The present invention relates to the fields of genetics and oncology and provides methods for detecting tumors as well as methods for treating patients and predicting the prognosis to a patient. Specifically, the present invention relates to a method of demonstrating the malignant character of a tumor or cell subpopulation in a subject, to a method of predicting a prognosis, to a method of treating a subject having a tumor with NAV3 copy number change and with over expression of at least one gene or gene product selected from specific lists, and to a method of selecting a treatment to a subject. The present invention also relates to uses of NAV3 gene or gene product and at least one gene and/or gene product selected from specific lists for demonstrating the malignant character of a tumor or cell sub-population, for predicting a prognosis to a subject, for selecting a treatment to a subject, and for cancer therapy in a subject having a tumor with NAV3 copy number change. Furthermore, the present invention also relates to a use of an antagonist, antibody or inhibitory molecule of at least one gene and/or gene product selected from specific lists for cancer therapy in a subject. Still, the present invention relates to a diagnostic kit comprising tools for detecting NAV3 copy number change in a biological sample and tools for detecting over expression of at least one gene or gene product selected from specific lists in a biological sample. The present invention also relates to a use of a diagnostic kit of the invention for demonstrating the malignant character of a tumor or cell subpopulation, for predicting a prognosis to a subject with a colorectal tumor, brain tumor or tumor of epidermal keratinocytes and for selecting a treatment to a subject with a colorectal tumor, brain tumor or tumor of epidermal keratinocytes.本発明は遺伝子学および腫瘍学の分野に関し、腫瘍の検出方法ならびに患者を処置し、患者に対する予後の予測方法を提供する。具体的には、本発明は、対象における腫瘍または細胞の亜集団の悪性形質を示す方法、予後の予測方法、ＮＡＶ３コピー数変化および、特定のリストから選択される少なくとも１つの遺伝子または遺伝子産物の
