Sentinel lymph node nonvisualization after intratumoral radioisotope tracer injection in breast cancer is not associated with a higher nodal metastasis rate or worse outcomes.

BACKGROUND AND OBJECTIVES: Preoperative lymphoscintigraphy does not always visualize a sentinel lymph node (SLN). The study aim was to investigate whether persistent nonvisualization after additional single-photon emission computed tomography (SPECT)/CT or a second radiotracer injection in breast cancer patients is associated with nodal metastases or worse outcome due to potential understaging and consequently undertreatment. METHODS: Altogether 2042 consecutive SLN procedures were evaluated. All patients were clinically node-negative, underwent axillary ultrasound and fine-needle aspiration cytology (US/FNAC) of suspicious nodes. Lymphoscintigraphy was performed at 3 to 4 hours after intratumoral injection of 99mTc-nanocolloid. SPECT/CT or a reinjection was performed when initial lymphoscintigraphy showed nonvisualization. RESULTS: Persistent nonvisualization was seen in 170 of 2042 procedures (8.3%). The nodal metastasis rate was 16.0% vs 18.0% for procedures with nonvisualization vs SLN visualization, respectively (P = 0.593). The regional recurrence rate of tumor-negative SLN biopsy procedures was equal between the visualization (0.7%, 11 of 1535) vs nonvisualization (0.7%, 1 of 144) group. Median follow-up was 48 months. Distant-metastasis free interval and overall survival was not significantly different between both groups ( P = 0.164 and 0.208, respectively). CONCLUSIONS: Persistent nonvisualization after lymphoscintigraphy plus SPECT/CT or radiotracer reinjection is not associated with a higher nodal metastasis rate or worse long term outcome when preoperative US/FNAC is performed.

Predictive risk factors for sentinel lymph node nonvisualization on planar lymphoscintigraphy using an intratumoral injection in patients with primary breast cancer.

OBJECTIVES: Lymphoscintigraphy is considered a useful tool to optimize sentinel lymph node (SLN) identification. Nonvisualization of the SLN is associated with a lower SLN identification rate. The aim of this study was to identify preoperative factors associated with SLN nonvisualization on lymphoscintigraphy. PATIENTS AND METHODS: A total of 2050 consecutive SLN procedures were evaluated from clinically node-negative breast cancer patients. Planar lymphoscintigraphy was performed at 3 h after an intratumoral injection of technetium-99m-nanocolloid. This technique was used for extra-axillary SLN identification. Patient, tumor, and treatment characteristics were analyzed for association with SLN nonvisualization. Factors with a P-value less than 0.1 in univariate analysis were included in a multivariate logistic regression model. RESULTS: The SLN visualization rate was 86.7%. In multivariate logistic regression, age of at least 70 years [odds ratio (OR): 3.24; 95% confidence interval (CI): 2.14-4.91)], BMI of at least 30 (OR: 1.93; 95% CI: 1.39-2.69), T3/T4-tumors (OR: 2.70; 95% CI: 1.37-5.32), medially/centrally located tumors (OR: 1.52; 95% CI: 1.17-1.99), previous mantle field radiation (OR: 4.04; 95% CI: 1.74-9.35), nonpalpable tumors (OR: 1.88; 95% CI: 1.36-2.60), and presence of iodine seeds (OR: 1.35; 95% CI: 1.02-1.78) were associated significantly with nonvisualization on lymphoscintigraphy. Nonvisualization was the strongest independent predictor of unsuccessful intraoperative SLN identification (P<0.001). Overall, the SLN identification rate was 97.7% because of the use of additional imaging and blue dye. CONCLUSION: This study reports new tumor and treatment-related risk factors for nonvisualization on lymphoscintigraphy by using an intratumoral injection in primary breast cancer. We recommend a periareolar subcutaneous injection to improve SLN visualization in patients with limited prognostic and therapeutic relevance of internal mammary chain SLN identification.