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.

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.