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  • 致癌物和癌症

    A hand holding a burning cigarette, with smoke rising from it.

    What's the worst thing you can do to hurt your health?
    ::最糟糕的事情是什么 你能做 伤害你的健康?

    Besides , many other dangers in the environment may negatively affect human health. For example, can cause lung . It can also make asthma and other diseases worse. is another potential threat in the environment. It may poison large numbers of people or cause epidemics of deadly diseases. But the worst thing you can do to yourself is smoke cigarettes.
    ::此外,环境中的许多其他危险也可能对人类健康产生不利影响,例如,可能导致肺部疾病,也可能使哮喘和其他疾病恶化,这是环境的另一个潜在威胁,可能毒害大量人口或造成致命疾病的流行,但最坏的办法是吸烟。

    Carcinogens and Cancer
    ::致癌物和癌症

    A carcinogen is anything that can cause cancer. Cancer is a disease in which divide out of control. Most carcinogens cause cancer by producing in .
    ::致癌物是致癌物。癌症是一种不能控制的疾病。大多数致癌物通过产生致癌物而致癌。

    Types of Carcinogens
    ::致癌物质类型

    There are several different types of carcinogens. They include pathogens, radiation, and chemicals. Some carcinogens occur naturally. Others are produced by human actions.
    ::有几种不同的致癌物,包括病原体、辐射和化学品,有些致癌物自然发生,其他致癌物由人类行为产生。

    • cause about 15 percent of all human cancers. For example, the virus called hepatitis B causes liver cancer.
      ::例如,乙型肝炎病毒导致肝癌。
    • UV radiation is the leading cause of skin cancer . The radioactive gas known as radon causes lung cancer.
      ::紫外线辐射是导致皮肤癌的主要原因,放射性气体,即,引起肺癌。
    • Tobacco smoke contains dozens of carcinogens, including nicotine and formaldehyde. Exposure to tobacco smoke is the leading cause of lung cancer.
      ::烟草烟雾含有数十种致癌物质,包括尼古丁和甲醛,接触烟草烟雾是肺癌的主要原因。
    • Some chemicals that were previously added to foods, such as certain dyes, are now known to cause cancer. Cooking foods at very high temperatures also causes carcinogens to form (see Figure ).
      ::以前添加到食品中的一些化学品,如某些染料,现在已知可致癌,在极高的温度下烹饪食物也会导致致癌(见图 )。

    Grilled meat cooking over an open flame, highlighting high-temperature food preparation.

    Barbecued foods are cooked at very high temperatures. This may cause carcinogens to form.
    ::烧烤食品在极高的温度下煮熟,可能导致致癌物形成。

    How Cancer Occurs
    ::癌症发生情况如何

    Mutations that lead to cancer usually occur in genes that control the . These include tumor-suppressor genes and proto-oncogenes .
    ::导致癌症的突变通常发生在控制肿瘤的基因中。这些基因包括肿瘤抑制基因和原致癌基因。

    • Tumor-suppressor genes normally prevent cells with damaged DNA from dividing. Mutations in these genes prevent them from functioning normally. As a result, cells with damaged DNA are allowed to divide.
      ::肿瘤抑制基因通常防止DNA受损的细胞分裂,这些基因中的突变使它们无法正常运转,因此,DNA受损的细胞可以分离。
    • Proto-oncogenes normally help control . Mutations in these genes turn them into oncogenes . Oncogenes promote the division of cells with damaged DNA.
      ::蛋白质通常有助于控制。这些基因的变异会把它们变成肿瘤。 蛋白质会促进细胞与受损的DNA的分离。

    Cells that divide uncontrollably may form a tumor , or abnormal mass of cells. Tumors may be benign or malignant. Benign tumors remain localized and generally do not harm health. Malignant tumors are cancerous. There are no limits to their growth, so they can invade and damage neighboring tissues . Cells from malignant tumors may also break away from the tumor and enter the bloodstream. They are carried to other parts of the body, where new tumors may form. The most common and the most deadly cancers for U.S. adults are listed in Table .
    ::无法控制分裂的细胞可能形成肿瘤或异常的细胞质量。肿瘤可能是良性或恶性。 恶性肿瘤仍然局部存在,一般不会损害健康。 恶性肿瘤是癌症。 恶性肿瘤是癌症。 没有限制其生长,因此它们可以侵入和破坏近身组织。 恶性肿瘤的细胞也可能脱离肿瘤,进入血液流。 它们被携带到身体的其他部分,那里可能形成新的肿瘤。 美国成年人最常见和最致命的癌症列在表格中。

    Gender Most Common Types of Cancer after Skin Cancer (% of all cancers) Most Common Causes of Cancer Deaths (% of all cancer deaths)
    Males prostate cancer (33%), lung cancer (13%) lung cancer (31%), prostate cancer (10%)
    Females breast cancer (32%), lung cancer (12%) lung cancer (27%), breast cancer (15%)

    More cancer deaths in adult males and females are due to lung cancer than any other type of cancer. Lung cancer is most often caused by exposure to tobacco smoke. What might explain why lung cancer causes the most cancer deaths when it isn’t the most common type of cancer?
    ::成年男性和女性死于肺癌的癌症多于其他癌症。 肺癌最常见的原因是吸烟。 是什么可以解释为什么肺癌不是最常见的癌症类型,导致癌症死亡最多的是肺癌呢?

       

     

    Cancer Treatment and Prevention
    ::癌症治疗和预防

    Most cancers can be treated, and some can be cured. The general goal of treatment is to remove the tumor without damaging other cells. A cancer patient is typically treated in more than one way. Possible treatments include surgery, drugs ( chemotherapy ), and radiation. Early diagnosis and treatment of cancer lead to the best chance for survival. That’s why it’s important to know the following warning signs of cancer:
    ::大部分癌症都可以治疗,有些可以治愈。 治疗的总目标是除去肿瘤而不伤害其他细胞。 癌症患者通常以不止一种方式接受治疗。 可能的治疗包括手术、药物(化学疗法)和辐射。 癌症的早期诊断和治疗可以带来最好的存活机会。 这就是为什么必须知道以下癌症的警告信号:

    • change in bowel or bladder habits
      ::肠胃或膀胱习惯的变化
    • sore that does not heal
      ::无法治愈的痛痛
    • unusual bleeding or discharge
      ::异常出血或排出
    • lump in the breast or elsewhere
      ::胸中或胸中
    • chronic indigestion or difficulty swallowing
      ::慢性消食不良或难吞咽
    • obvious changes in a wart or mole
      ::圆形或摩尔的明显变化
    • persistent coughing or hoarseness
      ::持续咳嗽或缺血

    Having one or more warning signs does not mean you have cancer, but you should see a doctor to be sure. Getting routine tests for particular cancers can also help detect cancers early, when chances of a cure are greatest. For example, getting the skin checked regularly by a dermatologist is important for early detection of skin cancer (see Figure ).
    ::具有一个或多个警告信号并不意味着你有癌症,但你应该看医生才能确定。 进行特定癌症的常规检查也可以帮助早期发现癌症,而当治愈的可能性最大时。 比如,皮肤科医生定期检查皮肤对于早期发现皮肤癌非常重要(见图 ) 。

    A healthcare professional examines a patient's skin for signs of skin cancer.

    Regular checkups with a dermatologist can detect skin cancers early. Why is early detection important?
    ::皮肤科医生的定期检查可以及早发现皮肤癌。 为什么早期发现很重要?

    You can take steps to reduce your own risk of cancer. For example, you can avoid exposure to carcinogens such as tobacco smoke and UV light. You can also follow a healthy lifestyle. Being active, eating a low-fat diet, and maintaining a normal weight can help reduce your risk of cancer.
    ::您可以采取措施降低自己患癌症的风险。例如,您可以避免接触烟草烟雾和紫外线光等致癌物质。您也可以采取健康的生活方式。积极工作、吃低脂肪饮食以及保持正常体重可以帮助降低癌症风险。

    Summary
    ::摘要

    • A carcinogen is anything that causes cancer.
      ::致癌物就是任何导致癌症的致癌物。
    • Most carcinogens produce mutations in genes that control the cell cycle.
      ::大多数致癌物产生基因突变,控制细胞循环。

    Review
    ::回顾

    1. What is a carcinogen? What is cancer?
      ::什么是致癌物?什么是癌症?
    2. How do most carcinogens cause cancer? Give two examples of carcinogens.
      ::多数致癌物如何致癌?请举两个致癌物的例子。
    3. Describe tumor-suppressor genes and describe how they cause cancer.
      ::描述肿瘤抑制基因并描述它们如何导致癌症。
    4. Identify three ways cancer can be treated.
      ::查明三种治疗癌症的方法。
    5. List four warning signs of cancer.
      ::列出四个癌症的警告迹象。
    6. What might explain why lung cancer causes the most cancer deaths when it isn’t the most common type of cancer?
      ::为何肺癌不是最常见的癌症类型, 导致癌症死亡人数最多?