In this article, we outline the two dominant concepts of personalized medicine put forward by epigenetics in the field of oncology. First, knowledge on the molecular processes involved in tumor progression contributes to molecularize medicine, extending genomic medicine. Then, the identification of epigenetic mechanisms underlying the environmental causes of cancers brings scientific legitimacy to products and services whose advertising promotes the ability of each person to protect herself from cancer by adapting her lifestyle. Lastly, we argue that research in environmental epigenetics could open a new route for personalized medicine in oncology, where epigenetics contributes to an individualized assessment of patients' life paths.

Succinate dehydrogenase (SDH) is a mitochondrial enzyme that participates in both the tricarboxylic acid cycle and the electron transport chain. Mutations in genes encoding SDH are responsible for a predisposition to pheochromocytomas and paragangliomas, and more rarely, to gastrointestinal stromal tumors or renal cell carcinomas. A decrease in SDH activity, not explained by genetics, has also been observed in more common cancers. One of the consequences of the inactivation of SDH is the excessive production of its substrate, succinate, which acts as an oncometabolite by promoting a pseudohypoxic status and an extensive epigenetic rearrangement. Understanding SDH-related oncogenesis now makes it possible to develop innovative diagnostic methods and to consider targeted therapies for the management of affected patients.

Round cell sarcomas represent a diagnostic challenge for pathologists due to the poorly differentiated pattern of these high-grade tumors. Their diagnosis often requires large immunohistochemical panels and the use of molecular pathology. These tumors are largely dominated by Ewing sarcomas, but new families are now well characterized, including in decreasing frequency order in bone, BCOR-altered sarcomas, NFATc2-rearranged sarcomas, mesenchymal chondrosarcomas and more rarely CIC-rearranged sarcomas and myoepithelial tumors. This progress report presents microscopic, immunohistochemical and molecular features of these tumors previously named by the inappropriate term "Ewing-like" sarcomas, in order to enable any pathologist to perceive the morphological features of these sarcomas, to select the immunohistochemical panel that will lead to the diagnosis and to better guide the molecular approach needed to establish the final diagnosis.

Translocations involving FN1 gene have been described in several tumours, which share the presence of a cartilaginous matrix with or without calcifications and a good prognosis. They encompass: soft tissue chondroma, synovial chondromatosis, calcifying aponeurotic fibroma, phosphaturic mesenchymal tumour and a new spectrum of tumours: "the calcified chondroid mesenchymal neoplasms". We review all the clinical, histopathological and molecular data of these tumours and discuss the differential diagnoses.

Current therapeutic developments in prostate cancer (PCa) tend to increasingly personalize the treatment strategy, in particular as a function of tumor genomics. Recently, poly ADP-ribose polymerase (PARPi) inhibitors have shown their efficacy at the stage of castration resistance, in case of alteration of DNA repair genes in tumor tissue.

Technological advances, in particular the development of high-throughput sequencing, have led to the emergence of a new generation of molecular biomarkers for tumors. These new tools have profoundly changed therapeutic management in oncology, with increasingly precise molecular characterization of tumors leading to increasingly personalized therapeutic targeting. Detection of circulating tumor cells and/or circulating tumor DNA in blood samples -so-called 'liquid biopsies'- can now provide a genetic snapshot of the patient's tumor through an alternative and less invasive procedure than biopsy of the tumor tissue itself. This procedure for characterizing and monitoring the disease in real time facilitates the search for possible relapses, the emergence of resistance, or emergence of a new therapeutic target. In the long term, it might also provide a means of early detection of cancer. These new approaches require the treatment of ever-increasing amounts of clinical data, notably, with the goal of calculating composite clinical-biological predictive scores. The use of artificial intelligence will be unavoidable in this domain, but it raises ethical questions and implications for the health-care system that will have to be addressed.

Molecular analyses have become mandatory for treatment choices in patients with various advanced cancers. Beside next generation sequencing (NGS) analyzing genes panels, non-NGS targeted analyses about the main biomarkers remain of interest. In this article, we review the data about the fast and fully automated real-time PCR platform Idylla™ (Biocartis, Mechelen, Belgium) permitting the mutational analyses of BRAF, KRAS, NRAS, EGFR and microsatellite instability notably in melanoma, non-small-cell lung cancer and colorectal cancer samples. Future applications as well as the implementation of Idylla™ in the workflow of pathology and/or molecular biology laboratories are also discussed.

Immunotherapies are part of the therapeutic strategy in many cancers and are indicated for metastatic colorectal adenocarcinoma with loss of expression of MisMatch Repair system proteins or with microsatelite instability (dMMR/MSI) in the United States. The rate of pathological response to immunotherapy remains poorly documented, but several cases of complete or major pathological response have recently been described. We decided to report the case of a complete pathological response to immunotherapy of a dMMR/MSI colorectal adenocarcinoma in a 74-year-old patient, initially inoperable due to duodenal invasion. Three months after the introduction of immunotherapy, the patient developed drug-induced colitis that contraindicated further treatment. Histological examination of the subtotal colectomy specimen revealed no residual tumour cells. The patterns of tumour regression were mainly represented by colloid regression, infarctoid-type necrosis and a resorptive inflammatory reaction. Although the operative indications for patients with metastatic dMMR/MSI colorectal cancer treated by immunotherapy are still very limited, the number of such specimens is expected to increase rapidly. The management of these specimens, as well as the possibility of a complete histological response, must be known by pathologists who play a key role in the pathophysiological knowledge of these lesions.

The third-generation tyrosine kinase inhibitor (TKI) osimertinib is recommended as a first-line treatment in advanced non-small cell lung cancer harboring an activating mutation of Epidermal Growth Factor Receptor (EGFR). Adverse pulmonary events related to osimertinib exposure have been reported, primarily in Japanese patients. They rarely occur in the Caucasian population.

Breast cancer with HER2-amplification accounts for 20 % of breast cancers. The management of patients has dramatically changed with the advent of anti-HER2 treatment, especially the monoclonal antibodies since 2000 in the metastatic and (neo)-adjuvant setting, leading to an improvement of patient outcomes. If therapeutic arsenal has been gradually enhanced with the targeting of HER receptors family, resistances to these treatments are observed, hence the development of new therapeutic strategies. This review provides an updated look of novel therapeutic strategies in HER2-positive breast cancer, as well as future perspectives, both in the adjuvant and metastatic setting.

The tumor biopsy remains essential for breast cancer diagnosis and characterization. Indeed, the treatment is decided according to histological subtype, and according to the presence of targetable molecular alterations. Notably, the presence of hormone receptors, ERBB2 hyperexpression or the existence of PIK3CA or ESR1 mutations are among the alterations commonly investigated. But these biological characteristics are determined only partially by tumor biopsy, due to tumor heterogeneity or tumor plasticity that happens spontaneously or under treatment. Liquid biopsy, and in particular circulating tumor DNA and circulating tumor cells, is a non-invasive method to identify and characterize the presence of cancer in the blood. The aim of this review is to determine the value of liquid biopsy to enhance or replace the data provided by a tumor biopsy.

HER2 is an important prognostic and predictive biomarker in breast cancer. Its detection makes it possible to define which patients will benefit from a targeted treatment. While assessment of HER2 status by immunohistochemistry in positive vs negative categories is well implemented and reproducible, the introduction of a new "HER2-low" category could raise some concerns about its scoring and reproducibility. We herein described the current HER2 testing methods and the application of innovative machine learning techniques to improve these determinations, as well as the main challenges and opportunities related to the implementation of digital pathology in the up-and-coming AI era.

Since the previous 2013 and 2016 recommendations for clinical practice (RPC) Nice/Saint-Paul-de-Vence for gynecological cancers, the management of ovarian cancer has become more complex with the evolution of the quality criteria recommended for surgery and the integration of molecular biology for the decision of medical treatments, especially for high grade epithelial ovarian cancers. Surgical indications have become more precise both in the first line and in the context of relapse. Treatments with PARP inhibitors is a major advance in medical management with significant efficacy in maintenance after response to platinum-based chemotherapy. The benefit already known in the case of late relapse has also been demonstrated in first-line treatment with progression-free survival never observed in this pathology with patients with very long responses, especially in the case of BRCA gene abnormalities (somatic or constitutional). In 2021, medical and surgical strategies in front line including PARP inhibitors associated or not with bevacizumab as a maintenance complement after platinum chemotherapy are guided by both response to platinum agents and molecular profiling including BRCA (somatic or constitutional) genetic status and homologous recombination pathway (HRD) abnormalities, that should be early tested. On behalf of the GINECO national oncologist group, we have updated the guidelines for high grade ovarian epithelial cancer (excepted rare tumors) in order to allow rapid dissemination of the latest advances to the medical community and improve daily practice.

To determine the value of performing a risk-reducting mastectomy (RRM) in the absence of a deleterious variant of a breast cancer susceptibility gene, in 4 clinical situations at risk of breast cancer.

Three-dimensional (3D) culture of organoids from primary cells (wild type) or tumoroids from tumor cells, is used to study the physiological mechanisms in vivo, in order to model normal or tumor tissues more accurately than conventional two-dimensional (2D) culture. The features of this 3D culture, such as the three-dimensional structure, the self-renewal capacity and differentiation are preserved and appropriate to cancer study since their cellular characteristics are very similar to in vivo models. Here, we summarize the recent advances in the rapidly evolving field of organoids and their applications to cancer biology, clinical research and personalized medicine.

Rapid technical advances in molecular biology allowed for the identification of key genetic alterations in central nervous system (CNS) tumors. Our ever-expanding knowledge of brain tumor genetics and the development of new technologies, such as DNA-methylation profiling, required an update of the 2016 fourth edition of the WHO classification of CNS tumors. Updates were regularly published by the Consortium to Inform Molecular Practical Approaches to CNS Tumor Taxonomy-Not Official WHO (c-IMPACT-NOW) until the publication of the fifth edition of the WHO classification of CNS tumors in 2021. In that edition, new types and subtypes are introduced and criteria for histo-molecular diagnostic and grading are refined, especially for diffuse gliomas. The definition of a broad category "diffuse glioma, pediatric subtype" (low or high grade) is a major improvement of the classification. Moreover, the nomenclature was simplified and aligned with that of other blue books. The 2021 edition truly advances the role of molecular diagnostics in CNS tumor classification. Methyloma profiling may become a cornerstone of CNS tumor diagnostic. The new WHO classification will lead to better management of brain tumor patients.

New molecular therapeutic approaches have emerged in recent years for advanced gynaecological cancers, including targeted therapies such as poly-ADP-ribose polymerase inhibitors (PARPi). These have demonstrated efficacy in high-grade serous ovarian cancers in patients carrying a mutation in the BRCA gene, which predisposes them to breast and ovarian cancers. Clinical and pre-clinical data suggest that the activity of PARPi inhibitors may not be limited to BRCA mutated tumours and may involve the homologous recombination pathway. These data raise the question of the potential efficacy of PARPi in advanced endometrial and cervical cancers where treatment options are currently limited. At present, there are few data available on the activity of PARPi in endometrial and cervical cancers, but some results seem promising. In this review, we present a synthesis of the available studies concerning PARPi in endometrial and cervical cancer.

PARP inhibitors are effective in different types of tumors such as ovarian, breast, prostate and pancreatic cancer. Many studies are in progress and may lead to prescription evolution. PARP inhibitors prescription is almost reserved to patients with a constitutional BRCA mutation or a somatic BRCA alteration or a tumor with a deficiency in homologous recombination. Nowadays, the diagnosis of homologous recombination deficit, HRD, is possible with the prescription of a myChoice CDx (Myriad) test. PARP inhibitors are studied in association with chemotherapy and targeted therapies but also with radiotherapy and with immune checkpoint inhibitors. Access to PARP inhibitors is challenged with the emergence of resistance mechanism. Various trials are now studying the possibility of reversing these resistance mechanisms.