Microvascular proliferation in luminal Aand basal-like breast cancer subtypes

Aims: The aims of this study were to examine microvessel density (MVD), proliferating MVD (pMVD) and Vascular Proliferation Index (VPI) in basal-like phenotype (BP) and luminal A subtypes of breast cancer and to study their prognostic value. Methods: Dual-colour immunohistochemistry for von Willebrand factor and Ki67 was done on sections from 62 luminal A and 62 BP tumours matched for grade and selected from 909 breast cancers previously reclassified into molecular subtypes. Associations between MVD, pMVD and VPI, molecular subtypes and breast cancer prognosis were estimated using linear regression and survival analyses. Results: Both pMVD (difference 1.9 microvessels/mm2 (p=0.002)) and VPI (difference 1.7 percentage points (p=0.014)) were higher in BP tumours compared with luminal A. No clear difference between subtypes was found for MVD. However, only MVD was associated with prognosis. HR for breast cancer death for all cases was 1.10 (95% CI 1.02 to 1.18) per 10 vessels increase. Among luminal A tumours, HR was 1.22 per 10 vessels increase (p<0.001) and in BP it was 1.04 (p=0.37). Conclusions: High MVD was associated with poor prognosis in luminal A, but not in BP cancers. Vascular proliferation was higher in BP, indicating a more active angiogenesis than in luminal A tumours. The luminal A subgroup comprised mostly histopathological grade 3 cancers in this selected series, and further studies are needed to clarify whether MVD provides additional prognostic information for luminal A tumours irrespective of grade. This may contribute to stratification of this large group of patients and may aid in identifying tumours with a particularly good prognosis.acceptedVersio

Tumour Vasculature in Subtypes of Breast Cancer

Breast cancer is a group of heterogeneous diseases. Using immunohistochemistry (IHC) and in situ hybridisation (ISH), they can be separated into molecular subtypes with distinct biology and prognosis. The Luminal A subtype has the best prognosis. It is positive for hormone receptors and has little potential for growth and proliferation. Patients with the hormone receptor negative subtypes, the non-luminal, have the poorest prognosis. Nonluminal subtypes are further classified into three groups, depending on their expression of a set of biomarkers (HER2 type, basal phenotype (BP), five-negative phenotype (5NP)). By studying the breast tumour, the Breast Cancer Subtypes (BCS) project aims to increase our understanding of the tumour biology, and to identify prognostic factors, in each molecular subtype. This dissertation is a result of three papers (two are published, one is presented as a manuscript). The work is based on a series of 909 women from Trøndelag county, diagnosed with breast from 1961 to 2008, and followed from the time of diagnosis to 2010. Tumours from these women were previously reclassified into molecular subtypes with IHC and ISH. Access to the vascular network is a prerequisite for tumour growth and metastasis. Angiogenesis, the sprouting of capillaries from existing vessels, is the most well-known mechanism for tumour cells to gain access to blood vessels, where nearby capillaries are stimulated to proliferation and infiltration into the tumour tissue. Microvessel density (MVD) describes the number of vessels in the most vessel-rich tumour region, called the vascular hotspot. MVD is the most commonly used method for vasculature quantification in tumour tissue. However, there are great methodological variations in MVD assessment between studies. This thesis studied three methods for quantifying the vasculature in breast cancer tumour tissue; MVD, described as the average number of vessels/mm2 in the vascular hotspot; proliferating MVD (pMVD), which is the average number of proliferating vessels measured in the same way as MVD; and vascular proliferation index (VPI) is the ratio of pMVD to MVD. In the first study, we compared BP and Luminal A, which are the most biologically distinct subtypes. BP tumours had higher pMVD and VPI than Luminal A, but the point estimate was low. Increased MVD was associated with poor prognosis in all cases combined. However, when separated according to subtype, MVD was a prognostic factor only in the Luminal A. The Luminal A tumours in this study represent a more aggressive subset than Luminal A tumours as a whole, so these results should be validated in a more representative selection of Luminal A tumours. In the second study, we considered MVD, pMVD and VPI in all the non-luminal subtypes. MVD was higher in 5NP tumours compared to both HER2 type and BP. Increasing MVD was associated with poor prognosis in all cases combined, but in analyses of each subtype separately, MVD only provided prognostic information in HER2 type and 5NP. This could imply that MVD is a prognostic factor in some subtypes, but not in others. pMVD and VPI were not associated with prognosis in either of the studies. Our results should be confirmed in a larger sample size. In the third study, we investigated which field area used for MVD assessment that provided the most accurate prognostic information. All cases from the two previous studies were included. Prognostic information became less accurate when a larger field area was included, and the most accurate prognostic information was obtained by including the two visual field with the highest number of vessels only. The results of these studies provide novel information about tumour biology for individual subtypes of breast cancer. They also provide information about prognostic factors in breast cancer, and imply that each subtype may have a different set of prognostic factors. By demonstrating that MVD provided the most accurate prognostic information when using a smaller field area with only the most vessel-dense visual fields, our results could contribute to a more efficient and standardised method for assessment of MVD in breast cancer

Quantifying tumour vascularity in non-luminal breast cancers

Aims: Microvessel density (MVD), proliferating MVD (pMVD) and vascular proliferation index (VPI) are methods used to quantify tumour vascularity in histopathological sections. In this study, we assessed MVD, pMVD and VPI in non-luminal subtypes of breast cancer. Differences between subtypes were studied, and the prognostic value of each method was assessed. Methods: All non-luminal subtypes (61 basal phenotype (BP), 60 human epidermal growth factor receptor 2 (HER2) type and 30 five negative phenotype (5NP)) were selected from a series comprising 909 cases of breast cancer. Sections were stained for Ki67 and von Willebrand factor. Associations between MVD, pMVD and VPI, molecular subtypes and prognosis were studied. Results: MVD was highest in 5NP (Δ54.3 microvessels/mm2 compared with BP, 95% CI 30.3 to 78.3), whereas no clear difference was found between HER2 type and BP (Δ8.8 microvessels/mm2, 95% CI −9.6 to 27.1). pMVD and VPI did not differ between subtypes. For MVD, HR was 1.07 (95% CI 1.03 to 1.11) per 10 vessel increase and 1.9 (95% CI 1.2 to 3.1) if MVD was greater than median value. High MVD was associated with poor prognosis in the HER2 type (HR 1.07 (95% CI 1.02 to 1.12)) and 5NP (HR 1.13 (95% CI 1.03 to 1.23)), but not in BP (HR 1.04 (95% CI 0.94 to 1.14) per 10 vessel increase). pMVD and VPI were not associated with prognosis. Conclusions: MVD appears to be an independent prognostic factor in HER2 and 5NP subtypes of breast cancer, where high MVD is associated with poor survival. MVD was higher in the 5NP compared with both BP and HER2 type

Microvascular proliferation in luminal Aand basal-like breast cancer subtypes

Aims: The aims of this study were to examine microvessel density (MVD), proliferating MVD (pMVD) and Vascular Proliferation Index (VPI) in basal-like phenotype (BP) and luminal A subtypes of breast cancer and to study their prognostic value. Methods: Dual-colour immunohistochemistry for von Willebrand factor and Ki67 was done on sections from 62 luminal A and 62 BP tumours matched for grade and selected from 909 breast cancers previously reclassified into molecular subtypes. Associations between MVD, pMVD and VPI, molecular subtypes and breast cancer prognosis were estimated using linear regression and survival analyses. Results: Both pMVD (difference 1.9 microvessels/mm2 (p=0.002)) and VPI (difference 1.7 percentage points (p=0.014)) were higher in BP tumours compared with luminal A. No clear difference between subtypes was found for MVD. However, only MVD was associated with prognosis. HR for breast cancer death for all cases was 1.10 (95% CI 1.02 to 1.18) per 10 vessels increase. Among luminal A tumours, HR was 1.22 per 10 vessels increase (p<0.001) and in BP it was 1.04 (p=0.37). Conclusions: High MVD was associated with poor prognosis in luminal A, but not in BP cancers. Vascular proliferation was higher in BP, indicating a more active angiogenesis than in luminal A tumours. The luminal A subgroup comprised mostly histopathological grade 3 cancers in this selected series, and further studies are needed to clarify whether MVD provides additional prognostic information for luminal A tumours irrespective of grade. This may contribute to stratification of this large group of patients and may aid in identifying tumours with a particularly good prognosis

Microvascular proliferation in luminal A and basal-like breast cancer subtypes

Aims The aims of this study were to examine microvessel density (MVD), proliferating MVD (pMVD) and Vascular Proliferation Index (VPI) in basal-like phenotype (BP) and luminal A subtypes of breast cancer and to study their prognostic value. Methods Dual-colour immunohistochemistry for von Willebrand factor and Ki67 was done on sections from 62 luminal A and 62 BP tumours matched for grade and selected from 909 breast cancers previously reclassified into molecular subtypes. Associations between MVD, pMVD and VPI, molecular subtypes and breast cancer prognosis were estimated using linear regression and survival analyses. Results Both pMVD (difference 1.9 microvessels/mm2 (p=0.002)) and VPI (difference 1.7 percentage points (p=0.014)) were higher in BP tumours compared with luminal A. No clear difference between subtypes was found for MVD. However, only MVD was associated with prognosis. HR for breast cancer death for all cases was 1.10 (95% CI 1.02 to 1.18) per 10 vessels increase. Among luminal A tumours, HR was 1.22 per 10 vessels increase (p<0.001) and in BP it was 1.04 (p=0.37). Conclusions High MVD was associated with poor prognosis in luminal A, but not in BP cancers. Vascular proliferation was higher in BP, indicating a more active angiogenesis than in luminal A tumours. The luminal A subgroup comprised mostly histopathological grade 3 cancers in this selected series, and further studies are needed to clarify whether MVD provides additional prognostic information for luminal A tumours irrespective of grade. This may contribute to stratification of this large group of patients and may aid in identifying tumours with a particularly good prognosis.acceptedVersion© 2015. This is the authors' accepted and refereed manuscript to the article. The final authenticated version is available online at: http://dx.doi.org/10.1136/jclinpath-2015-20303

The prognostic value of androgen receptors in breast cancer subtypes

Purpose Androgen receptor (AR) expression is frequent in breast cancer and has been associated with good prognosis in several studies. The present study investigates AR-expression in relation to molecular subtypes, clinicopathological features and prognosis in 1297 primary tumours and 336 paired axillary lymph node metastases (LNM) from two cohorts of Norwegian patients. Methods Immunohistochemistry for AR was performed on tumours previously reclassified into molecular subtypes using immunohistochemistry and in situ hybridisation. Associations between AR-expression and clinical features were studied using Chi-square tests. Cumulative incidence of breast cancer death and Cox regression analyses were used to assess prognosis. Results AR-positivity was found in 78.0% of all cases, 84.9% of luminal and 45.1% of non-luminal tumours. The highest proportion of AR-positivity was found in Luminal B tumours, and the lowest in the Basal phenotype. Discordance in AR-status between primary tumours and lymph node metastases was observed in 21.4% of cases. A switch from AR− primary tumour to AR+ lymph node metastasis was seen in 60/72 discrepant cases. AR-expression in primary tumours was an independent and favourable prognostic marker (HR 0.70, 95% CI 0.55–0.90), particularly in the Luminal A subtype, and in grade 3 tumours. Conclusions AR is an independent predictor of good prognosis in BC, particularly in grade 3 and Luminal A tumours. Discordant AR-expression between primary tumour and LNM was observed in 21.4% of cases and most often there was a switch from AR− primary tumour to AR+ axillary LNM