Prognostic relevance of DNA flow cytometry in breast cancer revisited: The 25-year experience of the Portuguese Institute of Oncology of Lisbon

DNA aneuploidy identifies a subset of Luminal subtype breast carcinoma patients with worse clinical outcome

AIM

In breast carcinoma (BC), the relationship between the ploidy pattern and molecular subtyping is still unknown. We aim to investigate the prognostic impact of DNA ploidy within molecular subtypes of a large cohort of BC patients.

METHODS

The series involved 520 BC patients with no neoadjuvant therapy and a median follow-up of 115.5 months. Immunohistochemical assessment of hormonal receptors, ERBB2 (HER2) status and Ki67 proliferative activity was the basis of the surrogate molecular subtyping. Ploidy was evaluated by DNA flow cytometry in fresh/frozen tumour samples. Kaplan-Meier (K-M) survival estimation was used for prognostic statistical analysis.

RESULTS

Luminal A subtype had the lowest prevalence of disease recurrences (23.6 %) and deaths from disease (18.3 %), while Luminal B (42.2 %/37.9 %), Triple-negative (46.4 %/40.6 %), and HER2-positive (55.9 %/50.0 %) subtypes had the highest. The Triple-positive subtype shows an intermediate/low frequency of adverse events (29.4 % of disease recurrences and 17.6 % of deaths from disease). Luminal A tumours were mostly diploid (55.3 %), while Triple-negative and HER2-positive tumours showed a high incidence of aneuploidy (82.6 % and 88.2 %, respectively). Luminal B and Triple-positive tumours had an intermediate percentage of aneuploidy (63.8 % and 70.6 %, respectively). K-M survival curves showed that DNA aneuploidy is significantly associated with shorter disease-free survival and overall survival in Luminal A and Luminal B molecular subtypes.

CONCLUSION

DNA aneuploidy identifies a subset of Luminal BC patients with worse clinical outcome, potentially eligible for more aggressive adjuvant therapy.

Advances in Intraoperative Flow Cytometry

Flow cytometry is the gold-standard laser-based technique to measure and analyze fluorescence levels of immunostaining and DNA content in individual cells. It provides a valuable tool to assess cells in the G0/G1, S, and G2/M phases, and those with polyploidy, which holds prognostic significance. Frozen section analysis is the standard intraoperative assessment for tumor margin evaluation and tumor resection. Here, we present flow cytometry as a promising technique for intraoperative tumor analysis in different pathologies, including brain tumors, leptomeningeal dissemination, breast cancer, head and neck cancer, pancreatic tumor, and hepatic cancer. Flow cytometry is a valuable tool that can provide substantial information on tumor analysis and, consequently, maximize cancer treatment and expedite patients’ survival.

S-phase fraction, lymph node status and disease staging as the main prognostic factors to differentiate between young and older patients with invasive breast carcinoma

The influence of age on the outcome of patients with invasive breast carcinoma (IBC) has not yet been fully established. The present study investigated two subgroups of patients either side of the age spectrum, and evaluated cytometric, histopathological and molecular characteristics. The series involved 219 patients with IBC that had long-term follow-up, which were divided into two subgroups: Young (≤45 years; n=103) and old patients (≥75 years; n=116). Immunohistochemical evaluation of hormonal receptors, Ki67 index and HER2 status (plus HER2 silver in situ hybridization in equivocal cases) were used as the basis for surrogate molecular subtyping. Ploidy and S-phase fraction (SPF) were analysed by DNA flow cytometry. Differences between the subgroups' characteristics were assessed by the two proportion Z test. Kaplan-Meier estimation and log-rank test were applied for survival analyses. The median age in the subgroups were 40 years (range, 19-45 years) in the young group and 78 years (range, 75-91 years) in the older subgroup. Young patients exhibited higher lymph node involvement, more advanced disease staging, higher SPF tumour proliferative activity, and a trend of lower incidence of Luminal A and higher incidence of Luminal B tumours. The median SPF value was significantly higher in young patients [7.1% (range, 1.5-23.7%) vs. 4.5% (range, 0.7-26.4%)], whereas the ploidy pattern showed no significant difference. In the whole series, as within IBC of no special type, young patients had a higher rate of recurrence (46.6 vs. 22.4%; P<0.001) and deaths from disease (35.9 vs. 20.7%; P=0.030), with a statistically significant difference for disease-free survival. In conclusion, the present study indicated that young patients with IBC exhibited more aggressive disease, with an increased risk of recurrence and shorter disease-free survival. SPF, lymph node status and staging appeared to be the main prognostic factors to differentiate young from older patients with IBC.

Multicolor flow cytometry immunophenotyping and characterization of aneuploidy in pediatric B-cell precursor acute lymphoblastic leukemia

The aim of this study was to assess the incidence of DNA aneuploidy in Polish children with B-cell precursor acute lymphoblastic leukemia (BCP-ALL) and the relationship between aneuploidy and immunological phenotype, age, leukocyte count, S-phase fraction (SPF) and early response to induction chemotherapy assessed by the percentage of residual blast cells in bone marrow aspirates. The study group consisted of 267 patients. DNA content and immunophenotype were assessed in the bone marrow before treatment using multicolor flow cytometry (FC). DNA aneuploidy was detected in 50/267 (19%) patients. High hyperdiploidy was found to be associated with lower leukocyte count (p = 0.006) and common ALL immunophenotype. Flow cytometry analysis revealed that high hyperdiploid BCP-ALL patients showed significantly higher expression of CD9, CD20, CD22, CD58, CD66c, CD86 and CD123 antigens as compared to other groups of ploidy. In contrast, CD45 showed decreased expression. The percentage of leukemic blasts at diagnosis was lower in high hyperdiploid BCP-ALL cases than in diploid (79% vs. 85.7%, p = 0.001). The difference in minimal residual disease (MRD) levels on day 15 and 33 of induction therapy between analyzed groups was not significant.

This study showed that high hyperdiploidy is associated with lower WBC count and specific immunological phenotype. Flow cytometric evaluation of expression of selected antigens can be used for fast identification of markers of aneuploidy in pediatric BCP-ALL, before genetic tests results are available. Understanding the biological significance of aneuploidy in leukemia can potentially be exploited therapeutically using targeted therapies against specific blast cell subclones.

Evaluation of DNA ploidy and S-phase fraction in fine needle aspirates from breast carcinoma

BACKGROUND

The use of fine-needle aspiration (FNA) as a primary tool in the diagnosis of breast carcinoma provides opportunity for early proliferative characterization of the tumor. This study was undertaken to assess DNA ploidy and S-phase (SPF) fraction by flow cytometry in fine needle aspirates of patients with breast cancer.

METHOD

Fifty patients of breast cancer diagnosed on fine needle aspiration cytology (FNAC) and who subsequently underwent either mastectomy or lumpectomy were included. Material obtained by FNAC was subjected to DNA ploidy and SPF analysis. Immunohistochemical estimation of Ki-67 was done on histopathology sections. The proliferation markers (SPF and Ki-67) were compared with each other and with the histopathologic parameters.

RESULTS

On DNA flow cytometry, 27 (54%) cases were aneuploid and 23 (46%) cases were diploid. The median SPF was 12.43% and 4.03% in aneuploid and diploid tumors respectively. Median Ki-67 among aneuploid tumors was 28.6% compared to 8.7% among diploid tumors. Aneuploid tumors were significantly associated with higher values of SPF and Ki-67, with Kappa 0.437 and agreement of 72%. Diploid tumors showed lower values of SPF and Ki-67, with Kappa 0.455 and agreement of 72.7%. Correlation among SPF and Ki-67 was highly significant with Kappa value 0.446, P value of .002 and agreement of 72.3%.

CONCLUSION

DNA ploidy and proliferative activity by flow cytometric SPF estimation on fine needle aspirates from breast cancer can provide valuable prognostic and predictive information at the time of diagnosis in patients with breast cancer. This might help in selection of appropriate treatment modality.

Novel insights into breast cancer copy number genetic heterogeneity revealed by single-cell genome sequencing

Copy number alterations (CNAs) play an important role in molding the genomes of breast cancers and have been shown to be clinically useful for prognostic and therapeutic purposes. However, our knowledge of intra-tumoral genetic heterogeneity of this important class of somatic alterations is limited. Here, using single-cell sequencing, we comprehensively map out the facets of copy number alteration heterogeneity in a cohort of breast cancer tumors. Ou/var/www/html/elife/12-05-2020/backup/r analyses reveal: genetic heterogeneity of non-tumor cells (i.e. stroma) within the tumor mass; the extent to which copy number heterogeneity impacts breast cancer genomes and the importance of both the genomic location and dosage of sub-clonal events; the pervasive nature of genetic heterogeneity of chromosomal amplifications; and the association of copy number heterogeneity with clinical and biological parameters such as polyploidy and estrogen receptor negative status. Our data highlight the power of single-cell genomics in dissecting, in its many forms, intra-tumoral genetic heterogeneity of CNAs, the magnitude with which CNA heterogeneity affects the genomes of breast cancers, and the potential importance of CNA heterogeneity in phenomena such as therapeutic resistance and disease relapse.

The role of automated cytometry in the new era of cancer immunotherapy

The introduction in the clinical practice of several new approaches to cancer immunotherapy has greatly increased the interest in analytical methodologies that can define the immunological profile of patients in the clinical setting. This requires huge effort to obtain reliable monitoring tools that could be used to improve the patient's clinical outcome. The clinical applications of flow cytometry (FCM) in oncology started with the measurement of DNA content for the evaluation of both ploidy and cell cycle profile as potential prognostic parameters in the majority of human solid cancer types. The availability of monoclonal antibodies widely broadened the spectrum of clinical applications of this technique, which rapidly became a fundamental tool for the diagnosis and prognosis of malignant hematological diseases. Among the emerging clinical applications of FCM, the study of minimal residual disease in hematological malignancies, the quantification of blood dendritic cells in various types of tumors, the study of metastatic spread in solid tumors throughout both the analysis of circulating endothelial progenitor cells and the identification and characterization of circulating tumor cells, all appear very promising. More recently, an advanced single cell analysis technique has been developed that combines the precision of mass spectrometry with the unique advantages of FCM. This approach, termed mass cytometry, utilizes antibodies conjugated to heavy metal ions for the analysis of cellular proteins by a mass spectrometer. It provides measurement of over 100 simultaneous cellular parameters in a single sample and has evolved from a promising technology to a high recognized platform for multi-dimensional single-cell analysis. Should a careful standardization of the analytical procedures be reached, both FCM and mass cytometry could effectively become ideal tools for the optimization of new immunotherapeutic approaches in cancer patients.