Cancer Chemoprevention

Chemoprevention refers to the use of drugs for purpose of preventing illnesses.  The goal is to intervene with  the disease development process.   Same methods are being studied in cancers with the ultimate goal of preventing cancers from occurring in man.

Antioxidant Supplementation:

various agents with antioxidant properties have been or currently undergoing scientific studies to determine their efficacy. In the early 1980s, there were indications that beta-carotene which is a precursor to Vitamin A may have a role in cancer prevention.  This substance belongs  to group of substance called carotenoids, which are found in nature and are responsible for the color red and orange in many plants and animals that consume them.     When looking into these agents for cancer prevention, one has to be careful and be meticulous in the method of studying them.

Antioxidant Supplementation and Lung Cancer:

Two studies of beta-carotene actually showed an increase in the risk of developing lung cancer.  The explanation is unclear.   These substances in nature are found in foods that contain a complex mixture of other substances. 

Selenium, with is a trace element has shown a protective effect in Lung cancer development, however it is not very conclusive and needs further investigations.

Antioxidant Supplementation and Prostate Cancer:

Vitamin E (which refers to eight natural compounds) is another antioxidant that along with Selenium and Beta-Carotene has shown a protective effect in development of prostate cancer.

Retinoid Chemoprevention for Head and Neck Cancer:

Retinoids are natural and synthetic substances of Vitamin A family which have the potential to cause tumor regression in certain conditions. One such substance is isotretinioin which has proven to cause regression of precancerous lesion of the mouth and also reduction in  the risk of developing subsequent oral cancers in high risk patients.

Antioxidant Supplementation and Colon Cancer:

The current data confirm that several years of beta-carotene or vitamin E will NOT alter the colorectal cancer risk.  Selenium has been suggested in one study to reduce the colorectal cancer risk.

Tamoxifen and Breast Cancer:

5 years of  treatment with Tamoxifen has proven to be able to prevent cancer recurrence risk in women with early stage breast cancer.  The benefit is seen in ER+ cancers only.  These preliminary studies prompted a trial of using 20 mg/day of Tamoxifen in more than 13,000 women without prior diagnosis of breast cancer however those who were considered high risk to develop breast cancer.  After 4.5 years, Tamoxifen reduced the risk of breast cancer by about 50%, however only ER+ tumors were affected. The risk of developing ER- tumors remained the same.