Metabolic intratumor heterogeneity of breast cancer

e23095

Background: Breast tumors are highly heterogeneous due to subpopulations of cancer cells that differ in genetic and phenotypic characteristics. Tumor heterogeneity has been associated with treatment resistance and relapse. Therefore, it can be questioned how representative one biopsy is for the whole tumor. Tumor phenotypic heterogeneity cannot be solely attributed to genetic differences, as epigenetics and interaction with the tumor microenvironment also contribute. In this study we have examined intra-tumor heterogeneity by measuring metabolite expression in breast cancer tissue compared with fibroadenomas. Methods: Fresh frozen tissue slices from surgically removed breast tumors were used. Five cores from different areas of the slices were drilled out from 10 tumors; 6 invasive ductal carcinomas grade 2-3, and 4 fibroadenomas. Histological examination of HES-stained sections from each core was done, and metabolic profiling was performed by magnetic resonance spectroscopy (MRS). The relative concentrations of 23 metabolites were quantified. Metabolic heterogeneity was assessed by coefficient of variation (CoV) and PLSDA classification was used for prediction of tumor origin. Results: Cancer tissue showed significantly higher heterogeneity than fibroadenomas for 16/23 metabolites (mean CoV range: 0.15-0.94 for cancer samples, 0.09-0.37 for fibroadenomas, p < 0.05). However, 23/50 samples did not contain tumor tissue on histological examination. After exclusion of tumor-free samples, the heterogeneity of 3 metabolites (glycine, glycerophosphocholine (GPC) and phosphocholine (PCho) remained significantly different between cancer and fibroadenomas (mean CoV range: 0.12-0.65 for cancer, 0.07-0.42 for fibroadenomas, p < 0.05). GPC and PCho are involved in building of cell membranes and may reflect cell-turnover. Multivariate classification could correctly predict which patient a sample belonged to with 78% accuracy. Conclusions: Metabolic heterogeneity could partly be explained by differences in tumor cell and stromal content, and the origin of an unknown sample could be successfully predicted, showing that metabolic intratumor heterogeneity is smaller than the heterogeneity between patients.

Community-Based Health Education has Positive Influence on the Attitude to Cervical Cancer Screening among Women in Rural Nepal

The main purpose of this study was to assess the knowledge of cervical cancer among women in rural Nepal and explore the feasibility and impact of a community-based awareness program on cervical cancer. Community-based educational meetings on cervical cancer and its prevention were conducted among women's groups in rural Nepal. Through a questionnaire, the women's baseline knowledge of risk factors, symptoms, and perceived risk of cervical cancer were identified. The willingness to participate in cervical cancer screening was compared before and after the educational meeting. The meetings were followed by a cervical cancer screening program. Among the 122 participants at the educational meeting, only 6 % had heard of cervical cancer. Their baseline knowledge of risk factors and symptoms was poor. The proportion of women willing to participate in cervical screening increased from 15.6 to 100 % after attending the educational meeting. All the study subjects participated in the screening program. Additionally, the study participants recruited a further 222 of their peers for screening. Poor knowledge of cervical cancer among women in rural Nepal highlights the urgency of public awareness programs for cervical cancer at a national level. A community-based awareness program can change women's attitude to cervical screening, and women's groups can play a major role in promoting participation in cervical cancer screening programs.

Metabolic characterization of triple negative breast cancer

Background

The aims of this study were to characterize the metabolite profiles of triple negative breast cancer (TNBC) and to investigate the metabolite profiles associated with human epidermal growth factor receptor-2/neu (HER-2) overexpression using ex vivo high resolution magic angle spinning magnetic resonance spectroscopy (HR MAS MRS). Metabolic alterations caused by the different estrogen receptor (ER), progesterone receptor (PgR) and HER-2 receptor statuses were also examined. To investigate the metabolic differences between two distinct receptor groups, TNBC tumors were compared to tumors with ER^pos/PgR^pos/HER-2^pos status which for the sake of simplicity is called triple positive breast cancer (TPBC).

Methods

The study included 75 breast cancer patients without known distant metastases. HR MAS MRS was performed for identification and quantification of the metabolite content in the tumors. Multivariate partial least squares discriminant analysis (PLS-DA) modeling and relative metabolite quantification were used to analyze the MR data.

Results

Choline levels were found to be higher in TNBC compared to TPBC tumors, possibly related to cell proliferation and oncogenic signaling. In addition, TNBC tumors contain a lower level of Glutamine and a higher level of Glutamate compared to TPBC tumors, which indicate an increase in glutaminolysis metabolism. The development of glutamine dependent cell growth or “Glutamine addiction” has been suggested as a new therapeutic target in cancer. Our results show that the metabolite profiles associated with HER-2 overexpression may affect the metabolic characterization of TNBC. High Glycine levels were found in HER-2^pos tumors, which support Glycine as potential marker for tumor aggressiveness.

Conclusions

Metabolic alterations caused by the individual and combined receptors involved in breast cancer progression can provide a better understanding of the biochemical changes underlying the different breast cancer subtypes. Studies are needed to validate the potential of metabolic markers as targets for personalized treatment of breast cancer subtypes.

Risk reducing mastectomy, breast reconstruction and patient satisfaction in Norwegian BRCA1/2 mutation carriers

The aim of this study was to evaluate the outcome of risk-reducing mastectomy in BRCA1/2 mutation carriers with and without breast cancer. Uptake, methods of operation and reconstruction, complications, patient satisfaction and histopathological findings were registered at all five departments of genetics in Norway. Data from 267 affected and unaffected BRCA1/2 mutation carriers were analyzed, including a study-specific questionnaire returned by 178 mutation carriers. There was a steady increase in the uptake of risk-reducing mastectomies during the study period. Complications were observed in 106/266 (39.7%) women. Patient satisfaction was high. The majority of women expressed great relief after risk-reducing mastectomy and would have chosen the same option again.

Low-molecular contrast agent dynamic contrast-enhanced (DCE)-MRI and diffusion-weighted (DW)-MRI in early assessment of bevacizumab treatment in breast cancer xenografts

PURPOSE

To investigate the effect of bevacizumab treatment on vascular architecture and function in two xenograft models with different angiogenic properties using diffusion-weighted magnetic resonance imaging (DW-MRI) and dynamic contrast-enhanced MRI (DCE-MRI).

MATERIALS AND METHODS

Mice carrying basal-like (MAS98.12) or luminal-like (MAS98.06) orthotopic breast cancer xenografts were treated with bevacizumab (5 mg/kg), doxorubicin (8 mg/kg), or both drugs in combination. DW-MRI and DCE-MRI were performed before and 3 days after treatment using a Bruker 7T preclinical scanner. Mean microvessel density (MVD) and proliferating microvessel density (pMVD) in the tumors were determined for evaluation of vascular response to bevacizumab treatment.

RESULTS

No changes in DCE-MRI or DW-MRI parameters were observed in untreated controls during the experiment period. DW-MRI showed increased apparent diffusion coefficient (ADC) values in all treatment groups in both basal-like and luminal-like xenografts. DCE-MRI showed increased contrast agent uptake, particularly in central regions of the tumors, after bevacizumab/combination treatment in both xenograft models. This was accompanied by decreased MVD and pMVD in basal-like xenografts. Doxorubicin treatment had no effect on DCE-MRI parameters in any of the xenograft models.

CONCLUSION

Both DW-MRI and DCE-MRI demonstrated an early response to bevacizumab treatment in the xenograft tumors. Increased contrast agent uptake and reduced MVD/pMVD is consistent with a normalization of vascular function.

Predicting long-term survival and treatment response in breast cancer patients receiving neoadjuvant chemotherapy by MR metabolic profiling

PURPOSE

This study aimed to evaluate whether MR metabolic profiling can be used for prediction of long-term survival and monitoring of treatment response in locally advanced breast cancer patients during neoadjuvant chemotherapy (NAC).

METHODS

High resolution magic angle spinning (HR MAS) MR spectra of pre- and post-treatment biopsies from 33 patients were acquired. Tissue concentrations of choline-containing metabolites (tCho), glycine and taurine were assessed using electronic reference to access in vivo concentration (ERETIC) of the signal and receiver operating characteristic (ROC) curves was used to define their potential to predict patient survival and treatment response. The metabolite profiles obtained by HR MAS spectroscopy were related to long-term survival and treatment response by genetic algorithm partial least squares discriminant analysis (GA PLS-DA).

RESULTS

Different pre-treatment MR metabolic profiles characterized by higher levels of tCho and lower levels of lactate were observed in patients with long-term survival (≥5 years, survivors) compared to patients who died of cancer recurrence (<5 years, non-survivors). A significant decrease in glycerophosphocholine (GPC) post-treatment was associated with long-term survival (p = 0.046) and partial response (p = 0.014) to NAC. Long-term survival was best predicted by GPC using ROC analyses (sens. 66.7%, spec. 62.5%), while taurine had the best predictive value of treatment response (sens. 72.7%, spec. 63.2%). GA PLS-DA multivariate classification models successfully discriminated between survivors and non-survivors, resulting in 82.7% and 90.2% cross-validation (CV) classification accuracy, pre- and post-treatment, respectively. Classification of treatment response using GA PLS-DA was not successful for this patient cohort.

CONCLUSIONS

Our results demonstrate that HR MAS MR metabolic profiles consisting of important metabolic characteristics of breast cancer tumors could potentially assist the classification and prediction of long-term survival in locally advanced breast cancer patients, in addition to being used as an adjunct for evaluation of treatment response to NAC.

Prognostic value of metabolic response in breast cancer patients receiving neoadjuvant chemotherapy

BACKGROUND

Today's clinical diagnostic tools are insufficient for giving accurate prognosis to breast cancer patients. The aim of our study was to examine the tumor metabolic changes in patients with locally advanced breast cancer caused by neoadjuvant chemotherapy (NAC), relating these changes to clinical treatment response and long-term survival.

METHODS

Patients (n = 89) participating in a randomized open-label multicenter study were allocated to receive either NAC as epirubicin or paclitaxel monotherapy. Biopsies were excised pre- and post-treatment, and analyzed by high resolution magic angle spinning magnetic resonance spectroscopy (HR MAS MRS). The metabolite profiles were examined by paired and unpaired multivariate methods and findings of important metabolites were confirmed by spectral integration of the metabolite peaks.

RESULTS

All patients had a significant metabolic response to NAC, and pre- and post-treatment spectra could be discriminated with 87.9%/68.9% classification accuracy by paired/unpaired partial least squares discriminant analysis (PLS-DA) (p < 0.001). Similar metabolic responses were observed for the two chemotherapeutic agents. The metabolic responses were related to patient outcome. Non-survivors (< 5 years) had increased tumor levels of lactate (p = 0.004) after treatment, while survivors (≥ 5 years) experienced a decrease in the levels of glycine (p = 0.047) and choline-containing compounds (p ≤ 0.013) and an increase in glucose (p = 0.002) levels. The metabolic responses were not related to clinical treatment response.

CONCLUSIONS

The differences in tumor metabolic response to NAC were associated with breast cancer survival, but not to clinical response. Monitoring metabolic responses to NAC by HR MAS MRS may provide information about tumor biology related to individual prognosis.

Risk of recurrence following delayed large flap reconstruction after mastectomy for breast cancer

BACKGROUND

The aim of this retrospective matched cohort study was to evaluate the rate of recurrence among women with delayed large flap breast reconstruction after mastectomy for breast cancer. The recurrence rate among women treated at a single hospital was compared with that in an individually matched control group of women with breast cancer who did not have reconstruction after mastectomy.

METHODS

Between 1982 and 2001, 125 women with previous invasive breast carcinoma underwent delayed large flap breast reconstruction with pedicled musculocutaneous or microvascular flaps (a median of 32 months after mastectomy). They were matched individually with 182 women with breast cancer who had a mastectomy but did not undergo breast reconstruction. Matching criteria were year of diagnosis, age at diagnosis and treating hospital. Medical records were evaluated until October 2007. Histopathological specimens for all included women were re-evaluated. The endpoint was locoregional or distant breast cancer recurrence. The risk of recurrent disease was calculated using a Cox proportional hazards analysis, adjusted for established prognostic factors.

RESULTS

Median follow-up for the entire cohort was 146 months. The reconstruction group had a 2·08 (95 per cent confidence interval 1·07 to 4·06) times higher risk of recurrent disease than the mastectomy only group.

CONCLUSION

Women with breast cancer who had delayed reconstruction with a large flap in this study had a higher risk of recurrent disease than those with mastectomy alone.

Ki-67 antigen detection in unstained and destained cytologic samples

OBJECTIVE

To evaluate the effect of different tissue preservation, fixation and staining procedures on the expression of proliferation-associated Ki-67 antigen in cytologic samples to establish an easy and uniform way to handle cytologic specimens with an automated staining technique.

STUDY DESIGN

Multiple touch imprints were made from eight breast tumors. The specimens were treated according to different protocols, and Ki-67 nuclear expression was compared to that in the corresponding histologic sections.

RESULTS

In the unstained specimens, air drying at room temperature for up to four months or ethanol spray fixation preserved the material and offered excellent results. Processing effectively removed previous stain without additional chemical destaining. Antigen retrieval was not achieved in the previously Giemsa stained imprints and was suboptimal in those stained according to Papanicolaou.

CONCLUSION

Immunocytochemical detection of Ki-67 is recommended for previously unstained cytologic specimens.

Prognosis of radically operated breast carcinoma patients. A retrospective study of 167 consecutive patients with emphasis on histopathological grading, reproducibility and mean nuclear area

A retrospective study of 167 consecutive radically treated breast cancer patients with histopathologically confirmed ductal carcinoma is presented. The aim was to establish the prognostic significance and reproducibility of histopathological grading done independently by two pathologists. Further-more, the value of measurements of mean nuclear area (MNA) in the primary tumour was assessed. The two pathologists reviewed the same histological sections using a three-point scoring system based on tubular structures, number of mitoses and nuclear pleomorphism. Grading was identical for 70% of the tumours (Kappa value 0.51). With increasing MNA, the fraction of poorly differentiated tumours increased. In the univariate analysis, tumour-related survival was significantly related to histopathological grading when G3 tumours were compared to G1/G2 tumours (p < 0.05). In the multivariate analysis, tumour size (pT category), lymph-node status and grading were the only significant factors influencing patient outcome (p < 0.05). MNA had no significant prognostic value. A combination of tumour size and histopathological grading identifies a group of node-negative patients (pT2 G2/G3) who may have a less favourable prognosis and for whom adjuvant treatment may be beneficial.