BACKGROUND: Tamoxifen (TAM) is well established in the adjuvant therapy of breast cancer. However, the timing of TAM therapy, concurrent or after radiotherapy, is controversial. METHOD: Literature is reviewed with respect to experimental and clinical data on interaction of TAM and radiation on tumor control and radiation side effects. RESULTS: In vitro data support the concept of antagonistic effects of concurrent TAM and radiation on tumor cells, but in animal models a synergistic effect was seen. Considering the modulation of TAM effects by estrogen and growth factor receptors, two-dimensional systems may not be suitable for studying the interaction of TAM and radiation. From a clinical perspective, a tumor-protective effect of TAM therapy concurrent with radiation was not evident. However, prospective studies addressing this question adequately are not available at the time. CONCLUSION: Although some studies indicate an enhancement of lung and subcutaneous fibrosis after TAM therapy, the side effects are mild and at this point do not seem to warrant withholding TAM.
BACKGROUND:Tamoxifen (TAM) is well established in the adjuvant therapy of breast cancer. However, the timing of TAM therapy, concurrent or after radiotherapy, is controversial. METHOD: Literature is reviewed with respect to experimental and clinical data on interaction of TAM and radiation on tumor control and radiation side effects. RESULTS: In vitro data support the concept of antagonistic effects of concurrent TAM and radiation on tumor cells, but in animal models a synergistic effect was seen. Considering the modulation of TAM effects by estrogen and growth factor receptors, two-dimensional systems may not be suitable for studying the interaction of TAM and radiation. From a clinical perspective, a tumor-protective effect of TAM therapy concurrent with radiation was not evident. However, prospective studies addressing this question adequately are not available at the time. CONCLUSION: Although some studies indicate an enhancement of lung and subcutaneous fibrosis after TAM therapy, the side effects are mild and at this point do not seem to warrant withholding TAM.