Intraoperative sentinel lymph node analysis in melanoma

Detection of cancer metastasis: past, present and future

The clinical importance of metastatic spread of cancer has been recognized for centuries, and melanoma has loomed large in historical descriptions of metastases, as well as the numerous mechanistic theories espoused. The "fatal black tumor" described by Hippocrates in 5000 BC that was later termed "melanose" by Rene Laennec in 1804 was recognized to have the propensity to metastasize by William Norris in 1820. And while the prognosis of melanoma was uniformly acknowledged to be dire, Samuel Cooper described surgical removal as having the potential to improve prognosis. Subsequent to this, in 1898 Herbert Snow was the first to recognize the potential clinical benefit of removing clinically normal lymph nodes at the time of initial cancer surgery. In describing "anticipatory gland excision," he noted that "it is essential to remove, whenever possible, those lymph glands which first receive the infective protoplasm, and bar its entrance into the blood, before they have undergone increase in bulk". This revolutionary concept marked the beginning of a debate that rages today: are regional lymph nodes the first stop for metastases ("incubator" hypothesis) or does their involvement serve as an indicator of aggressive disease with inherent metastatic potential ("marker" hypothesis). Is there a better way to improve prediction of disease outcome? This article attempts to address some of the resultant questions that were the subject of the session "Novel Frontiers in the Diagnosis of Cancer" at the 8th International Congress on Cancer Metastases, held in San Francisco, CA in October 2019. Some of these questions addressed include the significance of sentinel node metastasis in melanoma, and the optimal method for their pathologic analysis. The finding of circulating tumor cells in the blood may potentially supplant surgical techniques for detection of metastatic disease, and we are beginning to perfect techniques for their detection, understand how to apply the findings clinically, and develop clinical followup treatment algorithms based on these results. Finally, we will discuss the revolutionary field of machine learning and its applications in cancer diagnosis. Computer-based learning algorithms have the potential to improve efficiency and diagnostic accuracy of pathology, and can be used to develop novel predictors of prognosis, but significant challenges remain. This review will thus encompass latest concepts in the detection of cancer metastasis via the lymphatic system, the circulatory system, and the role of computers in enhancing our knowledge in this field.

Frozen section analysis of SLNs in trunk and extremity melanoma has a high false negative rate but can spare some patients a second operation

OBJECTIVES

The purpose of this study was to evaluate the accuracy of frozen section (FS) analysis of sentinel lymph nodes (SLN) in melanoma.

METHODS

Five hundred seventy-one patients underwent FS analysis of SLN between 1/2000 and12/2010. Surgical and pathological characteristics, recurrence, and survival were analyzed. Comparisons were made using χ² and Fisher's exact t-test.

RESULTS

One hundred thirty-three (23%) patients were SLN positive of which 63 (47.4%) were identified on FS. 16/70 SLN metastases not identified on FS (23%) were seen only on immunohistochemistry. FS analysis detected 84% of SLN metastasis >2 mm. SLN FS false negative rate was 53%, positive predictive value 100%, negative predictive value 88%, and overall accuracy 89%. Among patients with a FS positive SLN, 17/63 (27%) had additional positive nodes on CLND, versus 1 of 70 (1.4%) with a positive SLN identified only on permanent section pathology (P < 0.0001). The nodal recurrence rate following a negative SLN biopsy was 5%.

CONCLUSIONS

FS analysis for SLNs spared approximately half of patients a second operation. Patients with a positive SLN detected on FS were more likely to have further nodal involvement. In our experience intraoperative pathologic analysis of melanoma SLNs does not impair our ability to detect SLN metastasis or lead to a high rate of false positive results or nodal recurrences. J. Surg. Oncol. 2016;114:879-883. © 2016 2016 Wiley Periodicals, Inc.

Diagnostic value of intraoperative histopathological examination of the sentinel nodes in breast cancer and skin melanoma-Preliminary results of single centre retrospective study

OBJECTIVE

Intraoperative histopatological examination of the sentinel nodes enables selection of patients who need dissection of the regional lymphatic system during the same operation. The aim of this study is to evaluate the diagnostic value of intraoperative histopathological examination of the sentinel nodes in breast cancer and skin melanoma. Intraoperative histopathology of the sentinel nodes as a diagnostic method is used in patients with melanoma and breast cancer. Recent studies have proved it to be an effective method for evaluating the nodes in the final histopathology. Intraoperative histopathological examination of the sentinel nodes is not performed routinely and there is no clear position on this issue. In this paper we try to prove that intraoperative test gives patients the simultaneous benefits of removal of regional lymph nodes metastases and earlier initiation of adjuvant therapy.

METHODS

The study comprises 137 patients with breast cancer and 35 patients with malignant skin melanoma. Sentinel nodes were intraoperatively sectioned and examined by means of the imprint method and frozen section evaluation. The patients with positive sentinel nodes underwent immediate dissection of regional lymph nodes. Those with negative sentinel nodes diagnosed in the intraoperative examination, but positive in final pathologic results, underwent subsequent dissection of regional lymph nodes.

RESULTS

60 sentinel lymph nodes were found in 35 patients with skin melanoma. In 3 patients, 3 sentinel lymph nodes were false negative in the intraoperative histopathological examination. No false positive sentinel lymph nodes were found. 249 sentinel lymph nodes were found in the intraoperative histopathological examination in 137 patients with breast cancer. There were no false positive sentinel nodes, but there were 7 false negative sentinel nodes. In this study, only 5 (3.6%) patients with breast cancer and 3 (8.5%) patients with skin melanoma required another regional operation.

CONCLUSION

The method of intraoperative histopathological evaluation of the sentinel nodes enables identification of metastases in these lymph nodes and gives a possibility to carry out a one-step regional lymphadenectomy and start the adjuvant therapy earlier.