1. Lung cancer mortality among women is increasing faster than among men. What f
ID: 235934 • Letter: 1
Question
1. Lung cancer mortality among women is increasing faster than among men. What factor(s) would most likely account for this increased cancer rate?
Younger women are smoking more.
Older women are smoking more.
Women are smoking less.
Both A and B
2.
As an epidemiologist, you are going to investigate the effect of a drug suspected of causing malformations in newborn infants when the drug in question is taken by pregnant women during the course of their pregnancies. As your sample you will use the next 200 single births occurring in a given hospital. For each birth, a medication history will be taken from the new mother and from her doctor. In addition, you will review medical records to verify use of the drug. [Note: These mothers are considered to have been followed prospectively during the entire course of their pregnancies, because a complete and accurate record of drug use was maintained during pregnancy.]
The resultant data are:
Forty mothers have taken the suspected drug during their pregnancies. Of these mothers, 35 have delivered malformed infants. In addition, 10 other infants are born with malfunctions.
What type of study design is this?
Retrospective cohort study
Prospective cohort study
Historical prospective study
Ambispective cohort study
None of the above
3. As an epidemiologist you are going to investigate the effect of a drug suspected of causing malformations in newborn infants when the drug in question is taken by pregnant women during the course of their pregnancies. As your sample you will use the next 200 single births occurring in a given hospital. For each birth, a medication history will be taken from the new mother and from her doctor. In addition, you will review medical records to verify use of the drug. [Note: These mothers are considered to have been followed prospectively during the entire course of their pregnancies, because a complete and accurate record of drug use was maintained during pregnancy.]
The resultant data are:
Forty mothers have taken the suspected drug during their pregnancies. Of these mothers, 35 have delivered malformed infants. In addition, 10 other infants are born with malfunctions.
What type of study design is this?
Retrospective cohort study
Prospective cohort study
Historical prospective study
Ambispective cohort study
None of the above
Explanation / Answer
Answer for 1.
C. Women are somking less
Causes of Lung Cancer in Women:
Even though smoking is the number one cause of lung cancer in women, a higher percentage of women who develop lung cancer are life-long non-smokers. Some of the causes may include exposure to radon in our homes, secondhand smoke, otherenvironmental and occupational exposures, or a genetic predisposition.
Recent studies suggest infection with the human papilloma virus (HPV) may also play a role.
Smoking Status- Some, but not all, studies suggest that women may be more susceptible to the carcinogens in cigarettes, and women tend to develop lung cancer after fewer years of smoking.
Although smoking increases the risk of lung cancer dramatically, 1 in 5 women diagnosed with lung cancer have never smoked, whereas among men who develop lung cancer, only 1 in 12 have never smoked.46 Of all the types of lung cancer, women are more likely to develop adenocarcinoma, a type of non-small cell lung cancer (NSCLC), which is also the type of lung cancer more commonly found in non-smokers.
It is unclear why non-smoking women are at greater risk for developing lung cancer than non-smoking men. Studies indicate that biological and genetic differences between men and women play a role in susceptibility to lung cancer and the risk of dying from it. Some research shows that estrogen, a hormone found in both men and women but much higher in women, may help certain lung cancer cells to grow and spread throughout the lungs. For example, a 2009 study based on the Women’s Health Initiative showed that post-menopausal women who took estrogen and progesterone combined hormone therapy had an increased risk of dying from lung cancer, regardless of whether they had never smoked, stopped smoking, or were currently smoking (although current and former smokers were at the highest risk for death).7 A 2010 study indicated that post-menopausal women who took hormone therapy for more than 10 years were at an increased risk of developing lungcancer.8 In 2011, a study showed that women who take estrogen-blocking medication like tamoxifen to prevent a recurrence of breast cancer also reduce their risk of dying from lung cancer.9 For both the 2010 and 2011 studies, the link between hormones and lung cancer were maintained regardless of the person’s smoking status.
Answer for 2 and 3 rd
. Prospective cohort study
Prospective
A prospective study watches for outcomes, such as the development of a disease, during the study period and relates this to other factors such as suspected risk or protection factor(s). The study usually involves taking a cohort of subjects and watching them over a long period. The outcome of interest should be common; otherwise, the number of outcomes observed will be too small to be statistically meaningful (indistinguishable from those that may have arisen by chance). All efforts should be made to avoid sources of bias such as the loss of individuals to follow up during the study. Prospective studies usually have fewer potential sources of bias and confounding than retrospective studies.
Retrospective
A retrospective study looks backwards and examines exposures to suspected risk or protection factors in relation to an outcome that is established at the start of the study. Many valuable case-control studies, such as Lane and Claypon's 1926 investigation of risk factors for breast cancer, were retrospective investigations. Most sources of error due to confounding and bias are more common in retrospective studies than in prospective studies. For this reason, retrospective investigations are often criticised. If the outcome of interest is uncommon, however, the size of prospective investigation required to estimate relative risk is often too large to be feasible. In retrospective studies the odds ratio provides an estimate of relative risk. You should take special care to avoid sources of bias and confounding in retrospective studies.
Prospective investigation is required to make precise estimates of either the incidence of an outcome or the relative risk of an outcome based on exposure.
Retrospective cohort study
A retrospective cohort study, also called a historic cohort study, is a longitudinal cohort study that studies a cohort of individuals that share a commonexposure factor to determine its influence on the development of a disease, and are compared to another group of equivalent individuals that were not exposed to that factor. Retrospective cohort studies have existed for approximately as long as prospective cohort studies.
Prospective cohort study
A prospective cohort study is a longitudinal cohort study that follows over time a group of similar individuals (cohorts) who differ with respect to certain factors under study, to determine how these factors affect rates of a certain outcome.[1] For example, one might follow a cohort of middle-aged truck drivers who vary in terms of smoking habits, to test the hypothesis that the 20-year incidence rate of lung cancer will be highest among heavy smokers, followed by moderate smokers, and then nonsmokers.
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