相反的，子宮頸抹片檢查在所有種類的癌症篩檢中則具有最好的成本效益。以公共衛生考量來看，子宮頸癌的病程發展通常十分緩慢，長達數年，又具有明顯的危險因子（性接觸），因此有相當高的機會可在癌症仍是早期時篩檢出來，最重要的是，抹片的成本很低，能夠大量推行。基於這些原因，一項癌症篩檢是否應該進行，民眾的健康改善程度和篩檢的成本與治療的風險都必須列入考慮。
在正常细胞生长期间经常会发生基因突变。但细胞含有一种可识别何时发生错误并修复错误的机制。有时会漏掉某种错误。这种情况可能导致细胞癌变。
第二步——增生，突变后的细胞及其后代看起来仍然正常，但它们繁殖过多，这种 情况被称为增生。数年后，百万分之一的细胞（粉色）遭受另一种突变，这种突变 进一步放松了对细胞生长的控制。
某些癌症的成長會受某些荷爾蒙的增加或減少而抑制。對荷爾蒙敏感的腫瘤常見的例子有乳癌和前列腺癌，減低或增加體內雌激素或雄激素往往可用來做為補充治療的一種。
對於癌症高風險群，例如有家族病史，或是環境汙染（例如輻射屋居民）的人進行基因檢測，可做較深入仔細的檢查分析，服用預防藥物。確定有癌症相關基因突變的人，可藉由預防性的手術，降低癌症機會。
只有一小部分癌症是由于遗传疾病所致。如果癌症在您的家族中较为常见，则突变可能从一代传给下一代。您可能适合接受基因检测，以确认您是否遗传了可能增加某些癌症风险的突变。请记住，遗传基因突变并不表示肯定会罹患癌症。
Hormones are important brokers in intercourse-connected cancers, such as cancer with the breast, endometrium, prostate, ovary and testis and in addition of thyroid most cancers and bone cancer.[ninety five] Such as, the daughters of girls who definitely have breast cancer have significantly increased levels of estrogen and progesterone compared to daughters of girls devoid of breast cancer. These higher hormone degrees could explain their greater risk of breast cancer, even from the absence of the breast-most cancers gene.
[105] Just about every of those alterations regulates gene expression without having altering the fundamental DNA sequence. These alterations may well continue to be via cell divisions, endure for multiple generations, and might be regarded as similar to mutations.
除了切除原發性腫瘤之外，癌症的病程分期（英语：staging）也需要手術的協助。例如，確定腫瘤惡化的程度與是否發生淋巴結轉移。病程分期主要可用來推測預後和是否需要實行輔助治療（英语：adjuvant therapy）。有時手術也被用來控制症狀以減輕病人痛苦，如脊髓壓迫或腸阻塞，稱為紓緩治療。
如前所述，癌症源于正常细胞转变为肿瘤细胞的多阶段过程，通常从癌前病变发展 到恶性肿瘤。这些变化是一个人的遗传因素与三种外部因素相互作用的结果，外部 因素包括：
化学致癌物，例如石棉、烟草烟雾成分、酒精、黄曲霉毒素（一种食品污染物）、 砷（一种饮水污染物）、烷化剂、酰化剂、亚硝胺类、芳香胺、环氧化物等；巴豆油、 激素、酚类等物品，会增加致癌物质的效应。
It was observed that offering blended cytotoxic drugs is a lot better than one drug, a procedure named The mix therapy, which has a bonus from the statistics of survival and response on the tumor and during the development of the illness.
An invasive ductal carcinoma in the breast (pale area at the center) surrounded by spikes of whitish scar tissue and yellow fatty tissue
Some gradual-escalating cancers are especially typical, but often aren't lethal. Autopsy reports in Europe and Asia showed that 癌症 around 36% of people have undiagnosed and seemingly harmless thyroid most cancers at time of their deaths Which 80% of Males develop prostate most cancers by age eighty.