Where does sentinel collide?

In public health a sentinel is a deliberately chosen, closely watched subset that gives early warning about a population too large to monitor completely: a network of sentinel clinicians or sites reports selected conditions, and a sentinel health event is a single case whose occurrence signals a lapse in prevention or care. Rutstein and colleagues' 1976 Measuring the quality of medical care formalised the sentinel-event idea as an index of preventable disease and death. The referent is a monitoring device, a watched proxy for a whole population, and it is unrelated to a marker value in a program or the first lymph node draining a tumour beyond the shared image of a lookout.[1]

Unit

The signal from a monitored subset standing in for the whole population

Recovery means

Not applicable

Measured by

Tracked by case counts and trends from the sentinel network, read as an early indicator for the wider population

In surgical oncology the sentinel lymph node is the first node, or small set of nodes, that drains lymph from a primary tumour, and therefore the one most likely to harbour the earliest metastatic spread. Because its status predicts the rest of the nodal basin, surgeons map and biopsy it to decide whether wider dissection is warranted, sparing many patients a full lymphadenectomy. Morton and colleagues' 1992 Technical details of intraoperative lymphatic mapping for early stage melanoma established the mapping technique. The referent is an anatomical first-drainage node used as a staging proxy, a different construct from a surveillance lookout or a programming marker.[2]

Unit

The first-order drainage node identified for a given primary tumour

Recovery means

Not applicable

Measured by

Located by injected dye or radiotracer lymphatic mapping and examined histologically for metastatic cells