PET BIRDS AND RISK OF LUNG-CANCER IN SWEDEN - A CASE-CONTROL STUDY

Objective-To investigate the association between keeping birds and the risk of lung cancer in Sweden. Design-Case-control study based on cas es of lung cancer and community controls. Interviews were performed by two nurses specially trained for this project. Setting-Three major re ferral hospitals located in southwest Sweden. Subjects-All patients ag ed 75 and under with newly diagnosed lung cancer and of Scandinavian b irth who lived in one of 26 municipalities in Gothenburg and Bohus cou nty or Alvsborg county. Potential control subjects matched on county o f residence, sex, and closest date of birth were selected from populat ion registries. In the context of a larger case-control study, informa tion on pet birds was obtained from 380 patients with lung cancer (252 men) and 696 controls (433 men). Main outcome measures-Odds ratios fo r lung cancer in relation to whether or not pet birds were kept and th e duration of keeping pet birds. Results-The adjusted odds ratio for e ver versus never exposed to pet birds at home was 0.94 (95% confidence interval 0.64 to 1.39) for men and 1.10 (0.64 to 1.90) for women. The re was no evidence of a trend for increased risk of lung cancer with d uration of bird ownership. Conclusion-Bird keeping does not seem to co nfer any excess risk of lung cancer to Swedish men or women.