目的：本研究旨在探討2000年至2005年新發乳癌病人使用泰莫西芬（Tamoxifen, TAM）治療時間對其存活之影響。方法：本研究利用全民健康保險研究資料庫進行分析，以百分比呈現類別變項分佈情形，並以每千人年呈現TAM乳癌病人的全死因發生密度；推論性統計分析利用對數等級檢定評估不同治療時間乳癌病人的存活率。結果：研究期間新發乳癌病人共561位其平均年齡、Charlson Comorbidity Index（CCI）得分及治療時間分別為50.69歲，0.34分，3.29年；追蹤乳癌病人5,540人年共78個死亡，發生密度為14.08。Kaplan-Meier分析結果顯示，TAM治療時間越短存活率越低。控制其他變項後，獨立影響乳癌病人存活的因素有年別、年齡層別、CCI得分及治療時間類別。結論：乳癌病人接受TAM治療時間大於5年的存活率較2年以下及2至5年佳，相關單位應向民眾宣導勿擅自停藥，以延長乳癌病人的存活時間。

Objectives: The purpose of this study is to explore the impact of Tamoxifen treatment time on new-onset breast cancer patients on their survival from 2000 to 2005. Methods: This study used the National Health Insurance research database released by the National Health Research Institute (NHRI) and the distributions of category variables were presented as percentages. Then, the densities of breast cancer patient mortality were presented per 1,000 persons. Evaluation of survival rate of breast cancer patients at different treatment times using a log- rank test. Results: From 2000 to 2005, there were 561 patients newly diagnosed with breast cancer. In terms of basic data, the patients' average age, Charlson Comorbidity Index score and treatment time were 50.69 years, 0.34 points, and 3.29 years, respectively. In terms of the densities of incidences of all causes of death, tracking 78 cancer deaths in 5,540 person-years of breast cancer patients (the incidence density was 14.08 per 1,000 person-years). Kaplan-Meier's analysis results showed that the shorter the TAM treatment time, the lower the survival rate. After exerting control on the other variables, the factors independently affecting the survival of breast cancer patients in the TAM group include: year, age bracket, CCI category, and treatment time category. Conclusions: The survival rate of treatment times more than 5 years is better than that of less than 2 years and 2 to 5 years. Relevant agencies should advocate to the general public not to arbitrarily stop medications in order to prolong the survival time of breast cancer patients.