Incidence of breast cancer subtypes in immigrant and non-immigrant women in Norway.

BACKGROUND: Breast cancer incidence differs between non-immigrants and immigrants from low- and middle-income countries. This study investigates whether immigrants also have different subtype-specific incidences. METHODS: We used national health registries in Norway and calculated subtype-specific incidence rate ratios (IRRs) for invasive breast cancer among women aged 20-75 and 20-49 years between 2005 and 2015. Immigrant groups were classified by country of birth broadly defined based on WHO regional groupings. Subtype was defined using estrogen receptor (ER), progesterone receptor (PR) and human epidermal growth factor 2 (HER2) status as luminal A-like (ER+ PR+ HER2-), luminal B-like/HER2- (ER+ PR- HER2-), luminal B-like/HER2+ (ER+ PR any HER2+), HER2+ (ER-PR-HER2+) and triple-negative breast cancer (TNBC) (ER-PR-HER2-). RESULTS: Compared to non-immigrants, incidence of the luminal A-like subtype was lower in immigrants from Sub-Saharan Africa (IRR 0.43 95% CI 0.28-0.66), South East Asia (IRR 0.63 95% CI 0.51-0.79), South Asia (IRR 0.67 95% CI 0.52-0.86) and Eastern Europe (IRR 0.86 95% CI 0.76-0.99). Immigrants from South Asia had higher rates of HER2 + tumors (IRR 2.02 95% CI 1.26-3.23). The rates of TNBC tended to be similar regardless of region of birth, except that women from South East Asia had an IRR of 0.54 (95% CI 0.32-0.91). CONCLUSIONS: Women from Eastern Europe, Sub-Saharan Africa and Asia had different subtype-specific incidences compared to women from high-income countries (including non-immigrants). These differences in tumor characteristics between immigrant groups should be taken into consideration when planning preventive or screening strategies.

Cancer incidence in non-immigrants and immigrants in Norway.

BACKGROUND: Major cancers are associated with lifestyle, and previous studies have found that the non-immigrant populations in the Nordic countries have higher incidence rates of most cancers than the immigrant populations. However, rates are changing worldwide - so these differences may disappear with time. Here we present recent cancer incidence rates among immigrant and non-immigrant men and women in Norway and investigate whether previous differences still exist. MATERIAL AND METHODS: We took advantage of a recent change in the Norwegian Cancer Registry regulations that allow for the registry to have information on country of birth. The number of person years for 2014-2018 was aggregated for every combination of sex, five-year age-group and country of birth, by summing up each year's population in these groups. The number of cancer cases was then counted for the same groups, and age-standardised incidence rates calculated by weighing the age-specific incidence rates by the Nordic and World standard populations. Further, we calculated incidence rate ratios using the non-immigrant population as a reference. RESULTS: Immigrants from Eastern Europe, the Middle East, Africa and Asia had lower incidence of total cancer compared to the non-immigrant population in Norway and immigrants born in the other Nordic or high-income countries. However, some cancers were more common in certain immigrant groups. Asian men and women had threefold the incidence of liver cancer than non-immigrant men and women. Men from the other Nordic countries and from Eastern Europe had higher lung cancer rates than non-immigrant men. CONCLUSION: National registries should continuously monitor and present cancer incidence stratified on important population subgroups such as country of birth. This can help assess population subgroup specific needs for cancer prevention and treatment, and could eventually help reduce the morbidity and mortality of cancer.

Ethnic differences in the incidence of cancer in Norway.

Traditionally there have been differences in cancer incidence across geographic regions. When immigrants have moved from low-income to high-income countries, their incidence have changed as they have adapted to the lifestyle in the new host country. Given worldwide changes in lifestyle factors over time, we decided to examine cancer incidence in immigrant groups in Norway, a country with a recent immigration history, complete cancer registration and universal public health care. We linked immigration history for the complete population to information on cancer diagnosis from the Cancer Registry of Norway for the period 1990-2012. Age-standardized (world) overall and site-specific cancer incidence were estimated for different immigrant groups and compared to incidence among individuals born in Norway. Among 850,008 immigrants, 9,158 men and 10,334 women developed cancer, and among 5,508,429 Norwegian-born, 263,316 men and 235,020 women developed cancer. While incidence of breast and colorectal cancer were highest among individuals born in Norway and other high-income countries, other cancer types were higher in immigrants from low-income countries. Lung cancer incidence was highest in Eastern European men, and men and women from Eastern Europe had high incidence of stomach cancer. Incidence of liver cancer was substantially higher in immigrants from low-income countries than in individuals born in Norway and other high-income countries. Our results mirror known cancer challenges across the world. Although cancer incidence overall is lower in immigrants from low-income countries, certain cancers, such as lung, liver and stomach cancer, represent major challenges in specific immigrant groups.

Adiposity, physical activity, and risk of hypertension: prospective data from the population-based HUNT Study, Norway.

Adiposity and inactivity have been associated with increased risk of hypertension. However, reports on the joint effect of these two risk factors in relation to hypertension are scarce and their interaction poorly understood. We prospectively examined both independent and joint effects of measured body mass index (BMI) and self-reported physical activity on the risk of hypertension. We conducted a longitudinal study of 11,238 men and 15,301 women who participated in the Nord-Trøndelag Health Study (HUNT) in Norway. Poisson regression was used to estimate adjusted risk ratios (RRs) of hypertension (≥140/90 mmHg) according to BMI and physical activity. BMI was positively associated with risk of hypertension in both sexes (Ptrends < 0.001), whereas the independent effect of physical activity was less clear. Obese men who reported no physical activity had a RR of 1.50 (95% confidence interval (CI): 1.27-1.77) compared to normal weight men with a high activity level, whereas obese men who reported high activity levels had a RR of 1.16 (95% CI: 0.79-1.70). Correspondingly, obese and inactive women had a RR of 1.55 (95% CI: 1.35-1.77), whereas obese and highly active women had RRs of 1.41 (95% CI: 1.18-1.69). Our data suggest that high levels of physical activity could to some extent attenuate the unfavorable effect of adiposity on hypertension, particularly in men.