Methodological questions in sentinel lymph node analysis in breast cancer patients.

BACKGROUND: The sentinel lymph node (SLN) procedure has been proposed to women with breast cancer with clinically negative axillary lymph nodes, in order to avoid conventional axillary lymph node dissection and its associated side-effects. Methodological aspects of the validation of the SLN procedure are questioned here.

MATERIALS AND METHODS: The results of relevant published studies are reviewed, with emphasis on pathological techniques. The ability of the SLN procedure to diagnose lymph node metastases, the extent to which axillary lymph node dissection contributes to treatment, apart from identification of the stage, and the effect of a modified staging procedure on treatment strategies are analyzed.

RESULTS AND CONCLUSION: Both the sensitivity and the negative predictive value of the SLN procedure are overestimated if the probability of missing lymph node metastases is not taken into account, even when a complete axillary dissection is performed as a control. The SLN strategy and its effects on staging and treatment cannot be evaluated by comparison with conventional axillary lymph node dissection in a one-arm study but require carefully designed randomized trials.