The process of metastasisation for breast cancer

Low serum creatine kinase levels in breast cancer patients: a case-control study

BACKGROUND

Previous studies provide an ambiguous picture of creatine kinase (CK) expression and activities in malignancy. The aim of this study was to investigate the role of serum CK level in breast cancer patients.

PATIENTS AND METHODS

823 female patients diagnosed with breast cancer were consecutively recruited as cases, and 823 age-match patients with benign breast disease were selected as controls. Serum CK was analyzed by commercially available standardized methods.

RESULTS

Serum CK level was significantly associated with breast cancer (P = 0.005) and subtypes of breast cancer, including breast cancer with diameter>2 cm (P = 0.031) and stage IIIbreast cancer (P = 0.025). The mean serum CK level in patients with>2 cm tumor was significantly lower than that in≤2 cm (P = 0.0475), and the mean serum CK level of stage III breast cancer patients was significantly lower than that of stage I and II breast cancer patients (P = 0.0246). Furthermore, a significant difference (P = 0.004) was observed between serum CK level and ERBB2+breast cancer not other molecular subtypes.

CONCLUSIONS

Serum CK levels in cases was significantly lower compared with controls. Notably, our results indicated for the first time that there was a negative correlation between serum CK levels and breast cancer stage. Serum CK level, which may reflect the status of host immunity, may be an important factor in determining breast cancer development and progression.

Markers of circulating breast cancer cells

The detection of circulating tumor cells (CTC) aids in diagnosis of disease, prognosis, disease recurrence, and therapeutic response. The molecular aspects of metastasis are reviewed including its relevance in the identification and characterization of putative markers that may be useful in the detection thereof. Also discussed are methods for CTC enrichment using molecular strategies. The clinical application of CTC in the metastatic disease process is also summarized.

Altered local and systemic immune profiles underlie lymph node metastasis in breast cancer patients

Cancer-mediated immune dysfunction contributes to tumor progression and correlates with patient outcome. Metastasis to tumor draining lymph nodes (TDLNs) is an important step in breast cancer progression and is used to predict patient outcome and survival. Although lymph nodes are important immune organs, the role of immune cells in TDLNs has not been thoroughly investigated. We hypothesized that the host immune response in node negative (NN) patients is more intact and thereby can resist tumor invasion compared to node positive (NP) patients. As such, lymph node metastasis requires breakdown of the host immune response in addition to escape of cancer cells from the tumor. To investigate the immunological differences between NN and NP breast cancer patients, we purified and profiled immune cells from the three major compartments where cancer and immune cells interact: tumor, TDLNs and peripheral blood. Significant down-regulation of genes associated with immune-related pathways and up-regulation of genes associated with tumor-promoting pathways was consistently observed in NP patients' TDLNs compared to NN patients. Importantly, these signatures were seen even in NP patients' tumor-free TDLNs, suggesting that such immune changes are not driven solely by local tumor invasion. Furthermore, similar patterns were also observed in NP patients' tumor and blood immune cells, suggesting that immunological differences between NN and NP patients are systemic. Together, these findings suggest that alterations in overall immune function may underlie risk for LN metastasis in breast cancer patients.

Disseminated breast cancer cells acquire a highly malignant and aggressive metastatic phenotype during metastatic latency in the bone

Background

Disseminated tumor cells (DTCs) in the bone marrow may exist in a dormant state for extended periods of time, maintaining the ability to proliferate upon activation, engraft at new sites, and form detectable metastases. However, understanding of the behavior and biology of dormant breast cancer cells in the bone marrow niche remains limited, as well as their potential involvement in tumor recurrence and metastasis. Therefore, the purpose of this study was to investigate the tumorigenicity and metastatic potential of dormant disseminated breast cancer cells (prior to activation) in the bone marrow.

Methodology/Principal Findings

Total bone marrow, isolated from mice previously injected with tumorspheres into the mammary fat pad, was injected into the mammary fat pad of NUDE mice. As a negative control, bone marrow isolated from non-injected mice was injected into the mammary fat pad of NUDE mice. The resultant tumors were analyzed by immunohistochemistry for expression of epithelial and mesenchymal markers. Mouse lungs, livers, and kidneys were analyzed by H+E staining to detect metastases. The injection of bone marrow isolated from mice previously injected with tumorspheres into the mammary fat pad, resulted in large tumor formation in the mammary fat pad 2 months post-injection. However, the injection of bone marrow isolated from non-injected mice did not result in tumor formation in the mammary fat pad. The DTC-derived tumors exhibited accelerated development of metastatic lesions within the lung, liver and kidney. The resultant tumors and the majority of metastatic lesions within the lung and liver exhibited a mesenchymal-like phenotype.

Conclusions/Significance

Dormant DTCs within the bone marrow are highly malignant upon injection into the mammary fat pad, with the accelerated development of metastatic lesions within the lung, liver and kidney. These results suggest the acquisition of a more aggressive phenotype of DTCs during metastatic latency within the bone marrow microenvironment.

Microfabricated mimics of in vivo structural cues for the study of guided tumor cell migration

Guided cell migration plays a crucial role in tumor metastasis, which is considered to be the major cause of death in cancer patients. Such behavior is regulated in part by micro/nanoscale topographical cues present in the parenchyma or stroma in the form of fiber-like and/or conduit-like structures (e.g., white matter tracts, blood/lymphatic vessels, subpial and subperitoneal spaces). In this paper we used soft lithography micromolding to develop a tissue culture polystyrene platform with a microscale surface pattern that was able to induce guided cell motility along/through fiber-/conduit-like structures. The migratory behaviors of primary (glioma) and metastatic (lung and colon) tumors excised from the brain were monitored via time-lapse microscopy at the single cell level. All the tumor cells exhibited axially persistent cell migration, with percentages of unidirectionally motile cells of 84.0 ± 3.5%, 58.3 ± 6.8% and 69.4 ± 5.4% for the glioma, lung, and colon tumor cells, respectively. Lung tumor cells showed the highest migratory velocities (41.8 ± 4.6 μm h(-1)) compared to glioma (24.0 ± 1.8 μm h(-1)) and colon (26.7 ± 2.8 μm h(-1)) tumor cells. This platform could potentially be used in conjunction with other biological assays to probe the mechanisms underlying the metastatic phenotype under guided cell migration conditions, and possibly by itself as an indicator of the effectiveness of treatments that target specific tumor cell motility behaviors.

The association between psychosocial and medical factors with long-term sexual dysfunction after treatment for colorectal cancer

PURPOSE

Colorectal cancer patients usually receive treatments (e.g., pelvic surgery or radiotherapy, colostomy) that increase their risk for sexual problems. Previous research has mainly focused on demographic and medical risk factors. Because little is known about the role of psychosocial variables in sexual dysfunction, this research sought to identify the contribution of demographic, medical, and psychosocial factors to sexual dysfunction using multivariate analyses.

METHODS

Male and female colorectal cancer survivors (N = 261; mean, 2.5 years post-treatment) completed paper-pencil questionnaires assessing sexual function, psychosocial variables (e.g., depression, social support, body image, and dyadic adjustment), and demographics. Medical information was obtained from patients' self-report and medical records.

RESULTS

Multiple regression analyses revealed that older age, having received destructive surgery (i.e., abdominoperineal resection), and poor social support were uniquely and significantly associated with low international index of erectile function scores in men. For women, low female sexual function index scores were significantly associated with older age and poor global quality of life. Men, but not women, with rectal cancer reported worse sexual function compared to those with colon cancer.

CONCLUSIONS

Sexual dysfunction after colorectal cancer treatment is related to demographic, medical, and psychosocial factors. These associations can help to identify patients at high risk of sexual problems in order to assist restoring sexual functioning if desired.

A dynamic model for tumour growth and metastasis formation

A simple and fast computational model to describe the dynamics of tumour growth and metastasis formation is presented. The model is based on the calculation of successive generations of tumour cells and enables one to describe biologically important entities like tumour volume, time point of 1^st metastatic growth or number of metastatic colonies at a given time. The model entirely relies on the chronology of these successive events of the metastatic cascade. The simulation calculations were performed for two embedded growth models to describe the Gompertzian like growth behaviour of tumours. The initial training of the models was carried out using an analytical solution for the size distribution of metastases of a hepatocellular carcinoma. We then show the applicability of our models to clinical data from the Munich Cancer Registry. Growth and dissemination characteristics of metastatic cells originating from cells in the primary breast cancer can be modelled thus showing its ability to perform systematic analyses relevant for clinical breast cancer research and treatment. In particular, our calculations show that generally metastases formation has already been initiated before the primary can be detected clinically.

Emerging roles of the tumor-associated stroma in promoting tumor metastasis

The stroma in human carcinomas consists of extracellular matrix and various types of non-carcinoma cells, mainly leukocytes, endothelial cells, fibroblasts, myofibroblasts and bone marrow-derived progenitors. The tumor-associated stroma actively supports tumor growth by stimulating neo-angiogenesis, as well as proliferation and invasion of apposed carcinoma cells. It has long been accepted that alterations within carcinoma cells mediate metastasis in a cell-autonomous fashion. Recent studies have, however, suggested an additional notion that cancer cells instigate local and systemic changes in the tumor microenvironment and contribute to niche formation for metastasis. Research, aiming to establish the roles of the tumor-associated stroma in facilitating the spread of carcinoma cells into distant organs, has provided an abundance of data and greater knowledge of the biology of metastatic carcinoma cells and associated stromal cells. This has stimulated further advances in the development of novel therapeutic approaches targeting tumor metastasis.

MYC gene amplification is often acquired in lethal distant breast cancer metastases of unamplified primary tumors

In breast cancer, amplification of MYC is consistently observed in aggressive forms of disease and correlates with poor prognosis and distant metastases. However, to date, a systematic analysis of MYC amplification in metastatic breast cancers has not been reported. Specifically, whether the MYC amplification status may change in metastases in comparison to the corresponding primary breast tumor, and potential variability among different metastases within the same patient have also not been assessed. We generated single patient tissue microarrays consisting of both primary breast carcinomas and multiple matched systemic metastases from 15 patients through our previously described rapid autopsy program. In total, the 15 tissue microarrays contained 145 primary tumor spots and 778 spots derived from 180 different metastases. In addition, two separate tissue microarrays were constructed composed of 10 matched primary breast cancers and corresponding solitary metastases sampled not at autopsy but rather in routine surgical resections. These two tissue microarrays totaled 50 primary tumor spots and 86 metastatic tumor spots. For each case, hormone receptor status, HER2/neu, EGFR and CK5/6 expression were assessed, and the cases were characterized as luminal, basal-like or HER2 based on published criteria. Both fluorescence in situ hybridization and immunohistochemistry for MYC was performed on all cases. Of the 25 cases, 24 were evaluable. While 4 of 24 primary tumors (16%) demonstrated MYC amplification, an additional 6 (25% of total evaluable cases) acquired MYC amplification in their systemic metastases. Of note, there was remarkably little heterogeneity in MYC copy number among different metastases from the same patient. MYC immunoreactivity was increased in metastases relative to matched primaries in the surgical cohort, although there was no perfect correlation with MYC amplification. In conclusion, amplification of MYC is a frequent event in breast cancer, but occurs more frequently as a diffuse, acquired event in metastatic disease than in the corresponding primary. These observations underscore the importance of MYC in breast cancer progression/metastasis, as well as its relevance as a potential therapeutic target in otherwise incurable metastatic disease.

Selectin-deficiency reduces the number of spontaneous metastases in a xenograft model of human breast cancer

Metastasis formation is a complex process still poorly understood. Previous work in a colon cancer xenograft model showed that E(ndothelial) and P(latelet) selectins mediate spontaneous metastasis to the lungs. To investigate the functional role of selectins in breast cancer, human DU4475 breast cancer cells were injected subcutaneously into pfp-/-rag2-/- mice and in all their selectin-deficient variants (EP-/-, E-/- and P-/-). Pfp-/-rag2-/- mice as well as all their selectin-deficient variants developed primary tumours and spontaneous metastases. Compared with the wild-type mice, disseminated tumours cells were significantly lower (74% reduction, P=0.046) in the bone marrow of selectin-deficient mice. Pfp-/-rag2-/- mice developed significantly higher numbers of lung metastases (6644.83±741.77) than the E-/- (4053.33±112.58; P=0.002) and the EP-/- pfp-/-rag2-/- mice (4665.65±754.50; P<0.001). The results indicate that E- and P-selectins play a role in spontaneous metastasis formation both into bone marrow and lungs. However, spontaneous metastasis was not completely abrogated, hence additional cell adhesion molecules must be involved in the metastatic spread.

Metastasis is an early event in mouse mammary carcinomas and is associated with cells bearing stem cell markers

Introduction

It is still uncertain whether metastasis is predominantly an early or late event in tumor progression. The detection of early metastases and cells responsible for the dissemination may therefore have significant clinical implications.

Methods

Lung dissemination and/or metastasis were investigated in mice carrying the polyomavirus middle-T oncogene (PyMT) during different stages of mammary tumorigenesis using the colony forming assay. Immunocytochemical or immunohistochemical staining was used to identify subpopulations of cells responsible for lung dissemination and metastasis. Histological examination was used to show primary and metastatic tumors. The tumor-initiating and metastatic capacity of cells expressing stem cell markers was assessed in syngeneic wild-type (WT) mice whose mammary fat pads were injected with these cells.

Results

Metastatic mammary epithelial cells were detected in the lungs of mice carrying the PyMT oncogene (MMT mice). These cells were observed early in breast tumorigenesis when the mammary tree appeared by histological inspection to be normal (or at a premalignant stage), suggesting the possession of disseminating and metastatic capacity even before full malignant transformation. Some of the disseminated cells and lung metastases displayed surface stem cell markers. These findings suggest that stem cells from apparently precancerous primary lesions could be a source of metastasis. Indeed, injection of lung tissue cells from MMT mice into syngeneic WT mice resulted in the formation of mammary tumors. These tumors resembled their parent mammary tumors in the MMT donors as well as grafted tumors derived from mammary tumor cells. Furthermore, when we injected lung tissue cells from GFP MMT mice into the fat pads of recipient WT mice, disseminated or metastatic GFP-expressing cells were detected in the lungs, lymph nodes and blood of the recipient WT mice. We finally identified a subpopulation of mammary epithelial/tumor cells expressing CD44 and Sca1 that was largely responsible for dissemination and metastasis in MMT mice.

Conclusions

The tumorigenic and metastatic potential of a subpopulation of mammary epithelial/tumor cells in MMT mice is endowed relatively early in mammary neoplasms and suggests a potential role for cancer stem cell sub-populations in metastasis.

Why mammography screening has not lived up to expectations from the randomised trials

We analysed the relation between tumour sizes and stages and the reported effects on breast cancer mortality with and without screening in trials and observational studies. The average tumour sizes in all the trials suggest only a 12% reduction in breast cancer mortality, which agrees with the 10% reported in the most reliable trials. Recent studies of tumour sizes and tumour stages show that screening has not lowered the rate of advanced cancers. In agreement with this, recent observational studies of breast cancer mortality have failed to find an effect of screening. In contrast, screening leads to serious harms in healthy women through overdiagnosis with subsequent overtreatment and false-positive mammograms. We suggest that the rationale for breast screening be urgently reassessed by policy-makers. The observed decline in breast cancer mortality in many countries seems to be caused by improved adjuvant therapy and breast cancer awareness, not screening. We also believe it is more important to reduce the incidence of cancer than to detect it 'early.' Avoiding getting screening mammograms reduces the risk of becoming a breast cancer patient by one-third.

True local recurrences do not metastasize

Generally, the limits of local tumor control are in part connected with the term "field cancerization" and are known from oral, lung, prostate, or mammary cancer. With the example of breast cancer (BC), the problem of ipsilateral breast tumor recurrences (IBTR) after breast-conserving surgery will be reviewed. Three types of local recurrences are distinguished: true recurrences, new primaries, or residual tumors. Good data for BC allow the description of the time-dependent risk of these three types, relative to the diagnosis of the primary tumor, because the time of initiation and the growth duration of the IBTR can be estimated. Two hypotheses explain the data: first, local recurrences may be initiated years before the diagnosis of a primary tumor (PT) and can then appear as multifocal PT at diagnosis, and second, true local recurrences probably do not metastasize. The generalizability of these hypotheses for other tumors will be discussed.

Effect of very small tumor size on cancer-specific mortality in node-positive breast cancer

PURPOSE

Traditionally, larger tumor size and increasing lymph node (LN) involvement have been considered independent predictors of increased breast cancer-specific mortality (BCSM). We sought to characterize the interaction between tumor size and LN involvement in determination of BCSM. In particular, we evaluated whether very small tumor size may predict for increased BCSM relative to larger tumors in patients with extensive LN involvement.

PATIENTS AND METHODS

Using Surveillance, Epidemiology and End Results registry data, we identified 50,949 female patients diagnosed between 1990 and 2002 with nonmetastatic T1/T2 invasive breast cancer treated with surgery and axillary LN dissection. Primary study variables were tumor size, degree of LN involvement, and their corresponding interaction term. Kaplan-Meier methods, adjusted Cox proportional hazards models with interaction terms, and a linear trend test across nodal categories were performed.

RESULTS

Median follow-up was 99 months. In multivariable analysis, there was significant interaction between tumor size and LN involvement (P < .001). Using T1aN0 as reference, T1aN2+ conferred significantly higher BCSM compared with T1bN2+ (hazard ratio [HR], 20.66 v 12.53; P = .02). A similar pattern was seen among estrogen receptor (ER) -negative patients with T1aN2+ compared with T1bN2+ (HR, 24.16 v 12.67; P = .03), but not ER-positive patients (P = .52). The effect of very small tumor size on BCSM was intermediate among N1 cancers, between that of N0 and N2+ cancers.

CONCLUSION

Very small tumors with four positive LNs may predict for higher BCSM compared with larger tumors. In extensive node-positive disease, very small tumor size may be a surrogate for biologically aggressive disease. These results should be validated in future database studies.

Consensus recommendations for advancing breast cancer: risk identification and screening in ethnically diverse younger women

A need exists for a breast cancer risk identification paradigm that utilizes relevant demographic, clinical, and other readily obtainable patient-specific data in order to provide individualized cancer risk assessment, direct screening efforts, and detect breast cancer at an early disease stage in historically underserved populations, such as younger women (under age 40) and minority populations, who represent a disproportionate number of military beneficiaries. Recognizing this unique need for military beneficiaries, a consensus panel was convened by the USA TATRC to review available evidence for individualized breast cancer risk assessment and screening in young (< 40), ethnically diverse women with an overall goal of improving care for military beneficiaries. In the process of review and discussion, it was determined to publish our findings as the panel believes that our recommendations have the potential to reduce health disparities in risk assessment, health promotion, disease prevention, and early cancer detection within and in other underserved populations outside of the military. This paper aims to provide clinicians with an overview of the clinical factors, evidence and recommendations that are being used to advance risk assessment and screening for breast cancer in the military.

Local recurrence after breast cancer affects specific survival differently according to patient age

PURPOSE

Young age is known to be an independent factor for developing local recurrence (LR) in breast cancer patients. It has also been shown that the occurrence of LR negatively affects patient outcome, especially if LR occurs within 3 years after treatment of the primary tumour. The question whether the impact of LR on patient outcome differs according to the patient's age has not been addressed before. The purpose of the present study is to investigate cancer-specific survival (CSS) as well as overall survival after LR in young patients (<50 years old) and to compare it to older patients. The age cut-off level was taken as 50 to avoid strong imbalance in patient numbers between the 2 groups.

PATIENTS AND METHODS

Between 1974 and 2003, 2,130 breast cancer patients were treated with conservative surgery and axillary dissection. All of them received post-operative radiotherapy. Adjuvant chemo- and/or hormonal therapy was given according to the prognostic factors and the treatment policy at the time of diagnosis. Only biopsy-confirmed ipsilateral LRs were taken into account. Early LRs were those observed within 36 months after surgery, and late LRs were those which occurred thereafter. The median follow-up was 100 months. Survival analysis was conducted with the Kaplan-Meier method.

RESULTS

The median age was 59 years. There were 472 patients aged <50 years versus 1,658 older patients. Pathological tumour size, hormone receptor status and lymph node involvement were evenly distributed in the 2 groups. The 5- and 10-year CSS was 92.3 and 83.9% in young patients, and 94.4 and 87.6% in older patients (p = 0.061), respectively. Overall, 200 LRs were observed; 52 of them (26%) were early LRs. The rate of LR was significantly higher in young patients: at 5 years, it was 10.5 versus 3.7% in patients ≥50 years; the respective rates at 10 years were 17.8 and 8.8% (p < 0.0001). The 5- and 10-year CSS in patients who developed LR was 86.8 and 76.0%, versus 94.7 and 88.2% in patients who did not develop LR (p < 0.0001). The 5-year CSS after LR in young and older patients was 77.6 and 65.7%, respectively (p = 0.028).

CONCLUSION

Although young patients experience more LR than older ones, once LR occurs, young patients have a better outcome than the others. Possible hypotheses are: (1) more aggressive treatment in young patients after LR; (2) the treatment is better sustained in young patients; (3) biological differences in the characteristics of LR.

Distant metastases do not metastasize

Distant metastases (MET) are for most solid cancers decisive life-threatening events. Data about MET-free survival and survival after MET show a strong dependency on the kind of cancer and the prognostic features. Nonetheless, within biological subgroups, the MET process is very homogenous. Therefore, the growth rate can be estimated from initiation of MET to MET diagnosis and to time of death. Based on the known volume doubling time of breast cancer, the time of the first possible dissemination can also be estimated. Important consequences of these MET-initiation estimates are the hypotheses that almost all MET are initiated before removal of the primary tumor and that MET do not metastasize in a clinically relevant magnitude. Although breast cancer data were primarily used to form these hypotheses, the discussed MET process can be generalized to all solid cancers. The impact of these hypotheses on diagnostic, curative and palliative treatment, aftercare, and especially on clinical research would be important.

Unfavourable pattern of metastases in M0 breast cancer patients during 1978-2008: a population-based analysis of the Munich Cancer Registry

Little is known about time trends in metastases in the patients treated in routine health care facilities without metastases at diagnosis (M0) and about survival after these metastases. Data on 33,771 M0 patients with primary breast cancer diagnosed between 1978 and 2003 were obtained from the Munich Cancer Registry. Survival analyses were restricted to the patients with metastases within 5 years of the initial diagnosis. The incident number of the patients approximately doubled each period and 5-year overall survival increased from 77% in the first to 82% percent in the last period. 5490 (16%) M0 patients developed metastases within 5 years after the initial diagnosis. The hazard of developing metastases was lowest in the most recent period compared to the first period (HR = 0.50, P < 0.001). The hazard of dying after metastases was equal for patients diagnosed between 1978-1984 and 1995-2003 (HR 1.08, P = 0.3). The percentage of the patients that developed bone metastases decreased each time period, but the percentage primary liver and CNS metastases increased. Exclusion of site of metastases in the multivariate analysis led to a 20% (P = 0.02) higher hazard of dying following metastases in the last versus the first period. In the period 1978-2008, unfavourable changes in the pattern of metastases were exhibited and no improvement was observed in survival of the patients after occurrence of metastases. An explanation might be the increased use of adjuvant systemic treatment, which has less effect on the highly lethal liver and CNS metastases than on bone metastases. The increased use also appeared to contribute to the overall prevention of metastases in breast cancer and therefore to improve overall survival.

Alpha- and beta-adrenergic receptor (AR) protein expression is associated with poor clinical outcome in breast cancer: an immunohistochemical study

Breast cancer mortality is frequently associated with metastatic disease. Metastasis models have shown adrenoceptor (AR) stimulation induces cell migration which is inhibited by adrenoceptor antagonist drugs. We investigated adrenoceptor protein expression in clinical breast tumours and its association with disease progression and prognosis. Immunohistochemistry on tissue microarrays was used to characterise α1b, α2c and β(2)2 adrenoceptor protein expression in operable breast tumours. Associations with tumour-relevant biological markers and clinical outcome were statistically assessed. Strong α1b expression occurred in large high grade (P < 0.0001), HER2+ (P < 0.0001) or basal-like (CK5/6, P = 0.0005; CK14, P = 0.0001; EGFR, P = 0.003) cancers, showing increased proliferation (Mib1, P = 0.002), decreased apoptosis (Bcl2, P < 0.0001) and poor NPI membership (P = 0.001). α1b expression correlated with poor cancer-specific survival (LR = 7.628, P = 0.022) and tumour recurrence (LR = 6.128, P = 0.047). Strong α2c was over-expressed in high grade (P = 0.007), HER3+ (P = 0.002) and HER4+ (P < 0.0001) cancers with borderline increase in EGFR, p53 and MIB1 proteins, and inverse association with hormonal (PgR, P = 0.002) phenotype. In contrast, strong β(2) expression occurred in small-size, luminal-like (ER+, P < 0.001) tumours of low grade (P < 0.001) and lymph node stage (P = 0.027) that showed poor prognosis when hormonal treatment was withheld. Adrenoceptors were not found to be independent predictors of clinical outcome. Alpha1b and α2c AR is over-expressed in basal-like breast tumours of poor prognosis. Strong β(2) adrenoceptor expression is seen in patients with a luminal (ER+) tumour phenotype and good prognosis, due to benefits derived from hormonal therapy. These findings suggest a possible role for targeted therapy using adrenoceptor antagonists.

Cx43 suppresses mammary tumor metastasis to the lung in a Cx43 mutant mouse model of human disease

Gap junctions, the channels formed by the connexin (Cx) family of proteins, are responsible for direct intercellular communication. Although connexins are considered as tumor suppressors, their overall role in cancer onset, progression and metastasis is somewhat controversial. This study uses a novel Cx43 mutant mouse model (G60S mice) and cross-breeding strategies to determine the role of Cx43 in all stages of breast tumorigenesis. G60S mice were cross-bred with ErbB2 overexpressing mice, and spontaneous and 7,12-dimethylbenz[α]anthracene (DMBA)-induced tumor development was evaluated. Mice were killed when tumors reached ∼1 cm(3) or when mice showed signs of critical illness. In both spontaneous and DMBA studies, onset of palpable tumors was delayed in G60S mice compared with mice in control groups. Moreover, while tumors from control mice reached the size threshold, most DMBA-exposed Cx43 mutant mice were killed prematurely because of labored breathing, independent of the presence of a palpable tumor. Reduced Cx43 levels in Cx43 mutant mice were accompanied by extensive mammary gland hyperplasia. Lung histology revealed that all Cx43 mutant mice exhibited mammaglobin-positive mammary gland metastases to the lung, and the number of metastases was increased by threefold in Cx43 mutant mice on treatment with DMBA. Thus, while reduced levels of Cx43 delayed the onset of palpable tumors, normal Cx43 levels inhibited mammary gland tumor metastasis to the lungs. Understanding the mechanisms of how Cx43, which is expressed primarily in myoepithelial cells, inhibits mammary gland tumor metastasis is critical as Cx43 is assessed as a candidate for therapeutic intervention.

AACR centennial series: the biology of cancer metastasis: historical perspective

Metastasis resistant to therapy is the major cause of death from cancer. Despite almost 200 years of study, the process of tumor metastasis remains controversial. Stephen Paget initially identified the role of host-tumor interactions on the basis of a review of autopsy records. His "seed and soil" hypothesis was substantiated a century later with experimental studies, and numerous reports have confirmed these seminal observations. An improved understanding of the metastatic process and the attributes of the cells selected by this process is critical for the treatment of patients with systemic disease. In many patients, metastasis has occurred by the time of diagnosis, so metastasis prevention may not be relevant. Treating systemic disease and identifying patients with early disease should be our goal. Revitalized research in the past three decades has focused on new discoveries in the biology of metastasis. Even though our understanding of molecular events that regulate metastasis has improved, the contributions and timing of molecular lesion(s) involved in metastasis pathogenesis remain unclear. Review of the history of pioneering observations and discussion of current controversies should increase understanding of the complex and multifactorial interactions between the host and selected tumor cells that contribute to fatal metastasis and should lead to the design of successful therapy.

AACR centennial series: the biology of cancer metastasis: historical perspective

Metastasis resistant to therapy is the major cause of death from cancer. Despite almost 200 years of study, the process of tumor metastasis remains controversial. Stephen Paget initially identified the role of host-tumor interactions on the basis of a review of autopsy records. His "seed and soil" hypothesis was substantiated a century later with experimental studies, and numerous reports have confirmed these seminal observations. An improved understanding of the metastatic process and the attributes of the cells selected by this process is critical for the treatment of patients with systemic disease. In many patients, metastasis has occurred by the time of diagnosis, so metastasis prevention may not be relevant. Treating systemic disease and identifying patients with early disease should be our goal. Revitalized research in the past three decades has focused on new discoveries in the biology of metastasis. Even though our understanding of molecular events that regulate metastasis has improved, the contributions and timing of molecular lesion(s) involved in metastasis pathogenesis remain unclear. Review of the history of pioneering observations and discussion of current controversies should increase understanding of the complex and multifactorial interactions between the host and selected tumor cells that contribute to fatal metastasis and should lead to the design of successful therapy.

On the theory of tumor self-seeding: implications for metastasis progression in humans

Metastasis remains the leading cause of death among cancer patients because few effective treatment options are available. A recent paper proposes a new twist on metastasis. The paper shows that circulating tumor cells can return to the primary tumor, a process termed tumor self-seeding or cross-seeding, and that this helps breeding tumor cells that give rise to aggressive metastatic variants. A viewpoint presented here addresses the implications of these studies for human cancer metastasis.

Molecular MRI for sensitive and specific detection of lung metastases

Early and specific detection of metastatic cancer cells in the lung (the most common organ targeted by metastases) could significantly improve cancer treatment outcomes. However, the most widespread lung imaging methods use ionizing radiation and have low sensitivity and/or low specificity for cancer cells. Here we address this problem with an imaging method to detect submillimeter-sized metastases with molecular specificity. Cancer cells are targeted by iron oxide nanoparticles functionalized with cancer-binding ligands, then imaged by high-resolution hyperpolarized (3)He MRI. We demonstrate in vivo detection of pulmonary micrometastates in mice injected with breast adenocarcinoma cells. The method not only holds promise for cancer imaging but more generally suggests a fundamentally unique approach to molecular imaging in the lungs.

Changes in circulating tumor cell detection in patients with localized breast cancer before and after surgery

BACKGROUND

Few data exist on the potential role of circulating tumor cells (CTCs) in patients with operable breast cancer. If the presence of CTCs in early breast cancer could predict an increased risk for relapse, it might be an early marker for treatment efficacy and could help in deciding treatment continuation.

METHODS

Thirty milliliters of peripheral blood was taken from 56 breast cancer patients before surgery and again 5 days after surgery, and the presence of CTCs was evaluated. In case of positivity of one of the perioperative samples, another sample was taken after 30 days. The presence of CTCs was assessed with the CellSearch System (Veridex, Warren, NJ).

RESULTS

One to three CTCs were found in 16 (29%) of 56 patients before surgery, in 14 (30%) of 47 patients at day 5, and in 8 (30%) of 27 at day 30. No association with pathological characteristics was found, apart a borderline significant association between presence of CTCs at baseline and vascular invasion (P = 0.07). When we looked at concordance between CTCs at baseline and after day 5 (47 patients), we found 40% discordant samples (10 negative at baseline and positive at day 5, and 9 vice versa).

CONCLUSIONS

This study provides evidence of the presence of CTCs in approximately 30% of patients with localized breast cancer both before and after surgery, with change from positive to negative and vice versa in 40% of cases. No association with the pathological variables was found, except for vascular invasion and presence of preoperative CTCs. Long-term follow-up will be required to understand the significance of these data.

Clinical relevance associated to the analysis of circulating tumour cells in patients with solid tumours

The distant growth of tumour cells escaping from primary tumours, a process termed metastasis, represents the leading cause of death among patients affected by malignant neoplasias from breast and colon. During the metastasis process, cancer cells liberated from primary tumour tissue, also termed circulating tumour cells (CTCs), travel through the circulatory and/or lymphatic systems to reach distant organs. The early detection and the genotypic and phenotypic characterisation of such CTCs could represent a powerful diagnostic tool of the disease, and could also be considered an important predictive and prognostic marker of disease progression and treatment response. In this article we discuss the potential relevance in the clinic of monitoring CTCs from patients suffering from solid epithelial tumours, with emphasis on the impact of such analyses as a predictive marker for treatment response.

SIK1 couples LKB1 to p53-dependent anoikis and suppresses metastasis

Resistance to anoikis, the subtype of apoptosis triggered by lack of adhesion, contributes to malignant transformation and the development of metastasis. Although several lines of evidence suggest that p53 plays a critical role in anoikis, the pathway(s) that connect cell detachment to p53 remain undefined. Here, through the use of a kinome-wide loss-of-function screen, we identify the serine-threonine kinase SIK1 (salt-inducible kinase 1) as a regulator of p53-dependent anoikis. Inactivation of SIK1 compromised p53 function in anoikis and allowed cells to grow in an anchorage-independent manner. In vivo, SIK1 loss facilitated metastatic spread and survival of disseminated cells as micrometastases in lungs. The presence of functional SIK1 was required for the activity of the kinase LKB1 in promoting p53-dependent anoikis and suppressing anchorage-independent growth, Matrigel invasion, and metastatic potential. In human cancers, decreased expression of the gene encoding SIK1 closely correlated with development of distal metastases in breast cancers from three independent cohorts. Together, these findings indicate that SIK1 links LKB1 to p53-dependent anoikis and suppresses metastasis.

The role of HER2 in early breast cancer metastasis and the origins of resistance to HER2-targeted therapies

The HER2 gene encodes the receptor tyrosine kinase HER2 and is often over-expressed or amplified in breast cancer. Up-regulation of HER2 contributes to tumor progression. Many aspects of tumor growth are favorably affected through activation of HER2 signaling. Indeed, HER2 plays a role in increasing proliferation and survival of the primary tumor and distant lesions which upon completion of full transformation cause metastases. P185(HER2/neu) receptors and signaling from them and associated molecules increase motility of both intravasating and extravasating cells, decrease apoptosis, enhance signaling interactions with the microenvironment, regulate adhesion, as well as a multitude of other functions. Recent experimental and clinical evidence supports the view that the spread of incompletely transformed cells occurs at a very early stage in tumor progression. This review concerns the identification and characterization of HER2, the evolution of the metastasis model, and the more recent cancer stem cell model. In particular, we review the evidence for an emerging mechanism of HER2(+) breast cancer progression, whereby the untransformed HER2-expressing cell shows characteristics of stem/progenitor cell, metastasizes, and then completes its final transformation at the secondary site.

Learning therapeutic lessons from metastasis suppressor proteins

Metastasis suppressor proteins regulate multiple steps in the metastatic cascade, including cancer cell invasion, survival in the vascular and lymphatic circulation, and colonization of distant organ sites. Understanding the biology of metastasis suppressors provides valuable mechanistic insights that may translate to therapeutic opportunities. Several reports have explored novel strategies for restoring metastasis suppressor function, including gene transfer, induction of previously suppressed gene expression and exogenous administration of gene product. Pathways activated downstream of metastasis suppressor loss can also be targeted. Although none of these strategies are yet in routine clinical use, several are being tested preclinically and in clinical trials.

Parallel progression of primary tumours and metastases

Systemic cancer progression is accounted for in two basic models. The prevailing archetype places the engine of cancer progression within the primary tumour before metastatic dissemination of fully malignant cells. The second posits parallel, independent progression of metastases arising from early disseminated tumour cells. This Perspective draws together data from disease courses, tumour growth rates, autopsy studies, clinical trials and molecular genetic analyses of primary and disseminated tumour cells in support of the parallel progression model. Consideration of this model urges review of current diagnostic and therapeutic routines.

Microenvironmental regulation of metastasis

Metastasis is a multistage process that requires cancer cells to escape from the primary tumour, survive in the circulation, seed at distant sites and grow. Each of these processes involves rate-limiting steps that are influenced by non-malignant cells of the tumour microenvironment. Many of these cells are derived from the bone marrow, particularly the myeloid lineage, and are recruited by cancer cells to enhance their survival, growth, invasion and dissemination. This Review describes experimental data demonstrating the role of the microenvironment in metastasis, identifies areas for future research and suggests possible new therapeutic avenues.

Cyclophosphamide promotes pulmonary metastasis on mouse lung adenocarcinoma

Cyclophosphamide (CTX), as a common use of chemotherapeutic agent, has some side effects in clinical treatment. In our experiments, we studied CTX-treated T739 mice using histopathology, immunohistochemistry, reverse transcription polymerase chain reaction and Western blot for markers of proliferation, angiogenesis, tumor progression and distant metastasis. As a result, CTX increased the number and area of metastases and tumor embolus in lungs by effecting on the expression of matrix metalloproteinase-2, intercellular adhesion molecule-1 and tissue inhibitor of metalloproteinase-2. Taken together, it indicated that CTX enhanced the process of pulmonary metastasis by the synergistic effect of matrix-degrading proteases and adhesion proteins.

Systemic spread is an early step in breast cancer

It is widely accepted that metastasis is a late event in cancer progression. Here, however, we show that tumor cells can disseminate systemically from earliest epithelial alterations in HER-2 and PyMT transgenic mice and from ductal carcinoma in situ in women. Wild-type mice transplanted with single premalignant HER-2 transgenic glands displayed disseminated tumor cells and micrometastasis in bone marrow and lungs. The number of disseminated cancer cells and their karyotypic abnormalities were similar for small and large tumors in patients and mouse models. When activated by bone marrow transplantation into wild-type recipients, 80 early-disseminated cancer cells sufficed to induce lethal carcinosis. Therefore, release from dormancy of early-disseminated cancer cells may frequently account for metachronous metastasis.

Trends in the prognosis of patients with primary metastatic breast cancer diagnosed between 1975 and 2002

We performed a population-based study, including 1089 patients with primary metastatic breast cancer, diagnosed in South-East Netherlands between 1975 and 2002, and tried to give an answer to the question if prognosis of this patient group has improved or not. Follow-up was completed until 1 January 2005. The median survival times for patients with primary metastatic disease were 18, 17 and 20.5 months for patients diagnosed in the periods 1975-1984, 1985-1994 and 1995-2002, respectively. A multivariate analysis, including age, tumour size and information on the localization of metastatic disease and the number of metastatic sites, showed that patients diagnosed in the period 1995-2002 had a 18% lower death risk (95% confidence interval 5-30) compared to those diagnosed in the period 1985-1994. These data show that the prognosis of patients with primary metastatic breast cancer remained unchanged between 1975 and 1994 and that some progress has been made after 1994.

Routine Histologic Examination of 728 Mastectomy Scars: Did It Benefit Our Patients?

BACKGROUND

Routine histologic examination of secondarily excised mastectomy scars is considered good practice, even though the microscopic detection of a metastasis in clinically unsuspected mastectomy scars is rare. Because cost-effective use of histologic services is required, the occurrence rate of metastases in such scars needs to be established to assess the possible benefit of such routine examination.

METHODS

The histologic observations on 728 clinically unsuspected scars from prophylactic (n = 151) or curative (n = 395) mastectomy or breast-conservation treatment in 424 patients were traced and correlated to the indication of initial breast surgery, possible adjuvant therapy, and time lapse between initial surgery and scar examination.

RESULTS

In none of the 728 scars was a scar metastasis or de novo tumor found.

CONCLUSIONS

Routine histologic examination of clinically unsuspected scars excised at the time of breast reconstruction or scar correction after prophylactic or curative breast surgery did not benefit the authors' patients.