Intraoperative imprint cytology versus histological diagnosis for the detection of sentinel lymph nodes in breast cancer treated with neoadjuvant chemotherapy

Intraoperative evaluation of sentinel lymph nodes in patients with breast cancer treated with systemic neoadjuvant therapy

AIMS

Touch preparation (TP) and frozen section (FS) are the two methods routinely used in the intraoperative evaluation (IOE) of sentinel lymph nodes (SLNs) to detect metastases in patients with breast cancer. Both methods are extremely sensitive and specific in the primary surgery (non-neoadjuvant systemic therapy (non-NST)) setting. Since NST introduces unique challenges in the IOE of SLNs, the aim was to determine the accuracy of TP and FS in the IOE of SLNs in the NST setting and compare the results with the non-NST setting and to examine factors that contribute to any differences.

METHODS

We analysed 871 SLNs from 232 patients (615 SLNs from NST and 256 SLNs from non-NST settings) between 2016 through 2019.

RESULTS

In the NST group, TP alone (n=366) had a sensitivity of 45.7% and specificity of 99.7%; FS alone (n=90) had a sensitivity of 83.3% and specificity of 100%. When both TP and FS (n=135) were used, the sensitivity was 80.3% and the specificity was 98.6%.In the non-NST group, TP alone (n=193) had a sensitivity of 66.7% and specificity of 100%; FS alone (n=22) had a sensitivity and specificity of 100%; and combined TP and FS (n=34) had a sensitivity and specificity of 100% and 96%, respectively.

CONCLUSIONS

Evaluating SLNs intraoperatively in the NST setting can be challenging secondary to therapy-related changes. In the NST setting, FS has higher sensitivity and specificity compared with TP for the IOE of SLNs and should be the preferred method.

Intraoperative Lymph Node Assessment (Touch Preparation Only) for Metastatic Breast Carcinoma in Neoadjuvant and Non-neoadjuvant Settings

CONTEXT.—

Touch preparation (TP) alone is discouraged for intraoperative lymph node (LN) assessment in the neoadjuvant setting (NAS) owing to overall low sensitivity in detecting metastatic breast cancer.

OBJECTIVE.—

To compare the sensitivity, specificity, and negative predictive value of intraoperative LN assessment via TP and examine potential causes of discrepancies along with the clinical, radiologic, and pathologic parameters in the NAS and non-neoadjuvant setting (NNAS).

DESIGN.—

A total of 99 LNs from 47 neoadjuvant patients and 108 LNs from 56 non-neoadjuvant patients were identified. Discordant cases were reviewed retrospectively to reveal the discrepancy reasons. Clinical, radiologic, and pathologic data were obtained from chart review and the pathology CoPath database.

RESULTS.—

The sensitivity, specificity, and negative predictive value of TP in NAS and NNAS were 34.2% versus 37.5%, 100% versus 100%, and 70.9% versus 90.2%, respectively. In NAS, discrepancy reasons were interpretation challenge due to lobular histotype, poor TP quality secondary to therapy-induced histomorphologic changes, and undersampling due to small tumor deposits (≤2 mm); the latter was the major reason in NNAS. More cases with macrometastasis were missed in NAS compared to NNAS (14 of 25 versus 1 of 10). The parameters associated with discrepancy were lobular histotype, histologic grade 2, estrogen receptor positivity, HER2 human epidermal growth factor receptor 2 negativity, multifocality, and pathologic tumor size greater than 10 mm in NAS; and lymphovascular space involvement and pathologic tumor size greater than 20 mm in NNAS.

CONCLUSIONS.—

In NAS, intraoperative TP alone should be used very cautiously owing to a high false-negative rate of macrometastasis, especially for patients with invasive lobular carcinoma and known axillary LN metastasis before neoadjuvant therapy.

Proteomics of Sentinel Lymph Nodes in Early Breast Cancer for Identification of Thymidylate Synthase as a Potential Biomarker to Flag Metastasis: A Preliminary Study

Introduction

Breast cancer is the second most common cancer in women across the world. Some of the patients who present in the early stage of disease are affected by metastasis to the axillary group of lymph nodes. The first among this group that is affected is called as sentinel lymph node, and its diagnosis is crucial for the staging of cancer thereby dictating the type of surgical therapy. Therefore, the sentinel lymph node status provides the most relevant information to the surgeon and patient prognosis. The expanded utilization of breast conservation surgery has declined the morbidity associated with mastectomy and axillary lymph node surgery. Recent interest is, therefore, centered on techniques that allow accurate assessment of the sentinel lymph node metastasis. A current procedure such as sentinel lymph node biopsy (SLNB) that is used to assess axillary lymph node metastasis is neither specific nor sensitive, and besides, it is time-consuming.

Objective

To compare the protein profiles between metastatic and non-metastatic lymph nodes to identify a biomarker that can flag lymph node metastasis.

Materials and Methods

Women with early breast cancer were screened using mammography imaging and recruited to the study. Surgical resection was done to remove the breast tissue, and sentinel lymph node was identified using fluorescein and methylene blue tracer. Lymph node was sliced, and one set was sent for histopathology, which was considered the gold standard to assess the metastatic status of the lymph node. One set of slices was taken for proteomic experiments. Proteins were labelled with fluorescent cyanine tags and were subjected to difference gel electrophoresis experiment. Differentially expressed spots that had at least a twofold relative ratio and consistent pattern across three sets of biological replicate experiments were marked. Gel spots were trypsin digested and identified on mass spectrometry machine. Validation study was done by Western blot experiment on the same set of samples.

Results

Thymidylate synthase has a twofold higher expression in the metastatic sentinel lymph nodes as compared to non-metastatic lymph nodes in early breast cancer patients.

Conclusion

Differential in gel expression proteomics is an ideal platform for the identification of potential protein biomarker candidates that can differentiate metastatic from non-metastatic lymph nodes in early breast cancer. The identification of thymidylate synthase offers a scope to develop an on-table diagnostic kit to assess the status of sentinel lymph nodes during mastectomy procedure to guide surgical management of axillary lymph nodes in early breast cancer.

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