Journal of clinical oncology : official journal of the American Society of Clinical Oncology
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Carcinogenesis in the breast is a hormonally dependent process. Evidence implicating estrogen as a key breast carcinogen comes from various lines of investigation. Traditional epidemiologic studies demonstrate associations between estrogen exposure, both exogenous and endogenous, and increased breast cancer risk. ⋯ The implementation of tamoxifen for this indication has not become widespread in clinical practice, however, for a variety of reasons that we discuss. Results from the NSABP Study of Tamoxifen and Raloxifene, which compares the risk-reducing efficacy as well as toxicity of these two SERMs in a similar high-risk population, will be available in the near future. Based on promising data involving reduction of contralateral breast cancer risk in adjuvant studies, several aromatase inhibitors, including letrozole, anastrozole, and exemestane, are being incorporated into trials evaluating their efficacy as preventive agents in women at increased risk.
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Comparative Study
Sequence of radiotherapy with tamoxifen in conservatively managed breast cancer does not affect local relapse rates.
To evaluate whether the sequencing of tamoxifen (TAM) relative to radiation (RT) affects outcome in breast cancer patients treated with conservative surgery (CS) plus RT (lumpectomy with RT). ⋯ Although the concurrent use of TAM with RT may theoretically render cancer cells less responsive to RT, this retrospective study suggests that in practical application, concurrent administration of TAM with RT does not compromise local control.
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Randomized Controlled Trial Comparative Study Clinical Trial
Sequencing of tamoxifen and radiotherapy after breast-conserving surgery in early-stage breast cancer.
Tamoxifen (TAM) is thought to exert a cytostatic effect on hormone-sensitive breast cancer cells. Some preclinical studies show reduced radiosensitivity in irradiated malignant mammary epithelial cells when pretreated with TAM; other studies refute these results. Recent randomized clinical trials suggest an antagonistic effect of TAM on cytotoxic therapy, with improved disease-free survival (DFS) with sequential versus concurrent TAM. An exploratory analysis was undertaken to evaluate the optimal sequencing of TAM and radiotherapy (RT) after breast-conserving surgery. ⋯ The current analysis does not suggest an adverse effect on local or systemic control with CONC versus SEQ TAM and RT in node-negative breast cancer. A randomized trial is encouraged to validate these results.