# Science Olympiad» Disease Detectives Event » National Event Exercises Skin Cancer Module: Practice Exercises

Skin Cancer: Module 5

Question 1: Define incidence as used in this chart. What is in the numerator? What is in the denominator?

Answer: In this chart, incidence is the frequency with which cancer of the lung or bronchus occurs in a population. The numerator is the number of new cases of lung or bronchus cancer in the population during one year. The denominator is the total population followed by SEER during that time. (This is also called the population "at risk.")

Question 2: What does "age-adjustment" mean in this context? (Tip: The "standard population" used is listed above the graph, under "Selections.")

Answer: In this chart, age-adjustment means that the incidence rate has been changed. We have taken away the effect of different age distributions in the population studied versus the standard 1970 U.S. population.

Question 3: What was the age-adjusted incidence of lung and bronchus cancer for the total population in 1973? 1985? 1998? (Tip: The "total population" is males and females taken together. See the color key below the graph.) What was the age-adjusted incidence for men in 1973? 1985? 1998? What was the age-adjusted incidence for women in 1973? 1985? 1998?

Answer: The following incidence rates are estimated from the line chart. They reflect rates per 100,000:

• The age-adjusted incidence of lung and bronchus cancer for men and women in 1973 was 43 per 100,000. In 1985 it was 56, and in 1998 it was 55.
• Rates for men in these years (per 100,000) were 73, 84, and 70, respectively.
• Rates for women were 18, 35, and 43, respectively.

Question 4: How can you explain the trends in lung and bronchus cancer incidence in men compared to women over the past 25 years?