Mammography-detected ultrasound-negative asymptomatic micro-calcifications in Chinese women: Would it be safe to watch and wait?

Although mammography (MG) has been widely used for breast cancer screening in the western world, over-diagnosis remains controversial. Milestone studies showed that ultrasound (US) was an effective primary screening test for breast cancer both in the western world and in China. US improves the sensitivity of screening in Chinese women who have denser breasts and develop breast cancer earlier than Caucasian counterparts, and is used as the primary imaging test in the hospital-based opportunistic screening among asymptomatic self-referred women. Our previous work showed that US result might further differentiate the MG-detected breast cancers into low risk (US+) and ultra-low risk (US-). Indeed, most of the MG+/US- breast cancers would be ultra-low risk cancers and almost always present as MG micro-calcifications. Furthermore, majority of the commonest MG+/US- abnormal finding of micro-calcification is usually benign. Biopsy of benign breast disease increases not only the risk of breast cancer, but the expenses of screening and healthcare. Our hypothesis proposes that mammography-positive ultrasound-negative (MG+/US-) asymptomatic micro-calcifications might not need immediate invasive procedures and be safe to observe until the micro-calcifications increase significantly or become US-positive. If this hypothesis is proved, US would serve as the primary imaging test for breast cancer screening in China, with MG as the selective screening test and diagnostic tool for surgical plan. Unnecessary biopsy or surgery might be avoided with screening expenses considerably decrease.