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Aim: The present study examines the association between parity and survival following breast cancer diagnosis., Methods: Medical records of 4453 women diagnosed with breast cancer in Malmö, Sweden, between 1961 and 1991 were analysed. All women were followed until 31 December 2003, using the Swedish Cause-of-Death Registry. Breast cancer specific mortality rate was calculated in different levels of parity. Corresponding relative risks, with 95% confidence intervals (CI), were obtained using Cox's proportional hazards analysis. All analyses were adjusted for potential prognostic factors and stratified for age, menopausal status and diagnostic period., Results: As compared to women with one child, nulliparity (RR 1.27: 95% CI 1.09-1.47), and high parity (four or more children) (1.49: 1.20-1.85) were positively associated with a high mortality from breast cancer. When adjusted for potential confounders, the association was only statistically significant for high parity (1.33: 1.07-1.66). In the analyses stratified on age and menopausal status, there was a similar positive association between high parity and breast cancer death in all strata, although only statistically significant among women older than 45 years of age or postmenopausal. Nulliparity was associated with breast cancer death in women that were younger than 45 years of age (1.28: 0.79-2.09) or premenopausal (1.30: 0.95-1.80), but these associations did not reach statistical significance. There was no association between nulliparity and breast cancer death in women older than 45 years of age or postmenopausal. All associations were similar in analyses stratified for diagnostic period., Conclusion: Women with four or more children have a poor breast cancer survival as compared to women with one child.

Aim: This study investigates the potential relation between breast cancer location and axillary lymph node involvement (ALNI)., Methods: Out of all cases with unilateral first-time diagnosis of invasive breast cancer in Malmö, Sweden, between 1961 and 1991, 3472 underwent axillary dissection. The association between tumour location and ALNI was investigated using logistic regression analysis (adjusted for potential confounders) yielding odds ratios (OR), with a 95% confidence interval. All analyses were repeated in different birth-year cohorts., Results: Outer tumours (upper outer or lower outer quadrants), as compared to inner (upper inner and lower inner quadrants), were associated with a statistically significant risk of ALNI, OR: 1.31 (1.11-1.55). Central tumours were also associated with ALNI, OR: 2.61 (2.08-3.27). Among women born before 1909, corresponding OR:s for outer tumours was 1.61 (1.19-2.18), and for central tumours 3.50 (2.32-5.28)., Conclusions: Outer and central breast tumours are associated with a high risk of axillary lymph node involvement.

Breast cancer survival differs 9 percentage points between the neighbouring countries of Denmark and Sweden. The authors' aim was to analyse whether this was caused by early detection in Sweden. The extent of disease and outcome was compared in two population-based breast cancer cohorts in 1983-1989. Breast cancer management was decentralized in Denmark without mammography screening whereas treatment in Sweden was centralized and the population partly screened. Ten- and 15-year relative survival was 15% and 6% higher in Sweden (p<0.001) with corresponding differences in crude and disease-specific survival. Stage distribution was significantly more favourable in the Swedish cohort. In multivariate analysis age, tumour size, extent of axillary surgery, and spread affected survival; however, the impact of region persisted (p<0.001). Reanalysis without screening-detected patients only slightly affected the impact of region. It was concluded that early detection had significant impact on survival but other regional differences might be of importance.

Exposure to hormone-replacement therapy (HRT) has consistently been associated with an increased incidence of breast cancer, particularly of small tumours. Other tumour characteristics in relation to HRT have received less scientific attention. Our aim in this population-based prospective cohort study was to assess whether HRT is associated with an increased incidence of breast-cancer subgroups defined in terms of stage, type (according to the WHO system), Nottingham grade and the Nottingham Prognostic Index (NPI). Evaluation was based on a cohort of 5,865 post-menopausal women followed for an average of 9.8 years. Twenty percent of women reported current use of HRT at the time of the baseline interview. Record linkage with the Swedish Cancer Registry and local clinical registries identified 141 incident invasive breast-cancer cases. All tumours were reclassified by 1 pathologist. The incidence of breast cancer in HRT users was 377/10(5) and in non-users 221/10(5) person-years [relative risk (RR) = 1.72, 95% confidence interval (CI) 1.17-2.52]. This risk remained statistically significant after adjustment for established risk factors in a Cox proportional hazards analysis (RR = 1.66, 95% CI 1.12-2.45). Among HRT users, there was over-representation of cases with stage I tumours (adjusted RR = 2.33, 95% CI 1.44-3.76), of lobular carcinomas (RR = 4.38, 95% CI 1.60-12.0) and of tubular tumours (RR = 4.81, 95% CI 1.37-16.8). Nottingham grade I/II carcinomas (RR = 2.02, 95% CI 1.29-3.16) and cases with NPI < or = 3.4 (RR = 2.29, 95% CI 1.41-3.72) were similarly over-represented among HRT users. Incidence of breast cancer was increased in post-menopausal women who used HRT at baseline. Among HRT users, there was over-representation of tumours that, with regard to stage, type and grade, are associated with a favourable prognosis., (Copyright 2001 Wiley-Liss, Inc.)

According to several studies breast cancer is more common among former smokers. This study explores whether this association has any relationship with anthropometric measurements or blood lipid levels. The 2082 ex-smokers (mean age 49.9 years) in the Malmö Preventive Cohort were followed for an average of 13.3 years using official cancer registries. This yielded 93 incident breast cancer cases. Oestrogen receptor (ER) status was assessed by an immunological method. Incidence of breast cancer covaried with height, body mass index, weight gain and cholesterol levels. None of these associations reached statistical significance. Incidence of breast cancer increased over quartiles of serum triglycerides, Ptrend: 0.02, relative risk (RR) for triglycerides as a continuous variable: 1.46 (1.21-1.77). Nineteen tumours were ER negative; this subgroup was similarly related to high triglycerides, 1.76 (1.40-2.21). All results were similar when BMI and cholesterol levels were entered into the model. It is concluded that breast cancer incidence covaries with triglyceride levels in ex-smokers.

High plasma levels of oestrogens are associated with increased breast cancer risk. If smoking, as has been suggested, have both a tumour initiating mutagenic effect and a protective anti-oestrogenic effect, one would assume that smokers who give up smoking have the highest incidence of breast cancer. This was evaluated in the follow-up of a cohort of 10,902 women of whom 4,359 were premenopausal. Record-linkage with official cancer registries yielded 416 incident cases during an average follow-up of 13.6 years. The adjusted relative risk in all ex-smokers was 1.31 (1.02-1.69), as compared to never smokers, and in premenopausal ex-smokers it was 1.57 (1.07-2.30). Breast cancer incidence in premenopausal ex-smokers was inversely related to time since cessation, (p for trend = 0.01), and was highest among the women who had given-up smoking less than 12 months before screening: 2.76 (1.55-4.91). There was no significant association between current smoking and breast cancer risk. We conclude that incidence of breast cancer in premenopausal women who have given up smoking is higher than it is in smokers and never smokers. To what extent this may be related to endocrine effects associated with smoking cessation remains to be evaluated.

Study Objective: To assess whether in an urban population stage at breast cancer diagnosis is related to area of living and to what extent intra-urban differences in breast cancer mortality are related to incidence respectively stage at diagnosis., Design: National registries were used to identify cases. Mortality in 17 residential areas was studied in relation to incidence and stage distribution using linear regression analysis. Areas with high and low breast cancer mortality, incidence and proportion of stage II+ tumours at diagnosis were also compared in terms of their sociodemographic profile., Setting: City of Malmö in southern Sweden., Patients: The 1675 incident breast cancer cases and 448 deaths that occurred in women above 45 years of age in Malmö 1986-96., Main Results: Average annual age standardised breast cancer mortality ranged between residential areas, from 35/10(5) to 107/10(5), p = 0.04. Mortality of breast cancer was not correlated to incidence, r = 0.22, p = 0.39. The ratio of stage II+/0-I cancer incidence varied between areas from 0.45 to 1.99 and was significantly correlated to breast cancer mortality, r = 0.53, p = 0.03. Areas with high proportion of stage II+ cancers and high mortality/incidence ratio were characterised by a high proportion of residentials receiving income support, being foreigners and current smokers., Conclusions: Within this urban population there were marked differences in breast cancer mortality between residential areas. Stage at diagnosis, but not incidence, contributed to the pattern of mortality. Areas with high proportion of stage II+ tumours differed unfavourably in several sociodemographic aspects from the city average.

The validity of registered official cause of death (COD) concerning breast cancer patients in Malmö 1964-1992 was analysed. There was a high frequency of autopsy in the material and, therefore, the number of diagnostic errors should be low. Found discordance thus mostly reflect the quality of certifying and registration of COD. Of 2631 deaths discordance was found as to underlying COD in 121 cases (4.6%). Ninety-four of these represent outright errors. In 27 there was doubt about the reported COD. The number of discordant cases increased with age at death. Two kinds of systematic bias were found. One was a tendency to report breast cancer as contributing COD in patients with clinical cure. The other was a practice at the Registry to register breast cancer as underlying COD in cases with breast cancer reported as contributing COD. This practice was changed in 1981 causing an artificial decrease in registered breast cancer mortality.

To validate the Swedish Cancer Registry concerning breast tumours in female residents of Malmö 1971-1991, registry-entries were compared with clinical records. Correctness and completeness of entries was determined for invasive breast cancer (BC) and cancer in situ of the breast (CIS). As BC were registered 3,646 tumours. Of these 3,403 (93.3%) were confirmed as BC. Completeness was good with 1.1% of diagnosed tumours missing. Correctness of registered cases of CIS was 93.3%, but completeness only 63.3%. Most missing cases were registered as BC. In bilateral cancer correctness was 78.0% and completeness 77.2%. All aspects of registration improved during the period. Most differences between diagnosed and registered cases were due to coding CIS of intraductal type as BC. This practice changed in 1980 resulting in improved precision. Using registry data for epidemiological research the question of their validity must be addressed. Special consideration should be paid to coding practice at the registry.

The validity of the Swedish Cancer Registry data on invasive female breast cancer in Malmö 1961-1970 was investigated. A total of 1311 entries in the register were examined, each entry representing an individual tumour, and compared to data from medical records and local registries. In 137 cases (10.5%) registered in the Swedish Cancer Registry, divergencies were found, of which at least 121 were overregistrations (9.2%). Forty-three tumours were identified meriting inclusion but not registered, giving an underregistration of 3.5%. The age distribution among the excluded cases differed somewhat from that of the verified cases.