Fig. 1

Pathological illustrations of lymph node occult metastases and the different dynamics of disease recurrence in patients with pN0(i−), pN0(i+) and pN1mi early breast cancer. a–d Examples of lymph node occult metastases from early breast cancer patients analyzed by haematoxylin and eosin (H&E) staining and immunohistochemistry (IHC). Consecutive sections stained by H&E (a, c) and by IHC (b, d). The location of the single tumour cells is indicated by arrows. Panels a and b, lymph node pN0(i+) (nanometastases); c, d lymph node pN1mi (micrometastases). Original magnification 20× objective. e, Hazard rate for recurrence pattern for the investigated patients. There were 328 early breast cancer patients lymph nodes pathologically diagnosed as pN0(i−), 24 as pN0(i+) and 25 as pN1mi. The hazard curve of the pN1mi subcategory displays the usual recurrence pattern as previously observed for breast cancer patients diagnosed with pN1 and pN2 diseases, thereby demonstrating an early peak at the second year and a further increase at about 60 months. By contrast, the recurrence risk curve of pN0(i+) patients, after a relatively stable period during the first 2 years, displays a steady increase and then a plateau-like trend. The recurrence risk pattern for pN0(i−) patients remains largely stable with a hazard rate of about 0.01 recurrence/6 months. pN, pathologically diagnosed nodal subcategories; pN0(i−), no detectable tumor deposits; pN0(i+), lymph nodes containing isolated tumor cells (nanometastases); pN1mi, lymph nodes containing tumour foci with the largest diameter ranging between 0.2 and 2 mm (micrometastases)