ABSTRACT
Sentinel node (SN) is defined as the initial lymph node in a nodal basin that receives direct drainage from a tumor site (1-4). The procedure of sentinel lymph node biopsy (SNB) has evolved from the notion that tumors drain through the lymphatic system, initially to one or several SN(s) that lie on the direct drainage pathway of the individual tumor and, subsequently, to other nodes of that basin. As a consequence, the SN is likely to be the first node involved by a metastasis. A negative SN makes it unlikely that the more distal nodes in the same lymphatic basin are affected. The tumor status of the SN therefore represents the potential presence of metastatic spread in the entire regional nodal basin (5-7). Even in the era of emerging tumor imaging modalities, such as positron emission tomography (PET), SNB is considered the only reliable method to identify clinically occult micrometastatic disease in regional lymphatic nodes (8,9). Cabanas introduced the concept of ‘‘SN’’ in 1977 when using lymphangiograms to predict the nodal status of penile carcinoma (10,11). This concept of a nonrandom metastatic spread to regional lymph nodes is currently considered relevant in malignant melanoma, breast cancer, and mucosal tumors of the head and neck, as well as in various gynecological and gastrointestinal malignancies (2,11-16).
