No evidence for shedding of circulating tumor cells to the peripheral venous blood as a result of mammographic breast compression

EFFECT OF MAMMOGRAPHY IMAGING PROCEDURE ON SERUM INFLAMMATORY AND/OR TUMOR MARKER LEVELS

Mammography is one of the gold standard screening tests for breast cancer. The effects of mammography procedure on blood parameters are not known. This study aimed to investigate whether the procedure-associated breast compression affects the widely and simultaneously performed blood measurements of C-reactive protein (CRP), carcinoembryonic antigen (CEA), and cancer antigen (CA) 15-3. According to breast ultrasound examination results, participants were divided into 3 groups as follows: group 1 (participants with breast mass size ≥20.0 mm, n=48); group 2 (participants with breast mass size <20.0 mm, n=17); and group 3 (participants with no breast mass, n=23). In groups 1 and 2, on the day of the mammographic imaging study, serum CRP, CEA, and CA 15-3 levels were measured before and after the imaging study. Participants in group 3 had their blood parameters measured without mammography and/or any breast compression. Post-mammography blood measurements displayed a significant increase in serum CRP levels, and a significant decrease in serum CEA and CA 15-3 levels in group 1 (in comparison with the same day pre-mammography blood sampling levels; p<0.05 all). Although pre-mammography serum CEA levels in group 1 participants were significantly higher than those in group 2 and 3 participants, this significant elevation became nonsignificant at post-mammography measurements (p<0.05 and p>0.05, respectively). On the day of the mammographic imaging study, the optimal time of blood sampling for testing CRP, CEA and CA 15-3 levels in persons with a breast mass is before, but not after the mammographic imaging procedure. This issue requires additional detailed studies.

Finite element model of mechanical imaging of the breast

Purpose: Malignant breast lesions can be distinguished from benign lesions by their mechanical properties. This has been utilized for mechanical imaging in which the stress distribution over the breast is measured. Mechanical imaging has shown the ability to identify benign or normal cases and to reduce the number of false positives from mammography screening. Our aim was to develop a model of mechanical imaging acquisition for simulation purposes. To that end, we simulated mammographic compression of a computer model of breast anatomy and lesions. Approach: The breast compression was modeled using the finite element method. Two finite element breast models of different sizes were used and solved using linear elastic material properties in open-source virtual clinical trial (VCT) software. A spherical lesion (15 mm in diameter) was inserted into the breasts, and both the location and stiffness of the lesion were varied extensively. The average stress over the breast and the average stress at the lesion location, as well as the relative mean pressure over lesion area (RMPA), were calculated. Results: The average stress varied 6.2-6.5 kPa over the breast surface and 7.8-11.4 kPa over the lesion, for different lesion locations and stiffnesses. These stresses correspond to an RMPA of 0.80 to 1.46. The average stress was 20% to 50% higher at the lesion location compared with the average stress over the entire breast surface. Conclusions: The average stress over the breast and the lesion location corresponded well to clinical measurements. The proposed model can be used in VCTs for evaluation and optimization of mechanical imaging screening strategies.

VIRTUAL CLINICAL TRIALS IN MEDICAL IMAGING SYSTEM EVALUATION AND OPTIMISATION

Virtual clinical trials (VCTs) can be used to evaluate and optimise medical imaging systems. VCTs are based on computer simulations of human anatomy, imaging modalities and image interpretation. OpenVCT is an open-source framework for conducting VCTs of medical imaging, with a particular focus on breast imaging. The aim of this paper was to evaluate the OpenVCT framework in two tasks involving digital breast tomosynthesis (DBT). First, VCTs were used to perform a detailed comparison of virtual and clinical reading studies for the detection of lesions in digital mammography and DBT. Then, the framework was expanded to include mechanical imaging (MI) and was used to optimise the novel combination of simultaneous DBT and MI. The first experiments showed close agreement between the clinical and the virtual study, confirming that VCTs can predict changes in performance of DBT accurately. Work in simultaneous DBT and MI system has demonstrated that the system can be optimised in terms of the DBT image quality. We are currently working to expand the OpenVCT software to simulate MI acquisition more accurately and to include models of tumour growth. Based on our experience to date, we envision a future in which VCTs have an important role in medical imaging, including support for more imaging modalities, use with rare diseases and a role in training and testing artificial intelligence (AI) systems.

The Role of Liquid Biopsy in Early Diagnosis of Lung Cancer

Liquid biopsy is an emerging technology with a potential role in the screening and early detection of lung cancer. Several liquid biopsy-derived biomarkers have been identified and are currently under ongoing investigation. In this article, we review the available data on the use of circulating biomarkers for the early detection of lung cancer, focusing on the circulating tumor cells, circulating cell-free DNA, circulating micro-RNAs, tumor-derived exosomes, and tumor-educated platelets, providing an overview of future potential applicability in the clinical practice. While several biomarkers have shown exciting results, diagnostic performance and clinical applicability is still limited. The combination of different biomarkers, as well as their combination with other diagnostic tools show great promise, although further research is still required to define and validate the role of liquid biopsies in clinical practice.

Circulating tumor cells in precision oncology: clinical applications in liquid biopsy and 3D organoid model

Circulating tumor cells (CTCs) are a rare subset of cells found in the blood of patients with solid tumors, which function as a seed for metastases. Cancer cells metastasize through the bloodstream either as single migratory CTCs or as multicellular groupings-CTC clusters. The CTCs preserve primary tumor heterogeneity and mimic tumor properties, and may be considered as clinical biomarker, preclinical model, and therapeutic target. The potential clinical application of CTCs is being a component of liquid biopsy. CTCs are also good candidates for generating preclinical models, especially 3D organoid cultures, which could be applied in drug screening, disease modeling, genome editing, tumor immunity, and organoid biobanks. In this review, we summarize current knowledge on the value and promise of evolving CTC technologies and highlight cutting-edge research on CTCs in liquid biopsy, tumor metastasis, and organoid preclinical models. The study of CTCs offers broad pathways to develop new biomarkers for tumor patient diagnosis, prognosis, and response to therapy, as well as translational models accelerating oncologic drug development.

Detection of circulating tumor cells and circulating tumor DNA before and after mammographic breast compression in a cohort of breast cancer patients scheduled for neoadjuvant treatment

PURPOSE

It is not known if mammographic breast compression of a primary tumor causes shedding of tumor cells into the circulatory system. Little is known about how the detection of circulating biomarkers such as circulating tumor cells (CTCs) or circulating tumor DNA (ctDNA) is affected by breast compression intervention.

METHODS

CTCs and ctDNA were analyzed in blood samples collected before and after breast compression in 31 patients with primary breast cancer scheduled for neoadjuvant therapy. All patients had a central venous access to allow administration of intravenous neoadjuvant chemotherapy, which enabled blood collection from superior vena cava, draining the breasts, in addition to sampling from a peripheral vein.

RESULTS

CTC and ctDNA positivity was seen in 26% and 65% of the patients, respectively. There was a significant increase of ctDNA after breast compression in central blood (p = 0.01), not observed in peripheral testing. No increase related with breast compression was observed for CTC. ctDNA positivity was associated with older age (p = 0.05), and ctDNA increase after breast compression was associated with high Ki67 proliferating tumors (p = 0.04). CTCs were more abundant in central compared to peripheral blood samples (p = 0.04).

CONCLUSIONS

There was no significant release of CTCs after mammographic breast compression but more CTCs were present in central compared to peripheral blood. No significant difference between central and peripheral levels of ctDNA was observed. The small average increase in ctDNA after breast compression is unlikely to be clinically relevant. The results give support for mammography as a safe procedure from the point of view of CTC and ctDNA shedding to the blood circulation. The results may have implications for the standardization of sampling procedures for circulating tumor markers.

Clinical applications of the CellSearch platform in cancer patients

The CellSearch® system (CS) enables standardized enrichment and enumeration of circulating tumor cells (CTCs) that are repeatedly assessable via non-invasive "liquid biopsy". While the association of CTCs with poor clinical outcome for cancer patients has clearly been demonstrated in numerous clinical studies, utilizing CTCs for the identification of therapeutic targets, stratification of patients for targeted therapies and uncovering mechanisms of resistance is still under investigation. Here, we comprehensively review the current benefits and drawbacks of clinical CTC analyses for patients with metastatic and non-metastatic tumors. Furthermore, the review focuses on approaches beyond CTC enumeration that aim to uncover therapeutically relevant antigens, genomic aberrations, transcriptional profiles and epigenetic alterations of CTCs at a single cell level. This characterization of CTCs may shed light on the heterogeneity and genomic landscapes of malignant tumors, an understanding of which is highly important for the development of new therapeutic strategies.

Circulating Tumor Cells: Moving Biological Insights into Detection

Circulating tumor cells (CTCs) have shown promising potential as liquid biopsies that facilitate early detection, prognosis, therapeutic target selection and monitoring treatment response. CTCs in most cancer patients are low in abundance and heterogeneous in morphological and phenotypic profiles, which complicate their enrichment and subsequent characterization. Several methodologies for CTC enrichment and characterization have been developed over the past few years. However, integrating recent advances in CTC biology into these methodologies and the selection of appropriate enrichment and characterization methods for specific applications are needed to improve the reliability of CTC biopsies. In this review, we summarize recent advances in the studies of CTC biology, including the mechanisms of their generation and their potential forms of existence in blood, as well as the current CTC enrichment technologies. We then critically examine the selection of methods for appropriately enriching CTCs for further investigation of their clinical applications.

Characteristics of circulating tumor cells in organ metastases, prognosis, and T lymphocyte mediated immune response

Circulating tumor cells (CTCs) possess profound influence on tumor metastases and disease progression. This study aimed to investigate the correlation of CTCs with clinical characteristics and T-cell immunity, and to explore whether CTCs and the subpopulations can serve as an independent prognostic factor in advanced non-small cell lung cancer (NSCLC). A prospective study was conducted in late stages of NSCLC patients. The levels of overall CTCs and the three subpopulation CTCs were enumerated using the CanPatrol™ CTC enrichment system. The information about the patients which included the clinical characteristics, survival status at the 200th day postdiagnosis, and the levels of T cells was collected. Mann–Whitney U test, Kruskal–Wallis H test, Cox regression, and Spearman’s rank correlation coefficient were the statistical methods used in this study. We detected CTCs in 27 of the 31 eligible patients; the level of epithelial–mesenchymal circulating tumor cells (EMCTCs) was higher than that of epithelial circulating tumor cells and that of mesenchymal circulating tumor cells (MCTCs) in the majority of NSCLC patients. Organ metastases were positively associated with the levels of overall CTCs, EMCTCs, and MCTCs (P<0.05). EMCTCs and MCTCs were associated with worse clinical outcomes. Additionally, the levels of EMCTCs were negatively associated with the levels of CD3⁺ T cells (P=0.01) and CD8⁺ T cells (P=0.04). In conclusion, the levels of CTCs were positively associated with organ metastases, particularly bone metastases, but were negatively associated with T-cell levels. The levels of EMCTCs and MCTCs had negative prognostic value.

Can mechanical imaging increase the specificity of mammography screening?

Objectives

This study aimed to investigate the effects of adding adjunct mechanical imaging to mammography breast screening. We hypothesized that mechanical imaging could detect increased local pressure caused by both malignant and benign breast lesions and that a pressure threshold for malignancy could be established. The impact of this on breast screening was investigated with regard to reductions in recall and biopsy rates.

Methods

155 women recalled from breast screening were included in the study, which was approved by the regional ethical review board (dnr 2013/620). Mechanical imaging readings were acquired of the symptomatic breast. The relative mean pressure on the suspicious area (RMPA) was defined and a threshold for malignancy was established.

Results

Biopsy-proven invasive cancers had a median RMPA of 3.0 (interquartile range (IQR) = 3.7), significantly different from biopsy-proven benign at 1.3 (IQR = 1.0) and non-biopsied cases at 1.0 (IQR = 1.3) (P < 0.001). The lowest RMPA for invasive cancer was 1.4, with 23 biopsy-proven benign and 33 non-biopsied cases being below this limit. Had these women not been recalled, recall rates would have been reduced by 36% and biopsy rates by 32%.

Conclusions

If implemented in a screening situation, this may substantially lower the number of false positives.

Key Points

• Mechanical imaging is used as an adjunct to mammography in breast screening.

• A threshold pressure can be established for malignant breast cancer.

• Recalls and biopsies can be substantially reduced.

Raised mammographic density: causative mechanisms and biological consequences

High mammographic density is the most important risk factor for breast cancer, after ageing. However, the composition, architecture, and mechanical properties of high X-ray density soft tissues, and the causative mechanisms resulting in different mammographic densities, are not well described. Moreover, it is not known how high breast density leads to increased susceptibility for cancer, or the extent to which it causes the genomic changes that characterise the disease. An understanding of these principals may lead to new diagnostic tools and therapeutic interventions.

In Vivo Long-Term Monitoring of Circulating Tumor Cells Fluctuation during Medical Interventions

The goal of this research was to study the long-term impact of medical interventions on circulating tumor cell (CTC) dynamics. We have explored whether tumor compression, punch biopsy or tumor resection cause dissemination of CTCs into peripheral blood circulation using in vivo fluorescent flow cytometry and breast cancer-bearing mouse model inoculated with MDA-MB-231-Luc2-GFP cells in the mammary gland. Two weeks after tumor inoculation, three groups of mice were the subject of the following interventions: (1) tumor compression for 15 minutes using 400 g weight to approximate the pressure during mammography; (2) punch biopsy; or (3) surgery. The CTC dynamics were determined before, during and six weeks after these interventions. An additional group of tumor-bearing mice was used as control and did not receive an intervention. The CTC dynamics in all mice were monitored weekly for eight weeks after tumor inoculation. We determined that tumor compression did not significantly affect CTC dynamics, either during the procedure itself (P = 0.28), or during the 6-week follow-up. In the punch biopsy group, we observed a significant increase in CTC immediately after the biopsy (P = 0.02), and the rate stayed elevated up to six weeks after the procedure in comparison to the tumor control group. The CTCs in the group of mice that received a tumor resection disappeared immediately after the surgery (P = 0.03). However, CTC recurrence in small numbers was detected during six weeks after the surgery. In the future, to prevent these side effects of medical interventions, the defined dynamics of intervention-induced CTCs may be used as a basis for initiation of aggressive anti-CTC therapy at time-points of increasing CTC number.

Biology, detection, and clinical implications of circulating tumor cells

Cancer metastasis is the main cause of cancer-related death, and dissemination of tumor cells through the blood circulation is an important intermediate step that also exemplifies the switch from localized to systemic disease. Early detection and characterization of circulating tumor cells (CTCs) is therefore important as a general strategy to monitor and prevent the development of overt metastatic disease. Furthermore, sequential analysis of CTCs can provide clinically relevant information on the effectiveness and progression of systemic therapies (e.g., chemo-, hormonal, or targeted therapies with antibodies or small inhibitors). Although many advances have been made regarding the detection and molecular characterization of CTCs, several challenges still exist that limit the current use of this important diagnostic approach. In this review, we discuss the biology of tumor cell dissemination, technical advances, as well as the challenges and potential clinical implications of CTC detection and characterization.

Risk of breast cancer recurrence in patients receiving manual lymphatic drainage: a hospital-based cohort study

BACKGROUND

This retrospective cohort study evaluated whether manual lymphatic drainage (MLD) therapy increases the risk of recurrence of breast cancer.

METHODS

We analyzed 1,106 women who were diagnosed with stage 0-3 breast cancer between 2007 and 2011 and experienced remission after surgery and adjuvant therapy. The patients were divided into two groups: group A (n=996), in which patients did not participate in any MLD therapy, regardless of whether they developed breast cancer-related lymphedema (BCRL) after cancer treatment; and group B (n=110), in which patients participated in MLD therapy for BCRL. All patients were monitored until October 2013 to determine whether breast cancer recurrence developed, including local or regional recurrence and distant metastasis. Patients who developed cancer recurrence prior to MLD therapy were excluded from analysis. Risk factors associated with cancer recurrence were evaluated using Cox proportional hazards models.

RESULTS

During the monitoring period, 166 patients (15.0%) developed cancer recurrence, including 154 (15.5%) in group A and 12 (10.9%) in group B. The median period from surgery to cancer recurrence was 1.85 (interquartile range 1.18-2.93) years. Independent risk factors for cancer recurrence were tumor histological grading of grade 3, high number (≥3) of axillary lymph node invasion, and a large tumor size (>5 cm). Factors protecting against recurrence were positive progesterone receptor status and receiving radiation therapy. Receiving MLD therapy was not an outcome factor in multivariate analyses (hazard ratio 0.71, 95% confidence interval 0.39-1.29, P=0.259).

CONCLUSION

MLD is a gentle procedure that does not increase the risk of breast cancer recurrence in patients who develop BCRL.

Towards personalized compression in mammography: a comparison study between pressure- and force-standardization

OBJECTIVE

To compare a conventional 14 decanewton (daN) force-standardized compression protocol with a personalized 10kilopascal (kPa) pressure-standardized protocol.

METHODS

A new add-on contact area detector, which enables pressure-standardized compression, is validated in a double-blinded intra-individual comparison study. Breast screening participants (433) received one craniocaudal (CC) and one mediolateral oblique (MLO) compression for both breasts. Three of these compressions were force-standardized, and one, blinded and randomly assigned, was pressure-standardized. Participants scored their pain experience on an 11-point numerical rating scale (NRS). Three experienced breast-screening radiologists, blinded for compression protocol, indicated which images required retakes.

RESULTS

An unanticipated under-compression issue that occurred at forces below 5daN was effectively solved with minimal extra radiographer training during the study. For pressure-standardized compressions obtained at 5daN or more, the compressed breasts thickness increased on average 4.2% (MLO)-6.3% (CC), average pain scores were reduced by 10% (MLO)-17% (CC) and the proportion of women experiencing severe pain (NRS≥7) was reduced by 27% (MLO)-32% (CC), compared with force-standardized compressions (all p-values <0.05). Average glandular dose (AGD) and proportions of retakes were similar for both protocols.

CONCLUSION

Pressure-standardized compressions resulted in AGD values and a retake proportion similar to force-standardized compressions, while pain was significantly reduced.

Tumor cells are dislodged into the pulmonary vein during lobectomy

OBJECTIVE

Intraoperative tumor shedding may facilitate tumor dissemination. In earlier studies, shed tumor cells were defined primarily by cytomorphological examination, and normal epithelial cells could not always be distinguished from tumor cells. We sought to accurately identify tumor cells using single-cell sequencing and determine whether these cells were mobilized into the circulation during pulmonary lobectomy.

METHODS

Forty-two blood samples collected from the tumor-draining pulmonary vein at the end of lobectomy procedures were analyzed. Arrays of nanowells were used to enumerate and retrieve single EpCAM(+) cells. Targeted sequencing of 10 to 15 cells and nested polymerase chain reaction of single cells detected somatic mutations in shed epithelial cells consistent with patient-matched tumor but not normal tissue.

RESULTS

The mean number of EpCAM(+) cells in video-assisted thoracoscopy (VATS) lobectomy (no wedge) specimens (n = 16) was 165 (median, 115; range, 0-509) but sampling cells from 3 patients indicated that only 0% to 38% of the EpCAM(+) cells were tumor cells. The mean number of EpCAM(+) cells in VATS lobectomy (wedge) specimens (n = 12) was 1128 (median, 197; range, 47-9406) and all of the EpCAM(+) cells were normal epithelial cells in 2 patients sampled. The mean number of EpCAM(+) cells in thoracotomy specimens (n = 14) was 238 (median, 22; range, 9-2920) and 0% to 50% of total EpCAM(+) cells were tumor cells based on 4 patients sampled.

CONCLUSIONS

Surgery mobilizes tumor cells into the pulmonary vein, along with many normal epithelial cells. EpCAM alone cannot differentiate between normal and tumor cells. On the other hand, single-cell genetic approaches with patient-matched normal and tumor tissues can accurately quantify the number of shed tumor cells.