Prospective Radiologic-Pathologic Correlation of Macroscopic Volume and Microscopic Extension of Nonsolid Lung Nodules on Thin-section CT Images for Sublobar Resection and Stereotactic Radiotherapy Planning

INTRODUCTION

The objective of this study was to determine whether computed tomography (CT) could be a useful tool for nonsolid lung nodule (NSN) treatment planning, surgery or stereotactic body radiation therapy (SBRT), by assessing the macroscopic and microscopic extension of these nodules.

METHODS

The study prospectively included 23 patients undergoing anatomic resection at the Foch Hospital in 2020/2021 for NSN with a ground-glass component of more than 50%. Firstly, for each patient, both the macroscopic dimensions of the NSN were assessed on CT and during pathologic analysis. Secondly, the microscopic extension was assessed during pathologic examination. Wilcoxon sign rank tests were used to compare these dimensions. Spearman correlation test and Bland-Altman analysis were used to evaluate the agreement between radiological and pathologic measurements.

RESULTS

On CT, the median largest diameter and volume of NSN were 21 mm and 3780 cc, while on pathologic analysis, they were 15 mm and 1800 cc, respectively. Therefore, the largest diameter and volume of the NSN were significantly higher on CT than on pathological analysis. For microscopic extension, the median largest diameter and volume of NSN were 17 mm and 2040 cc, respectively. No significant difference was observed between the macroscopic size and the microscopic extension assessed during pathologic analysis. Moreover, correlation analysis and Bland-Altman plots showed that radiological and pathologic measurements could provide equivalent precision.

CONCLUSION

Our study showed that CT did not underestimate the macroscopic size and microscopic extension of NSN and confirmed that CT can be used for NSN treatment planning.

Multi-site tumor sampling highlights molecular intra-tumor heterogeneity in malignant pleural mesothelioma

Background

Malignant pleural mesothelioma (MPM) is a heterogeneous cancer. Better knowledge of molecular and cellular intra-tumor heterogeneity throughout the thoracic cavity is required to develop efficient therapies. This study focuses on molecular intra-tumor heterogeneity using the largest series to date in MPM and is the first to report on the multi-omics profiling of a substantial series of multi-site tumor samples.

Methods

Intra-tumor heterogeneity was investigated in 16 patients from whom biopsies were taken at distinct anatomical sites. The paired biopsies collected from apex, side wall, costo-diaphragmatic, or highest metabolic sites as well as 5 derived cell lines were screened using targeted sequencing. Whole exome sequencing, RNA sequencing, and DNA methylation were performed on a subset of the cohort for deep characterization. Molecular classification, recently defined histo-molecular gradients, and cell populations of the tumor microenvironment were assessed.

Results

Sequencing analysis identified heterogeneous variants notably in NF2, a key tumor suppressor gene of mesothelial carcinogenesis. Subclonal tumor populations were shared among paired biopsies, suggesting a polyclonal dissemination of the tumor. Transcriptome analysis highlighted dysregulation of cell adhesion and extracellular matrix pathways, linked to changes in histo-molecular gradient proportions between anatomic sites. Methylome analysis revealed the contribution of epigenetic mechanisms in two patients. Finally, significant changes in the expression of immune mediators and genes related to immunological synapse, as well as differential infiltration of immune populations in the tumor environment, were observed and led to a switch from a hot to a cold immune profile in three patients.

Conclusions

This comprehensive analysis reveals patient-dependent spatial intra-tumor heterogeneity at the genetic, transcriptomic, and epigenetic levels and in the immune landscape of the tumor microenvironment. Results support the need for multi-sampling for the implementation of molecular-based precision medicine.

Supplementary Information

The online version contains supplementary material available at 10.1186/s13073-021-00931-w.

Abstract 3128: Spatial intra-tumor molecular heterogeneity in malignant pleural mesothelioma

Introduction: Malignant pleural mesothelioma (MPM) is a heterogeneous cancer characterized by a diffuse locoregional growth within the thoracic cavity. Better knowledge of molecular and cellular intra-tumor heterogeneity throughout the thoracic cavity is required to develop efficient therapies.

Methods: Intra-tumor heterogeneity was investigated in 16 patients biopsied at distinct anatomic sites (apex, side wall, costo-diaphragmatic and highly metabolic site detected by PET scan when present). Paired biopsies and five derived primary cell lines were screened by targeted sequencing. Part of the cohort was also deeply characterized by whole exome sequencing, RNA-seq and DNA methylation profiling. Molecular classification and recently defined histo-molecular gradients were assessed, as were the cell populations infiltration of the tumor microenvironment.

Results: Sequencing analysis showed that most of the protein-altering somatic variants were common between paired samples from a given patient. However, we identified heterogeneous variants notably in NF2, the well-known mesothelioma driver tumor suppressor gene. Furthermore, we highlighted subclonal tumor populations shared among paired biopsies, suggesting a polyclonal dissemination of the tumor. Chromosomal abnormalities profiles were similar between different regions within the same tumor suggesting that the main chromosomal alterations occurring in MPM are early events of mesothelial carcinogenesis. Transcriptomic analysis showed major differential gene expression between anatomic sites, leading to the dysregulation of specific pathways notably linked to cell adhesion and extracellular matrix. Accordingly, histo-molecular gradient determining the proportions of epithelioid-like and sarcomatoid-like cellular entities varied between these samples. These changes were linked to epigenetic mechanisms in two patients. Finally, we found consequent spatial intra-tumor heterogeneity of the immune microenvironment with differential expression of immune mediators and immune checkpoints, and differential infiltration of immune populations. These changes led to a switch from a hot to a cold immune profile in three patients.

Conclusions: This study is the first to report on the multi-omics profiling of a substantial series of multi-site MPM tumor samples. Spatial intra-tumor heterogeneity is complex in MPM and varies among patients. We highlighted multiple types of heterogeneity, i.e. (i) genetic, (ii) transcriptomic, (iii) epigenetic and (iv) in the immune landscape of the tumor microenvironment. These results support the need for multi-sampling for the implementation of molecular-based precision medicine in MPM.

Citation Format: Clément Meiller, François Montagne, Théo Z. Hirsch, Stefano Caruso, Julien de Wolf, Quentin Bayard, Jean-Baptiste Assié, Léa Meunier, Yuna Blum, Lisa Quetel, Laure Gibault, Ecaterina Pintilie, Cécile Badoual, Marie-Christine Copin, Eric Letouzé, Arnaud Scherpereel, Jessica Zucman-Rossi, Françoise Le Pimpec-Barthes, Marie-Claude Jaurand, Didier Jean. Spatial intra-tumor molecular heterogeneity in malignant pleural mesothelioma [abstract]. In: Proceedings of the American Association for Cancer Research Annual Meeting 2021; 2021 Apr 10-15 and May 17-21. Philadelphia (PA): AACR; Cancer Res 2021;81(13_Suppl):Abstract nr 3128.

The role of three-dimensional reconstructions in understanding the intersegmental plane: an anatomical study of segment 6

OBJECTIVES

The identification of the intersegmental plane during lung segmentectomies remains a practical difficulty, notably with minimally invasive approaches. The intraoperative techniques are based on demarcating either the bronchial or the vascular territories. The goal of this study was to evaluate the use of 3-dimensional reconstructions in understanding the intersegmental plane of segment 6.

METHODS

Between March and September 2018, Synapse 3-dimensional programme was used to carry out bilateral venous, arterial and bronchial segmentations of segment 6. All computed tomography (CT) scans were contrast-enhanced and of a high resolution (0.6 mm slices). The patients had normal results on respiratory function tests. The volumes obtained from each of the 3 modalities were then compared. The results are presented as mean and standard deviation and as median and interquartile ranges for lung volume measurements.

RESULTS

During the aforementioned period, 15 high-resolution chest CT scans were selected (8 men and 7 women). The median age was 70 years. In all of the studied segments (N = 30, 15 right S6 and 15 left S6), the segmental volume of the vein was greater than the segmental volumes of the bronchus and the artery. A significant difference was found between the segmental volumes obtained from the 3 modalities (P = 0.001). The segmental volume of the vein was significantly higher than the segmental volume of the bronchus (P < 0.001) and the segmental volume of the artery (P < 0.001). On the other hand, the segmental volume of the artery was significantly higher than the segmental volume of the bronchus (P = 0.01).

CONCLUSIONS

Within the limits of this study, the segmental venous volume of S6 was greater than the volumes of the segmental bronchial and arterial volumes. Thus, depending solely on bronchial techniques might lead to leaving a border zone in venous congestion.

Successful management of donor-acquired fat embolism after lung transplantation

Fat embolism is a serious complication in patients with multiple traumatic injuries. It is often asymptomatic during the first hours of resuscitation, thus remains underdiagnosed in patients who progress to brain death. Lung transplantation issued from such grafts can lead to severe lung primary graft dysfunction, the management of which is deemed difficult. Herein, we report a successful management of donor-acquired fat embolism syndrome after lung transplant in a 22 years old woman for cystic fibrosis. Fat embolism was suspected because of the donor's traumatic injuries and confirmed by histopathological analysis. An immediate postoperative primary graft dysfunction was successfully managed with veno-arterial extracorporeal membrane oxygenation. The patient is alive 31 months after surgery.

Genetic alterations of malignant pleural mesothelioma: association with tumor heterogeneity and overall survival

Development of precision medicine for malignant pleural mesothelioma (MPM) requires a deep knowledge of tumor heterogeneity. Histologic and molecular classifications and histo‐molecular gradients have been proposed to describe heterogeneity, but a deeper understanding of gene mutations in the context of MPM heterogeneity is required and the associations between mutations and clinical data need to be refined. We characterized genetic alterations on one of the largest MPM series (266 tumor samples), well annotated with histologic, molecular and clinical data of patients. Targeted next‐generation sequencing was performed focusing on the major MPM mutated genes and the TERT promoter. Molecular heterogeneity was characterized using predictors allowing classification of each tumor into the previously described molecular subtypes and the determination of the proportion of epithelioid‐like and sarcomatoid‐like components (E/S.scores). The mutation frequencies are consistent with literature data, but this study emphasized that TERT promoter, not considered by previous large sequencing studies, was the third locus most affected by mutations in MPM. Mutations in TERT promoter, NF2, and LATS2 were more frequent in nonepithelioid MPM and positively associated with the S.score. BAP1, NF2, TERT promoter, TP53, and SETD2 mutations were enriched in some molecular subtypes. NF2 mutation rate was higher in asbestos unexposed patient. TERT promoter, NF2, and TP53 mutations were associated with a poorer overall survival. Our findings lead to a better characterization of MPM heterogeneity by identifying new significant associations between mutational status and histologic and molecular heterogeneity. Strikingly, we highlight the strong association between new mutations and overall survival.

Contingency arrangements do not necessarily equal fraud and abuse

Many healthcare organizations avoid entering contingency-based arrangements with consulting firms that specialize in Medicare revenue optimization because they fear Federal investigation of such an arrangement might lead to a finding of fraud and abuse. A Medicare fraud alert issued by the HHS Office of the Inspector General (OIG) appears to justify that fear, suggesting that contingency arrangements are inherently unethical. Nonetheless, current Federal regulations clearly allow healthcare organizations to enter into contingency-based relationships with consulting firms to seek legitimate optimal payment. Healthcare organizations may do so without fear of Federal legal action if they ensure that the consultant is ethical and competent and that the DRG review process used is both legitimate and retrospective, subjecting all recommended changes to approval by both the healthcare organization and appropriate peer review organization.

[Myxoid schwannoma of the forearm. A case report]

Tumors arising from or located within a peripheral nerve are not common and recognition and treatment are difficult. We report a patient with a myxoid swannoma surrounding the axon of ulnar nerve. This 50-year old woman had pain and tenderness. Careful clinical and technical investigation--including CT and angiography--could not give a definite diagnosis preoperatively. The patient was cured by simple enucleation without damage to the axon bundles. At surgery the appearance of the tumor was typical. An oval, encapsulated mass measuring up to 5.5 by 9 centimeters in diameter was seen. Only biopsy and pathologic examination can exclude malignancy. After follow-up of 48 months no local recurrence of the tumor was found.