What can National Registry data tell us about occult breast cancer?
Axillary metastasis from an undetectable carcinoma of the breast is known as occult breast cancer (OBC) and accounts for less than 1% of all breast cancer (1-3). Management of OBC initially favoured axillary lymph node dissection (ALND) with mastectomy (4). However there have also been series reporting the use of ALND with breast conserving surgery (BCS), whole breast radiotherapy (WBRT) and observation of the breast (5,6). Due to its rarity, data on OBC is often from small series collected over long periods of time. National registry provides the opportunity to accrue larger numbers, determining more accurate incidence, and where possible generating epidemiological and clinicopathological data. The Surveillance, Epidemiological and End Results (SEER) database is a project of the American National Cancer Institute, the function of which is to routinely collect various cancer data on patients from various American states, covering 28% of the population.