Question

A study was conducted on the association between human papillomavirus and oropharyngeal cancer. It identified 102 patients with newly diagnosed squamous-cell carcinomas of the head and neck in Baltimore from 2000 through 2005. The comparison group consisted of 200 patients without a history of cancer who were seen for benign conditions between 2000 and 2005 in the same clinic. All patients completed a computer-assisted self-administered interview that recorded information about demographic characteristics, past oral hygiene, medical history, family history of cancer, lifetime sexual behaviors, and lifetime history of marijuana, tobacco, and alcohol use. Part of their results focused on the association between oral hygiene and oropharyngeal cancer. Among the 102 subjects with oropharyngeal cancer 64 reported no tooth loss, and 38 reported some or complete tooth loss. Among the 198 subjects without oropharyngeal cancer 161 reported no tooth loss, and 37 reported some or complete tooth loss.

a. Set up the 2x2 table using these data. (2 points)

	Oropharyngeal cancer
	Yes	No	Total
Tooth loss
Yes
No
Total

b. What is the odds ratio for the association between tooth loss and oropharyngeal cancer? (2 points)

c. State in words your interpretation of this odds ratio. (1 point)

Answer 1

(a)
From the given data, the following 2X 2 frequency table is formed:

	Oropharyngeal cancer Yes	Oropharyngeal cancer No	Total
Tooth loss: Yes	a = 38	b = 37	75
Tooth loss: No	c= 64	d = 161	225
Total	102	198	300

(b)

Odds Ratio (OR) s given by:

(c)

The Odds Ratio = 2.5836 is the measure of association for the given case control study of tooth loss and Oropharyngeal cancer.

Since here OR = 2.5836 is greater than 1.0, we conclude that the odds of exposure among case - patients are greater than the odds of exposure among controls. The exposure might be a risk factor for the disease.