignant lesions, which in principle may be diagnosed. Second, there is growing evidence of a genetic link to many types of cancer, and this again enables at-risk groups of people to be identified.
More than 50 clinical trials are underway, testing various compounds and drugs for anti-cancer action. A study published early in 2003 demonstrated that low doses of aspirin can prevent development of pre-cancerous polyps in persons with a family history of colon cancer. A large study is currently underway which is testing whether selenium and vitamin E supplementation can prevent prostate cancer.
Another investigation is testing the anti-inflammatory drug Celebrex, used originally to treat arthritis. This has already been shown to reduce pre-cancerous polyps in patients with a rare genetic syndrome that causes colon cancer. Now studies are evaluating whether it will also help protect against the formation of such polyps in average individuals.
But the use of chemopreventive drugs is controversial. This is partly because it is harder to pinpoint who would most benefit from the treatment -- and thus weigh against the potential risks. In the case of treating known disease, this decision is much clearer. Thus cancer prevention has usually focused on diet and lifestyle changes, rather than using drugs. But for some people, particularly those with an unfavorable genetic predisposition, such changes may not be enough.
However, it should be pointed out that some previous chemoprevention trials have produced unexpected negative or confusing results. Some years ago the vitamin-A precursor Beta-carotene seemed promising as a treatment to reduce the risk of lung cancer. But trials on heavy smokers showed that those taking this supplement actually got cancer at a higher rate than the control group. Another not totally encouraging example is the use of Finsteride to prevent prostate cancer. In the trial, this drug clearly did reduce the risk of getting prostate cancer. But the reported side-effects included decreases in libido and potency, and, more worryingly, those who did get cancer appeared to have a higher risk of getting it in more severe form. More research is needed to understand this effect.
A landmark study by the American Association for Cancer Research, published in 2002, concludes that many cancers start as pre-malignant lesions, that over time develop into cancer. Many specialists argue that by treating these lesions with drugs, the process by which they become cancerous can be halted or at least delayed. Finding these lesions is not so simple as measuring high blood-cholesterol or hypertension; but screening techniques are constantly advancing, and an aging population is becoming more accustomed to regular health-screening tests. Treating "pre-cancer" will probably be an increasing focus of cancer-prevention efforts.
For more information about anti-cancer drugs please visit www.Anti-Cancer-Drugs.com
