Method for detecting cancer

A method for selecting a gene used as an index of cancer classification based on pathological findings selected from the group consisting of states of infiltration to peripheral tissues, sensitivity against drugs and states of metastasis in lymph nodes, comprising the following steps of:

• (1) determining expression levels in cancer samples to be tested for E2F-1 gene and then comparing the determined expression levels with an expression level of the E2F-1 gene in a control sample, thereby evaluating alterations in the expression level of the E2F-1 gene, wherein the control sample is a normal tissue, or a cancer sample with low malignancy;
• (2) classifying the cancer samples to be tested into plural numbers of types, based on alterations in expression levels of the E2F-1 gene evaluated in the above step (1) and said pathological findings for the cancer samples to be tested;
• and
• (3) examining alterations in expressions for plural numbers of genes in each of the cancer samples to be tested classified in the above step (2), to select a gene, wherein expression of said gene is altered independently to the E2F-1 gene and expression level of said gene is specifically altered depending on every type of cancer samples to be tested classified in the above step (2);
• thereby a gene is selected to be used as an index of cancer classification.