Table 5.

Hazard Ratios and 95% Confidence Intervals for the Association of Thyroid Cancer With Physical Activity Level Over the Past Year, US Radiologic Technologists Study, 1983–2006

	Women			Men
	No. of Casesa	HRb	95% CI	No. of Casesa	HRb	95% CI
Strenuous exercisec
None	57	1.00	Reference	9	1.00	Reference
<1 hour/week	26	0.96	0.60, 1.53	3	0.58	0.15, 2.16
≥1 hours/week	29	0.81	0.51, 1.29	6	0.77	0.26, 2.23
P-trend*		0.40			0.59
Walking/hiking for exercisec
None	24	1.00	Reference	5	1.00	Reference
<1 hour/week	27	0.79	0.45, 1.37	6	0.93	0.28, 3.08
≥1 hours/week	64	0.92	0.58, 1.49	6	0.59	0.18, 1.97
P-trend*		0.94			0.37
Walking at home or workc
None	3	0.52	0.16, 1.64	1	0.86	0.11, 6.65
<1 hour/week	18	1.05	0.64, 1.74	4	1.37	0.44, 4.23
≥1 hours/week	95	1.00	Reference	13	1.00	Reference
P-trend*		0.47			0.82
Total MET-score tertilec,d
1: Low activity	31	1.00	Reference	7	1.00	Reference
2: Medium activity	38	1.33	0.83, 2.14	3	0.50	0.13, 1.94
3: High activity	40	1.37	0.85, 2.20	7	1.11	0.38, 3.20
P-trend*		0.19			0.92

Abbreviations: CI, confidence interval; HR, hazard ratio; MET, metabolic equivalent task.

*P-trend based on ordinal score variable.

^aNumber of cases may be inconsistent because of missing values.

^bAdjusted for birth year, smoking status, body mass index, number of personal radiographs to the head or neck, cumulative occupational radiation dose, and medical history of benign thyroid conditions.

^cCollected in only the second questionnaire (1994–1998) (89.6% of the study population).

^dMET tertiles—women: <20, 20–55, ≥56; men: <18, 18–49, ≥50.