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1. Criticize the statement: "The best way to prevent cancer is toban all known carcinogens."

Banning carcinogens will certainly reduce the incidence of

cancerbut it is not necessarily the best way. And the reason isthat many carcinogens play a necessary role in of our daily lives.

Sunlight, emissions from cars and factories, charcoalthese are

all carcinogens. Yet its hard to imagine life without automobilesand the factories that produce many of our goods. So unless we

find alternatives to these conveniences of modern life, banningcarcinogens may not be a viable solution.

At the same time, banning carcinogens will not magically prevent

all cancers. Many cancers have unknown causes; pediatric

cancers are often inherited; and more importantly, cancer is theproduct of genetic susceptibility and exposure to carcinogens. Somany people will not get cancer even if exposed to carcinogens.

The question is, then, should we ban many carcinogens that playimportant roles in our daily life to prevent cancer in those

susceptible?

And thats certainly debatable. We must engage in a cost-benefit

analysis. What are we willing to give up? Do we have saferalternatives to carcinogens that serve the same function? Howstrong is the correlation between the cancer and the exposure to

the carcinogen?

In what sense is the origin of cancer related to the second law ofthermodynamics?

The second law of thermodynamics states that all order is

temporary and there is a tendency toward disorder. Aninterpretation of this statement is that all living things must die.

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In a sense, then, cancer cells defy the second law on the cellularlevel at least temporarily. Normal cells usually die after 50 celldivisions because of the shortening of their telomeres. Cancer

cells live indefinitely because of their telomerase enzyme, which

prevents shortening of telomeres; and so they can continue todivide after 50 cell divisions.

Yet, in the bigger picture, the process of cancer obeys the secondlaw of thermodynamics. As the second law states, all things must

die. Likewise, cancer disrupts the homeostasisbalance betweeninhibitory and growth factors, etcthe body strives to maintain,

eventually leading to death.

How are pediatric cancers different from adult cancers in terms of

etiology?

Pediatric cancers are caused by the inheritance of certain genes,while adult cancers are the products of genetic predisposition and

repeated exposure to environmental carcinogens.

And the etiological difference between pediatric and adult cancers

is completely logical, if you think about it. Adult cancers arise

when there is an accumulation of specific mutations that throwoff the balance between inhibitory and growth factors. This

accumulation takes time and repeated exposure to carcinogens.In prostate cancer, for example, the primary risk factor is simply

age; it is very uncommon in men younger than 45.

But children, usually, will not have lived long enough to berepeatedly exposed to carcinogens and to accumulate thenecessary genetic mutations. So if children do have cancer, itsprobable that they already inherited oncogenes, or mutant

cancer-causing genes.