摘要
婦女罹患單側乳癌後，其得對側乳癌之機會比一般先前未罹患乳癌而初次得乳癌高2-6倍，其年發生率大約介於0.5-1.0%，10年累積發生率約爲6-11%。第一側乳癌發病的年齡較早，有乳癌家族史，動情激素受體狀態，小葉癌，接受放射治療及未接受泰莫西酚治療是發生雙側乳癌的危險因子。我們的統計有類似發現：更年期狀態，侵入性小葉癌，接受化療和／或放射治療是發展雙邊乳癌的危險因素，而服用泰莫西酚則是保護因素。根據雙側乳癌兩側發病的時間間隔又可分爲同時性及異時性的雙側乳癌。雙側乳癌是否爲影響預後的危險因子，先前的研究報告未有一致性的結論。然而，由最近瑞典的大型世代追蹤研究及我們的經驗都顯示異時性雙側乳癌的預後最差，台灣婦女的預後更甚於瑞典。至於是否接受化學治療則與預後無關。
關鍵字
無資料並列摘要
A personal history of breast cancer is a well established risk factor for subsequent new primary breast tumors. The annual incidence is 0.5-1.0%, 2 to 6 times higher than the incidence of normal women in Western countries to develop primary breast cancer. The 10-year cumulative incidence is around 6-11%. The early age of diagnosis, family history of breast cancer, estrogen receptor status, lobular carcinoma histology, previous radiotherapy and a lack of tamoxifen treatment are thought to be risk factors of bilateral breast cancer. Our investigation also shows menopause, invasive lobular carcinoma, and previous chemotherapy and/or radiotherapy to be risk factors of developing bilateral breast cancer, and tamoxifen therapy to be a protective factor. Regarding prognosis, previous studies comparing survivals between Western women with bilateral and those with unilateral breast cancer have yielded inconsistent results. However, recent reports from a large Sweden cohort and our study have shown that women with metachronous bilateral breast cancer had a worse survival as compared with those with unilateral breast cancer and synchronous bilateral breast cancer. Taiwanese women had a poorer survival than Swedish women. Chemotherapy showed no significant effects on survival in Taiwanese women.