Question

A number of studies have shown a relationship between obesity or body mass index (BMI) and endometrial cancer. Weiderpass and colleagues (2000) conducted a population-based case control study in Sweden among post-menopausal women aged 50-74. The following table shows the association between obesity and endometrial cancer in the Weiderpass et al study. [Source: Fleming Cases and Concepts]

                        Cases              Controls
Obese             205                 350
Nonobese      387                 2,171
Total               592                 2,521

Calculate and interpret the odds ratio and choose from the answers below

3.3; Obese women have greater odds of developing endometrial cancer than nonobese women

3.0; Obese women have lesser odds of developing endometrial cancer than nonobese women

3.1; Obese women have lesser odds of developing endometrial cancer than nonobese women

3.2; Obese women have greater odds of developing endometrial cancer than nonobese women

Answer 1

The data is as follows:

	Cases (Cancer)	Controls (no cancer)
Obese	a = 205	b = 350
Non-Obese	c = 387	d = 2171
Total	a+c = 592	b+d = 2521

The Odds ratio OR is defined as:
OR = (a/c)/(b/d)
=> OR = (205/387)/(350/2171)
=> OR = 0.5297/0.1612
=> OR = 3.286

The OR is 3.286 which is > 1.
=> Since odds ratio is greater than one we can say that the obese woman have greater chance of developing endometrial cancer than the non-obese woman.

Hence the answer will be 'Obese women have greater odds of developing endometrial cancer than non-obese women'.

Hope this helped!