Authors: WenHung Kuo Amy MingFang Yen PoHuang Lee MingFeng Hou ShinCheh Chen KaiMo Chen Tony HsiuHsi Chen KingJen Chang
Publish Date: 2006/03/17
Volume: 99, Issue: 2, Pages: 221-228
Abstract
This study aims to examine the incidence and risk factors of bilateral breast cancer in area with low incidence rate A total of 120 and 1902 women with bilateral and unilateral breast cancers were enrolled various factors including those concerning their medical history and life style were extracted Using Kaplan–Meier method we calculate the cumulative incidence of contralateral breast cancer The results show as follows The cumulative incidences of contralateral breast cancer at 1 3 5 years after diagnosis of first breast cancer were 115 194 and 297 respectively The statistically significant risk factors included menopause Hazard Ratio HR =156 100–242 invasive lobular carcinoma HR=298 135–656 receiving chemotherapy HR=221 143–342 and/or radiotherapy HR=332 219–505 and a protective factor was tamoxifen therapy HR=05 034–074 Size of the second occurred tumour 297 cm tended to be smaller than the first one 358 cm with borderline statistical significance p=00731 Comparing to the existing data on Western countries we find a higher risk for developing contralateral breast cancer in Taiwan where a low incidence of first breast cancer rate with early age diagnosis is noted It suggests that first primary breast tumour with early age of onset and lobular carcinoma are found more likely to develop bilateral breast cancers
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