Disseminated cancer cells detected by immunocytology in lymph nodes of NSCLC patients are highly prognostic and undergo parallel molecular evolution

Abstract

In melanoma, immunocytology (IC) after sentinel lymph node disaggregation not only enables better quantification of disseminated cancer cells (DCCs) than routine histopathology (HP) but also provides a unique opportunity to detect, isolate, and analyse these earliest harbingers of metachronous metastasis. Here, we explored lymph node IC in non‐small cell lung cancer (NSCLC). For 122 NSCLC patients, 220 lymph nodes (LNs) were split in half and prepared for IC and HP. When both methods were compared, IC identified 22% positive patients as opposed to 4.5% by HP, revealing a much higher sensitivity of IC (p < 0.001). Assessment of all available 2,952 LNs of the same patients by HP uncovered additional patients escaping detection of lymphatic tumour spread by IC alone, consistent with the concept of skip metastasis. A combined lymph node status of IC and complete HP on a larger cohort of patients outperformed all risk factors in multivariable analysis for prognosis (p < 0.001; RR = 2.290; CI 1.407–3.728). Moreover, isolation of DCCs and single‐cell molecular characterization revealed that (1) LN‐DCCs differ from primary tumours in terms of copy number alterations and selected mutations and (2) critical alterations are acquired during colony formation within LNs. We conclude that LN‐IC in NSCLC patients when combined with HP improves diagnostic precision, has the potential to reduce total workload, and facilitates molecular characterization of lymphatically spread cancer cells, which may become key for the selection and development of novel systemic therapies. © 2022 The Authors. The Journal of Pathology published by John Wiley & Sons Ltd on behalf of The Pathological Society of Great Britain and Ireland.

Ex vivo expansion of lung cancer‐derived disseminated cancer cells from lymph nodes identifies cells associated with metastatic progression

“…Then, we tested whether EpCAM‐positive cells from LNs confer prognostic information. Here, we found detection of EpCAM‐positive DCCs to be the most informative variable for outcome prediction in multivariable analysis 17 …”

“…Apparently, a high number of DCCs in LNs reflects a proliferative phenotype and genotype that also enables sphere formation. In addition, specific genomic aberrations are acquired during proliferation within the LNs, 17 which may drive sphere formation. This is consistent with observations in melanoma, where we previously found that xenograft formation and acquisition of specific alterations within the LN are intimately linked 23 .…”

“…Here, we found detection of EpCAM-positive DCCs to be the most informative variable for outcome prediction in multivariable analysis. 17 Although EpCAM-positive cells have thus become prime candidates for metastasis founder cells, we set out to investigate the following questions. First, we asked whether sphere formation under stem-like-cell selecting conditions is associated with disease progression; second, whether sphere formation is associated with EpCAM-positivity in immunocytologically analyzed samples and third, if spheres are formed, which molecular features were associated with expansion and possibly with disease progression.…”

Metastasis founder cells activate immunosuppression early in human melanoma metastatic colonization

“…We previously found that (i) most of these early disseminated cancer cells (DCC) are not (yet) able to form a metastatic colony as they are lacking important genetic changes and (ii) that such changes are acquired during cell divisions within the metastatic site 2 . We therefore concluded that melanomas (and other cancers such as non-small-cell-lung cancer as well 3 ) undergo molecular evolution at distant sites in parallel to the primary tumour 4 . Yet, the metastasis founder cells and the molecular features enabling and driving this evolution are currently unknown.…”