Breast Sentinel Lymph Node Frozen Section Practice: An Enterprise Audit as a Guide for Moving Forward

Diagnostic accuracy and challenges of intraoperative frozen section evaluation for axillary sentinel lymph node biopsy and breast margins

AIMS

Our study aims to audit and evaluate the accuracy and pitfalls of intraoperative evaluation of frozen sentinel lymph nodes (IOE-FSLN) and resection margins (IOE-FSM) compared to final findings in paraffin sections.

METHODS

A total of 264 cases underwent intraoperative evaluation, encompassing 688 sentinel lymph nodes (SLNs) and 1186 surgical margins. Frozen section (FS) diagnoses were compared with corresponding permanent sections of FS (PFS). Sensitivity, specificity, false-negative rate, false-positive rate, and concordance rates were assessed. Cases with discrepancies underwent a detailed histological review.

RESULTS

The study predominantly comprised cases of invasive breast carcinoma (IBC) (74%). For FSLN reporting, sensitivity was 88.1%, specificity 100%, and FS-PFS concordance 99.0%. FSM reporting showed sensitivity of 85.0%, specificity 99.9%, and concordance 98.4%. Sampling errors accounted for 86% (FSLN) and 88% (FSM) of discrepancies, with interpretive errors present in 1/7 FSLN and in 2/17 FSM cases. The shave margin method demonstrated a higher false-negative rate in FSM reporting. The rate of final positive margins was reduced from 21.3% to 11.4% when IOE-FSM was utilized.

CONCLUSION

IOE-FSLN and IOE-FSM showed high reliability in guiding intraoperative decisions for axillary lymph node dissection and achieving free surgical margins in one-stage surgeries. However, limitations include challenges in distinguishing metastatic carcinoma from benign mimics in FSLN and diagnosing certain features such as IBC with post-treatment changes, invasive lobular carcinoma in FSLN and FSM; IBC rich in tumour-infiltrating lymphocytes, low-grade (DCIS/IBC in FSM) without immunohistochemical studies.

The Prevalence of Sentinel Lymph Node Positivity and Implications for the Utility of Frozen Section Diagnosis Following Neoadjuvant Systemic Therapy in Patients with Clinically Node-Negative HER2-Positive or Triple-Negative Breast Cancer

BACKGROUND

Axillary dissection is the standard of care for patients with positive sentinel lymph nodes (SLNs) following neoadjuvant systemic therapy. Frozen section can provide intraoperative information regarding the need for axillary dissection during the index operation. However, there are limited data on the utility of frozen section in patients with clinically node-negative (cN0) HER2-positive or triple-negative breast cancer.

METHODS

We conducted a single-institution observational cohort study including patients with non-inflammatory, cN0, HER2-positive or triple-negative breast cancer treated with neoadjuvant systemic therapy between 2015 and 2019. We estimated the prevalence of SLN positivity and the diagnostic test characteristics of SLN frozen section.

RESULTS

Overall, 662 patients were eligible for inclusion, and 44 patients had one or more positive SLNs (prevalence: 6.6%, 95% confidence interval [CI] 4.9-8.8). There were 490 (74.0%) patients who had intraoperative frozen section, and 19 (3.9%) tested positive among 33 (6.7%) with positive final pathology. Frozen section sensitivity was 57.6% (95% CI 39.2-74.5), specificity was 100% (95% CI 99.2-100), positive predictive value was 100% (95% CI 82.4-100), and negative predictive value was 97.0% (95% CI 95.1-98.4). The sensitivity of frozen section for detection of micrometastases or isolated tumor cells was 35.3% (95% CI 14.2-61.7).

CONCLUSION

In patients with cN0 HER2-positive or triple-negative breast cancer who have been treated with neoadjuvant therapy, positive SLNs are uncommon and frozen section sensitivity is modest. Decisions to defer SLN evaluation to final pathology, which may be reasonable in many settings, can be informed, in part, by these findings.

Challenges and Clinical Relevance of Modern Breast Pathology Reporting: Your Questions Answered

BACKGROUND

Breast pathology reporting, especially for breast cancer, has evolved through the years, from terse succinct diagnostic conclusions with scant histological details to the current comprehensive reporting guidelines issued by major pathology colleges and bodies, including the International Collaboration on Cancer Reporting. Pathology elements included in reporting guidelines are evidence based and contribute significantly to individualised and personalised patient management.

SUMMARY

This article is based on the lively interactive question and answer session that followed the breast pathology segment in the symposium jointly organised by the British Association of Urological Pathology, British Association of Gynaecological Pathologists, British Society of Gastroenterology and the Association of Breast Pathology, in November 2022, titled "Personalised histopathology reporting for personalised medicine."

KEY MESSAGES

The breast pathology session emphasised the clinical utility of breast pathology data items, incorporating a case-based approach by highlighting the relevance of pathology information in various clinical scenarios. This review included clinico-pathological discussion points on florid lobular carcinoma in situ, atypical apocrine adenosis, post-neoadjuvant chemotherapy reporting, atypical ductal hyperplasia presenting at the margin, flat epithelial atypia versus columnar cell change, papilloma on core needle biopsy, margin status, mucocele-like lesion, total duct excision/microdochectomy specimen, and anterior and nipple margins in skin-sparing mastectomy. Effective communication and regular involvement of pathologists in breast multidisciplinary tumour boards are crucial.

Update on Sentinel Lymph Node Methods and Pathology in Breast Cancer

Breast cancer stands out as the most commonly diagnosed cancer among women globally. Precise lymph node staging holds critical significance for both predicting outcomes in early-stage disease and formulating effective treatment strategies to control regional disease progression in breast cancer patients. No imaging technique possesses sufficient accuracy to identify lymph node metastases in the early stages (I or II) of primary breast cancer. However, the sentinel node procedure emerges as a valuable approach for identifying metastatic axillary nodes. The sentinel lymph node is the hypothetical first lymph node or group of nodes draining a cancer. In case of established cancerous dissemination, it is postulated that the sentinel lymph nodes are the target organs primarily reached by metastasizing cancer cells from the tumor. The utilization of the sentinel node technique has brought about changes in the assessment of lymph nodes. It involves evaluating the sentinel node during surgery, enabling prompt lymph node dissection when the sentinel node procedure is positive. Additionally, histological ultra-stratification is employed to uncover occult metastases. This review aims to provide an update of this valuable technique, with focus on the practical aspects of the procedure and the different histological protocols of sentinel node evaluation in breast cancer.

Impact of analysis of the sentinel lymph node by one-step nucleic acid amplification (OSNA) compared to conventional histopathology on axillary and systemic treatment: data from the Dutch nationwide cohort of breast cancer patients

PURPOSE

The outcome of the sentinel lymph node in breast cancer patients affects adjuvant treatment. Compared to conventional histopathology, analysis by one-step nucleic acid amplification (OSNA) harvests more micrometastasis, potentially inducing overtreatment. In this study we investigated the impact of OSNA analysis on adjuvant treatment, compared to histopathological analysis.

METHODS

Data from T1-3 breast cancer patients with sentinel nodes analysed between January 2016 and December 2019 by OSNA (OSNA group, n = 1086) from Zuyderland Medical Centre, the Netherlands, were compared to concurrent data from the Netherlands Cancer Registry (NKR) where sentinel nodes were examined by histology (histology group, n = 35,143). Primary outcomes were micro- or macrometastasis, axillary treatments (axillary lymph node dissection (ALND) or axillary radiotherapy (ART)), chemotherapy, and endocrine therapy. Statistics with Pearson Chi-square.

RESULTS

In the OSNA group more micrometastasis (14.9%) were detected compared to the histology group (7.9%, p < 0.001). No difference in axillary treatment between groups was detected (14.3 vs. 14.4%). In case of mastectomy and macrometastasis, ALND was preferred over ART in the OSNA group (14.9%) compared to the histology group (4.4%, p < 0.001). In cases of micrometastasis, no difference was seen. There was no difference in administration of adjuvant chemotherapy between groups. Endocrine treatment was administrated less often in the OSNA group compared to the histology group (45.8% vs. 50.8%, p < 0.002).

CONCLUSION

More micrometastasis were detected by OSNA compared to histopathology, but no subsequent increase in adjuvant axillary and systematic treatment was noticed. When performing mastectomy and OSNA, there was a preference for ALND compared to ART.

Update on sentinel node pathology in breast cancer

Pathologic examination of the sentinel lymph nodes (SLNs) in patients with breast cancer has been impacted by the publication of practicing changing trials over the last decade. With evidence from the ACOSOG Z0011 trial to suggest that there is no significant benefit to axillary lymph node dissection (ALND) in early-stage breast cancer patients with up to 2 positive SLNs, the rate of ALND, and in turn, intraoperative evaluation of SLNs has significantly decreased. It is of limited clinical significance to pursue multiple levels and cytokeratin immunohistochemistry to detect occult small metastases, such as isolated tumor cells and micrometastases, in this setting. Patients treated with neoadjuvant therapy, who represent a population with more extensive disease and aggressive tumor biology, were not included in Z0011 and similar trials, and thus, the evidence cannot be extrapolated to them. Recent trials have supported the safety and accuracy of sentinel lymph node biopsy (SLNB) in these patients when clinically node negative at the time of surgery. ALND remains the standard of care for any amount of residual disease in the SLNs and intraoperative evaluation of SLNs is still of value for real time surgical decision making. Given the potential prognostic significance of residual small metastases in treated lymph nodes, as well as the decreased false negative rate with the use of cytokeratin immunohistochemistry (IHC), it may be reasonable to maintain a low threshold for the use of cytokeratin IHC in post-neoadjuvant cases. Further recommendations for patients treated with neoadjuvant therapy await outcomes data from ongoing clinical trials. This review will provide an evidence-based discussion of best practices in SLN evaluation.

Standardizing Pathologic Evaluation of Breast Carcinoma After Neoadjuvant Chemotherapy

CONTEXT.—

Neoadjuvant systemic therapy refers to the use of systemic agent(s) for malignancy prior to surgical treatment and has recently emerged as an option for most breast cancer patients eligible for adjuvant systemic therapy. Consequently, treated breast carcinomas have become routine specimens in pathology practices. A standard protocol has not yet been universally adopted for the evaluation and reporting of these specimens. The American Joint Committee on Cancer staging system recognizes the challenges in staging breast carcinomas after neoadjuvant treatment and provides important data points but does not currently provide detailed guidance in estimating the residual tumor burden in the breast and lymph nodes. The Residual Cancer Burden system is the only Web-based system that quantifies treatment response as a continuous variable using residual tumor burden in the breast and the lymph nodes.

OBJECTIVE.—

To provide clarifications and guidance for evaluation and reporting of postneoadjuvant breast specimens, discuss issues with the current staging and reporting systems, and provide specific suggestions for future modifications to the American Joint Committee on Cancer system and the Residual Cancer Burden calculator.

DATA SOURCES.—

English-language literature on the subject and the data from the I-SPY 2, a multicenter, adaptive randomization phase 2 neoadjuvant platform trial for early-stage, high-risk breast cancer patients.

CONCLUSIONS.—

This article highlights challenges in the pathologic evaluation and reporting of treated breast carcinomas and provides recommendations and clarifications for pathologists and clinicians. It also provides specific recommendations for staging and discusses future directions.

Frozen section telepathology service: Efficiency and benefits of an e-health policy in South Tyrol

OBJECTIVE/BACKGROUND

Telepathology has been widely adopted to allow intraoperative pathology examinations to be performed remotely and for obtaining second opinion teleconsultation. In the Italian northern region of South Tyrol, the widespread geographical distances and consequent cost for the health system of having a travelling pathologist cover intraoperative consultations in peripheral hospitals was a key driver for the implementation of a telepathology system.

METHODS

In 2010, four Menarini D-Sight whole slide scanners to digitize entire pathology slides were placed in the peripheral hospitals of Merano, Bressanone, Brunico, and in the hub hospital of Bolzano. Digital workstations were also installed to allow pathologists to remotely perform intraoperative consultations with digital slides. This study reviews the outcome after 12 years of telepathology for this intended clinical use.

RESULTS

After an initial validation phase with 100 cases which yielded a sensitivity of 65% (CI 43-84%) and specificity of 100% (CI 95-100%), there were 2058 intraoperative consultations handled by telepathology. The cases evaluated were mainly breast sentinel lymph nodes, followed by urological, gynecological and general surgical pathology frozen section specimens. There were no false-positive cases and 165 (8%) false-negative cases, yielding an overall sensitivity and specificity of 65% (CI 61-69%) and 100% (CI 99-100%), respectively.

CONCLUSION

Telepathology is reliable for remote intraoperative diagnosis and, despite technical issues and initial acquaintance issues, proved beneficial for patient care in satellite hospitals, improved standardization, promoted innovation, and resulted in cost savings for the health system.