Aims: 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.
Methods: 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.
Results: 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%).
Conclusion: 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.