Case Study on Cancer Radiation Treatment Paper

Case Study on Cancer Radiation Treatment Paper

Case Study on Cancer Radiation Treatment Paper

Question 1

Of 2,872 persons who had received radiation treatment in childhood because of an enlarged thymus, cancer of the thyroid developed in 24 and a benign tumor developed in 52. A comparison group consisted of 5,055 children who had received no such treatment (brothers and sisters of the children who had received radiation treatment). During the follow-up period, none of the comparison group developed thyroid cancer, but benign thyroid tumors developed in 6. Calculate the relative risk for benign thyroid tumors.

Correct Answer:

The correct answer is 15.2. Children who were exposed to radiation treatment due to enlarged thymus were 15.2 times more likely to develop benign thyroid tumors.

Relative risk = incidence rate of benign tumors in the group exposed to radiation treatment/incidence rate of benign tumor among children non exposed to radiation treatment

Incidence rate among exposed = 52 benign tumors/2,872 persons exposed = 0.01811

Incidence rate among the non exposed = 6 benign tumors/5,055 persons non-exposed =0.00119

Relative risk = 0.018/0.0011 = 15.2

Question 2

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:

What is the estimated relative risk of cancer when analyzing this study as a matched-pairs study?

Correct Answer: 3.00

Response Feedback:

Estimated relative risk is the term used for odds ratio

a, pairs (both were exposed) =2

b, pairs (case exposed, control not exposed) = 6

c, pairs (case not exposed, control exposed) = 2

d, pairs (both non exposed) = 2

Create the following 2 x 2 table

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 =( 8×8)/(4×4) = 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.