癌症是一组可影响身体任何部位的多种疾病的通称。使用的其它术语为恶性肿瘤和赘生物。癌症的一个决定性特征是异常细胞快速生成，这些细胞超越其通常边界生长并可侵袭身体的临近部位和扩散到其它器官。后者被称为转移。广泛转移是癌症死亡的主要原因。
世卫组织和国际癌症研究机构与包括国际原子能机构在内的其他联合国组织和伙伴合作，以便：
Metastasis is typical within the late levels of cancer and it may occur by using the blood or even the lymphatic method or both of those. The standard actions in metastasis are nearby invasion, intravasation in to the blood or lymph, circulation through the overall body, extravasation in to the new tissue, proliferation and angiogenesis.
癌症易复发、转移，早期患者复发率、转移率偏低，有些可治愈，中晚期患者复发率、转移率、致死率高，通常预后不良。
Some different types of cancer are named for the size and form on the cells less than a microscope, like large cell carcinoma, spindle cell carcinoma and modest-mobile carcinoma.
癌症篩檢，是希望在一般大眾身上提早找出潛在未發現與早期無症狀的癌症。所進行的測試必須適合廣大民眾能夠負擔，並且安全，無侵入性而且不易有假陽性結果產生。一旦發現癌症的跡象，更精確的後續檢驗，或使用侵入性手術取得組織切片以確定篩檢結果則是必要的。
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
The main element innovation listed here lies in the use of protein cage nanoparticle-centered programs. These techniques are engineered to hold signals that catch the attention of NK cells on to the tumor, beating among the list of key challenges in most cancers immunotherapy: ensuring the immune cells obtain and attack just the most cancers cells without having harming healthy tissue.
第一步——基因突变，当正常细胞（米色）中的某些细胞（橙色）发生基因突变， 使其在正常状态下增殖的倾向增加时，肿瘤就开始发展了。
症状性癌症的早期诊断在所有环境中并且对大多数癌症都意义重大。癌症规划应旨在减少诊断、治疗和支持性护理方面的延误和障碍。
Elective abortions usually are not essential and, for the commonest sorts and levels of most cancers, do not Increase the mom's survival.
上述中各種症狀都有可能由其他的疾病引起，癌症不一定是產生這些症狀的主因，確切原因仍需要鑑別診斷診察。
Radiation therapy is used in about 50 % of conditions. The radiation is usually both from internal resources (brachytherapy) or external resources. The radiation is mostly low Electrical power X-rays for managing skin cancers, though better Strength X-rays are used for cancers in the entire body.[193] Radiation 癌症 is often employed Along with surgical procedure and/or chemotherapy.
Deficient expression of DNA repair proteins as a result of an inherited mutation can boost cancer dangers. People with an inherited impairment in almost any of 34 DNA maintenance genes (see posting DNA maintenance-deficiency ailment) have greater cancer risk, with a few defects making certain a 100% life span probability of cancer (e.