In a nutshell
Tamoxifen is one of the main drugs used for hormonal treatment of breast cancer. The aim of this article was to establish the value of Tamoxifen as a preventive agent for women who have high chances of developing breast cancer. Main finding: Tamoxifen notably reduces the risk of developing breast cancer in easily identifiable higher risk groups of women.
Due to various genetic and environmental factors, some women are at high risk of breast cancer. Nowadays it is possible to identify these women and monitor them more closely. Tamoxifen has a potential as preventive agent since it is a relatively safe drug.
Methods & findings
In this trial, 13,388 participants with predictable 5-year breast cancer risk of 1.66% or more were given either Tamoxifen or placebo for 5 years. After this period the initial findings were disclosed and participants who wished to continue were followed up for 7 more years.
Tamoxifen almost halved the prevalence of invasive breast cancer compared to placebo in this group of patients (from 4.25% to 2.48%). The reduction of the rate of non-invasive breast cancer was also very significant, of more than 30%. A 32% reduction in the risk of osteoporotic fractures was also noted.
In terms of adverse effects, women taking tamoxifen demonstrated higher rates of endometrial cancer, pulmonary embolism and deep-vein thrombosis. The frequency of undesirable effects depended on age and race.
The bottom line
Despite the potential side effects, the net benefits of Tamoxifen in preventing invasive breast cancer are obvious.
The fine print
The authors suggest that approximately 2.5 million women in the US alone can benefit from this treatment. Similar studies provide evidence that preventive Tamoxifen reduces overall breast cancer-related mortality.
Published By :
Journal of the National Cancer Institute (JNCI)
Nov 16, 2005
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