Utility of single-photon emission tomography/computed tomography for sentinel lymph node localization in breast cancer patients

99mTc-labeled colloid SPECT/CT versus planar lymphoscintigraphy for sentinel lymph node detection in patients with breast cancer: a meta-analysis

Background

The aim of this meta-analysis was to compare single-photon emission computed tomography (SPECT/CT) and planar lymphoscintigraphy (PL) in patients with primary breast cancer, undergoing lymphoscintigraphy at initial staging. Specifically, we assessed the detection rate (DR) for sentinel lymph node (SLN), the absolute number of detected SLNs by each technique, and the proportion of patients with additional SLNs detected by one technique compared to the other one. Finally, we aimed to evaluate the impact of SPECT/CT on the surgical approach.

Methods

Original articles, providing a head-to-head comparison between SPECT/CT and PL, including patients with primary breast cancer at first presentation, were searched in PubMed/MEDLINE and Scopus databases through March 31st, 2022. The DR of the imaging techniques was calculated on a per-patient analysis; studies were pooled on their odds ratios (ORs) with a random-effects model to assess the presence of a significant difference between the DRs of SPECT/CT and PL. The number of additional SLNs, calculated as relative risk (RR), and the pooled proportion of patients with additional SLNs using one imaging technique rather than the other one were investigated. The pooled ratio of surgical procedures (SLN harvesting) influenced by the use of SPECT/CT, according to the surgeons, was calculated.

Results

Sixteen studies with 2693 patients were eligible for the calculation of the DR of SPECT/CT and PL. The DR was 92.11% [95% confidence interval (95% CI) 89.32–94.50%] for SPECT/CT, and 85.12% (95% CI 80.58–89.15%) for PL, with an OR of 1.96 (95% CI 1.51–2.55) in favor of SPECT/CT. There was a relative risk of detection of larger number of SLNs (RR: 1.22, 95% CI 1.14–1.32; 12 studies; 979 patients) for SPECT/CT (n = 3983) compared to PL (n = 3321) and a significant proportion of patients with additional SLNs detected by SPECT/CT, which were missed by PL (18.88%, 95% CI: 11.72%-27.27%; 13 studies). Four articles, with a total number of 1427 patients, revealed that 23.98% of the surgical procedures benefited from the use of SPECT/CT.

Conclusions

This meta-analysis favors SPECT/CT over PL for the identification of SLN in patients with primary breast cancer at staging due to higher DR, more SLNs depicted, and a significant proportion of subjects with additional detected SLNs by SPECT/CT compared to PL. Furthermore, SPECT/CT positively influences the surgical procedure. However, PL remains a satisfactory imaging option for imaging departments not equipped with SPECT/CT due to its good patient-based DR.

Can axillary lymphadenectomy be avoided in breast cancer with positive sentinel lymph node biopsy? Predictors of non-sentinel lymph node metastasis

PURPOSE

Completion axillary lymph node dissection (cALND) can currently be avoided in those patients with a low tumor load (LTL) and/or a low-risk profile that tested with positive sentinel lymph node biopsy (SLNB). Our objective is to identify prognostic factors that significantly influence axillary lymph node involvement to identify patients who could benefit from surgery without axillary lymphadenectomy.

METHODS

This is an observational retrospective study of consecutive patients diagnosed and operated of breast cancer between 2000 and 2014 at University Hospital La Ribera (UHR).

RESULTS

The size of the sample was 1641 patients, from which 1174 underwent SLNB. In the multivariate analysis, we objectify a raise of risk of positive sentinel lymph node (SLN) up to 5.2% for every millimeter of increase. The risk of positive SLNB when showing lymphovascular invasion seems to be 2.80 times greater but becomes lower when SLN involvement appears in luminal A, luminal B and triple-negative types, regarding HER2. In case of triple negatives, the difference is statistically significant. 16.7% present affected additional lymph nodes. The proportion of patients with affected additional lymph nodes increase dramatically above OSNA values of 12,000 copies/μl of CK19 mRNA and it depends on tumor size and lymphovascular infiltration.

CONCLUSIONS

Tumors smaller than 5 cm whose OSNA SLNB analysis is less than 12,000 copies/μl of CK19 mRNA have a low chance to develop additional affected lymph nodes, thus cALND can be avoided.

Value of Quantitative SPECT/CT Lymphoscintigraphy in Improving Sentinel Lymph Node Biopsy in Breast Cancer

Methods

We retrospectively enrolled breast cancer patients who underwent SPECT/CT prior to sentinel lymph node biopsy. Quantification of radiotracer uptake from SPECT/CT data was performed. A radioactivity count threshold (R_SPECT) using SPECT/CT was calculated for detecting metastatic sentinel lymph nodes. To localize sentinel lymph nodes exactly, we compared the positions of sentinel lymph nodes localized using SPECT/CT with positions localized surgically using an intraoperative γ-probe.

Results

491 patients were included, with a median of 3 sentinel lymph nodes/patient detected by the γ-probe and 2 sentinel lymph nodes/patient detected by SPECT/CT. As the number of sentinel lymph nodes visualized on SPECT/CT images, the metastasis incidence of lymph nodes in the ≤2 SLNs group was significantly higher than that in the >2 SLNs group (35% vs. 15%, P < 0.001). No metastasis was found in lymph nodes with R_SPECT ≤ 30% in the >2 SLNs group, and thus, 30% (157/526) of SPECT/CT-identified nodes would avoid unnecessary removal. The positions of sentinel lymph nodes localized by SPECT/CT and γ-probe were identical in 42% (39/93) of patients.

Conclusions

Quantitative Tc-99 m SC SPECT/CT imaging has the potential to preoperatively locate sentinel lymph nodes and intraoperatively avoid unnecessary sentinel lymph node biopsy.

Anatomy and physiology of the sentinel lymph nodes of the upper extremity: Implications for axillary reverse mapping in breast cancer

BACKGROUND

This study characterizes the physiological drainage of the normal upper extremity using single-photon emission computed tomography/computed tomography (SPECT/CT) lymphoscintigraphy axillary reverse lymphatic mapping (ARM).

METHODS

A consecutive series of patients assessed with SPECT/CT lymphoscintigraphy ARM of the upper extremity were included. Anatomical localization of the axillary sentinel lymph nodes (SLN) was completed in normal axillae in relation to consistent anatomic landmarks. Retrospective case note analysis was performed to collect patient demographic data.

RESULTS

A total of 169 patients underwent SPECT/CT lymphoscintigraphy, and imaging of 182 normal axillae was obtained. All patients (100%) had an axillary SLN identified: 19% had a single contrast-enhanced SLN in the axilla and the remainder had multiple. The SLN(s) of the upper extremity was located in the upper outer quadrant (UOQ) of the axilla in 97% of cases (177 axillae). When the SLN(s) was found in the UOQ of the axilla, second-tier lymph nodes were found predominantly in the upper inner quadrant (50% of cases).

CONCLUSIONS

The upper extremity SLN(s) is located in a constant region of the axilla. This study provides the most complete investigation to date and results can be directly applied clinically to ARM techniques and adjuvant radiation planning.

Effect of Topical Anesthetic Cream on Pain During Periareolar Injection of Technetium Tc99m Sulfur Colloid for Sentinel Lymph Node Biopsy in Breast Cancer: A Randomized Control Trial

BACKGROUND

Injection of Tc99m to localize nodes for sentinel lymph node biopsy is reported by patients as very painful. The purpose of this study was to determine if anesthetic cream reduces pain associated with periareolar injection of Tc99m and to help elucidate conflicting literature regarding the efficacy of anesthetic cream for this procedure.

METHODS

A randomized, double-blind, placebo-controlled methodology was used for adult females with breast cancer undergoing periareolar injection of Tc99m for sentinel lymph node biopsy. Pain levels were compared using anesthetic cream (2.5% lidocaine/2.5% prilocaine) vs. placebo. Patient exclusion criteria included use of opioids or adjuvant pain medication or injecting Tc99m the day before surgery. The Numerical Rating Scale was used to assess pain levels immediately after the injections.

RESULTS

Comparing 23 experimental and 26 control patients, there was no significant difference between the experimental (median = 4) and the control group (median = 5) on level of pain experienced U= 0.492, P > .05.

CONCLUSIONS

The experimental group had a slightly lower median pain score; however, there was no statistically significant difference between those who used the cream compared with those who used a placebo, supporting the conclusion that anesthetic cream does not reduce pain during Tc99m injections. This study adds to the current literature to provide a stronger position that there is no benefit to using anesthetic cream for this procedure.