Reduced expression of DNA repair service genes disrupts DNA restore. This is often proven in the figure within the 4th level through the leading. (In the figure, pink wording indicates the central position of DNA destruction and defects in DNA fix from the development to most cancers.) When DNA fix is deficient DNA problems continues to be in cells at a higher than typical degree (5th amount) and causes enhanced frequencies of mutation and/or epimutation (sixth amount).

癌症的症状多样，除可引起局部压迫和阻塞等症状外，还可因浸润和转移而导致相应的临床表现，有时会出现贫血、发热、体重下降、夜汗、感染、恶病质等全身表现。

Veterinary oncology, concentrating mostly on cats and canine, is usually a expanding specialty in wealthy nations and the key kinds of human treatment method for instance surgery and radiotherapy might be provided.

Most cancers screening is just not obtainable for many forms of cancers. Even though assessments can be obtained, they is probably not recommended for everybody. Common screening or mass screening consists of screening Anyone.

Some varieties of cancer are named for the dimensions and condition of the cells below a microscope, for example huge mobile carcinoma, spindle mobile carcinoma and smaller-mobile carcinoma.

Attainable harms from 癌症 the screening exam: one example is, X-ray photos involve exposure to likely hazardous ionizing radiation

全身性的症狀：體重減輕、食欲不振、惡病體質、大量出汗（夜間盜汗）、貧血

Cancer prognosis could potentially cause psychological distress and psychosocial interventions, including chatting therapy, may perhaps assist individuals with this.

药物治疗通常可分为：并发症治疗药物以及癌症靶向治疗药物。前者通常是治疗 患癌后出现的一些并发症如局部感染、病毒感染和疼痛。这类药物本身并不能治疗 癌症，但是能减轻患者的痛苦程度。而后者即常说的化疗，有多种类型，常见药物 有利妥昔单抗、曲妥珠单抗等。这些药物对肿瘤更有针对性，效率高、疗效显著、 不良反应较少。但仅适用于具有某类靶点的肿瘤患者，具有局限性；而且治疗费用 较高，可能会出现耐药性(即药物失效)，很难实现治愈。

微量營養素缺乏被認為與癌症有關，但是進行隨機臨床實驗需要眾多人數參與，需時多年才能完成，因此花費也極為昂貴和複雜，所以很少實施。而通常只能以單劑量來做實驗，缺乏其他濃度比較，使得難以評估實際臨床所需的量也是一大問題。

不斷增生的癌細胞撐破腫瘤，癌細胞因而擴散至腫瘤周遭的組織及鄰近的淋巴結甚至更遠處。此時癌細胞流竄於原始病灶附近，必需借助循環全身的化學治療藥物治療。

癌症的存活率，會因腫瘤長的位置、大小、數目及癌症的分期而有不同，一般來說，只要早期發現，治癒率就越高；根據統計，發現許多癌症零期（原位癌）的病人，五年存活率幾乎接近百分之百，不過存活率會隨著期別愈晚而降低。（延伸閱讀：原位癌是什麼？剖析癌症進化史）

疼痛。尽管不是所有癌症都会引起疼痛，但癌症或癌症治疗会引起疼痛。药物和其他方法可以有效地治疗癌性疼痛。

通过穿刺、活检或根治手术获得病变组织，结合免疫组化染色、特殊染色、分子病理检测等，能明确癌症的类型、分化程度、分期等信息，以指导临床下一步治疗。