Reproductive Factors, Use of Exogenous Hormones, and Pancreatic Cancer Incidence: The Norwegian Women and Cancer Study

Introduction: The incidence of pancreatic cancer is increasing worldwide and characterized by a particularly low survival rate. Studies have reported weak and inconsistent evidence for associations among reproductive factors, use of exogenous hormones, and pancreatic cancer incidence in women. Purpose: To investigate relationships between reproductive factors, exogenous hormones, and the rate of pancreatic cancer incidence in a large population-based prospective cohort of women in Norway. Methods: We used data from the Norwegian Women and Cancer study on 588 incident cases of pancreatic cancer diagnosed among 165,419 women, with mean follow-up of 18.7 years. Cox proportional-hazard models were used to estimate HRs and 95% CIs for associations of interest. Results: Cumulative breastfeeding duration > 24 months was associated with 63% decreased incidence of pancreatic cancer compared to no breastfeeding. We observed an inverse linear dose–response trend between cumulative breastfeeding duration and pancreatic cancer incidence, which was confirmed in parous women and ever-smokers. Higher age at first birth and menopause were inversely associated with pancreatic cancer incidence, though with less precise effect estimates. Current use of oral contraceptives was associated with a doubling of pancreatic cancer incidence, but the analysis was hampered by a small number of cases. There was no evidence of any associations between age at menarche, parity or use of menopausal hormone therapy, and incidence of pancreatic cancer. Conclusion: Our results suggest a potential protective effect of breastfeeding duration against pancreatic cancer incidence. Inconsistent results for the other reproductive factors suggested no important role of estrogens in pancreatic cancer etiology

Physical activity and mortality among Norwegian women – the Norwegian Women and Cancer Study

Physical activity (PA) and its relationship with all-cause mortality suggest a strong and consistent inverse association. This study prospectively investigated the association between PA level and mortality among participants of the Norwegian Women and Cancer (NOWAC) Study. A total of 66,136 NOWAC participants were followed-up until December 31st 2008. PA level and possible confounding factors were obtained through a self-administered questionnaire at enrolment. Cox proportional hazards regression was used to calculate adjusted relative risks (RRs) and 95% confidence intervals (CIs) for all-cause, cardiovascular disease (CVD) and cancer mortality and PA levels defined from 1 to 10 on a global scale. PA levels 1–4 were associated with a significantly increased risk of all-cause mortality (level 1 RR = 2.35; 95% CI: 1.94–2.84, level 2 RR = 1.71; 95% CI: 1.45–2.00, level 3 RR = 1.30; 95% CI: 1.14–1.49, level 4 RR = 1.07; 95% CI: 0.95–1.22), compared with PA level 5. CVD mortality risk increased in PA levels 1–3 (level 1 RR = 3.50; 95% CI: 2.41–5.10, level 2 RR = 1.50; 95% CI: 0.99–2.25, level 3 RR = 1.12; 95% CI: 0.79–1.60) as did cancer mortality risk (RR = 1.32; 95% CI: 0.96–1.81, RR = 1.48; 95% CI: 1.19–1.84, RR = 1.26; 95% CI: 1.06–1.50, respectively). The magnitude of the associations was consistent across strata of age, smoking, and body mass index. The population attributable fractions for PA levels 1–4 were: all-cause mortality, 11.5%; CVD mortality, 11.3%; cancer mortality, 7.8%. There is a significant trend of increased risk of all-cause, CVD and cancer mortality in relation to low PA levels among Norwegian women

Risk of lung cancer and physical activity by smoking status and body mass index, the Norwegian Women and Cancer Study

We aimed to investigate physical activity (PA) and risk of different histological subtypes of lung cancer according to smoking status and body mass index using repeated measurements in a large cohort of women in Norway. The study sample for the multiple imputation analyses consisted of 86,499 and for the complete-case analysis 80,802 women. Repeated measurements of PA level, smoking habits, weight, and height were available for 54,691 women (63.2%), who were included in repeated measurement analyses combined with multiple imputation to address attrition. Cox proportional hazards regression models were used to calculate hazard ratios with 95% confidence intervals. During a median follow-up of 12.9years, 866 cases of primary lung cancer were identified. We found an inverse association between PA and lung cancer overall. The results were consistent from multiple imputed data analysis to complete-case analysis of PA and possible confounders. We observed a similar trend for adenocarcinoma, but not for squamous cell or small cell carcinomas. Our findings suggest a more pronounced association between lung cancer overall and PA levels in current and former smokers, and in normal-weight and overweight participants with increasing PA levels. The potential of a modifiable lifestyle factor as PA to reduce the risk of lung cancer independently of smoking status is important in public health.Peer reviewe

Physical activity before and after breast cancer diagnosis and survival - the Norwegian women and cancer cohort study

Background: The main aim of this study was to investigate pre- and post-diagnostic physical activity (PA) levels, as well as changes in pre- and post-diagnostic PA levels, and their association with all-cause and breast cancer-specific mortality in women with breast cancer. Our study will add to the knowledge on whether a modifiable behavior such as PA can improve survival. Methods: We included 1,327 women with breast cancer from the population-based Norwegian Women and Cancer study, which enrolled women from 1991 to 2003. Breast cancer cases were identified through linkage to the Cancer Registry of Norway; date and cause of death were obtained from the National Register for Causes of Death through 31 December 2012. Self-reported pre- and post-diagnostic PA levels were assessed, and Cox proportional hazard regression and spline regression were used to evaluate the associations. Results: Pre-diagnostic PA levels were not associated with all-cause or breast cancer-specific mortality. Post-diagnostic PA levels were associated with a significant trend (P <0.001) of decreased all-cause and breast cancer-specific mortality, which was stronger among older women (aged 50-74 years) and did not differ across categories of body mass index. All-cause mortality (hazard ratio [HR] = 1.76, 95 % confidence interval [CI] 1.21-2.56) and breast cancer-specific mortality (HR = 2.05, 95 % CI 1.35-3.10) increased among women who reduced their post-diagnostic PA level. These values were similar among women whose maintained an inactive PA level pre- and post-diagnosis. Conclusion: Overall, we observed a dose-response trend, with an inverse association between increased post-diagnostic PA level and all-cause and breast cancer-specific mortality, as well as a higher mortality risk among women who reduced their post-diagnostic PA levels. Our results are very promising for women with breast cancer, and indicate that health care professionals should consider adding PA as a part of primary cancer treatment.Peer reviewe

Physical activity in Sami and non-Sami populations in rural Northern Norway, the SAMINOR 2 Clinical Survey

Background - The Sami people is an indigenous minority population living in the northern parts of Norway and mainly in rural areas. We lack data of contemporary levels of physical activity (PA) in rural regions of Northern Norway and in the Sami population in particular. We aimed to describe the PA levels and investigate whether PA levels differs between Sami and non-Sami and between coastal and inland areas. Methods - We used data from the second survey of the Population-based Study on Health and Living Conditions in Regions with Sami and Norwegian Populations – the SAMINOR 2 Clinical Survey (2012–2014) that includes the adult population in 10 municipalities in the counties Troms, Finnmark and Nordland. Participants self-reported on PA, ethnicity and modifiable lifestyle factors. Twelve thousand four hundred fifty-five individuals were invited with a response rate of 48.2% (n = 6004 participants). We tested differences using chi-square tests, two sample t-tests and linear regression models. Results - Among 5628 participants, 41.1 and 40.9% of men and women, respectively, were defined as Sami. We found no ethnic differences in PA in men overall. However, Sami men living in Tana, and Nesseby reported higher PA compared to non-Sami men in the same area. For Sami women there was overall lower PA levels compared to non-Sami women, especially pronounced in Kautokeino/ Karasjok. Conclusion - This study showed small differences in PA levels between Sami and non-Sami men. Sami women had lower PA levels compared to their non-Sami counterparts. It is important to identify whether there are differences in various ethnic populations, together with other predictors for PA in future planning of public health interventions

The burden of colon cancer attributable to modifiable factors—The Norwegian Women and Cancer Study

Colon cancer is the second most frequently diagnosed cancer in women in Norway, where incidence rates of colon cancer increased 3-fold between 1955 and 2014, for unknown reasons. We aimed to assess the burden of colon cancer attributable to modifiable risk factors in Norwegian women using the data from the Norwegian Women and Cancer (NOWAC) study. Self-reported information from 35 525 women from the NOWAC study were available. These included the following exposures: smoking status, alcohol consumption, body mass index, physical activity, intake of calcium, fibers, and red and processed meat. Colon cancer cases were identified from the Cancer Registry of Norway. A parametric piecewise constant hazards model was used to estimate the strength of exposure-cancer associations. Population attributable fractions with 95% confidence intervals (CIs) were calculated considering competing risk of death. The fraction of incident colon cancer attributable to ever smoking was 18.7% (95% CI 4.7%-30.6%), low physical activity 10.8% (95% CI −0.7% to 21.0%), alcohol consumption 14.5% (95% CI −2.8% to 28.9%), and low intake of calcium 10.0% (95% CI −7.8% to 24.8%). A small proportion of colon cancer cases was attributable to combined intake of red and processed meat over 500 g/week, overweight/obesity, and low intake of fibers. Jointly, these seven risk factors could explain 46.0% (95% CI 23.0%-62.4%) of the colon cancer incidence burden. Between 23% and 62% of the colon cancer burden among women in Norway was attributable to modifiable risk factors, indicating an important preventive potential of a healthy lifestyle

Combined Lifestyle Behaviors and the Incidence of Common Cancer Types in the Norwegian Women and Cancer Study (NOWAC)

Introduction: Only a small number of studies have examined the impact of combined lifestyle behaviors on cancer incidence, and never in a Norwegian population. Purpose: To examine linear and nonlinear associations of combined lifestyle factors, assessed through a healthy lifestyle index (HLI), with the incidence of postmenopausal breast, colorectal, lung, postmenopausal endometrial, postmenopausal ovarian, pancreatic, and kidney cancer among women in Norway. Methods: This prospective study included 96,869 women enrolled in the Norwegian Women and Cancer (NOWAC) cohort. Baseline information on lifestyle factors was collected between 1996 and 2004. The HLI was constructed from five lifestyle factors: physical activity level, body mass index, smoking, alcohol consumption, and diet. Each factor contributed 0 to 4 points to the HLI score, which ranged from 0 to 20, with higher scores representing a healthier lifestyle. Multiple imputation was used to handle missing data. Cox proportional hazard regression models were used to estimate hazard ratios (HR) and 95% confidence intervals (CI). Restricted cubic splines were used to examine nonlinearity in the associations. Results: The HRs for a one-point increment on the HLI score were 0.97 (95% CI: 0.96– 0.98) for postmenopausal breast cancer, 0.98 (0.96– 1.00) for colorectal cancer, 0.86 (0.84– 0.87) for lung cancer, 0.93 (0.91– 0.95) for postmenopausal endometrial cancer, 0.99 (0.96– 1.02) for postmenopausal ovarian cancer, 0.92 (0.89– 0.95) for pancreatic cancer, and 0.94 (0.91– 0.97) for kidney cancer. Nonlinearity was observed for the inverse associations between HLI score and the incidence of lung cancer and postmenopausal breast cancer. Conclusion: Based on our results, healthier lifestyle, as assessed by the HLI score, was associated with lower incidence of postmenopausal breast, colorectal, lung, postmenopausal endometrial, pancreatic, and kidney cancer among women, although the magnitude and linearity varied. Adoption of healthier lifestyle behaviors should be a public health priority to reduce the cancer burden among Norwegian women

Validity of self-reported myocardial infarction and stroke in regions with Sami and Norwegian populations: The SAMINOR 1 Survey and the CVDNOR project

Published version. Source at http://dx.doi.org/10.1136/bmjopen-2016-012717 Objective: Updated knowledge on the validity of self- reported myocardial infarction (SMI) and self-reported stroke (SRS) is needed in Norway. Our objective was to compare questionnaire data and hospital discharge data from regions with Sami and Norwegian populations to assess the validity of these outcomes by ethnicity, sex, age and education. Design: Validation study using cross-sectional questionnaire data and hospital discharge data from all Norwegian somatic hospitals. Participants and setting: 16 865 men and women aged 30 and 36–79 years participated in the Population-based Study on Health and Living Conditions in Sami and Norwegian Populations (SAMINOR) 1 Survey in 2003–2004. Information on SMI and SRS was available from self-administered questionnaires for 15 005 and 15 088 of these participants, respectively. We compared this information with hospital discharge data from 1994 until SAMINOR 1 Survey attendance. Primary and secondary outcomes: Sensitivity, specificity, positive predictive value (PPV), negative predictive value and κ. Results: The sensitivity and PPV of SMI were 90.1% and 78.9%, respectively; the PPV increased to 93.1% when all ischaemic heart disease (IHD) diagnoses were included. The SMI prevalence estimate was 2.3% and hospital-based 2.0%. The sensitivity and PPV of SRS were 81.1% and 64.3%, respectively. The SRS prevalence estimate was 1.5% and hospitalisation- based 1.2%. Moderate to no variation was observed in validity according to ethnicity, sex, age and education. Conclusions: The sensitivity and PPV of SMI were high and moderate, respectively; for SRS, both of these measures were moderate. Our results show that SMI from the SAMINOR 1 Survey may be used in aetiological/analytical studies in this population due to a high IHD-specific PPV. The SAMINOR 1 questionnaire may also be used to estimate the prevalence of acute myocardial infarction and acute stroke

No association between physical activity and primary melanoma thickness in a cohort of Norwegian women

Knowledge about factors associated with melanoma thickness, the most important prognostic factor for localized primary melanoma survival,1 may help reduce the risk of melanoma deaths. Previously reported associations of melanoma thickness with pigmentary characteristics, number of naevi, diet quality and body mass index (BMI)2–4 may be explained by behavioural and biological mechanisms. Physical activity (PA) has been associated with improved outcomes for several cancers,5 but its relation with melanoma thickness and prognosis is unknown

Physical activity and cutaneous melanoma risk: A Norwegian population-based cohort study

Physical activity (PA) is an important factor in cancer prevention, but positive association between PA and risk of cutaneous melanoma found in recent studies may complicate this strategy. Ultraviolet radiation (UVR) exposure during outdoor PA is a plausible explanation for a positive association. We investigated the associations between PA, UVR and melanoma risk in the Norwegian Women and Cancer cohort. Overall PA was reported by 151,710 women, aged 30–75 at inclusion, using a validated 10-point-scale at enrolment and during follow-up, together with recent numbers of sunburns, indoor tanning sessions and weeks on sunbathing vacations. Seasonal outdoor walking and seasonal PAs were recorded in subsamples (n = 102,671 and n = 29,077, respectively). Logistic and Cox regression were used. Mean follow-up was 18.5 years, and 1565 invasive incident melanoma cases were diagnosed. Overall PA was inversely associated with sunburns, while positively associated with sunbathing vacations and indoor tanning. Overall PA was not associated with melanoma risk in all body sites combined (ptrend = 0.61), but reduced risk was found in upper limb melanomas (hazard ratio (HR) = 0.70, 95% confidence interval (CI) 0.51–0.96; high versus low PA). Non-significant reduced risks were found for seasonal outdoor walking >2 h/day versus 30–60 min/day (summer HR = 0.81, 95% CI 0.66–1.00; autumn HR = 0.74, 95%CI 0.55–1.01). Seasonal PAs were not associated with melanoma risk. In conclusion, we found positive associations between overall PA and sunbathing vacations and indoor tanning, and, unlike literature, inverse association between overall PA and sunburns. Our results do not support a positive association between PA and melanoma risk in Norwegian women