Stage-specific survival has improved for young breast cancer patients since 2000: but not equally.

PURPOSE: The stage-specific survival of young breast cancer patients has improved, likely due to diagnostic and treatment advances. We addressed whether survival improvements have reached all socioeconomic groups in a country with universal health care and national treatment guidelines. METHODS: Using Norwegian registry data, we assessed stage-specific breast cancer survival by education and income level of 7501 patients (2317 localized, 4457 regional, 233 distant and 494 unknown stage) aged 30-48 years at diagnosis during 2000-2015. Using flexible parametric models and national life tables, we compared excess mortality up to 12 years from diagnosis and 5-year relative survival trends, by education and income as measures of socioeconomic status (SES). RESULTS: Throughout 2000-2015, regional and distant stage 5-year relative survival improved steadily for patients with high education and high income (high SES), but not for patients with low education and low income (low SES). Regional stage 5-year relative survival improved from 85 to 94% for high SES patients (9% change; 95% confidence interval: 6, 13%), but remained at 84% for low SES patients (0% change; - 12, 12%). Distant stage 5-year relative survival improved from 22 to 58% for high SES patients (36% change; 24, 49%), but remained at 11% for low SES patients (0% change; - 19, 19%). CONCLUSIONS: Regional and distant stage breast cancer survival has improved markedly for high SES patients, but there has been little survival gain for low SES patients. Socioeconomic status matters for the stage-specific survival of young breast cancer patients, even with universal health care.

Socioeconomic inequalities in stage-specific breast cancer incidence: a nationwide registry study of 1.1 million young women in Norway, 2000-2015.

BACKGROUND: Women with high socioeconomic status (SES) have the highest incidence rates of breast cancer. We wanted to determine if high SES women only have higher rates of localized disease, or whether they also have higher rates of non-localized disease. To study this, we used data on a young population with universal health care, but not offered screening. MATERIAL AND METHODS: Using individually linked registry data, we compared stage-specific breast cancer incidence, by education level and income quintile, in a Norwegian cohort of 1,106,863 women aged 30-48 years during 2000-2015 (N = 7531 breast cancer cases). We calculated stage-specific age-standardized rates and incidence rate ratios and rate differences using Poisson models adjusted for age, period and immigration history. RESULTS: Incidence of localized and regional disease increased significantly with increasing education and income level. Incidence of distant stage disease did not vary significantly by education level but was significantly reduced in the four highest compared to the lowest income quintile. The age-standardized rates for tertiary versus compulsory educated women were: localized 28.2 vs 19.8, regional 50.8 vs 40.4 and distant 2.3 vs 2.6 per 100,000 person-years. The adjusted incidence rate ratios (tertiary versus compulsory) were: localized 1.40 (95% CI 1.25-1.56), regional 1.25 (1.15-1.35), distant 0.90 (0.64-1.26). The age-standardized rates for women in the highest versus lowest income quintile were: localized 28.9 vs 17.7, regional 52.8 vs 41.5 and distant 2.3 vs 3.2 per 100,000 person-years. The adjusted incidence rate ratios (highest versus lowest quintile) were: localized 1.63 (1.42-1.87), regional 1.27 (1.09-1.32), distant 0.64 (0.43-0.94). CONCLUSION: Increased breast cancer rates among young high SES women is not just increased detection of small localized tumors, but also increased incidence of tumors with regional spread. The higher incidence of young high SES women is therefore real and not only because of excessive screening.

Breast cancer-specific survival by clinical subtype after 7 years follow-up of young and elderly women in a nationwide cohort.

Age and tumor subtype are prognostic factors for breast cancer survival, but it is unclear which matters the most. We used population-based data to address this question. We identified 21,384 women diagnosed with breast cancer at ages 20-89 between 2005 and 2015 in the Cancer Registry of Norway. 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-negative (ER+PR-HER2-), luminal B-like HER2-positive (ER+PR+/-HER2+), HER2-positive (ER-PR-HER2+) and triple-negative (TNBC) (ER-PR-HER2-). Cox regression estimated hazard ratios (HR) for breast cancer-specific 7-year survival by age and subtype, while adjusting for year, grade, TNM stage and treatment. Young women more often had HER2-positive and TNBC tumors, while elderly women (70-89) more often had luminal A-like tumors. Compared to age 50-59, young women had doubled breast cancer-specific mortality rate (HR = 2.26, 95% CI 1.81-2.82), while elderly had two to five times higher mortality rate (70-79: HR = 2.25, 1.87-2.71; 80-89: HR = 5.19, 4.21-6.41). After adjustments, the association was non-significant among young women but remained high among elderly. Young age was associated with increased breast cancer-specific mortality among luminal A-like subtype, while old age was associated with increased mortality in all subtypes. Age and subtype were strong independent prognostic factors. The elderly always did worse, also after adjustment for subtype. Tumor-associated factors (subtype, grade and stage) largely explained the higher breast cancer-specific mortality among young. Future studies should address why luminal A-like subtype is associated with a higher mortality rate in young women.

Cancer trends and population structure in Norway 1990-2016. / Kreftutvikling og befolkningssammensetning i Norge 1990­2016.

BAKGRUNN: Befolkningssammensetningen i Norge har endret seg, og innvandrere utgjør nå nær 14 % av befolkningen. Vi vet ikke hvordan dette påvirker kreftbildet. I denne studien presenterer vi forekomst av kreft for den norskfødte delen av befolkningen for å kunne få et bilde på hvordan forekomsten har endret seg, sett bort fra effekten av innvandring. MATERIALE OG METODE: Data fra Kreftregisteret og populasjonsdata fra Statistisk sentralbyrå ble benyttet for å beregne aldersstandardiserte insidensrater av kreft i Norge i perioden 1990-2016. RESULTATER: Studiepopulasjonen besto av 6 703 675 personer, hvorav 82,3 % ble definert som norskfødte. Ratene for alle kreftformer samlet hos norskfødte og totalbefolkningen fulgte hverandre mer eller mindre jevnt. I siste femårsperiode (2012-16) var ratene for den norskfødte delen av befolkningen 2 % høyere enn de nasjonale ratene, og føflekk- og livmorhalskreft hadde den største prosentvise forskjellen med 6-8 % høyere rater. Raten for leverkreft var 3-4 % lavere for norskfødte sammenlignet med totalbefolkningen. FORTOLKNING: De nasjonale ratene har så langt gitt et godt bilde på kreftutviklingen i den norskfødte delen av befolkningen. Siden forskjellen mellom ratene økte mot slutten av tidsperioden, kan fødeland være en viktig faktor å ta hensyn til i presentasjonen av kreftforekomst.

Volumetric Mammographic Density, Age-Related Decline, and Breast Cancer Risk Factors in a National Breast Cancer Screening Program.

Background: Volumetric mammographic density (VMD) measures can be obtained automatically, but it is not clear how these relate to breast cancer risk factors.Methods: The cohort consisted of 46,428 women (ages 49-71 years) who participated in BreastScreen Norway between 2007 and 2014 and had information on VMD and breast cancer risk factors. We estimated means of percent and absolute VMD associated with age, menopausal status, body mass index (BMI), and other factors.Results: The associations between VMD and most breast cancer risk factors were modest, although highly significant. BMI was positively associated with absolute VMD, whereas inversely associated with percent VMD. Percent VMD was inversely associated with a 5-year older age at screening in premenopausal and postmenopausal women (-0.18% vs. -0.08% for percent VMD and -0.11 cm3 vs. -0.03 cm3 for absolute VMD). This difference was largest among postmenopausal women with BMI < 25 kg/m2 (P for interaction with percent VMD < 0.0001), never users of postmenopausal hormone therapy (P for interaction < 0.0001), and premenopausal women with a family history of breast cancer (P for interaction with absolute VMD = 0.054).Conclusions: VMD is associated with several breast cancer risk factors, the strongest being BMI, where the direction of the association differs for percent and absolute VMD. The inverse association with age appears modified by menopausal status and other breast cancer risk factors.Impact: Because VMD methods are becoming widely available in screening and clinical settings, the association between VMD measures and breast cancer risk factors should be investigated further in longitudinal studies. Cancer Epidemiol Biomarkers Prev; 27(9); 1065-74. ©2018 AACR.

Adiposity, physical activity and risk of diabetes mellitus: prospective data from the population-based HUNT study, Norway.

BACKGROUND: Physical activity may counteract the adverse effects of adiposity on cardiovascular mortality; however, the evidence of a similar effect on diabetes is sparse. This study examines whether physical activity may compensate for the adverse effect of adiposity on diabetes risk. METHODS: The study population consisted of 38 231 individuals aged 20 years or more who participated in two consecutive waves of the prospective longitudinal Nord-Trøndelag Health Study in Norway: in 1984-1986 and in 1995-1997. A Poisson regression model with SEs derived from robust variance was used to estimate adjusted risk ratios of diabetes between categories of body mass index and physical activity. RESULTS: Risk of diabetes increased both with increasing body mass (Ptrend <0.001) and with decreasing physical activity level (Ptrend <0.001 in men and 0.01 in women). Combined analyses showed that men who were both obese and had low activity levels had a risk ratio of 17 (95% CI 9.52 to 30) compared to men who were normal weight and highly active, whereas obese men who reported high activity had a risk ratio of 13 (95% CI 6.92 to 26). Corresponding analysis in obese women produced risk ratios of 15 (95% CI 9.18 to 25) and 13 (95% CI 7.42 to 21) among women reporting low and high activity levels, respectively. CONCLUSIONS: This study shows that overweight and obesity are associated with a substantially increased risk of diabetes, particularly among those who also reported being physically inactive. High levels of physical activity were associated with a lower risk of diabetes within all categories of body mass index, but there was no clear evidence that being physically active could entirely compensate for the adverse effect of adiposity on diabetes risk.

Alcohol, Physical Activity, Smoking, and Breast Cancer Subtypes in a Large, Nested Case-Control Study from the Norwegian Breast Cancer Screening Program.

Background: To what extent alcohol, smoking, and physical activity are associated with the various subtypes of breast cancer is not clear. We took advantage of a large population-based screening cohort to determine whether these risk factors also increase the risk of the poor prognosis subtypes.Methods: We conducted a matched case-control study nested within the Norwegian Breast Cancer Screening Program during 2006-2014. A total of 4,402 breast cancer cases with risk factor and receptor data were identified. Five controls were matched to each case on year of birth and year of screening. Conditional logistic regression was used to estimate ORs of breast cancer subtypes adjusted for potential confounders.Results: There were 2,761 luminal A-like, 709 luminal B-like HER2-negative, 367 luminal B-like HER2-positive, 204 HER2-positive, and 361 triple-negative cancers. Current alcohol consumption was associated with breast cancer risk overall [OR 1.26; 95% confidence interval (CI), 1.09-1.45] comparing 6+ glasses a week to never drinkers. However, this risk increase was found only for luminal A-like breast cancer. Smoking 20+ cigarettes a day was associated with an OR of 1.41 (95% CI, 1.06-1.89) overall, with significant trends for luminal A-like and luminal B-like HER2-negative cancer. Current physical activity (4+ hours/week compared with none) was associated with 15% decreased risk of luminal A-like cancer, but not clearly with other subtypes.Conclusions: In this large study, alcohol, smoking, and physical activity were predominantly associated with luminal A-like breast cancer.Impact: Alcohol, smoking, and physical activity were associated with luminal A-like breast cancer subtype. Cancer Epidemiol Biomarkers Prev; 26(12); 1736-44. ©2017 AACR.