Essential Cell Biology 5th edition

734 CHAPTER 20 Cell Communities: Tissues, Stem Cells, and Cancer
the number of cases of colon cancer diagnosed per 100,000
women per year as a function of age. Why is this graph
so steep and curved, if mutations occur with a similar
frequency throughout a person’s life-span?
QUESTION 20–17
Heavy smokers or industrial workers exposed for a limited
time to a chemical carcinogen that induces mutations in
DNA do not usually begin to develop cancers characteristic
of their habit or occupation until 10, 20, or even more years
after the exposure. Suggest an explanation for this long
delay.
QUESTION 20–18
High levels of the female sex hormone estrogen increase
the risk of some forms of cancer. Thus, some early types
of contraceptive pills containing high concentrations of
estrogen were eventually withdrawn from use because this
was found to increase the risk of cancer of the lining of the
uterus. Male transsexuals who use estrogen preparations
to give themselves a female appearance have an increased
risk of breast cancer. High levels of androgens (male sex
hormones) increase the risk of some other forms of cancer,
such as cancer of the prostate. Can one infer that estrogens
and androgens are mutagenic?
QUESTION 20–19
Is cancer hereditary?