肿瘤一般分为良性与恶性两类。良性肿瘤对人的损害小;而恶性肿瘤(癌与肉瘤)严重威胁着人的生命,且其发病率有所上升。癌细胞至少表现出三个生物学特征:无限制增生;低度分化;对周围组织浸润与转移。由于细胞的行为决定于大分子(DNA、RNA和蛋白质)的结构与组成,因而当正常细胞转变成癌细胞时,首先就反映在细胞的大分子组成上。 Tumors are generally divided into benign and malignant categories. Benign tumors cause little damage to humans; while malignant tumors (carcinoma and sarcoma) are a serious threat to human life, and their incidence has increased. Cancer cells exhibit at least three biological features: unrestricted proliferation; low differentiation; and infiltration and metastasis of surrounding tissues. Since the behavior of cells is determined by the structure and composition of macromolecules (DNA, RNA, and protein), when normal cells are transformed into cancer cells, they are first reflected in the macromolecular composition of the cells.