Overweight and obesity increase the risk of numerous chronic diseases, including several forms of cancer. However, the association between excess body weight and all-cause mortality among young and middle-aged women is incompletely known, and the impact of menopausal status on the association has hardly been investigated. We studied prospectively a cohort comprising a population sample of 102,446 women from Norway and Sweden aged 30-50 years when they answered an extensive questionnaire in 1991/1992. During follow-up through year 2000, 1187 women in the cohort died. We used Cox proportional hazard models to estimate multivariate Hazard rate ratios (HRR) with 95% confidence intervals (CI) of death in relation to body mass index (BMI, weight (kg)/height (m(2))) at start of follow-up. Both in age-adjusted models and in models adjusting for several variables (including smoking and physical activity) mortality increased with increasing BMI among premenopausal women, whereas a U-shaped relationship was seen among the postmenopausal women. Among premenopausal women obesity (BMI 30.0) doubled the mortality (HRR = 2.2, 95% CI: 1.7-3.0) when compared to women of normal weight (BMI 18.5-24.9), whilst the association was modest after menopause. Although we had limited power to analyze women who were underweight (BMI
The aim of our study was to examine the risk of breast cancer according to specific types of estrogens and progestagens in oral contraceptives (OCs) based on the prospective Norwegian Women and Cancer study (NOWAC). Between 1991-97 women aged 30-70 years were drawn at random from the central person register and mailed an invitation and a questionnaire. Women (102,443) were enrolled with follow-up information collected throughout 1999 by linkage with national registries of cancer, mortality and emigration based on the unique national identification number. Among the 96,362 women included in the present analysis 851 invasive breast cancer were diagnosed. The adjusted risk of breast cancer increased with 25% for ever use of OCs and the risk increased with increasing duration of use (test for trend: p = 0.007). No association between time since last use and breast cancer risk was found after stratification on duration of use. Positive trend was still found for total duration of use among women who used OCs more than 5 years ago. Second generation of OCs had an increased risk with increasing duration of use. Classifying progestagens according to chemical groups, the relative risk increased significantly with increasing cumulative dose of levonorgestrel progestagen. It was difficult to conclude for the other groups due to lack of power. In a multivariate analysis the cumulative dose for all progestagen groups were non-significant, although we observed a significant increased risk with increasing milligram-months of estrogen exposure (p = 0.002). In conclusion, the increased risk of breast cancer related with OC formulations could be due mostly to estrogen component.
An organized mammography screening program was gradually implemented in Norway during the period 1996-2004. Norwegian authorities have initiated an evaluation of the program. Our study focused on breast cancer mortality. Using Poisson regression, we compared the change in breast cancer mortality from before to during screening in four counties starting the program early controlling for change in breast cancer mortality during the same time in counties starting the program late. A follow-up model included death in all breast cancers diagnosed during the follow-up period. An evaluation model included only breast cancers diagnosed in ages where screening was offered. The study group had been invited for screening one to three times and followed for on average of 5.9 years. In the follow-up model, 314 breast cancer deaths were observed in the study group, and 523, 404 and 638, respectively, in the four control groups. The ratio between the changes in breast cancer mortality between early and late starting counties was 0.93 (95% confidence interval [CI] 0.77-1.12). In the evaluation model, this ratio was 0.89 (95% CI: 0.71-1.12). In Norway, where 40% of women used regular mammography prior to the program, the implementation of the organized mammography screening program was associated with a statistically nonsignificant decrease in breast cancer mortality of around 11%.
Comment In: Int J Cancer. 2013 Apr 1;132(7):1721-222933058
Comment In: Int J Cancer. 2013 Apr 1;132(7):1723-422933134
Comment In: Int J Cancer. 2013 Apr 1;132(7):172722933244
Comment In: Int J Cancer. 2013 Apr 1;132(7):1725-622933188
OBJECTIVE: To examine the effect of smoking on breast cancer risk in a large population-based cohort of women, many of whom started smoking as teenagers.METHODS: We followed 102,098 women, ages 30 to 50 years, completing a mailed questionnaire at recruitment to the Norwegian-Swedish Cohort Study in 1991/1992, through December 2000. We used Cox proportional hazard regression models to estimate relative risk (RR) of breast cancer associated with different measures of smoking initiation, duration, and intensity adjusting for confounding variables. We conducted analyses on the entire study population, among women who had smoked for at least 20 years, among nondrinkers, and separately for each country.RESULTS: Altogether, 1,240 women were diagnosed with incident, invasive breast cancer. Compared with never smokers, women who smoked for at least 20 years and who smoked 10 cigarettes or more daily had a RR of 1.34 (95% CI, 1.06-1.70). Likewise, those who initiated smoking prior to their first birth (1.27, 1.00-1.62), before menarche (1.39, 1.03-1.87), or before age 15 (1.48, 1.03-2.13) had an increased risk. In contrast, women who had smoked for at least 20 years, but started after their first birth, did not experience an increased breast cancer risk. The increased RR associated with smoking was observed among nondrinkers of alcohol, women with and without a family history of breast cancer, premenopausal and postmenopausal women, and in both countries.CONCLUSION: Our results support the notion that women who start smoking as teenagers and continue to smoke for at least 20 years may increase their breast cancer risk.
The traditional northern Norwegian fish dish "mølje", consisting of boiled cod, cod liver, cod liver oil and hard roe, is still consumed frequently during the winter months January to March. The liver of the cod is rich in lipids and the levels of persistent organic pollutants (POPs) are relatively high. To better understand the short-term consequences of this traditional meal on the plasma levels of PCBs and p,p'-DDE, individual intake of liver and cod liver oil during one meal was measured. Blood samples were collected from 33 participants before the meal, and then 4 h, 12 h and 5 days after it. Lipid-weight and wet-weight levels of 10 PCB congeners and p,p'-DDE were determined in the plasma samples and the food. The plasma levels of p,p'-DDE was found to increase significantly from 0 to 4 h, both when expressed as wet-weight (35% change) and lipid-weight (20% change). The corresponding changes (0-4 h) in wet-weight levels of the most prevalent PCB congeners were non significant. By contrast, PCB congeners with low levels in the food showed a significant drop in lipid-weight levels during the first 4 h. The observed changes were independent of amount consumed. Significant differences in fasting and non-fasting samples were found for most PCBs and p,p'-DDE. For the lipid weight levels of sum PCBs there was a significant decrease of 16% from non-fasting to fasting samples. To obtain reliable data on human levels of POPs it is, on the basis of these findings, recommended that blood samples should be collected from fasting individuals and both wet-weight and lipid-weight levels should be reported.
To assess changes in plasma 25-hydroxy vitamin D (25(OH)D) concentrations after ingestion of , a traditional north Norwegian fish dish rich in vitamin D.
Thirty-three volunteers all living in the city of Tromsø, located in northern Norway (latitude 690), were served a "Mølje" meal consisting of cod, hard roe, cod liver, and fresh cod-liver oil. The amounts of liver, and cod-liver oil consumed were weighed and recorded. Blood samples were collected before the meal, and at 4 hours, 12 hours and 5 days after it. The cod liver and cod-liver oil were analysed for vitamin D content and the plasma samples for the metabolite 25(OH)D. Trends in plasma 25(OH)D levels during the five-day observation period were analysed. The study was conducted at the beginning of April of 2000.
Among the 33 participating subjects, 69.7% had baseline plasma 25(OH)D concentrations below 50 nmol/l and for one-quarter of the subjects, they were
To investigate dietary and non-dietary characteristics of wholegrain bread eaters in the Norwegian Women and Cancer study.
Cross-sectional study using an FFQ.
Women were divided into two groups according to wholegrain bread consumption.
Adult women (n 69 471).
Median daily consumption of standardized slices of wholegrain bread was 2·5 in the low intake group and 4·5 in the high intake group. The OR for high wholegrain bread consumption was 0·28, 2·19 and 4·63 for the first, third and fourth quartile of energy intake, respectively, compared with the second quartile. Living outside Oslo or in East Norway and having a high level of physical activity were associated with high wholegrain bread consumption. BMI and smoking were inversely associated with wholegrain bread consumption. Intake of many food items was positively associated with wholegrain bread consumption (P trend
The association between cigarette smoking and colorectal cancer (CRC) is still not established. In 2002, Norwegian women had the second highest incidence of CRC in the world. A large proportion of Norwegian women are ever smokers. We examined the association between cigarette smoking and CRC incidence among Norwegian women.
We followed 68,160 women, aged 30-69 years, from the Norwegian Women and Cancer Study who completed a questionnaire in 1996 or 1998 by linkages to national registers through 31 December 2005. Rate ratios (RRs) and 95% confidence intervals (CIs) were estimated by fitting Cox proportional hazard models. Subsequently, we estimated the population attributable fraction.
Altogether, 425 incident cases of primary, invasive CRC were identified. Ever smokers had a 20% increased risk of CRC (RR = 1.2; 95% CI = 1.0-1.5), a 30% increased risk of colon (RR = 1.3; 95% CI = 1.0-1.7), and a 10% increased risk of rectal (RR = 1.1; 95% CI = 0.7-1.5) cancer compared to never smokers. The population attributable fraction was estimated to be 12% which indicated that approximately one in eight of the CRC cases could have been prevented at a population level.
Our results support the hypothesis that cigarette smoking is a preventable cause of CRC among women.
Cites: Int J Cancer. 2001 Feb 15;91(4):585-711251986
An association between coffee consumption and cancer has long been investigated. Coffee consumption among Norwegian women is high, thus this is a favorable population in which to study the impact of coffee on cancer incidence. Information on coffee consumption was collected from 91,767 women at baseline in the Norwegian Women and Cancer Study. These information were applied until follow-up information on coffee consumption, collected 6-8 years after baseline, became available. Multiple imputation was performed as a method for dealing with missing data. Multivariable Cox regression models were used to calculate hazard ratios (HR) for breast, colorectal, lung, and ovarian cancer, as well as cancer at any site. We observed a 17 % reduced risk of colorectal cancer (HR = 0.83, 95 % CI 0.70-0.98, p trend across categories of consumption = 0.10) and a 9 % reduced risk of cancer at any site (HR = 0.91, 95 % CI 0.86-0.97, p trend = 0.03) in women who drank more than 3 and up to 7 cups/day, compared to women who drank =1 cup/day. A significantly increased risk of lung cancer was observed with a heavy coffee consumption (>7 vs. =1 cup/day HR = 2.01, 95 % CI 1.47-2.75, p trend 5 vs. =1 cup/day HR = 1.42, 95 % CI 0.44-4.57, p trend = 0.30). No significant association was found between coffee consumption and the risk of breast or ovarian cancer. In this study, coffee consumption was associated with a modest reduced risk of cancer at any site. Residual confounding due to smoking may have contributed to the positive association between high coffee consumption and the risk of lung cancer.
Cites: Public Health Nutr. 2007 Oct;10(10):1094-103 PMID 17381903