Cancer Question Answer

Odds ratio (matched pairs) = b/c = 6/2= 3.0

Women with uterine cancer were 3 times more likely to have been used estrogen than the women without uterine cancer.

Question 3

In a small pilot study, 12 women with uterine cancer and 12 with no apparent disease were contacted and asked whether they had ever used estrogen. Each woman with cancer was matched by age, race , weight, and parity to a woman without disease. The results are shown below:

Unmatch the pairs. What is the estimated relative risk of cancer when analyzing this study as an unmatched study design?

Correct Answer: 4.00

Response Feedback:

Estimated relative risk is the term used for odds ratio

Create the following 2 x 2 table

These numbers are derived by counting the number of estrogen users and non users in each column.

Odds Ratio = ad/bc =( 8x8)/(4x4) = 64/16=4.0

Question 4

In a study of a disease in which all cases that developed were ascertained, if the relative risk for the association between a factor and the disease is equal to or less than 1.0, then:

Correct Answer: There is either no association or a negative association between the factor and the disease

Question 5

Talbot and colleagues carried out a study of sudden unexpected death in women. Data on smoking history are shown in the following table.

Calculate the matched-pairs odds ratio for these data.

Correct Answer:

The correct answer is 4.5 See page 224-225.

Odds ratio for matched pair = b/c = 36/8 = 4.5

Question 6

Talbot and colleagues carried out a study of sudden unexpected death in women. Data on smoking history are shown in the following table.

Using data from the table, unmatch the pairs and calculate an unmatched odds ratio.

Correct Answer:

The correct answer is 6.3 Those who dies suddenly were 6.3 times more likely to have smoked more than one pack a day than those who didn’t die suddenly.

Cell a 2 smokers who died suddenly (cases)and 2 smokers who didn’t die suddenly (controls)

Cell b 36 smokers who died suddenly (cases) and 36 non smokers who didn’t die suddenly (controls)

Cell c 8 nonsmokers who died suddenly (cases) and 8 smokers who did not die suddenly (controls)

Cell d 34 nonsmokers who died suddenly (cases) and 34 nonsmokers who didn’t die suddenly (controls)

Therefore the unmatched 2 x 2 table is as follows:

Odds ratio = ad/bc=(38x70)/(10 x 42) = 2660/420 = 6.3

Question 7

What are the odds that the controls smoke 1+ pack/day?

Correct Answer:

The correct answer is 1:7. You get this from the 2 x 2 table comparing cell b to cell d.

Question 8

Questions 8 and 9 are based on the information given in the table below:

The relative risk for developing ASHD subsequent to entering this study in men compared to women is:

Correct Answer:

Lowest in the oldest age group

Response Feedback:

The correct answer is e.

Relative risk = incidence rate in exposed/ incidence rate among nonexposed

In this case the exposed are the men and the nonexposed are the women

Relative risk =Incidence rate among men/incidence rate among women for each age category

29-34 RR is undefined (cannot divide by 0)

35-44 RR= 40/2.1 = 19

45-54 RR=106.5/29.4 = 3.6

55-62 RR = 209.1/117.8 = 1.8

Question 9

The most likely explanation for the differences in rates of ASHD between the initial examination and the yearly follow-up examinations in men is:

Correct Answer:

The initial examination measures the prevalence of ASHD, whereas the subsequent examinations primarily measure the incidence of