决策树是通过递回分割.pptxVIP

A Five-Gene Signature and Clinical Outcomein Non–Small-Cell Lung Cancer;Background;決策樹是通過遞迴分割〔recursive partitioning〕建立而成，遞迴分割是一種把資料分割成不同小的局部的疊代過程;cDNA microarray schema;Microarray analysis;Microarray Processing sequence;Gene-expression profiling by means of microarrays and reverse-transcriptase polymerase chain reaction (RT-PCR) examined gene expression in 125 surgical specimens of NSCLC, using microarrays and real-time RT-PCR to identify a gene signature correlated with clinical outcome ;Methods;125 specimens-- 60 were adenocarcinomas, 52 were squamous-cell carcinomas, and 13 were other types of cancer not received adjuvant chemotherapy 672 genes associated with invasive activity, identified in a previous study--- rearrayed in duplicate on a nylon membrane 4 μg of total RNA from each specimen ;validate levels of expression of genes found on microarray analysis ? RT-PCR was performed on 16 genes and a control gene for TATA-box–binding protein (TBP), with use of specific TaqMan probes and primer sets --- transcripts were amplified with reagent (TaqMan One-Step RT-PCR Master Mix Reagent, Applied Biosystems) and a sequence detection system (ABI Prism 7900HT, Applied Biosystems) ;;To reduce background noise ? background intensity values of less than 3000 were assigned value of 3000?log-transformed to a base-2 scale Genes with coefficients of variation of less than 3% were excluded from further analyses the gene-expression intensity values were transformed to ordinal coding values by ranking of level of gene expression among the 485 genes in 125 patients (60,625 observations) ;intensity value was coded as 1-2-3-4 according to 0-25%-50%-75%-100% Hazard ratios from univariate Cox regression analysis to determine which genes associated with death from any cause or recurrence of cancer Protective genes were defined with a hazard ratio for death of 1; risk genes were defined with a hazard ratio for death of 1 ;univariate Cox proportional-hazards regression analysis Ge