Mosaic BRCA1 promoter methylation contribution in hereditary breast/ovarian cancer pedigrees.

PURPOSE: Mosaic BRCA1 promoter methylation (BRCA1meth) increases the risk of early-onset breast cancer, triple-negative breast cancer and ovarian cancer. As mosaic BRCA1meth are believed to occur de novo, their role in family breast/ovarian cancer has not been assessed. PATIENTS: Blood-derived DNA from 20 unrelated affected cases from families with aggregation of breast/ovarian cancer, but with no germline pathogenic variants in BRCA1/2, PALB2 or RAD51C/D, were screened by methylation-sensitive high-resolution melting. CpG analysis was performed by pyrosequencing on blood and buccal swab. Two probands carried a pathogenic variant in a moderate-penetrance gene (ATM and BARD1), and 8 of 18 others (44%) carried BRCA1meth (vs none of the 20 age-matched controls). Involvement of BRCA1 in tumourigenesis in methylated probands was demonstrated in most tested cases by detection of a loss of heterozygosity and a homologous recombination deficiency signature. Among the eight methylated probands, two had relatives with breast cancer with detectable BRCA1meth in blood, including one with high methylation levels in two non-tumour tissues. CONCLUSIONS: The high prevalence of mosaic BRCA1meth in patients with breast/ovarian cancer with affected relatives, as well as this first description of a family aggregation of mosaic BRCA1meth, shows how this de novo event can contribute to hereditary breast/ovarian cancer pedigrees.

APC germline pathogenic variants and epithelial ovarian cancer: causal or coincidental findings?

APC germline pathogenic variants result in predisposition to familial adenomatous polyposis and extraintestinal tumours such as desmoid fibromatosis, medulloblastomas and thyroid cancers. They have also been recently involved in ovarian microcystic stromal tumours. APC inactivation has been described at the tumour level in epithelial ovarian cancers (EOCs). Here, we report the identification of APC germline pathogenic variants in two patients diagnosed with premenopausal EOC in early 30s, with no other pathogenic variant detected in the known ovarian cancer predisposing genes. Subsequent tumour analysis showed neither a second hit of APC inactivation nor ß-catenin activation. Both tumours did not have a homologous recombination (HR) deficiency, pointing towards the implication of other genes than those involved in HR. APC may contribute to the carcinogenesis of EOC in a multifactorial context. Further studies are required to clarify the role of APC in predisposition to EOC.

Adaptive nanopore sequencing to determine pathogenicity of BRCA1 exonic duplication.

BRCA1 and BRCA2 are tumour suppressor genes that have been characterised as predisposition genes for the development of hereditary breast and ovarian cancers among other malignancies. The molecular diagnosis of this predisposition syndrome is based on the detection of inactivating variants of any type in those genes. But in the case of structural variants, functional consequences can be difficult to assess using standard molecular methods, as the precise resolution of their sequence is often impossible with short-read next generation sequencing techniques. It has been recently demonstrated that Oxford Nanopore long-read sequencing technology can accurately and rapidly provide genetic diagnoses of Mendelian diseases, including those linked to pathogenic structural variants. Here, we report the accurate resolution of a germline duplication event of exons 18-20 of BRCA1 using Nanopore sequencing with adaptive sampling target enrichment. This allowed us to classify this variant as pathogenic within a short timeframe of 10 days. This study provides a proof-of-concept that nanopore adaptive sampling is a highly efficient technique for the investigation of structural variants of tumour suppressor genes in a clinical context.

Co-occurrence of germline BRCA1 and CDH1 pathogenic variants.

INTRODUCTION: We report a very rare case of familial breast cancer and diffuse gastric cancer, with germline pathogenic variants in both BRCA1 and CDH1 genes. To the best of our knowledge, this is the first report of such an association.Family description: The proband is a woman diagnosed with breast cancer at the age of 52 years. She requested genetic counselling in 2012, at the age of 91 years, because of a history of breast cancer in her daughter, her sister, her niece and her paternal grandmother and was therefore concerned about her relatives. Her sister and maternal aunt also had gastric cancer. She was tested for several genes associated with hereditary breast cancer. RESULTS: A large deletion of BRCA1 from exons 1 to 7 and two CDH1 pathogenic cis variants were identified. CONCLUSION: This complex situation is challenging for genetic counselling and management of at-risk individuals.

[2021 update of the GEFPICS' recommendations for HER2 status assessment in invasive breast cancer in France]. / Mise à jour 2021 des recommandations du GEFPICS pour l'évaluation du statut HER2 dans les cancers infiltrants du sein en France.

The last international guidelines on HER2 determination in breast cancer have been updated in 2018 by the American Society of Clinical Oncology and College of American Pathologists, on the basis of a twenty-year practice and results of numerous clinical trials. Moreover, the emerging HER2-low concept for 1+ and 2+ non amplified breast cancers lead to refine French practices for HER2 status assessment. The GEFPICS group, composed of expert pathologists, herein presents the latest French recommendations for HER2 status evaluation in breast cancer, taking into account the ASCO/CAP guidelines and introducing the HER2-low concept. In the era of personalized medicine, HER2 status assessment remains one of the most important biomarkers in breast cancer and its quality guaranties the optimal patients' care. French pathologists' commitment in theranostic biomarker quality is more than ever required to provide the most efficient cares in oncology.

Predictive factors of 5-year relapse-free survival in HR+/HER2- breast cancer patients treated with neoadjuvant endocrine therapy: pooled analysis of two phase 2 trials.

BACKGROUND: Few data are available on survival and predictive factors in early breast cancer (BC) patients treated with neoadjuvant endocrine therapy (NET). METHODS: This is a pooled analysis of two multicentre, randomised non-comparative phase 2 clinical trials evaluating neoadjuvant anastrozole and fulvestrant efficacy for postmenopausal HR+/HER2- breast cancer patients: HORGEN (NCT00871858) and CARMINA02 (NCT00629616) studies. RESULTS: In total, 236 patients were included in CARMINA02 and HORGEN trials. Modified intention-to-treat analysis was available for 217 patients. Median follow-up was 65.2 months. Relapse-free survival (RFS) and overall survival (OS) at 5 years were 83.7% (95% CI: 77.9-88) and 92.7% (95% CI: 88.2-95.6), respectively, with no difference between treatment arms. On univariate analysis, tumour staging (T2 vs T3-4; p = 0.0001), Ki-67 at surgery (≤10% vs >10%; p = 0.0093), pathological tumour size (pT1-2 vs pT3-4; p = 0.0012) and node status (pN negative vs positive; p = 0.007), adjuvant chemotherapy (p = 0.0167) and PEPI score (PEPI group I + II vs III; p = 0.0004) were associated with RFS. No events were observed in patients with pathological response according to the Sataloff classification. Multivariate analysis showed that preoperative endocrine prognostic index (PEPI) group III was associated with significantly worse RFS (p = 0.0069, hazard ratio = 3.33 (95% CI: 1.39-7.98)). CONCLUSIONS: Postmenopausal HR+/HER2- breast cancer patients receiving NET generally have a favourable outcome. The PEPI score identifies a subset of patients of poorer prognosis who are candidates for further additional treatment.

Molecular apocrine tumours in EORTC 10994/BIG 1-00 phase III study: pathological response after neoadjuvant chemotherapy and clinical outcomes.

BACKGROUND: We explored, within the EORTC10994 study, the outcomes for patients with molecular apocrine (MA) breast cancer, and defined immunohistochemistry (IHC) as androgen-receptor (AR) positive, oestrogen (ER) and progesterone (PR) negative. We also assessed the concordance between IHC and gene expression arrays (GEA) in the identification of MA cancers. METHODS: Centrally assessed biopsies for AR, ER, PR, HER2 and Ki67 by IHC were classified into six subtypes: MA, triple-negative (TN) basal-like, luminal A, luminal B HER2 negative, luminal B HER2 positive and "other". The two main objectives were the pCR rates and survival outcomes in the overall MA subtype (and further divided by HER2 status) and the remaining five subtypes. RESULTS: IHC subtyping was obtained in 846 eligible patients. Ninety-three (11%) tumours were classified as the MA subtype. Both IHC and GEA data were available for 64 patients. In this subset, IHC concordance was 88.3% in identifying MA tumours compared with GEA. Within the MA subtype, pCR was observed in 33.3% of the patients (95% CI: 29.4-43.9) and the 5-year recurrence-free interval was 59.2% (95% CI: 48.2-68.6). Patients with MA and TN basal-like tumours have lower survival outcomes. CONCLUSIONS: Irrespective of their HER2 status, the prognosis for MA tumours remains poor and adjuvant trials evaluating anti-androgens should be considered.

The iron chelator deferasirox synergises with chemotherapy to treat triple-negative breast cancers.

To ensure their high proliferation rate, tumor cells have an iron metabolic disorder causing them to have increased iron needs, making them more susceptible to iron deprivation. This vulnerability could be a therapeutic target. In breast cancers, the development of new therapeutic approaches is urgently needed for patients with triple-negative tumors, which frequently relapse after chemotherapy and suffer from a lack of targeted therapies. In this study, we demonstrated that deferasirox (DFX) synergises with standard chemotherapeutic agents such as doxorubicin, cisplatin and carboplatin to inhibit cell proliferation and induce apoptosis and autophagy in triple-negative breast cancer (TNBC) cells. Moreover, the combination of DFX with doxorubicin and cyclophosphamide delayed recurrences in breast cancer patient-derived xenografts without increasing the side-effects of chemotherapies alone or altering the global iron storage of mice. Antitumor synergy of DFX and doxorubicin seems to involve downregulation of the phosphoinositide 3-kinase and nuclear factor-κB pathways. Iron deprivation in combination with chemotherapy could thus help to improve the effectiveness of chemotherapy in TNBC patients without increasing toxicity. Copyright © 2018 Pathological Society of Great Britain and Ireland. Published by John Wiley & Sons, Ltd.

[GEFPICS' guidelines for management of breast cancer tissue samples in the neoadjuvant setting]. / Recommandations du GEFPICS pour la prise en charge des prélèvements dans le cadre du traitement néoadjuvant du cancer du sein.

Neoadjuvant therapy is an increasing treatment option in the management of breast cancer. The tumor response to neoadjuvant therapy, especially the pathological complete response, is a validated endpoint frequently used in clinical trials. However, there is still a lack of standardization for the surgical specimen management in the neoadjuvant setting. This leads to heterogeneity in the specimen handling and might lead to significant bias for the prognostic assessment of patients or in clinical trials. The GEFPICS group, composed of expert breast cancer pathologists, herein presents guidelines for the management of breast and axillary specimen before treatment (management of biopsy, items of the pathological report) and after neoadjuvant therapy (specimen handling, histological assessment of response, items of the pathological report and response grading systems).

Lymphovascular invasion after neoadjuvant chemotherapy is strongly associated with poor prognosis in breast carcinoma.

PURPOSE: Few studies evaluated the prognostic value of the presence of lymphovascular invasion (LVI) after neoadjuvant chemotherapy (NAC) for breast cancer (BC). METHODS: The association between LVI and survival was evaluated in a cohort of BC patients treated by NAC between 2002 and 2011. Five post-NAC prognostic scores (ypAJCC, RCB, CPS, CPS + EG and Neo-Bioscore) were evaluated and compared with or without the addition of LVI. RESULTS: Out of 1033 tumors, LVI was present on surgical specimens in 29.2% and absent in 70.8% of the cases. Post-NAC LVI was associated with impaired disease-free survival (DFS) (HR 2.54; 95% CI 1.96-3.31; P < 0.001), and the magnitude of this effect depended on BC subtype (Pinteraction = 0.003), (luminal BC: HR 1.83; P = 0.003; triple negative BC: HR 3.73; P < 0.001; HER2-positive BC: HR 6.21; P < 0.001). Post-NAC LVI was an independent predictor of local relapse, distant metastasis, and overall survival; and increased the accuracy of all five post-NAC prognostic scoring systems. CONCLUSIONS: Post-NAC LVI is a strong independent prognostic factor that: (i) should be systematically reported in pathology reports; (ii) should be used as stratification factor after NAC to propose inclusion in second-line trials or adjuvant treatment; (iii) should be included in post-NAC scoring systems.

Randomized phase 2 neoadjuvant trial evaluating anastrozole and fulvestrant efficacy for postmenopausal, estrogen receptor-positive, human epidermal growth factor receptor 2-negative breast cancer patients: Results of the UNICANCER CARMINA 02 French trial (UCBG 0609).

BACKGROUND: Treatment strategies for locally advanced breast cancer in elderly patients too frail to receive neoadjuvant chemotherapy and the introduction of new classes of drugs in the early 2000s have led to the consideration of endocrine therapy as a neoadjuvant treatment for younger hormone receptor (HR)-positive, postmenopausal patients not eligible for primary breast-conserving surgery (BCS). METHODS: This was a multicenter, phase 2, randomized trial designed to evaluate as its primary objective the clinical response rate after up to 6 months of neoadjuvant endocrine therapy (NET) alone in HR-positive/human epidermal growth factor receptor 2 (HER2)-negative patients with 1 mg of anastrozole (arm A) or 500 mg of fulvestrant (arm B). Secondary objectives included the BCS rate, tumor response assessment (breast ultrasound and magnetic resonance imaging), pathological response (Sataloff classification), safety profile, relapse-free survival (RFS), and predictive markers of responses and outcomes. RESULTS: From October 2007 to April 2011, 116 women (mean age, 71.6 years) with operable infiltrating breast adenocarcinoma (T2-T4, N0-N3, M0) were randomized to receive anastrozole or fulvestrant. The clinical response rates at 6 months were 52.6% (95% confidence interval [CI], 41%-64%) in arm A and 36.8% (95% CI, 25%-49%) in arm B. BCS was performed for 57.6% of arm A patients and 50% of arm B patients. The RFS rates at 3 years were 94.9% in arm A and 91.2% in arm B. The Preoperative Endocrine Prognostic Index status was significantly predictive of RFS. Both treatments were well tolerated. CONCLUSIONS: Both drugs are effective and well tolerated as NET in postmenopausal women with HR-positive/HER2-negative breast cancer. NET could be considered a treatment option in this subpopulation. Cancer 2016;122:3032-3040. © 2016 American Cancer Society.

Histo-genomic stratification reveals the frequent amplification/overexpression of CCNE1 and BRD4 genes in non-BRCAness high grade ovarian carcinoma.

The treatment of epithelial ovarian cancer (EOC) is narrowly focused despite the heterogeneity of this disease in which outcomes remain poor. To stratify EOC patients for targeted therapy, we developed an approach integrating expression and genomic analyses including the BRCAness status. Gene expression and genomic profiling were used to identify genes recurrently (>5%) amplified and overexpressed in 105 EOC. The LST (Large-scale State Transition) genomic signature of BRCAness was applied to define molecular subgroups of EOC. Amplified/overexpressed genes clustered mainly in 3q, 8q, 19p and 19q. These changes were generally found mutually exclusive. In the 85 patients for which the genomic signature could be determined, genomic BRCAness was found in 52 cases (61.1%) and non-BRCAness in 33 (38.8%). A striking mutual exclusivity was observed between BRCAness and amplification/overexpression data. Whereas 3q and 8q alterations were preferentially observed in BRCAness EOC, most alterations on chromosome 19 were in non-BRCAness cases. CCNE1 (19q12) and BRD4 (19p13.1) amplification/overexpression was found in 19/33 (57.5%) of non-BRCAness cases. Such disequilibrium was also found in the TCGA EOC data set used for validation. Potential target genes are frequently amplified/overexpressed in non-BRCAness EOC. We report that BRD4, already identified as a target in several tumor models, is a new potential target in high grade non-BRCAness ovarian carcinoma.

[Pre-analytical stage for biomarker assessment in breast cancer: 2014 update of the GEFPICS' guidelines in France]. / Recommandations du GEFPICS concernant la phase pré-analytique pour l'évaluation de HER2 et des récepteurs hormonaux dans le cancer du sein : mise à jour 2014.

Biomarker assessment of breast cancer tumor samples is part of the routine workflow of pathology laboratories. International guidelines have recently been updated, with special regards to the pre-analytical steps that are critical for the quality of immunohistochemical and in situ hybridization procedures, whatever the biomarker analyzed. Fixation and specimen handling protocols must be standardized, validated and carefully tracked. Cooperation and training of the personnel involved in the specimen workflow (e.g. radiologists, surgeons, nurses, technicians and pathologists) are of paramount importance. The GEFPICS' update of the recommendations herein details and comments the different steps of the pre-analytical process. Application of these guidelines and participation to quality insurance programs are mandatory to ensure the correct evaluation of oncotheranostic biomarkers.

[2014 update of the GEFPICS' recommendations for HER2 status determination in breast cancers in France]. / Mise à jour 2014 des recommandations du GEFPICS pour l'évaluation du statut HER2 dans les cancers du sein en France.

International guidelines on HER2 determination in breast cancer have just been updated by the American Society of Clinical Oncology (ASCO) and College of American Pathologists (CAP), on the basis of more than ten-year practice, results of clinical trials and concordance studies. The GEFPICS group, composed of expert pathologists in breast cancer, herein presents these recommendations, adapted to the French routine practice. These guidelines highlight the possible diagnosis difficulties with regards to HER2 status determination, such as intra-tumor heterogeneity, special histological subtypes and biomarker re-evaluation during metastatic relapse. Pre-analytical issues and updated scoring criteria (especially for equivocal cases) are detailed, in order to decrease the occurrence of false negative cases. In the era of personalized medicine, pathologists are more than ever involved in the quality of oncotheranostic biomarker evaluation.

Residual ANTXR1+ myofibroblasts after chemotherapy inhibit anti-tumor immunity via YAP1 signaling pathway.

Although cancer-associated fibroblast (CAF) heterogeneity is well-established, the impact of chemotherapy on CAF populations remains poorly understood. Here we address this question in high-grade serous ovarian cancer (HGSOC), in which we previously identified 4 CAF populations. While the global content in stroma increases in HGSOC after chemotherapy, the proportion of FAP+ CAF (also called CAF-S1) decreases. Still, maintenance of high residual CAF-S1 content after chemotherapy is associated with reduced CD8+ T lymphocyte density and poor patient prognosis, emphasizing the importance of CAF-S1 reduction upon treatment. Single cell analysis, spatial transcriptomics and immunohistochemistry reveal that the content in the ECM-producing ANTXR1+ CAF-S1 cluster (ECM-myCAF) is the most affected by chemotherapy. Moreover, functional assays demonstrate that ECM-myCAF isolated from HGSOC reduce CD8+ T-cell cytotoxicity through a Yes Associated Protein 1 (YAP1)-dependent mechanism. Thus, efficient inhibition after treatment of YAP1-signaling pathway in the ECM-myCAF cluster could enhance CD8+ T-cell cytotoxicity. Altogether, these data pave the way for therapy targeting YAP1 in ECM-myCAF in HGSOC.

Evolution of synchronous female bilateral breast cancers and response to treatment.

Synchronous bilateral breast cancer (sBBC) occurs after both breasts have been affected by the same germline genetics and environmental exposures. Little evidence exists regarding immune infiltration and response to treatment in sBBCs. Here we show that the impact of the subtype of breast cancer on levels of tumor infiltrating lymphocytes (TILs, n = 277) and on pathologic complete response (pCR) rates (n = 140) differed according to the concordant or discordant subtype of breast cancer of the contralateral tumor: luminal breast tumors with a discordant contralateral tumor had higher TIL levels and higher pCR rates than those with a concordant contralateral tumor. Tumor sequencing revealed that left and right tumors (n = 20) were independent regarding somatic mutations, copy number alterations and clonal phylogeny, whereas primary tumor and residual disease were closely related both from the somatic mutation and from the transcriptomic point of view. Our study indicates that tumor-intrinsic characteristics may have a role in the association of tumor immunity and pCR and demonstrates that the characteristics of the contralateral tumor are also associated with immune infiltration and response to treatment.

Rates of upgrade to malignancy for 271 cases of flat epithelial atypia (FEA) diagnosed by breast core biopsy.

Flat epithelial atypia (FEA) is a borderline lesion that might represent an early stage in the development of certain low-grade carcinomas in situ and invasive cancers. There are no guidelines on its management. Our objectives were to determine the upgrade to malignancy rate and identify a subpopulation of patients that might undergo just mammographic surveillance. We retrospectively reviewed the data for 271 FEA cases among 5,555 breast core biopsies obtained over a 7-year period (January 2003-2010). We collated clinical data (age, history of cancer, menopausal status), radiological data (lesion type, size, Bi-Rads category), technical data (number of biopsies, needle gauge, excision quality) and histological data and sought correlations between these factors and upgrade rate. The 271 FEA comprised 128 cases of pure FEA, 135 cases of FEA + atypical ductal hyperplasia, and 8 cases of FEA + atypical lobular hyperplasia. Overall, 184 patients underwent surgery and 46 mammographic surveillance. Surgery detected 34 cases of malignancy (23 CIS, 7 invasive cancers, and 4 mixed cases) giving a 15% upgrade rate. Quality of excision was the only factor associated with under-diagnosis. The presence of FEA at biopsy warrants surgery.

TP53 status for prediction of sensitivity to taxane versus non-taxane neoadjuvant chemotherapy in breast cancer (EORTC 10994/BIG 1-00): a randomised phase 3 trial.

BACKGROUND: TP53 has a crucial role in the DNA damage response. We therefore tested the hypothesis that taxanes confer a greater advantage than do anthracyclines on breast cancers with mutated TP53 than in those with wild-type TP53. METHODS: In an open-label, phase 3 study, women (age <71 years) with locally advanced, inflammatory, or large operable breast cancers were randomly assigned in a 1:1 ratio to either a standard anthracycline regimen (six cycles of intravenous fluorouracil 500 mg/m², epirubicin 100 mg/m², and cyclophosphamide 500 mg/m² every 21 days [FEC100], or fluorouracil 600 mg/m², epirubicin 75 mg/m², cyclophosphamide 900 mg/m² [tailored FEC] starting on day 1 and then every 21 days) or a taxane-based regimen (three cycles of docetaxel 100 mg/m², intravenously infused over 1 h on day 1 every 21 days, followed by three cycles of intravenous epirubicin 90 mg/m² and docetaxel 75 mg/m² on day 1 every 21 days [T-ET]) at 42 centres in Europe. Randomisation was by use of a minimisation method that stratified patients by institution and initial tumour stage. The primary endpoint was progression-free survival (PFS) according to TP53 status. Analysis was by intention to treat. This is the final analysis of this trial. The study is registered with ClinicalTrials.gov, number NCT00017095. FINDINGS: 928 patients were enrolled in the FEC group and 928 in the T-ET group. TP53 status was not assessable for 183 (20%) patients in the FEC group and 204 (22%) patients in the T-ET group mainly because of low tumour-cell content in the biopsy. 361 primary endpoint events were recorded in the FEC group and 314 in the T-ET group. In patients with TP53-mutated tumours, 5-year PFS was 59·5% (95% CI 53·4-65·1) in the T-ET group (n=326) and 55·3% (49·2-60·9) in the FEC group (n=318; hazard ratio 0·84, 98% CI 0·63-1·14; p=0·17). In patients with TP53 wild-type tumours, 5-year PFS was 66·8% (95% CI 61·4-71·6) in the T-ET group (n=398) and 64·7% (59·6-69·4) in the FEC group (n=427; 0·89, 98% CI 0·68-1·18; p=0·35). For all patients, irrespective of TP53 status, 5-year PFS was 65·1% (95% CI 61·6-68·3) in the T-ET group and 60·8% (57·3-64·2) in the FEC group (0·85, 98% CI 0·71-1·02; p=0·035). At the sites using FEC100 versus T-ET, the most common grade 3 or 4 adverse events were febrile neutropenia (75 [9%] of 803 vs 173 [21%] of 809, respectively), and neutropenia (653 [81%] vs 730 [90%], respectively). At the sites using tailored FEC versus T-ET, the most common grade 3 or 4 adverse events were febrile neutropenia (ten [8%] of 118 vs 26 [22%] of 116, respectively), and neutropenia (100 [85%] vs 115 [99%], respectively). Two patients died of toxicity during or within 30 days of chemotherapy completion and without disease relapse (one in each group). INTERPRETATION: Although TP53 status was prognostic for overall survival, it was not predictive of preferential sensitivity to taxanes. TP53 status tested by use of the yeast assay in this patient population cannot be used to select patients for an anthracycline-based chemotherapy versus a taxane-based chemotherapy. FUNDING: US National Cancer Institute, La Ligue Nationale Contre le Cancer, European Union, Pharmacia, and Sanofi-Aventis.

A catalog of numerical centrosome defects in epithelial ovarian cancers.

Centrosome amplification, the presence of more than two centrosomes in a cell is a common feature of most human cancer cell lines. However, little is known about centrosome numbers in human cancers and whether amplification or other numerical aberrations are frequently present. To address this question, we have analyzed a large cohort of primary human epithelial ovarian cancers (EOCs) from 100 patients. We found that rigorous quantitation of centrosome number in tumor samples was extremely challenging due to tumor heterogeneity and extensive tissue disorganization. Interestingly, even if centrosome clusters could be identified, the incidence of centrosome amplification was not comparable to what has been described in cultured cancer cells. Surprisingly, centrosome loss events where a few or many nuclei were not associated with centrosomes were clearly noticed and overall more frequent than centrosome amplification. Our findings highlight the difficulty of characterizing centrosome numbers in human tumors, while revealing a novel paradigm of centrosome number defects in EOCs.