概念
tumor
Tumors 更多的是指肿块，但这些肿块并非全部都是恶性的，其中存在一些是良性，所以需要记住 tumors 和 cancers 并非同义词。 cancers是tumors中的一部分（恶性部分）。
cancer
是tumor中的一种，特指恶性肿瘤（malignant tumor），癌症是用来形容具有异常的失控的细胞分裂，并能侵入其他组织的疾病的一个术语。癌细胞可通过血液和淋巴系统扩散到身体的其他部位。cancer本身也不是一个单一的疾病而是100多种癌症的总称。大多数癌症以其出现的器官或细胞类型命名， 例如，始发于结肠的癌症，被称为结肠癌，始发于皮肤基底细胞的癌症称为基底细胞癌。
癌症类型可归为广义范畴。癌症的种类主要包括：
Carcinoma
cancer that begins in the skin or in tissues that line or cover internal organs.
癌-起始于皮肤或组织，呈线条状或覆于内脏的癌症。
Sarcoma（肉瘤）
cancer that begins in bone, cartilage, fat, muscle, blood vessels, or other connective or supportive tissue.
起始于骨，软骨，脂肪，肌肉，血管，或其他结缔组织或支持组织的癌症。
Leukemia（白血病）
cancer that starts in blood-forming tissue such as the bone marrow and causes large numbers of abnormal blood cells to be produced and enter the blood.
起始于造血组织，如骨髓，可生成大量异常血细胞并进入血液的癌症。
Lymphoma and myeloma（淋巴瘤和骨髓瘤）
cancers that begin in the cells of the immune system.
起始于免疫系统细胞的癌症
Central nervous system cancers（中枢神经系统癌症）
cancers that begin in the tissues of the brain and spinal cord.
起始于大脑和脊髓组织的癌症。
癌症的起源
All cancers begin in cells, the body’s basic unit of life. To understand cancer, it’s helpful to know what happens when normal cells become cancer cells.
所有的癌症起始于细胞---人体基本的生命单位。为了理解癌症，了解正常细胞何时会变为癌细胞非常有用。
The body is made up of many types of cells. These cells grow and divide in a controlled way to produce more cells as they are needed to keep the body healthy. When cells become old or damaged, they die and are replaced with new cells.
身体是由许多类型的细胞构成。因为他们需要保持身体健康，这些细胞在一个可控制的方式下生长和分化，以产生更多的细胞。当细胞衰老或损坏时，细胞死亡并被新的细胞所取代。
However, sometimes this orderly process goes wrong. The genetic material (DNA) of a cell can become damaged or changed, producing mutations that affect normal cell growth and division. When this happens, cells do not die when they should and new cells form when the body does not need them. The extra cells may form a mass of tissue called a tumor.
但是，有时这种有序的过程也会出现错误。一个细胞的遗传物质（DNA），可受损或改变，产生基因突变，从而影响正常的细胞生长和分裂。在这种情况下，细胞应该死亡但并未死亡，身体并不需要时新细胞形成。额外的细胞可能形成一个所谓的肿瘤组织肿块。
Not all tumors are cancerous; tumors can be benign or malignant.
并非所有的肿瘤都是癌症性的，肿瘤也可是良性或恶性。
Benign tumors aren’t cancerous. They can often be removed, and, in most cases, they do not come back. Cells in benign tumors do not spread to other parts of the body.
良性肿瘤不是癌性的。它们通常可以切除，并且，在大多数情况下，不会复发。良性肿瘤的细胞不会扩散到身体的其他部位。
Malignant tumors are cancerous. Cells in these tumors can invade nearby tissues and spread to other parts of the body. The spread of cancer from one part of the body to another is called metastasis.
恶性肿瘤是癌性的。这些肿瘤细胞可侵入附近组织并扩散到身体的其他部位。癌症从身体的一部分扩散至另一部分称为转移。
Some cancers do not form tumors. For example, leukemia is a cancer of the bone marrow and blood.
有些癌症不形成肿瘤。例如，白血病是骨髓和血液的一种癌症。
理解癌症
Cancer begins in cells, the building blocks that form tissues. Tissues make up the organs of the body.
癌症细胞起始于细胞，并形成肿块。
Normally, cells grow and divide to form new cells as the body needs them. When cells grow old, they die, and new cells take their place.
通常情况下，细胞生长、分裂，形成新的细胞，这是人体所需要的。当细胞衰老时，细胞死亡，新细胞取代其位置。
Sometimes, this orderly process goes wrong. New cells form when the body does not need them, and old cells do not die when they should. These extra cells can form a mass of tissue called a growth or tumor.
有时，这种有序的过程中出现错误。当身体并不需要时，新细胞形成，衰老的细胞应该死亡但并未死亡。这些额外的细胞可以形成一个组织团块称为增生或肿瘤。
Tumors can be benign or malignant:
肿瘤可以是良性或恶性：
Benign tumors are not cancer:
良性肿瘤不是癌性的：
Benign tumors are rarely life-threatening.
良性肿瘤很少危及生命。
Generally, benign tumors can be removed, and they usually do not grow back.
一般来说，良性肿瘤可以切除，而他们通常不会复发。
Cells from benign tumors do not invade the tissues around them.
良性肿瘤细胞不侵入周围组织。
Cells from benign tumors do not spread to other parts of the body.
良性肿瘤细胞不会扩散到身体的其他部位。
Malignant tumors are cancer:
恶性肿瘤是癌性的：
Malignant tumors are generally more serious than benign tumors. They may be life-threatening.
恶性肿瘤一般都比良性肿瘤严重。他们可能会危及生命。
Malignant tumors often can be removed, but sometimes they grow back.
恶性肿瘤往往可以切除，但有时它们重新生长出来（复发）。
Cells from malignant tumors can invade and damage nearby tissues and organs.
恶性肿瘤细胞可侵入和破坏邻近组织和器官。
Cells from malignant tumors can spread (metastasize) to other parts of the body. Cancer cells spread by breaking away from the original (primary) tumor and entering the bloodstream orlymphatic system. The cells can invade other organs, forming new tumors that damage these organs. The spread of cancer is called metastasis.
恶性肿瘤细胞可以扩散（转移）到身体的其他部位。癌细胞经脱离原（主）肿瘤并进入血液系统或淋巴系统发生扩散。细胞可以侵入其他器官，形成新的肿瘤并损害这些器官。癌症的扩散称为转移。
Most cancers are named for where they start. For example, lung cancer starts in the lung, and breast cancer starts in the breast. Lymphoma is cancer that starts in the lymphatic system. And leukemia is cancer that starts in white blood cells (leukocytes).
大多数癌症以其起始部位命名。例如，肺癌起始于肺，乳腺癌起始于乳腺。淋巴瘤是起始于淋巴系统的癌症。白血病是起始于白细胞的癌症。
When cancer spreads and forms a new tumor in another part of the body, the new tumor has the same kind of abnormal cells and the same name as the primary tumor. For example, if prostate cancer spreads to the bones, the cancer cells in the bones are actually prostate cancer cells. The disease is metastatic prostate cancer, not bone cancer. For that reason, it is treated as prostate cancer, not bone cancer. Doctors sometimes call the new tumor “distant” or metastatic disease.
当癌细胞扩散，并在身体的其他部位形成一种新的肿瘤时，新的肿瘤具有同一种异常细胞，名称与原发肿瘤相同。例如，如果前列腺癌扩散到骨，骨头的癌细胞其实是前列腺癌细胞。这种疾病是转移性前列腺癌，而不是骨癌。出于这个原因，被视为前列腺癌进行治疗，而不是骨癌。医生有时称之为“远部”新肿瘤或转移性疾病。