癌症有超過一百個種類，一般可依據癌細胞原發部位來分類，例如肺癌、乳癌等；另外能根據不同組織或細胞做以下分類：
Genetic alterations can arise at distinctive degrees and by various mechanisms. The gain or loss of a complete chromosome can manifest through faults in mitosis. A lot more prevalent are mutations, which happen to be changes during the nucleotide sequence of genomic DNA.
Some alternative treatment options are already investigated and shown to get ineffective but still continue for being marketed and promoted. Cancer researcher Andrew J. Vickers said, "The label 'unproven' is inappropriate for these kinds of therapies; it is time to assert that lots of choice most cancers therapies are already 'disproven'."[204]
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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。
The commonest varieties of cancer differ, but the cancer burden looks not less than as higher in pets as in people. Animals, commonly rodents, are sometimes Employed in most cancers exploration and experiments of normal cancers in much larger animals may benefit study into human most cancers.[272]
突发卫生事件 新闻和特写 疾病爆发新闻 情况报告 世卫组织在紧急情况下 数据
健康饮食。选择富含水果和蔬菜的饮食。选择全谷物和瘦肉蛋白质。限制摄入加工肉类。
腫瘤較小且尚未擴散/轉移（癌細胞可被定位、手術移除，不需借助循環全身的化學藥物治療）
畸胎瘤是性腺或胚胎剩件中的全能细胞发生的肿瘤，常发生于性腺，一般含有两个以上胚层的成分，结构混乱，也有良性和恶性之分。
Persons in the slightest degree phases of cancer treatment method ordinarily receive some sort of palliative treatment. Sometimes, health-related specialty professional corporations suggest that sufferers and physicians respond to cancer only with palliative treatment. This applies to sufferers who:[196]
One particular plan about why individuals with cancer are blamed or 癌症 stigmatized, known as the just-earth fallacy, is usually that blaming cancer on the client's actions or attitudes allows the blamers to regain a way of Regulate.
癌症治療會有許多後遺症，過程十分不易，因此治療後的照顧相當重要，包括疼痛控制、改善食慾、心理調適等，需要不同醫療團隊的合作，提高癌症病人的生活品質。（延伸閱讀：不是放棄治療！剖析緩和與安寧照護的真相）
理論上，若是以手術完全移除腫瘤細胞，癌症是可以被治癒的。但並非總是如此簡單，外科手術通常無法切除已經轉移到其他部位的癌細胞。使用外科手術治療癌症的例子包括以乳房切除术治療乳癌或是進行前列腺切除術（英语：prostatectomy）治療前列腺癌。手術的目的在於移除腫瘤細胞或是整個器官，雖然將主要的腫瘤經外科手術切除，但仍有些潛伏在腫瘤所生長的器官週遭的單一腫瘤細胞是無法被察覺的。隨著時間過去，又會重新生長成一個新的腫瘤，稱為癌症復發。為此，手術切除下的腫瘤需要經病理學家的檢視，以確定切下的腫瘤週遭都是正常組織，減少腫瘤切除不完全的機會。