Isotope labelling and axillary node harvesting strategies for breast cancer

The objective of this study was to assess the value of superficial (intradermal) and paratumoral (above the tumor) (ID) injection of labeled colloids for imaging sentinel lymph nodes (SLN) as a rescue technique in breast cancer patients for whom deep (intraparenchymatous) and peritumoral (around the tumor) (IP) injections had failed.

We assessed data from 2 groups of women: 469 women for whom IP injections successfully visualized a SLN (IP-only) and 52 women for whom IP injections were unsuccessful and ID injection was performed (IP0-ID). Patient characteristics and SLN results were compared.

Most characteristics of the two patients series were similar. However, IP0-ID patients were on average 10years older than the IP-only patients and had more grade-III tumors. The false negative rate (FNR) for the IP0-ID patients (9/25, 23.8%) was significantly higher than for the IP-only patients (12/240, 5%; p<0.01) and for a subgroup of IP-only patients older than 50 years (8/159, 5%; p=0.009). Four of five false negatives in the IP0-ID group involved a tumor in the outer quadrants. The FNR for cases with external tumors was 33% for the IP0-ID patients, a percentage significantly higher than the corresponding values for the IP-only patients (5.8%) and for the IP-only patients older than 50 years (5.7%).

In patients with unsuccessful deep IP injections, superficial ID injections lead to a high percentage of false negative SLN conclusions, merely when tumours were located in the outer quadrants. Thus, it is recommended that patients with unsuccessful intra-parenchymatous and peritumoral injections of radiocolloids for tumors in outer quadrants undergo complete axillary dissection.