Breast cancer incidence after the start of mammography screening in Denmark

Mammography screening may lead to overdiagnosis of asymptomatic breast cancers, that would otherwise not have given rise to clinical symptoms. This aspect was studied in three regional screening programmes in Denmark, which started in Copenhagen municipality, Fyn county, and Frederiksberg municipality in 1991, 1993, and 1994, respectively. In these regions, we compared time trends in incidence of invasive breast cancer with the rest of Denmark. Since the number of clinical mammograms was relatively low, it was reasonable to assume that the breast cancer incidence outside the three screening regions represented the incidence of a population with low-intensity opportunistic screening. In Copenhagen and Fyn, a prevalence peak in incidence was seen during the first invitation round. During the subsequent invitation rounds, the incidence dropped to a level in line with the incidence expected without screening. The pattern was different in the small municipality of Frederiksberg, where the sensitivity was low during the first invitation round. Inclusion of screen-detected ductal carcinoma in situ cases did not change these results. The experiences from Copenhagen and Fyn show that organised mammography screening can operate without overdiagnosis of breast cancer

The relation between socioeconomic and demographic factors and tumour stage in women diagnosed with breast cancer in Denmark, 1983–1999

The authors investigated the association between socioeconomic position and stage of breast cancer at the time of diagnosis in a nationwide Danish study. All 28 765 women with a primary invasive breast cancer diagnosed between 1983 and 1999 were identified in a nationwide clinical database and information on socioeconomic variables was obtained from Statistics Denmark. The risk of being diagnosed with a high-risk breast cancer, that is size >20 mm, lymph-node positive, ductal histology/high histologic grade and hormone receptor negative, was analysed by multivariate logistic regression. The adjusted odds ratio (OR) for high-risk breast cancer was reduced with longer education with a 12% reduced risk (95% confidence interval (CI), 0.80,0.96) in women with higher education and increased with reduced disposable income (low income group: OR, 1.22; 95% CI, 1.10,1.34). There was an urban–rural gradient, with higher risk among rural women (OR 1.10; 95 % CI, 1.02, 1.18) and lower risk among women in the capital suburbs (OR, 0.85; 95% CI, 0.78, 0.93) and capital area (OR, 0.93; 95% CI, 0.84–1.02). These factors were significant only for postmenopausal women, although similar patterns were observed among the premenopausal women, suggesting a subgroup of aggressive premenopausal breast cancers less influenced by socioeconomic factors

Mammography-based screening program: preliminary results from a first 2-year round in a Brazilian region using mobile and fixed units

RLH, TBS and ALF made substantial contributions to the conception and design of the article, the acquisition, analysis and interpretation of the data, and drafting of the article. ECM, JSCM and NB made substantial contributions to the conception and design of the study.Background: Breast cancer is the most frequently diagnosed cancer and the leading cause of cancer deaths among women worldwide. The use of mobile mammography units to offer screening to women living in remote areas is a rational strategy to increase the number of women examined. This study aimed to evaluate results from the first 2 years of a government-organized mammography screening program implemented with a mobile unit (MU) and a fixed unit (FU) in a rural county in Brazil. The program offered breast cancer screening to women living in Barretos and the surrounding area. Methods: Based on epidemiologic data, 54 238 women, aged 40 to 69 years, were eligible for breast cancer screening. The study included women examined from April 1, 2003 to March 31, 2005. The chi-square test and Bonferroni correction analyses were used to evaluate the frequencies of tumors and the importance of clinical parameters and tumor characteristics. Significance was set at p < 0.05. Results: Overall, 17 964 women underwent mammography. This represented 33.1% of eligible women in the area. A mean of 18.6 and 26.3 women per day were examined in the FU and MU, respectively. Seventy six patients were diagnosed with breast cancer (41 (54%) in the MU). This represented 4.2 cases of breast cancer per 1000 examinations. The number of cancers detected was significantly higher in women aged 60 to 69 years than in those aged 50 to 59 years (p < 0.001) or 40 to 49 years (p < 0.001). No difference was observed between women aged 40 to 49 years and those aged 50 to 59 years (p = 0.164). The proportion of tumors in the early (EC 0 and EC I) and advanced (CS III and CS IV) stages of development were 43.4% and 15.8%, respectively. Conclusions: Preliminary results indicate that this mammography screening program is feasible for implementation in a rural Brazilian territory and favor program continuation

Effect of population breast screening on breast cancer mortality up to 2005 in England and Wales: an individual-level cohort study.

Background Population breast screening has been implemented in the UK for over 25 years, but the size of benefit attributable to such programmes remains controversial. We have conducted the first individual-based cohort evaluation of population breast screening in the UK, to estimate the impact of the NHS breast screening programme (NHSBSP) on breast cancer mortality.Methods We followed 988 090 women aged 49-64 years in 1991 resident in England and Wales, who because of the staggered implementation of the NHSBSP, included both invited subjects and an uninvited control group. Individual-level breast screening histories were linked to individual-level mortality and breast cancer incidence data from national registers. Risk of death from breast cancer was investigated by incidence-based mortality analyses in relation to intention to screen and first round attendance. Overdiagnosis of breast cancer following a single screening round was also investigated.Results Invitation to NHSBSP screening was associated with a reduction in breast cancer mortality in 1991-2005 of 21% (RR=0.79, 95% CI: 0.73-0.84, P<0·001) after adjustment for age, socioeconomic status and lead-time. Breast cancer deaths among first invitation attenders were 46% lower than among non-attenders (RR=0.54, 95% CI: 0.51-0·57, P<0.001) and 32% lower following adjustment for age, socioeconomic status and self-selection bias (RR=0.68, 95% CI: 0.63-0·73, P<0.001). There was little evidence of overdiagnosis associated with invitation to first screen.Conclusions The results indicate a substantial, statistically significant reduction in breast cancer mortality between 1991 and 2005 associated with NHSBSP activity. This is important in public health terms