Screen detected breast cancer in an Asian population: pathological findings of the Singapore breast screening project

We document the pathological characteristics of 135 cancers detected in 132 predominantly Chinese women in the Singapore breast screening project. Thirty-four (25%) screen detected tumours were in situ ductal cancers; 98 (73%) invasive, while three (2%) women with malignant fine needle aspirate smears refused further treatment. The median size of in situ cancers was 10 mm; the majority (56%) demonstrated a comedo pattern. Of the invasive tumours which had a median size of 15 mm, three (3%) were microinvasive, 75 (77%) infiltrative ductal, three (3%) invasive lobular, and the remaining 17 (17%) special types or others. Histologic grading revealed 23 (24%) grade I, 52 (53%) grade II, 19 (19%) grade III and four (4%) ungraded cases. Sixty-three (65%) of the invasive cancers were node negative, while 64% of all screen detected malignancies were Stages 0 (in situ) or I. From the pathological perspective, problems of borderline lesions, microinvasion, grade assessment and histological subtyping have to be addressed.