Early detection of breast cancer rectifies inequality of breast cancer outcomes.

OBJECTIVES: To explain apparent differences among mammography screening services in Sweden using individual data on participation in screening and with breast cancer-specific survival as an outcome. METHODS: We analysed breast cancer survival data from the Swedish Cancer Register on breast cancer cases from nine Swedish counties diagnosed in women eligible for screening. Data were available on 38,278 breast cancers diagnosed and 4312 breast cancer deaths. Survival to death from breast cancer was estimated using the Kaplan-Meier estimate, for all cases in each county, and separately for cases of women participating and not participating in their last invitation to screening. Formal statistical comparisons of survival were made using proportional hazards regression. RESULTS: All counties showed a reduction in the hazard of breast cancer death with participation in screening, but the reductions for individual counties varied substantially, ranging from 51% (95% confidence interval 46-55%) to 81% (95% confidence interval 74-85%). Survival rates in nonparticipating women ranged from 53% (95% confidence interval 40-65%) to 74% (95% confidence interval 72-77%), while the corresponding survival in women participating in screening varied from 80% (95% confidence interval 77-84%) to 86% (95% confidence interval 83-88%), a considerably narrower range. CONCLUSIONS: Differences among counties in the effect of screening on breast cancer outcomes were mainly due to variation in survival in women not participating in screening. Screening conferred similarly high survival rates in all counties. This indicates that the performance of screening services was similar across counties and that detection and treatment of breast cancer in early-stage reduces inequalities in breast cancer outcome.

Mammography screening reduces rates of advanced and fatal breast cancers: Results in 549,091 women.

BACKGROUND: It is of paramount importance to evaluate the impact of participation in organized mammography service screening independently from changes in breast cancer treatment. This can be done by measuring the incidence of fatal breast cancer, which is based on the date of diagnosis and not on the date of death. METHODS: Among 549,091 women, covering approximately 30% of the Swedish screening-eligible population, the authors calculated the incidence rates of 2473 breast cancers that were fatal within 10 years after diagnosis and the incidence rates of 9737 advanced breast cancers. Data regarding each breast cancer diagnosis and the cause and date of death of each breast cancer case were gathered from national Swedish registries. Tumor characteristics were collected from regional cancer centers. Aggregated data concerning invitation and participation were provided by Sectra Medical Systems AB. Incidence rates were analyzed using Poisson regression. RESULTS: Women who participated in mammography screening had a statistically significant 41% reduction in their risk of dying of breast cancer within 10 years (relative risk, 0.59; 95% CI, 0.51-0.68 [P < .001]) and a 25% reduction in the rate of advanced breast cancers (relative risk, 0.75; 95% CI, 0.66-0.84 [P < .001]). CONCLUSIONS: Substantial reductions in the incidence rate of breast cancers that were fatal within 10 years after diagnosis and in the advanced breast cancer rate were found in this contemporaneous comparison of women participating versus those not participating in screening. These benefits appeared to be independent of recent changes in treatment regimens.

Prospective blinded surveillance screening of Swedish women with increased hereditary risk of breast cancer.

PURPOSE: To evaluate the sensitivity and specificity of different screening modalities in women with a family history of breast cancer. METHODS: Our blinded, prospective, comparative cohort analysis included three types of screening, mammography, ultrasound, and clinical breast examination once per year for 6 years. Eligible patients for this study were healthy women with ≥ 17% lifetime risk of breast cancer or with a mutation in BRCA1 or BRCA2. RESULTS: A total of 632 women were screened between 2002 and 2012 (each for 6 years). During the study, 30 women were diagnosed with breast cancer, with 10 of these diagnoses occurring between screening visits, and six of the 10 diagnosed women were gene carriers. The clinical presentation for the women diagnosed with breast cancer was followed until 2017. No consistent patterns for the diagnostic capacity of the different screening modalities were found, although mammography showed low sensitivity, whereas ultrasound showed better sensitivity in three of the six rounds. The specificity was high in mammography and improved in ultrasound over time. Most importantly, clinical breast examination provided no additional information toward the diagnosis of breast cancer. CONCLUSION: Neither mammography nor ultrasound performed yearly were sensitive enough as standalone modalities, although high specificity was confirmed. Our findings indicate that high risk (> 29% life time risk) individuals and gene carriers can be screened biannually, using the same protocol as used in mutation carriers. Our results also suggest that low-risk groups (< 20%) may continue to be referred to population mammography screening program, while clinical breast examination may be omitted in all risk groups, and could be optional in gene carriers.