Discordance between PAM50 intrinsic subtyping and immunohistochemistry in South African women with breast cancer.

PURPOSE: Breast cancer is a heterogeneous disease with different gene expression profiles, treatment options and outcomes. In South Africa, tumors are classified using immunohistochemistry. In high-income countries multiparameter genomic assays are being utilized with implications for tumor classification and treatment. METHODS: In a cohort of 378 breast cancer patients from the SABCHO study, we investigated the concordance between tumor samples classified by IHC and the PAM50 gene assay. RESULTS: IHC classified patients as ER-positive (77.5%), PR-positive (70.6%), and HER2-positive (32.3%). These results, together with Ki67, were used as surrogates for intrinsic subtyping, and showed 6.9% IHC-A-clinical, 72.7% IHC-B-clinical, 5.3% IHC-HER2-clinical and 15.1% triple negative cancer (TNC). Typing using the PAM50 gave 19.3% luminal-A, 32.5% luminal-B, 23.5% HER2-enriched and 24.6% basal-like. The basal-like and TNC had the highest concordance, while the luminal-A and IHC-A group had the lowest concordance. By altering the cutoff for Ki67, and realigning the HER2/ER/PR-positive patients to IHC-HER2, we improved concordance with the intrinsic subtypes. CONCLUSION: We suggest that the Ki67 be changed to a cutoff of 20-25% in our population to better reflect the luminal subtype classifications. This change would inform treatment options for breast cancer patients in settings where genomic assays are unaffordable.

FGFR2 genetic variants in women with breast cancer.

Black African populations are more genetically diverse than others, but genetic variants have been studied primarily in European populations. The present study examined the association of four single nucleotide polymorphisms (SNPs) of the fibroblast growth factor receptor 2, associated with breast cancer in non­African populations, with breast cancer in Black, southern African women. Genomic DNA was extracted from whole blood samples of 1,001 patients with breast cancer and 1,006 controls (without breast cancer), and the rs2981582, rs35054928, rs2981578, and rs11200014 polymorphisms were analyzed using allele­specific Kompetitive allele­specific PCR™, and the χ2 or Fisher's exact tests were used to compare the genotype frequencies. There was no association between those SNPs and breast cancer in the studied cohort, although an association was identified between the C/C homozygote genotype for rs2981578 and invasive lobular carcinoma. These results show that genetic biomarkers of breast cancer risk in European populations are not necessarily associated with risk in sub­Saharan African populations. African populations are more heterogenous than other populations, and the information from this population can help focus genetic risks of cancer in this understudied population.

Regional Variation in the Tumor Microenvironment, Immune Escape and Prognostic Factors in Breast Cancer in Sub-Saharan Africa.

The low overall survival rates of patients with breast cancer in sub-Saharan Africa (SSA) are driven by regionally differing tumor biology, advanced tumor stages at diagnosis, and limited access to therapy. However, it is not known whether regional differences in the composition of the tumor microenvironment (TME) exist and affect patients' prognosis. In this international, multicentre cohort study, 1,237 formalin-fixed, paraffin-embedded breast cancer samples, including samples of the "African Breast Cancer-Disparities in Outcomes (ABC-DO) Study," were analyzed. The immune cell phenotypes, their spatial distribution in the TME, and immune escape mechanisms of breast cancer samples from SSA and Germany (n = 117) were investigated using histomorphology, conventional and multiplex IHC, and RNA expression analysis. The data revealed no regional differences in the number of tumor-infiltrating lymphocytes (TIL) in the 1,237 SSA breast cancer samples, while the distribution of TILs in different breast cancer IHC subtypes showed regional diversity, particularly when compared with German samples. Higher TIL densities were associated with better survival in the SSA cohort (n = 400), but regional differences concerning the predictive value of TILs existed. High numbers of CD163+ macrophages and CD3+CD8+ T cells accompanied by reduced cytotoxicity, altered IL10 and IFNγ levels and downregulation of MHC class I components were predominantly detected in breast cancer samples from Western SSA. Features of nonimmunogenic breast cancer phenotypes were associated with reduced patient survival (n = 131). We therefore conclude that regional diversity in the distribution of breast cancer subtypes, TME composition, and immune escape mechanisms should be considered for therapy decisions in SSA and the design of personalized therapies. See related Spotlight by Bergin et al., p. 705.

Ki67 Immunohistochemistry Quantification in Breast Carcinoma: A Comparison of Visual Estimation, Counting, and ImmunoRatio.

BACKGROUND: Molecular analysis has shown that breast carcinomas can be classified into several intrinsic subtypes, with implications for management and prognosis. In the majority of pathology laboratories molecular analysis of each case is not possible and immunohistochemistry is used for subtyping. This includes analysis of hormone receptors as well as HER2-neu and Ki67. The methodology for the interpretation of the proliferation index using Ki67 remains an area of uncertainty. We investigated the degree of agreement between different methods of Ki67 interpretation. MATERIALS AND METHODS: We analyzed 204 breast core biopsies diagnostic of breast carcinoma using visual estimation/eyeballing (EB), ImmunoRatio, and counting by 2 pathologists (CP1 and CP2). The correlation between the different methods and the interobserver agreement between the 2 pathologists was assessed. Specific analysis was also done with respect to classification of cases into low Ki67 groups (using Ki67 values<14% and <20%) since this is critical in classifying tumors into luminal A and luminal B subtypes. RESULTS: Correlation between the different methods was best achieved comparing ImmunoRatio and CP1, and worst comparing CP1 and EB. Correlation was better when considering interobserver variability (CP1 vs. CP2). Comparing the number of cases classified as low Ki67 (<14% and <20%) the Cohen κ statistic varied from κ=0.267 to 0.814 with different methods. When limiting the analysis to cases with a Ki67 of 10% to 25% according to any method, there was greater disagreement. CONCLUSIONS: At the higher and lower Ki67 levels, the correlation between the methods of assessment was acceptable, however, at levels close to the cut-off values for lumial A versus luminal B, several patients would be differently classified by the different methods and therefore potentially receive suboptimal management.

Low-grade squamous intraepithelial lesions among women with HIV.

OBJECTIVES: To assess whether women with HIV who had low-grade squamous intraepithelial lesions (LSIL) on cytology had cervical disease. METHODS: The present retrospective cross-sectional study included data from women with LSIL who attended a tertiary hospital in South Africa between April 1, 2003, and December 31, 2013. Patient information was extracted from a colposcopy database. RESULTS: The study included 652 patients. The median age was 36 years (interquartile range [IQR] 31-42 years; range 18-66 years) and the median parity was three (IQR 2-5; range 0-10). In all, 266 (40.8%) women had a histology result of HPV or cervical intraepithelial neoplasia 1 (CIN1); 386 (59.2%) had a histology result of CIN2 or higher. The median cluster of differentiation 4 (CD4) count was 275.00 cells/mm3 (IQR 173.50-434.00 cells/mm3 ; range 2-1211 cells/mm3 ). A total of 312 (47.9%) women were using antiretroviral therapy. Use of antiretroviral therapy (unadjusted odds ratio 0.57; P=0.001) and a CD4 count of at least 200 cells/mm3 (unadjusted odds ratio 0.81; P=0.002) were associated with a histology result of HPV or CIN1. CONCLUSION: Most of the women with a cytology report of LSIL had CIN2 or higher, suggesting that the practice of referral for colposcopy should continue.

Effect of 2 referral intervals on diagnostic discordance between cytology and histology at a colposcopy clinic.

OBJECTIVE: To determine the effect of the time interval between cervical cytology screening and histology at treatment on grade of cervical disease. METHODS: In a retrospective cross-sectional study at a colposcopy clinic in Soweto, Johannesburg, South Africa, data were compared from women with cytologic abnormalities referred for colposcopy between April 2003 and June 2010 to determine whether early (≤ 180 days) or late (> 180 days) referral had an impact on dysplasia grade. RESULTS: In the early and late referral groups, there were 213 (13.43%) and 201 (14.63%) women, respectively, with upgrading of cervical dysplasia (P=0.35), and 1373 (86.57%) and 1173 (85.37%) women, respectively, with downgrading or no change (P=0.35). Risk factors for upgrading were HIV infection (odds ratio [OR], 1.63; P<0.001) and condom use (OR, 1.30; P=0.02). Four cases (0.68%) of invasion among women with low-grade squamous intraepithelial lesion (LSIL) and 50 cases (2.11%) among women with high-grade SIL (HSIL) were not detected by cytology. Risk factors for invasive disease on histology were age (OR, 1.09 per year; P<0.001), parity (OR, 1.32 per pregnancy; P<0.001), and HSIL on cytology (OR, 3.17; P=0.03). CONCLUSION: There was no difference in the up- or downgrading of cervical dysplasia between the 2 referral groups.