[Thymoma and squamous thymic carcinoma diagnosis; experience from the RYTHMIC network]

The RYTHMIC network, supported by the French National Cancer Institute is dedicated to the management of patients with thymic epithelial tumors through regional and national multidisciplinary tumor boards. Tumor board decisions are based on the initial pathology diagnoses. However, following clinical inclusion in the network, a central pathology review is organized, implicating a panel of pathologists, for histotype and stage classification, which is different from a classical second opinion from pathologist to pathologist for a difficult case. Thanks to the participation of all French pathologists, more than 1000 cases have been reviewed by the panel. The aim of this review is to share with the French pathology community, the experience of the group. It underlines the importance of macroscopy and surgeon-pathologist involvement to allow a good central review, the main histopathological and immunophenotypical patterns of the most frequent thymomas and thymic carcinoma types, the differential diagnoses, as well as the difficulties for the panel to reproducibly assess on slides, stage, for some cases.

Circulating tumor DNA in advanced prostate cancer: transitioning from discovery to a clinically implemented test

The genomic landscape of metastatic castration-resistant prostate cancer (mCRPC) differs from that of the primary tumor and is dynamic during tumor progression. The real-time and repeated characterization of this process via conventional solid tumor biopsies is challenging. Alternatively, circulating cell-free DNA (cfDNA) containing circulating tumor DNA (ctDNA) can be obtained from patient plasma using minimally disruptive blood draws and is amenable to sequential analysis. ctDNA has high overlap with the genomic sequences of biopsies from metastases and has the advantage of being representative of multiple metastases. The availability of techniques with high sensitivity and specificity, such as next-generation sequencing (NGS) and digital PCR, has greatly contributed to the development of the cfDNA field and enabled the detection of genomic alterations at low ctDNA fractions. In mCRPC, a number of clinically relevant genomic alterations have been tracked in ctDNA, including androgen receptor (AR) aberrations, which have been shown to be associated with an adverse outcome to novel antiandrogen therapies, and alterations in homologous recombination repair (HRR) genes, which have been associated with a response to PARP inhibitors. Several clinical applications have been proposed for cfDNA analysis, including its use as a prognostic tool, as a predictive biomarker, to monitor tumor response and to identify novel mechanisms of resistance. To date, the cfDNA analysis has provided interesting results, but there is an urgent need for these findings to be confirmed in prospective clinical trials.