It is important that the introduction of breast screening is closely monitored. The anticipated effect on breast cancer mortality will take 10 years or more fully to emerge, and will only occur if a succession of more short-term end points are met. Data from the Swedish two-county randomised trial provide targets that should be achieved, following a logical progression of compliance with the initial invitation, prevalence and stage distribution at the prevalence screen, the rate of interval cancers after the initial screen, the pick-up rate and stage distribution at later screening tests, the rate of interval cancers after later tests, the absolute rate of advanced cancer and finally the breast cancer mortality rate. For evaluation purposes, historical data on stage at diagnosis is desirable; it is suggested that tumour size is probably the most relevant variable available in most cases.
OBJECTIVES: Previous randomised studies of mammography screening have shown a significant effect on breast cancer mortality, particularly in women aged 50-69 at randomisation. Breast cancer mortality has traditionally been studied by judgments on causes of death, either from cause of death registers or from medical records. In this study an alternative method was used, estimating the excess mortality associated with breast cancer. SETTING: In 1990 two counties of northern Sweden started population based mammography screening of women aged 40-74. The unscreened population in the two other counties of the same region were selected as controls. RESULTS: Excess mortality associated with breast cancer was lower in the screened population, and was discernible three to four years after the start of screening. The relative risk estimate, based on the cumulative excess number of deaths from breast cancer during 1990-95 in the screened versus the control population aged 40-74 (at diagnosis of breast cancer), was 0.72 (95% confidence interval (CI) 0.53 to 0.99). For women aged 50-69 it was 0.67 (95% CI 0.46 to 0.99). In the 50-69 age group the estimated excess number of deaths from breast cancer during 1995 was 17.0 per 100,000 women (95% CI 5.0 to 29.0) in the screened counties and 51.1 per 100,000 (95% CI 30.2 to 71.9) in the unscreened counties. CONCLUSIONS: Population based routine screening has substantial effects on breast cancer mortality in women aged 50-69. Estimation of excess mortality can be used in future studies to evaluate the effects of mammography screening on breast cancer mortality.
The validity of the reported geographic variations of breast carcinoma incidence in Sweden was assessed by examination of two possible sources of bias: non-notification to the Cancer Registry of diagnosed carcinoma cases and 'biologically benign' breast carcinoma, i.e. with a low disease-specific lethality, e.g. detected accidentally at autopsy. No significant geographic differences in registration deficit were found even though non-notification tended to be slightly higher for old patients in low-incidence areas. Autopsy cases were estimated to account for less than one per cent of all cases and tended to be more frequent in high-incidence areas but the regional differences were generally small and not significant. An analysis of the relationship between 10-year relative survival and age-standardized incidence in 27 different regions revealed no significant correlation, whereas there was a significant positive correlation between age-standardized incidence and mortality. These findings indicate that non-lethal breast carcinoma cases do not explain the variations of incidence. In conclusion, no evidence was found suggesting that the geographic differences were artifactual. Registration deficit and autopsy cases, however, may have slightly increased the variations among elderly women.
This study describes trends in breast cancer incidence and survival in Stockholm County during 1961-1973. A discrepancy between increasing incidence and constant mortality rates was reflected in a significantly improved survival of the more recently treated patients. However, no change in survival was found when the patients were classified by axillary node status. The improvement thus seemed entirely the result of a more favorable stage distribution. The shift towards less advanced tumors was mainly caused by an increased age-standardized incidence of node-negative tumors, whereas the incidence of more advanced tumors seemed relatively unchanged. The survival from first distant metastasis was significantly increased; the use of combination chemotherapy might have contributed to this. The increase, however, was only moderate and did not seem to have contributed much to the improved overall survival. It is concluded that several confounding factors must be recognized when time trends in breast cancer are analyzed. A straightforward interpretation of observed changes is therefore not always possible. An increasing detection of tumors with relatively benign biological properties or lead time bias may well contribute to seemingly improved results.
The contemporary impact of heart failure (HF) versus the most common forms of cancer as reflected by related first-ever hospitalizations and subsequent case-fatality rates is unknown.
Using a national registry in Sweden, we compared the rate of first-ever hospitalization and associated short- and long-term survival for HF, acute myocardial infarction (AMI), and the most common forms of cancer on an age and sex-specific basis during 1988 to 2004 in 949 733 Swedish patients (1 162 309 hospital admissions in total). Annual incidence of first-ever hospitalization for HF, AMI, and cancer in Sweden were 484, 424, and 373 (lung, colorectal, prostate, and bladder cancer combined) per 100 000 men and 470, 280, and 350 (lung, colorectal, bladder, breast, and ovarian cancer combined) per 100 000 women age >20 years. The ratio of individual cases of HF to cancer was 1.37:1 (465 998 versus 340 738). Despite improvements in 30-day and 5-year survival (adjusted 7% and 6% increase per calendar year for men and women, respectively), HF was associated with unadjusted case-fatality rate of 59% within 5 years and 196 400 deaths versus 58% and 131 000 deaths in patients with cancer. During 10-year follow-up, HF was associated with 66 318 versus 55 364 premature life-years lost than all common forms of cancer in men. In women, the equivalent figures were 59 535 versus 64 533 premature life-years lost.
These data confirm that, like most common forms of cancer combined, HF exerts a major health burden in respect to age-adjusted rates of first hospitalization, poor overall survival, and premature life-years lost.