Differences in sentinel lymph node pathology protocols lead to differences in surgical strategy in breast cancer patients.

Background: Internationally, there is no consensus on the pathology protocol to be used to examine the sentinel lymph node (SN). At present, therefore, various hospitals use different SN pathology protocols of which the effect has not been fully elucidated. We hypothesized that differences between hospitals in SN pathology protocols affect subsequent surgical treatment strategies.
Methods: Patients from four hospitals (A-D) were prospectively registered when they underwent an SN biopsy. In hospitals A, B, and C, three levels of the SN were examined pathologically, whereas in hospital D, at least seven additional levels were examined. In the absence of apparent metastases with hematoxylin and eosin examination, immunohistochemical examination was performed in all four hospitals.
Results: In total, 541 eligible patients were included. In hospital D, more patients were diagnosed with a positive SN (P < .001) as compared with hospitals A, B, and C, mainly because of increased detection of isolated tumor cells. This led to more completion axillary lymph node dissections in hospital D (66.3% of patients (P < .0001), compared with 29.0% in hospitals A, B, and C combined). Positive non-SNs were detected in 13.9% of patients in hospital D, compared with 9.7% in hospitals A, B, and C (P = .70). That is, in 52.4% of patients in hospital D, a negative completion axillary lymph node dissection was performed, compared with 19.3% of patients in hospitals A, B, and C combined.
Conclusions: Differences in SN pathology protocols between hospitals do have a substantial effect on SN findings and subsequent surgical treatment strategies. Whether ultrastaging and, thus, additional surgery can offer better survival remains to be determined.