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Pia K Verkasalo

Publications and source records attributed to Pia K Verkasalo.

10 recordsLinked to original sources
PubMed2006

Does incidence of breast cancer and prostate cancer decrease with increasing degree of visual impairment.

OBJECTIVE: The issue of light at night and cancer continuously attracts discussion. The major hypotheses are that melatonin may decrease risk of hormone-related cancers, particularly breast cancer, or even act as a potent antioxidant and thus have a protective effect against cancer development in general. METHODS: We tested the hypothesis that blind persons are at lower risk of cancer in a follow-up study linking a cohort of 17,557 persons with visual impairment identified from the Finnish Register of Visual Impairment with cancer incidence data of the Finnish Cancer Registry for years 1983-2003. RESULTS: Breast cancer risk in females decreased by degree of visual impairment, and a similar but less consistent trend was observed for prostate cancer in males. The incidence for the remaining cancers among nearly to totally blind persons was significantly higher than in average Finnish population. CONCLUSIONS: Our findings add to the suggestive epidemiological evidence for a decreased risk of hormone-related cancers in people with visual impairment and, consequently, a relationship between visible light at night and breast cancer risk. The result is strongly against the hypothesis of a systemic protective effect related lack of visible light.

Blindness↗
PubMed2005

Sleep duration and breast cancer: a prospective cohort study.

Breast cancer incidence has increased during recent decades for reasons that are only partly understood. Prevalence of sleeping difficulties and sleepiness has increased, whereas sleeping duration per night has decreased. We hypothesized that there is an inverse association between sleep duration and breast cancer risk, possibly due to greater overall melatonin production in longer sleepers. This population-based study includes information from women born in Finland before 1958. Sleep duration, other sleep variables, and breast cancer risk factors were assessed by self-administered questionnaires given in 1975 and in 1981. Breast cancer incidence data for 1976 to 1996 was obtained from the Finnish Cancer Registry. Hazard ratios (HR) and 95% confidence intervals (CI) were obtained from Cox proportional hazards models adjusting for potential confounders. Altogether, 242 cases of breast cancer occurred over the study period among the 12,222 women with sleep duration data in 1975. For these women, the HRs for breast cancer in the short (< or =6 hours), average (7-8 hours), and long sleep (> or =9 hours) duration groups were 0.85 (CI, 0.54-1.34), 1.0 (referent), and 0.69 (CI, 0.45-1.06), respectively. Analysis restricted to the 7,396 women (146 cases) whose sleep duration in 1975 and 1981 were in the same duration group (stable sleepers) yielded HRs of 1.10 (CI, 0.59-2.05), 1.0, and 0.28 (CI, 0.09-0.88), with a decreasing trend (P = 0.03). This study provides some support for a decreased risk of breast cancer in long sleepers.

Adult↗
PubMed2005

Good outcome of teenage pregnancies in high-quality maternity care.

BACKGROUND: Teenage pregnancies have been associated with fetal growth restriction, low birth weight, preterm birth and neonatal mortality. These could be due to biological immaturity, lifestyle factors or inadequate attendance to maternity care. The objective of this study was to assess the relationship between young age of the mother and pregnancy risk factors and adverse pregnancy outcome in conditions of high-quality maternity care used by almost the entire pregnant population. METHODS: We analysed a population-based database of 26,967 singleton pregnancies during 1989-2001. Only 185 of these mothers were under 18 years old. Data were collected using a self-administered questionnaire at 20 weeks of pregnancy and clinical records of pregnancy, delivery and newborn child. The information covered maternal risk factors, pregnancy characteristics and obstetric outcomes. Odds ratios (ORs) for adverse pregnancy outcomes in teenage compared with older mothers were obtained from multiple logistic regression models. RESULTS: Teenage mothers smoked, were unemployed and had anaemia or chorioamnionitis more often than older mothers. On the other hand, they were overweight and had maternal diabetes less often than adults. Teenage mothers had as many instrumented deliveries (OR 0.70; 95% confidence interval 0.39-1.27) but fewer Caesarean sections (0.62; 0.39-0.97) than adults. We found no evidence for increased risk of preterm delivery, fetal growth restriction, low birth weight, or fetal or perinatal death in teenage mothers. CONCLUSIONS: These results suggest that increased risks for adverse pregnancy outcomes in teenage pregnancies can most probably be overcome by means of high-quality maternity care with complete coverage.

Adolescent↗
PubMed2004

Improving the efficiency of nested case-control studies of interaction by selecting controls using counter matching on exposure.

BACKGROUND: Studies of the effect of exposure to a risk factor measured in an entire cohort may be augmented by nested case-control subsets to investigate confounding or effect modification by additional factors not practically assessed on all cohort members. We compared three control-selection strategies-matching on exposure, counter matching on exposure, and random sampling-to determine which was most efficient in a situation where exposure is a known, continuous variable and high doses are rare. METHODS: We estimated the power to detect interaction using four control-to-case ratios (1:1, 2:1, 4:1, and 8:1) in a planned case-control study of the joint effect of atomic bomb radiation exposure and serum oestradiol levels on breast cancer. Radiation dose is measured in the entire cohort, but because neither serum oestradiol level nor the true degree of interaction was known, we simulated values of oestradiol and hypothetical levels of oestradiol-radiation interaction. RESULTS: Compared with random sampling, power to detect interaction was similarly higher with either matching or counter matching with two or more controls. CONCLUSIONS: Because counter matching is generally at least as efficient as random sampling, whereas matching on exposure can result in loss of efficiency and precludes estimation of exposure risk, we recommend counter matching for selecting controls in nested case-control studies of the joint effects of multiple risk factors when one is previously measured in the full cohort.

Breast Neoplasms↗
PubMed2004

Cancer risk near a polluted river in Finland.

The River Kymijoki in southern Finland is heavily polluted with polychlorinated dibenzo-p-dioxins and dibenzofurans and may pose a health threat to local residents, especially farmers. In this study we investigated cancer risk in people living near the river (less than 20.0 km) in 1980. We used a geographic information system, which stores registry data, in 500 m times 500 m grid squares, from the Population Register Centre, Statistics Finland, and Finnish Cancer Registry. From 1981 to 2000, cancer incidence in all people (N = 188884) and in farmers (n = 11132) residing in the study area was at the level expected based on national rates. Relative risks for total cancer and 27 cancer subtypes were calculated by distance of individuals to the river in 1980 (reference: 5.0-19.9 km, 1.0-4.9 km, less than 1.0 km), adjusting for sex, age, time period, socioeconomic status, and distance of individuals to the sea. The respective relative risks for total cancer were 1.00, 1.09 [95% confidence interval (CI), 1.04-1.13], and 1.04 (95% CI, 0.99-1.09) among all residents, and 1.00, 0.99 (95% CI, 0.85-1.15), and 1.13 (95% CI, 0.97-1.32) among farmers. A statistically significant increase was observed for basal cell carcinoma of the skin (not included in total cancers) in all residents less than 5.0 km. Several other common cancers, including cancers of the breast, uterine cervix, gallbladder, and nervous system, showed slightly elevated risk estimates at less than 5.0 km from the river. Despite the limitations of exposure assessment, we cannot exclude the possibility that residence near the river may have contributed to a small increase in cancer risk, especially among farmers.

Adolescent↗
PubMed2003

Stressful life events and risk of breast cancer in 10,808 women: a cohort study.

The authors prospectively investigated the relation between stressful life events and risk of breast cancer among 10,808 women from the Finnish Twin Cohort. Life events and breast cancer risk factors were assessed by self-administered questionnaire in 1981. A national modification of a standardized life event inventory was used, examining accumulation of life events and individual life events and placing emphasis on the 5 years preceding completion of the questionnaire. Through record linkage with the Finnish Cancer Registry, 180 incident cases of breast cancer were identified in the cohort between 1982 and 1996. The multivariable adjusted hazard ratio for breast cancer per one-event increase in the total number of life events was 1.07 (95% confidence interval (CI): 1.00, 1.15). This risk estimate rose to 1.35 (95% CI: 1.09, 1.67) when only major life events were taken into account. Independently of total life events, divorce/separation (hazard ratio (HR) = 2.26, 95% CI: 1.25, 4.07), death of a husband (HR = 2.00, 95% CI: 1.03, 3.88), and death of a close relative or friend (HR = 1.36, 95% CI: 1.00, 1.86) were all associated with increased risk of breast cancer. The findings suggest a role for life events in breast cancer etiology through hormonal or other mechanisms.

Adult↗
PubMed2002

Risk factors for breast cancer at young ages in twins: an international population-based study.

BACKGROUND: Breast cancer etiology in women may relate to exposures early in life as well as in adulthood, but it has been difficult to gain information on childhood variables, and evidence on their effects is very limited. Comparison of risk factor levels between affected probands and unaffected twins in twin pairs can provide a unique method to investigate risk factors that act in early life. METHODS: We conducted four population-based case-control studies of breast cancer risk in twins in Denmark, England and Wales, Finland, and Sweden and pooled the data from these studies. The case patients were 400 women with incident breast cancer before the age of 50 years, and the control subjects were their twin sisters who had not had breast cancer by that time. Data on risk factors (e.g., demographic and anthropomorphic variables, reproductive history, and family history) were collected by interview and by a mailed questionnaire and were analyzed by calculating matched odds ratios [ORs]. All statistical tests were two-sided. RESULTS: The risk of breast cancer was increased for women who were less obese (OR = 1.44, 95% confidence interval [CI] = 1.08 to 1.91) or taller (OR = 1.27, 95% CI = 0.95 to 1.70) than their co-twin at age 10 years, for women who developed breasts earlier than their co-twin (OR = 1.53, 95% CI = 1.14 to 2.06), and for women who had a smaller waist-to-hip ratio at age 20 years than their co-twin (OR = 1.79, 95% CI = 1.00 to 3.21). Analysis according to family history of breast cancer showed that the associations of childhood height and weight with risk of breast cancer were only apparent in women without a family history of breast cancer. CONCLUSIONS: Childhood growth before puberty may affect the risk of premenopausal breast cancer, at least in women without a family history of breast cancer. The distribution of body fat in young adulthood may also be related to breast cancer risk.

Adolescent↗
PubMed2002

Personality characteristics and the risk of breast cancer: a prospective cohort study.

Various personality characteristics have been suggested to increase the risk of breast cancer but reliable epidemiologic data on this issue are limited. We prospectively investigated the relationship between personality characteristics and the risk of breast cancer in 12,499 Finnish women aged 18 years or more. In health questionnaires in 1975 and 1981, these women completed at least one of the following personality scales: Eysenck extroversion, Bortner type A behaviour and author-constructed measure of hostility. They also reported about other potential breast cancer risk factors. From 1976-1996, 253 cases of breast cancer were identified by record linkage with the Finnish Cancer Registry. Proportional hazard models were used to estimate hazard ratios (HR) and 95% confidence intervals (CI). The multivariable HRs of breast cancer for women with intermediate level (scores 3-6) and high level (7-9) of extroversion in 1975 were 1.18 (95% CI 0.87-1.60) and 0.97 (95% CI 0.64-1.47), respectively, compared to those with low level (0-2). These results remained unaltered when the level of extroversion was determined as the average of the 1975 and 1981 reports. There was also no increase in breast cancer risk in relation to type A behaviour and hostility. Furthermore, we observed no substantial joint effects of personality characteristics on the risk of breast cancer. In conclusion, our data do not support the existence of an important role for personality in the aetiology of breast cancer. These findings are reassuring to those who have believed the contrary.

Adult↗
PubMed2002

A prospective study of life satisfaction, neuroticism and breast cancer risk (Finland).

OBJECTIVE: To prospectively investigate whether life satisfaction and neuroticism, two measures reflecting aspects of anxiety/depression, are related to risk of breast cancer. METHODS: The study population comprised 12,032 women from the population-based Finnish Twin Cohort. Life satisfaction and neuroticism were assessed in health questionnaires in 1975 and 1981. During 21 years of follow-up, 238 cases of breast cancer were documented in the study cohort through record linkage to the Finnish Cancer Registry. RESULTS: After adjustment for age and other important covariates, the hazard ratios were 1.0 (reference), 0.9 (95% confidence interval 0.6-1.3) and 1.0 (0.7-1.6) by decreasing level of life satisfaction (satisfied, intermediate, dissatisfied), and 1.0 (reference), 1.0 (0.7-1.4) and 0.8 (0.6-1.2) by increasing level of neuroticism (low, intermediate, high). These results did not change after accounting for possible changes in the levels of life satisfaction and neuroticism between 1975 and 1981. The null results were also confirmed with the use of a nested case-control study within twin pairs that became discordant for breast cancer during the follow-up. CONCLUSIONS: Our data indicate that life satisfaction and neuroticism are not substantially associated with breast cancer risk. These findings provide epidemiological evidence against the doubts that breast cancer would be more likely to occur in unhappy, dissatisfied, and worrying women.

Adult↗