Blood Pressure, Smoking, and the Incidence of Lung Cancer in Hypertensive Men in North Karelia, Finland
Annamarja Lindgren
)
2
Eero Pukkala
1
Aulikki Nissinen
0
3
Jaakko Tuomilehto
0
0
Department of Epidemiology and Health Promotion, National Public Health Institute
,
Helsinki
,
Finland
1
Finnish Cancer Registry
,
Helsinki
,
Finland
2
Department of Public Health and General Practice, University of Kuopio
,
Kuopio
,
Finland
3
Department of Neurology, Kuopio University Hospital
,
Kuopio
,
Finland
Few studies have suggested that elevated blood pressure might be associated with increased risk of lung cancer and that this association might vary according to smoking status. The aim of this study was to assess the effect of blood pressure and its possible interaction with smoking on lung cancer incidence in hypertensive patients. Lung cancer incidence was determined for 7,908 men enrolled in the hypertension register of the North Karelia Project between 1972 and 1988 by record linkage to the nationwide Finnish Cancer Registry. In a Cox regression model, both systolic and diastolic blood pressures were significant predictors of lung cancer, with a 10% increase in risk per 10-mmHg increment in blood pressure. In smokers, the age-adjusted hazard ratio associated with a 10-mmHg increment in diastolic blood pressure was 1.17 (95% confidence interval: 1.05, 1.29), and in nonsmokers it was 0.98 (95% confidence interval: 0.80, 1.16). For systolic blood pressure, these hazard ratios were 1.11 (95% confidence interval: 1.05, 1.17) for smokers and 1.04 (95% confidence interval: 0.95, 1.14) for nonsmokers. These findings suggest that high blood pressure levels are associated with increased risk of lung cancer in smoking, hypertensive men. hypertension; incidence; lung neoplasms; medical record linkage; risk; smoking
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Lung cancer is the most common malignancy in men
worldwide, with increasing significance also in women.
Smoking is the well-established and prime risk factor for
lung cancer (1), but other factors also play a role in the
development of lung cancer, and some other factors may modify
the effect of smoking. Further clarification in the etiology of
lung cancer, as well as better identification of the factors
causing the heterogeneity in lung cancer risk among
smokers, requires attention.
In some studies reporting a positive association between
hypertension and all-site cancer risk (211), lung cancer has
been found to be one of the cancer types related to elevated
blood pressure (2, 9, 11). Wannamethee and Shaper (9)
showed that the risk of lung cancer remained similar in
nonsmokers regardless of their blood pressure level, but in
current smokers the risk increased sharply with increasing
systolic blood pressure. Studies reporting no association
between hypertension and lung cancer also exist (35, 10,
12).
In the present study, we have assessed the effects of
systolic and diastolic blood pressures and their interaction
with smoking on lung cancer incidence among a large,
population-based cohort of hypertensive patients in North
Karelia, Finland.
MATERIALS AND METHODS
The study cohort consisted of 8,029 male hypertensive
patients included in the community-based hypertension
register of the North Karelia Project. The details of the
register are described elsewhere (1315). This
provincewide register was established in 1972, and new cases were
entered into the register until 1988. The register was run
within the primary health care system in North Karelia as
part of the North Karelia Project (16, 17). All subjects who
either were previously on antihypertensive drug treatment or
had elevated blood pressure in three subsequent
measurements were eligible to be registered. The blood pressure
criteria were as follows: 150 and/or 90 mmHg (29 years),
160 and/or 95 mmHg (3064 years), and 170 and/or 95
mmHg (65 years). Blood pressure was measured from the
right arm of the patient who was in a sitting position by local
nurses and physicians after a 5- to 10-minute rest. Diastolic
blood pressure was recorded as the fifth phase of Korotkoff
sounds. The local nurses and physicians, following the
common protocol of the hypertension register, completed the
record forms after clinical examination of the patient.
The functional diagnosis of hypertension was based on
World Health Organization recommendations (18). Stage I
denoted elevated blood pressure without evidence of organic
changes in the cardiovascular system. Stage II denoted high
blood pressure with left ventricular hypertrophy but without
evidence of other organ damage, and stage III denoted high
blood pressure with other organ damage attributable to
hypertension.
Since January 1, 1967, all residents of Finland have had a
unique personal identifier, which is used in all the main
registers in Finland. The validity of the personal identifiers
of the cohort members was checked with a linkage to
Population Register of Finland. Dates of death and emigrations
were obtained from the same source. Eighteen subjects (0.2
percent) were excluded from the cohort because they could
no (...truncated)