Real-World Data on NGS Diagnostics: a survey from the Italian Society of Pathology (SIAPeC) NGS Network.

Next Generation Sequencing (NGS) is increasingly used in diagnostic centers for the assessment of genomic alterations to select patients for precision oncology. The Italian Society of Anatomic Pathology and Diagnostic Cytopathology (SIAPEC) through the Molecular Pathology and Predictive Medicine Study Group (PMMP) has been following the progressive development of centers that have adopted NGS technology in diagnostics over time. In July 2017, a study network on massive parallel sequencing was activated in Italy and recognized as the NGS SIAPeC National Network by the SIAPeC Scientific Society Board. Since then, activities have been implemented within the network that provide for alignment of laboratories through diagnostic concordance analysis and monitoring of centers adhering to the Network. Recently, considering the growing need for extended genomic analyses, the PMMP distributed a national survey to assess activities related to the use of genomic diagnostics in oncology within the NGS SIAPEC National Network.Thirty centers participated in the survey. Eighty percent of the centers are laboratories within Pathology Departments. The distribution of laboratories in the country, the diagnostic laboratory/population ratio, the staff dedicated, the type and number of sequencing and mechatronics platforms available, the genomic panels utilized, and the type and number of diagnostic tests carried out in the last year in each center, are reported.The centers were also asked whether they participated in a multidisciplinary Molecular Tumor Board (MTB) for management of patients. Thirty percent of the centers had a MTB that was ratified by regional decree. The professionals most frequently involved in the core team of the MTB are the pathologist, oncologist, molecular biologist, geneticist, pharmacologist, and bioinformatician.The data from this survey indicate that NGS diagnostics in Italy is still heterogeneous in terms of geographical distribution and the characteristics of laboratories and diagnostic test performed. The implementation of activities that favors harmonization, the logistics and the convergence of biological material in reference centers for molecular analyses is a priority for the development of a functional laboratory network.

TLR3 Expression Induces Apoptosis in Human Non-Small-Cell Lung Cancer.

The prognostic value of Toll-like receptor 3 (TLR3) is debated in cancer, differing between tumor types, methods, and cell types. We recently showed for the first time that TLR3 expression on early stage non-small-cell lung cancer (NSCLC) results associated with a good prognosis. Here, we provide experimental evidences explaining the molecular reason behind TLR3's favorable prognostic role. We demonstrated that TLR3 activation in vitro induces apoptosis in lung cancer cell lines and, accordingly, that TLR3 expression is associated with caspase-3 activation in adenocarcinoma NSCLC specimens, both evaluated by immunohistochemistry. Moreover, we showed that TLR3 expression on cancer cells contributes to activate the CD103+ lung dendritic cell subset, that is specifically associated with processing of antigens derived from apoptotic cells and their presentation to CD8+ T lymphocytes. These findings point to the relevant role of TLR3 expression on lung cancer cells and support the use of TLR3 agonists in NSCLC patients to re-activate local innate immune response.

Toll-like receptor 3 as a new marker to detect high risk early stage Non-Small-Cell Lung Cancer patients.

Immune and epithelial cells express TLR3, a receptor deputed to respond to microbial signals activating the immune response. The prognostic value of TLR3 in cancer is debated and no data are currently available in NSCLC, for which therapeutic approaches that target the immune system are providing encouraging results. Dissecting the lung immune microenvironment could provide new prognostic markers, especially for early stage NSCLC for which surgery is the only treatment option. In this study we investigated the expression and the prognostic value of TLR3 on both tumor and immune compartments of stage I NSCLCs. In a cohort of 194 NSCLC stage I, TLR3 immunohistochemistry expression on tumor cells predicted a favorable outcome of early stage NSCLC, whereas on the immune cells infiltrating the tumor stroma, TLR3 expression associated with a poor overall survival. Patients with TLR3-positive immune infiltrating cells, but not tumor cells showed a worse prognosis compared with all other patients. The majority of TLR3-expressing immune cells resulted to be macrophages and TLR3 expression associates with PD-1 expression. TLR3 has an opposite prognostic significance when expressed on tumor or immune cells in early stage NCSCL. Analysis of TLR3 in tumor and immune cells can help in identifying high risk stage I patients for which adjuvant treatment would be beneficial.

BRCA1/2 Molecular Assay for Ovarian Cancer Patients: A Survey through Italian Departments of Oncology and Molecular and Genomic Diagnostic Laboratories.

In Italy, 5200 new ovarian cancers were diagnosed in 2018, highlighting an increasing need to test women for BRCA1/2. The number of labs offering this test is continuously increasing. The aim of this study was to show the results coming from the intersociety survey coordinated by four different Clinical and Laboratory Italian Scientific Societies (AIOM, SIAPEC-IAP, SIBIOC, and SIGU). A multidisciplinary team belonging to the four scientific societies drew up two different questionnaires: One was targeted toward all Italian Departments of Medical Oncology, and the second toward laboratories of clinical molecular biology. This survey was implemented from September 2017 to March 2018. Seventy-seven out of 305 (25%) Departments of Medical Oncology filled our survey form. Indeed, 59 molecular laboratories were invited. A total of 41 laboratories (70%) filled in the questionnaire. From 2014 to 2017, 16 new molecular laboratories were activated. A total of 12,559 tests were performed in the year 2016, with a mean of 339 tests and a median of 254 tests per laboratory, showing a glimpse of an extreme low number of tests performed per year by some laboratories. In terms of the type and number of professionals involved in the pre- and post-test counseling, results among the onco-genetic team were heterogeneous. Our data show that the number of laboratories providing BRCA1/2 germline assays is significantly increased with further implementation of the somatic test coming soon. The harmonization of the complete laboratory diagnostic path should be encouraged, particularly in order to reduce the gap between laboratories with high and low throughput.

Recommendations for the implementation of BRCA testing in ovarian cancer patients and their relatives.

The current availability of new Poly(ADP-ribose) Polymerase (PARP)-inhibitors for the treatment of ovarian cancer patients independently of the presence of a BRCA pathogenic variant, together with the validation of somatic test for the analysis of BRCA1/2 genes, involves the need to optimise the guidelines for BRCA testing. The AIOM-SIGU-SIBIOC-SIAPEC-IAP Italian Scientific Societies, in this position paper, recommend the implementation of BRCA testing with 2 main objectives: the first is the identification of ovarian cancer patients with higher probability of benefit from specific anticancer treatments (test for response to therapy); the second goal, through BRCA testing in the family members of ovarian cancer patients, is the identification of carriers of pathogenic variant, who have inheredited predisposition to cancer development (test for cancer risk). These individuals with increased risk of cancer, should be encouraged to participate in dedicated high-risk surveillance clinics and specific risk-reducing measures (primary and/or secondary prevention programs).

Prognostic Impact of Immunohistochemical p53 Expression in Bone Marrow Biopsy in Higher Risk MDS: a Pilot Study.

BACKGROUND AND OBJECTIVES: Mutations of the TP53 gene have an unfavorable prognosis in Myelodysplastic Syndromes (MDS). The product of the TP53 gene is the p53 protein. Most of the TP53 mutations entail the accumulation of the protein in the nucleus of tumor cells. The immunohistochemical (IHC) staining for p53 can be a surrogate suggesting a mutational status and, if overexpressed, seems to be of prognostic value by itself. The best prognostic cut-off value of overexpression is controversial. The aim of this pilot study is to investigate the correct value from a homogenous group of patients with higher IPSS-R risk MDS. METHODS: In sixty consecutive patients diagnosed with MDS and categorized as "intermediate," "high" and "very high" IPSS-risk, the bone marrow biopsies performed at diagnosis were retrospectively re-examined for IHC p53 expression. The result of p53 expression was subsequently related to survival. RESULTS: A worse overall survival was observed both in patients whose IHC p53 expression was ≥5% and ≥ 10% compared to patients with a p53 expression below 5% (p= 0.0063) or 10% (p=0.0038) respectively. CONCLUSIONS: The ICH p53 expression in bone marrow biopsy in higher risk MDS was confirmed to have prognostic value. These results indicate more than 10% expression as the best cut off value.

Combined Low Densities of FoxP3+ and CD3+ Tumor-Infiltrating Lymphocytes Identify Stage II Colorectal Cancer at High Risk of Progression.

The densities of CD3+ and CD8+ tumor-infiltrating lymphocytes (TILs), combined with tumor-node-metastasis (TNM) staging, have prognostic value for patients with nonmetastatic colorectal cancer. We compared the prognostic value of CD3+ and FoxP3+ TILs at the invasive front, TNM classifiers, and microsatellite (MS) status in a trial set of patients with stage II and III colorectal cancer (n = 413), by recursive partitioning with a classification and regression tree (CART). Significant prognostic factors and interactions were reassessed by logistic regression and Cox proportional-hazards modeling in the trial and a validation set (n = 215) of patients with stage II colorectal cancer. In the trial set, CART indicated that TIL numbers were of value only in predicting recurrence risk for stage II cancers, where low densities of FoxP3+ TILs ranked first and low densities of CD3+ TILs further stratifying risk. Multivariate analysis showed that TILs interacted with tumor stage (FoxP3+, P = 0.06; CD3+, P = 0.02) and MS instability (MSI; FoxP3+; P = 0.02). In stage II MS-stable cancers, concomitant low densities of both FoxP3+ and CD3+ TILs identified patients with the highest progression risk in the trial [HR 7.24; 95% confidence interval (CI), 3.41-15.4; P < 0.001] and the validation (HR 15.16; 95% CI, 3.43-66.9; P < 0.001) sets. FoxP3+ and CD3+ TIL load in colorectal cancer was more informative than other prognostic factors before the cancer progressed to lymph nodes. This prognostic information about TILs, including FoxP3+ cells, suggests that randomized controlled trials might be refined to include interactions between TNM status, molecular classifiers, and postsurgical treatments.

Radiologic and Genomic Evolution of Individual Metastases during HER2 Blockade in Colorectal Cancer.

Targeting HER2 is effective in 24% of ERBB2 amplified metastatic colorectal cancer; however, secondary resistance occurs in most of the cases. We studied the evolution of individual metastases during treatment to discover spatially resolved determinants of resistance. Circulating tumor DNA (ctDNA) analysis identified alterations associated with resistance in the majority of refractory patients. ctDNA profiles and lesion-specific radiographic reports revealed organ- or metastasis-private evolutionary patterns. When radiologic assessments documented progressive disease in target lesions, response to HER2 blockade was retained in other metastases. Genomic and functional analyses on samples and cell models from eight metastases of a patient co-recruited to a postmortem study unveiled lesion-specific evolutionary trees and pharmacologic vulnerabilities. Lesion size and contribution of distinct metastases to plasma ctDNA were correlated.

TRKA expression and NTRK1 gene copy number across solid tumours.

AIMS: Neurotrophic Tropomyosin Kinase Receptor 1 (NTRK1) gene encodes for the protein Tropomyosin-related kinase A (TRKA). Deregulated activity of TRKA has been shown to have oncogenic potential. We present here the results of an immunohistochemical (IHC) observational cohort study of TRKA expression together with gene copy number (GCN) assessment in various solid tumours. METHODS: Formalin-fixed, paraffin-embedded consecutive samples of different tumour types were tested for TRKA expression. Samples showing TRKA IHC staining in at least 10% of cells were analysed by fluorescence in situ hybridisation to assess NTRK1 gene rearrangements and/or individual GCN gain. All patients underwent this molecular assessment within the phase I ALKA-001 clinical trial. RESULTS: 1043 samples were tested and annotation for histology was available in 1023. Most of the samples were colorectal adenocarcinoma (CRC) (n=550, 52.7%) and lung adenocarcinoma (n=312, 29.9%). 24 samples (2.3%) were biliary tract carcinoma (BTC). Overall, 17 (1.6%) samples were characterised by TRKA IHC expression (four weak, eight moderate, five strong): 9/17 lung adenocarcinoma, 3/17 CRC, 3/17 BTC, 1/17 thyroid cancer and 1/17 cancer of unknown primary. Of these, 1/17 with strong TRKA IHC staining displayed NTRK1 gene rearrangement and 15/17 NTRK1 GCN gain by FISH. No correlation was found between intensity of TRKA IHC staining and number of copies of NTRK1. CONCLUSIONS: TRKA expression can be found in 1.6% of solid tumours and can be paralleled by NTRK1 gene rearrangements or mostly GCN gain. The prognostic and translational therapeutic impact of the latter remains to be established.

Discovery of methylated circulating DNA biomarkers for comprehensive non-invasive monitoring of treatment response in metastatic colorectal cancer.

OBJECTIVE: Mutations in cell-free circulating DNA (cfDNA) have been studied for tracking disease relapse in colorectal cancer (CRC). This approach requires personalised assay design due to the lack of universally mutated genes. In contrast, early methylation alterations are restricted to defined genomic loci allowing comprehensive assay design for population studies. Our objective was to identify cancer-specific methylated biomarkers which could be measured longitudinally in cfDNA (liquid biopsy) to monitor therapeutic outcome in patients with metastatic CRC (mCRC). DESIGN: Genome-wide methylation microarrays of CRC cell lines (n=149) identified five cancer-specific methylated loci (EYA4, GRIA4, ITGA4, MAP3K14-AS1, MSC). Digital PCR assays were employed to measure methylation of these genes in tumour tissue DNA (n=82) and cfDNA from patients with mCRC (n=182). Plasma longitudinal assessment was performed in a patient subset treated with chemotherapy or targeted therapy. RESULTS: Methylation in at least one marker was detected in all tumour tissue samples and in 156 mCRC patient cfDNA samples (85.7%). Plasma marker prevalence was 71.4% for EYA4, 68.5% for GRIA4, 69.7% for ITGA4, 69.1% for MAP3K14-AS1% and 65.1% for MSC. Dynamics of methylation markers was not affected by treatment type and correlated with objective tumour response and progression-free survival. CONCLUSION: This five-gene methylation panel can be used to circumvent the absence of patient-specific mutations for monitoring tumour burden dynamics in liquid biopsy under different therapeutic regimens. This method might be proposed for assessing pharmacodynamics in clinical trials or when conventional imaging has limitations.

External quality assessment for EGFR mutations in Italy: improvements in performances over the time.

External quality assessment (EQA) schemes are essential procedures to assess the quality level of laboratories performing molecular testing of the epidermal growth factor receptor (EGFR) gene in non-small cell lung cancer. The Italian Association of Medical Oncology (AIOM) and the Italian Society of Pathology (SIAPEC-IAP) organise EGFR EQA programmes to ensure that the Italian laboratories achieve the quality standard levels required. Comparing the 2011, 2013 and 2015 EGFR EQA schemes, it was possible to observe improvements in the methodologies used and the outcomes. The use of direct sequencing was reduced from 78.7% in 2011 to only 14.1% in 2015, whereas the use of pyrosequencing and real-time PCR increased. The number of rounds in which centres using direct sequencing failed was significantly higher than the number of rounds that failed using other methods, both when analysing each single scheme and when combining the three EQAs together. In 2011 and 2013, about 29% of the participants failed the first phase of the programmes, compared with the 13% of centres failing in 2015, suggesting that the switch to more sensitive and robust methods could allow to increase the percentage of good performers. Although the molecular analyses are performed with good quality in Italy, the continuous education carried out by AIOM and SIAPEC-IAP remains a fundamental tool to maintain this quality level.

Pooled Analysis of Clinical Outcome of Patients with Chemorefractory Metastatic Colorectal Cancer Treated within Phase I/II Clinical Studies Based on Individual Biomarkers of Susceptibility: A Single-Institution Experience.

BACKGROUND: Patients with metastatic colorectal cancer (mCRC) refractory to standard therapies have a poor prognosis. In this setting, recruitment into clinical trials is warranted, and studies driven by selection according to individual tumor molecular characteristics are expected to provide added value. OBJECTIVE: We retrospectively analyzed data from patients with mCRC refractory to or following failure of standard therapies who were enrolled into phase I/II clinical studies at the Niguarda Cancer Center based on the presence of a specific molecular profile expected to represent the target of susceptibility to the experimental drug(s). PATIENTS AND METHODS: From June 2011 to May 2016, 2044 patients with mCRC underwent molecular screening. Eighty patients (3.9%) were enrolled in ad hoc studies; the median age was 60 years (range 36-86) and the median number of previous treatment lines was five (range 2-8). Molecular characteristics exploited within these studies were MGMT promoter hypermethylation (48.7%), HER2 amplification (28.8%), BRAF V600E mutation (20%), and novel gene fusions involving ALK or NTRK (2.5%). RESULTS: One patient (1%) had RECIST (Response Evaluation Criteria In Solid Tumors) complete response (CR), 13 patients (16.5%) experienced a partial response (PR), and 28 (35%) stable disease (SD). Median progression-free survival (PFS) was 2.8 months (range 2.63-3.83), with 24% of patients displaying PFS >5 months. Median growth modulation index (GMI) was 0.85 (range 0-15.61) and 32.5% of patients had GMI >1.33. KRAS exon 2 mutations were found in 38.5% of patients, and among the 78 patients with known KRAS status, those with wild-type tumors had longer PFS than those with mutated tumors (3.80 [95% CI 2.80-5.03] vs. 2.13 months [95% CI 1.77-2.87], respectively, p = 0.001). Median overall survival (OS) was 7.83 months (range 7.17-9.33) for all patients, and patients with KRAS wild-type tumors had longer OS than those with mutated tumors (7.83 [95% CI 7.33-10.80] vs. 7.18 months [95% CI 5.63-9.33], respectively, p = 0.06). CONCLUSIONS: This single-institution retrospective study indicates that in a heavily pretreated population approximately 4% of mCRC tumors display a potential actionable molecular context suitable for therapeutic intervention. Application of molecular selection is challenging but improves clinical outcome even in later lines of treatment.

A Case of Blastic Plasmacytoid Dendritic Cell Neoplasm Extensively Studied by Flow Cytometry and Immunohistochemistry.

Blastic plasmacytoid dendritic cell neoplasm (BPDCN) is a rare hematologic malignancy with aggressive clinical course and poor prognosis. Diagnosis is based on detection of CD4+ CD56+, CD123high, TCL-1+, and blood dendritic cell antigen-2/CD303+ blasts, together with the absence of lineage specific antigens on tumour cells. In this report we present a case of BPDCN presenting with extramedullary and bone marrow involvement, extensively studied by flow cytometry and immunohistochemistry, who achieved complete remission after acute lymphoblastic leukemia like chemotherapy and allogeneic hematopoietic stem cell transplantation.

Effect of KRAS and BRAF Mutations on Survival of Metastatic Colorectal Cancer After Liver Resection: A Systematic Review and Meta-Analysis.

BACKGROUND: The purpose of the study was to evaluate whether the mutational status of Kirsten rat sarcoma viral oncogene homolog (KRAS) or b-viral oncogene homolog B1 (BRAF) could be an independent prognostic factor in the subset of patients with colorectal cancer liver metastases (CRLM) who undergo complete liver resection. MATERIALS AND METHODS: A systematic literature review was performed to identify articles reporting relapse-free survival (RFS) and/or overall survival (OS) of patients who underwent complete liver resection for CRLM, stratified according to KRAS and BRAF mutational status. Hazard ratios (HRs) from multivariate analyses were pooled in the meta-analysis. RESULTS: Eleven studies, including 1833 patients, were eligible for the meta-analysis. Nine of them reported OS stratified according to KRAS mutation. The pooled analysis revealed that KRAS mutation was negatively associated with OS (HR, 1.674; 95% confidence interval [CI], 1.341-2.089; P < .001). Nine among 11 studies reported RFS stratified according to KRAS mutation and HRs in multivariate analysis were available in 7. In a pooled analysis, KRAS mutation was negatively associated with RFS (HR, 1.529; 95% CI, 1.287-1.817; P < .001). In 3 studies HRs of the multivariate analysis regarding the OS according to BRAF mutational status were also available, showing a negative association with OS (HR, 3.055; 95% CI, 1.794-5.204; P < .001). CONCLUSION: KRAS mutations are negatively associated with OS and RFS in patients who undergo complete liver resection for CRLM. A similar negative effect on OS was observed also for BRAF mutation, although fewer studies were included. These data support integration of KRAS and BRAF mutational status into a combined predictive score for prospective assessment of outcome after resection of CRLM in clinical studies.

A non-invasive approach to monitor chronic lymphocytic leukemia engraftment in a xenograft mouse model using ultra-small superparamagnetic iron oxide-magnetic resonance imaging (USPIO-MRI).

Chronic lymphocytic leukemia (CLL) is the most prevalent leukemia among adults. Despite its indolent nature, CLL remains an incurable disease. Herein we aimed to monitor CLL disease engraftment and, progression/regression in a xenograft CLL mouse model using ultra-small superparamagnetic iron oxide-magnetic resonance imaging (USPIO-MRI). Spleen contrast enhancement, quantified as percentage change in signal intensity upon USPIO administration, demonstrated a difference due to a reduced USPIO uptake, in the spleens of mice injected with CLL cells (NSG-CLL, n=71) compared to controls (NSG-CTR, n=17). These differences were statistically significant both after 2 and 4weeks from CLL cells injection. In addition comparison of mice treated with rituximab with untreated controls for changes in spleen iron uptake confirmed that it is possible to monitor treatment efficacy in this mouse model of CLL using USPIO-enhanced MRI. Further applications could include the preclinical in vivo monitoring of new therapies and the clinical evaluation of CLL patients.

Molecular Landscape of Acquired Resistance to Targeted Therapy Combinations in BRAF-Mutant Colorectal Cancer.

Although recent clinical trials of BRAF inhibitor combinations have demonstrated improved efficacy in BRAF-mutant colorectal cancer, emergence of acquired resistance limits clinical benefit. Here, we undertook a comprehensive effort to define mechanisms underlying drug resistance with the goal of guiding development of therapeutic strategies to overcome this limitation. We generated a broad panel of BRAF-mutant resistant cell line models across seven different clinically relevant drug combinations. Combinatorial drug treatments were able to abrogate ERK1/2 phosphorylation in parental-sensitive cells, but not in their resistant counterparts, indicating that resistant cells escaped drug treatments through one or more mechanisms leading to biochemical reactivation of the MAPK signaling pathway. Genotyping of resistant cells identified gene amplification of EGFR, KRAS, and mutant BRAF, as well as acquired mutations in KRAS, EGFR, and MAP2K1 These mechanisms were clinically relevant, as we identified emergence of a KRAS G12C mutation and increase of mutant BRAF V600E allele frequency in the circulating tumor DNA of a patient at relapse from combined treatment with BRAF and MEK inhibitors. To identify therapeutic combinations capable of overcoming drug resistance, we performed a systematic assessment of candidate therapies across the panel of resistant cell lines. Independent of the molecular alteration acquired upon drug pressure, most resistant cells retained sensitivity to vertical MAPK pathway suppression when combinations of ERK, BRAF, and EGFR inhibitors were applied. These therapeutic combinations represent promising strategies for future clinical trials in BRAF-mutant colorectal cancer. Cancer Res; 76(15); 4504-15. ©2016 AACR.

Tumor Heterogeneity and Lesion-Specific Response to Targeted Therapy in Colorectal Cancer.

UNLABELLED: How genomic heterogeneity associated with acquired resistance to targeted agents affects response to subsequent therapy is unknown. We studied EGFR blockade in colorectal cancer to assess whether tissue and liquid biopsies can be integrated with radiologic imaging to monitor the impact of individual oncogenic alterations on lesion-specific responses. Biopsy of a patient's progressing liver metastasis following prolonged response to cetuximab revealed a MEK1(K57T) mutation as a novel mechanism of acquired resistance. This lesion regressed upon treatment with panitumumab and the MEK inhibitor trametinib. In circulating tumor DNA (ctDNA), mutant MEK1 levels declined with treatment, but a previously unrecognized KRAS(Q61H) mutation was also identified that increased despite therapy. This same KRAS mutation was later found in a separate nonresponding metastasis. In summary, parallel analyses of tumor biopsies and serial ctDNA monitoring show that lesion-specific radiographic responses to subsequent targeted therapies can be driven by distinct resistance mechanisms arising within separate tumor lesions in the same patient. SIGNIFICANCE: Molecular heterogeneity ensuing from acquired resistance drives lesion-specific responses to subsequent targeted therapies. Analysis of a single-lesion biopsy is inadequate to guide selection of subsequent targeted therapies. ctDNA profiles allow the detection of concomitant resistance mechanisms residing in separate metastases and assessment of the effect of therapies designed to overcome resistance.

Demographic, tumor and clinical features of clinical trials versus clinical practice patients with HER2-positive early breast cancer: results of a prospective study.

BACKGROUND: Several randomized clinical trials (RCTs) have demonstrated the efficacy of trastuzumab-based adjuvant therapy in HER2-positive breast cancer (BC). However, RCT patients may not invariably be representative of patients routinely seen in clinical practice (CP). To address this issue, we compared the clinical and tumor features of RCT and CP patients with HER2-positive BC. PATIENTS AND METHODS: From January to December 2012, 650 consecutive patients with HER2-positive early BC, treated in 36 different types of Italian healthcare facilities, were enrolled in this study. Age, treatment, tumor size (T), nodes (N), grade (G), estrogen receptor (ER) and progesterone receptor (PgR) status were prospectively collected in these CP patients. The same data were extracted from the main adjuvant trastuzumab RCTs and pooled using the random-effects model of DerSimonian and Laird. RCT and CP patients were compared by using the Cochran Q statistics. RESULTS: Versus RCT patients, CP patients were more likely to be older than 50 years (65 vs. 49 %; p < 0.0001) and to have HR (ER and/or PgR)-positive (72 vs. 54 %; p < 0.0001) BC and less likely to have tumor >2 cm (T ≥ 2 cm 39 vs. 59 %; p < 0.0001), positive N (47 vs. 89 %; p < 0.0001) and a high G (61 vs. 67 %; p = 0.0241). CP patients more frequently received adjuvant endocrine therapy (70 vs. 57 %; p < 0.0003) and less frequently adjuvant chemotherapy (97 vs. 99.7 %; p < 0.0001). CONCLUSIONS: Most tumor and clinical features differed significantly between CP and RCT patients. These data raise concerns about the applicability of RCT results to CP patients.