Survival rates in lung cancer patients with and without bronchial asthma

Bronchial asthma itself or the treatment of asthma may modify the immunological response to cancer. The survival of lung cancer patients with a preceding diagnosis of bronchial asthma was compared with that of non-asthmatic lung cancer patients in Finland during 1970-1989. This was accomplished by linking two nation-wide data registers, the medication reimbursement register and the cancer registry. For 921 out of the 926 asthmatic patients with lung cancer diagnosed after the diagnosis of bronchial asthma, a non-asthmatic referent patient, matching with respect to sex, anatomical site, and histological type of tumour, as well as to age and year of lung cancer diagnosis, was successfully found in the files of the Cancer Registry. Another referent group was formed by using the stage of lung cancer at diagnosis as an extra matching criterion; this search was successful for 895 asthmatic lung cancer patients. The corrected 5-year survival rate of asthmatic lung cancer patients was 8.4% and that of the referent patients, not matched for stage, 9.6%. When stage was included as matching criterion the corresponding rates were 8.5% and 8.1% respectively. None of these differences were significant. The prognosis of asthmatic and non-asthmatic lung cancer patients thus seemed to be similar.