Tissue microarrays (TMAs) are potentially suited to find associations between molecular features and clinical outcome. Enhanced cell proliferation, as measured by Ki67 immunohistochemistry, is related to poor patient prognosis in many different tumor types. Ki67 expression shows considerable intratumoral heterogeneity. It is unclear if the TMA format is suitable for the analysis of potentially heterogeneous markers because of the small size of TMA spots. We have analyzed a breast cancer TMA containing 2,517 breast tissues, including 2,222 neoplastic and 295 normal or premalignant samples, for Ki67 labeling index (Ki67 LI) and additional markers with a known relationship to Ki67 LI by immunohistochemistry (ER, PR, Bcl-2, Egfr, p16, p53) and Fluorescence in situ hybridization (HER2, MDM2, CCND1, MYC). A high Ki67 LI was linked to tumor phenotype including grade (p < 0.0001), stage (p < 0.0001), nodal stage (p = 0.0018), and patient prognosis (p < 0.0001), elevated protein levels of p53, p16 and Egfr, reduced levels of Bcl2, ER, and PR (p < 0.0001 each), as well as amplifications of HER2, MYC, CCND1 and MDM2 (p < 0.0001 each). In summary, all expected associations between Ki67 and the analyzed molecular markers could be reproduced with high statistical significance using a TMA containing only one tissue sample per tumor, measuring 0.6 mm in diameter. We conclude that associations with cell proliferation can be reliably analyzed in a TMA format.

BackgroundInfectious diseases are the leading cause of hospital admissions in young children. Hospitalisation with an infectious disease is a recurrent event for some children. Our objective was to describe risk factors for infectious disease readmission following hospital admission with an infectious disease in the first two years of life.MethodsWe performed a national cohort study of New Zealand children, born 2005–2009, with an infectious disease admission before age 24 months. Children readmitted with an infectious disease within 12 months of the first infectious disease admission were identified. Every infectious disease admission was categorised as a respiratory, enteric, skin and soft tissue, urinary or other infection. Independent associations of demographic and child health factors with infectious disease readmission were determined using multiple variable logistic regression.ResultsFrom 2005 to 2011, there were 69,902 infectious disease admissions for 46,657 children less than two years old. Of these 46,657 children, 10,205 (22%) had at least one infectious disease readmission within 12 months of their first admission. The first infectious disease admission was respiratory (54%), enteric (15%), skin or soft tissue (7%), urinary (4%) or other (20%). Risk of infectious disease readmission was increased if the first infectious disease admission was respiratory (OR = 1.87, 95% CI 1.78–1.95) but not if it was in any other infectious disease category.Risk factors for respiratory infectious disease readmission were male gender, Pacific or Māori ethnicity, greater household deprivation, presence of a complex chronic condition, or a first respiratory infectious disease admission during autumn or of ≥3 days duration. Fewer factors (younger age, male gender, presence of a complex chronic condition) were associated with enteric infection readmission. The presence of a complex chronic condition was the only factor associated with urinary tract infection readmission and none of the factors were associated with skin or soft tissue infection readmission.ConclusionsIn children less than two years old, infectious disease readmission risk is increased if the first infectious disease admission is a respiratory infectious disease but not if it is another infectious disease category. Risk factors for respiratory infectious disease readmission are different from those for other infectious disease readmissions.Electronic supplementary materialThe online version of this article (10.1186/s12887-018-1079-x) contains supplementary material, which is available to authorized users.