Breast cancer in Norway 1970-1993: a population-based study on incidence, mortality and survival

Ethnoracial and social trends in breast cancer staging at diagnosis in Brazil, 2001-14: a case only analysis

BACKGROUND

Policies for early detection of breast cancer, including clinical breast examinations and mammographic screening, were introduced in Brazil in 2004, but their effect on disease stage at diagnosis is unclear. We aimed to assess whether these policies have led to a decrease in the prevalence of late-stage breast cancer at diagnosis.

METHODS

In this case only analysis, using an anonymised nationwide hospital based-cancer registry network, we identified women aged 18-89 years who had been diagnosed with an invasive breast cancer in Brazil during 2001-14. We extracted individual patient-level data on patient demographics, tumour variables, and health-care provider variables for the centre where the patient was diagnosed. Our objectives were to estimate the prevalence of late-stage breast cancer (TNM stage III or IV) at diagnosis overall, across age groups, and by ethnoracial and social strata (ie, self-reported ethnoracial group, as white, black, brown, Asian, or Indigenous, and educational level, marital status, and region of residence) across the study period, and compare these estimates with international data from high-income countries (Norway and the USA). We used logistic regression to estimate odds ratios (ORs) for late-stage versus early-stage (TNM stage I or II) breast cancer at diagnosis in relation to relevant exposures, either minimally adjusted (for age, year of diagnosis, and region of residence) or fully adjusted (for all patient, tumour, and health-care provider variables).

FINDINGS

We identified 247 719 women who were diagnosed with invasive breast cancer between Jan 1, 2001, and Dec 31, 2014, with a mean age at diagnosis of 55·4 years (SD 13·3), of whom 36·2% (n=89 550) identified as white, 29·8% (n=73 826) as black or brown, and 0·7% (n=1639) as Asian or Indigenous. Prevalence of late-stage breast cancer at diagnosis remained high throughout 2001-14, at approximately 40%, was inversely associated with educational level (p value for linear trend <0·0001), and was higher for women who identified as black (minimally adjusted OR 1·61, 95% CI 1·53-1·70; fully adjusted OR 1·45, 95% CI 1·38-1·54) and brown (minimally adjusted OR 1·26, 95% CI 1·22-1·30; fully adjusted OR 1·18, 1·14-1·23) than those who identified as white. The predicted prevalence of late-stage cancer at diagnosis was highest for women who were black or brown with little or no formal education (48·8%, 95% CI 48·2-49·5) and lowest for women who were white with university education (29·4%, 28·2-30·6), but both these prevalences were higher than that of all women diagnosed with breast cancer in Norway before the introduction of mammography screening (ie, 16·3%, 95% CI 15·4%-17·2% in 1970-74). Similar ethnoracial and social patterns emerged in analyses restricted to the age group targeted by screening (50-69 years).

INTERPRETATION

The persistently high prevalence of late-stage breast cancer at diagnosis across all ethnoracial and social strata in Brazil, although more substantially among the most disadvantaged populations, implies that early detection policies might have had little effect on breast cancer mortality so far, and highlights the need to focus primarily on timely diagnosis of symptomatic breast cancer rather than on screening for asymptomatic disease.

FUNDING

Newton Fund, Research Councils UK, and Conselho Nacional das Fundações Estaduais de Amparo à Pesquisa.

Do changes in lymph node status distribution explain trends in survival of breast cancer patients in Denmark?

We studied the impact on survival of changes in breast cancer patients' distribution by lymph node status at the time of diagnosis. Our study included breast cancer patients diagnosed from 1978 to 1994 in Denmark, where the treatment schemes for breast cancer patients were fairly stable, and where mammography screening was limited. We measured lymph node status by the proportion of positive lymph nodes of all excised lymph nodes, as assessed by a pathologist. This measure was available for two-thirds of the breast cancer patients. The outcome was 5-year relative survival. Changes in lymph node status distribution explained half of the improvement in 5-year relative survival, and seem to be the single most important cause behind the improved survival of breast cancer patients in Denmark.

Mortality from breast carcinoma among US women: the role and implications of socio-economics, heterogeneous insurance, screening mammography, and geography

Despite rapid advances in medicine and beneficial lifestyle changes, the incidence and mortality rate of gynecologic carcinoma remains high worldwide. This paper presents the econometric model findings of the major drivers of breast cancer mortality among US women. The results have implications for public health policy formulation on disease incidence and the drivers of mortality risks. The research methodology is a fixed-effects GLS regression model of breast cancer mortality in US females age 25 and above, using 1990-1997 time-series data pooled across 50 US states and DC. The covariates are age, years schooled, family income, 'screening' mammography, insurance coverage types, race, and US census region. The regressions have strong explanatory powers. Finding education and income to be significantly and positively correlated with mortality supports the 'life in the fast lanes' hypothesis of Phelps. The policy of raising a woman's education at a given income appears more beneficial than raising her income at a given education level. The relatively higher mortality rate for Blacks suggests implementing culturally appropriate set of disease prevention and health promotion programs and policies. Mortality differs across insurance types with Medicaid the worst suggesting need for program reform. Mortality is greater for women ages 25-44 years, females 40-49 years who have had screening mammography, smokers, and residents of some US states. These findings suggest imposing more effective tobacco use control policies (e.g., imposing a special tobacco tax on adult smokers), creating a more tractable screening mammography surveillance system, and designing region-specific programs to cut breast cancer mortality risks.

Age-period-cohort modelling of breast cancer incidence in the Nordic countries

The Nordic countries have experienced a steady increase in breast cancer incidence throughout the past 35 years. We analysed the incidence in Denmark, Finland, Norway and Sweden during the period 1958 to 1992 using age-period-cohort models and taking the systematic mammography screening into account. Assuming the age dependency of the incidence pattern in old age to be common for the Nordic countries, an internal comparison could be made among the four countries of the cohort effects and the period effects. The study indicated that the period effects have been of importance for the increase in breast cancer incidence seen in the Nordic countries. The widespread practice of neglecting the period effects in age-period-cohort analysis of time trends in breast cancer incidence therefore probably needs reconsideration. A key finding was that Danish women born in the 20th century seem to have been exposed to an increasing load of cohort borne breast cancer risk factors not experienced to the same extent by Norwegian women, whereas they were seemingly subjected to the same period effects.