Delivery of premature newborns and maternal breast-cancer risk.
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Breast Neoplasms↗
Biomedical subjects
A Ekbom
Publications and source records attributed to A Ekbom.
Sunlight and non-Hodgkin's lymphoma: a population-based cohort study in Sweden.
Indirect evidence, notably ecological comparisons and an association with skin cancer, links non-Hodgkin's lymphoma (NHL) with exposure to sunlight. We conducted a population-based, nationwide cohort study with exposure to outdoor work inferred from job titles reported in the population and housing censuses in 1960 and/or 1970 and by classifying each individual's work and home addresses according to latitude. Follow-up for cancer incidence was accomplished through record linkages with the virtually complete Swedish Cancer Registry. The cohort included all Swedish residents who were recorded as gainfully employed in both censuses. Altogether 4,171,175 individuals contributing 69,639,237 person-years accrued through 1989 were included in the analyses. We identified 10,381 cases of NHL, 4,018 cases of chronic lymphocytic leukemia (CLL), 11,398 cases of malignant melanoma (MM) and 11,913 cases of squamous cell skin cancer (SCC). We calculated age-adjusted relative risks for NHL, CLL, MM and SCC in strata based on estimated residential and occupational sunlight exposure. Interaction effects were considered for pesticide and solvent exposure. NHL, MM and SCC, but not CLL, were positively associated with increasingly southerly residential latitude, with stronger associations seen for skin cancer compared to NHL. Occupational sun exposure was not associated with the risk of developing any of the studied cancers. Pesticides and solvents also were not related to an increased risk of NHL, nor did these exposures enhance effects of residential or occupational sunlight exposure. Our results provide some support for an association of sunlight exposure with NHL incidence based on the associations seen using geographic latitude of residence as a proxy for exposure. Although type of occupation may be an imperfect index of the biologically relevant ultraviolet (UV) light dose, our data on individual exposure are not consistent with an important role of sunlight in the etiology of NHL.
Age Factors↗
The role of reproductive factors and use of oral contraceptives in the aetiology of breast cancer in women aged 50 to 74 years.
It is unclear whether age at menarche is causally involved in breast-cancer aetiology, or serves a correlate of other early-life exposures. Other aspects of reproductive life, including cycle length and regularity, climacteric symptoms, reproductive history and oral contraceptive use, are also incompletely investigated. We examined these issues in a population-based case-control study, including 3,016 women aged 50 to 74 years with invasive breast cancer, and 3,263 controls of similar age. Mailed questionnaires and telephone interviews were used to collect information on menstrual and reproductive characteristics as well as use of oral contraceptives. We found a statistically significant negative association between increasing age at menarche and breast-cancer risk in women born before 1925 but not after. Length of the menstrual cycle at age 30 seemed to be adversely related to breast-cancer risk, with OR for women with cycle lengths < 24 days and > 30 days being 0.76 and 1.18, as compared with women with a cycle length of 28 days. There was a strong trend of decreasing breast-cancer risk with increasing parity (OR per borne child 0.85, 95% CI 0.80-0.90). Lactation, menopausal symptoms or past use of oral contraceptives did not appear associated with breast-cancer risk. Our findings provide some evidence of a role of environmental correlates of early menarche in breast-cancer aetiology, and underline the importance of childbirth, especially early in life, in the prevention of breast cancer. Our data are not readily compatible with an important influence of former oral contraceptive use on post-menopausal breast-cancer risk.
Aged↗
Ovarian cancer in young women in Sweden, 1989-1991.
The present study is an evaluation of the symptoms and gynecological status, at the time of seeking medical advice, among women of reproductive age diagnosed with ovarian malignancies. The study was based on the medical records of all women in Sweden between 15 and 40 years of age who were diagnosed with ovarian malignancies during a 3-year period (1989-1991). The study focused on the diagnosis and panorama of symptoms. These data were compared to the records of more than 10,000 women in this age group during the same period of time who underwent surgery for ovarian changes that resulted in benign diagnoses. The 152 cases of ovarian cancer included only 1 patient who was without symptoms, had normal pelvic status upon manual examination, and a sonographically diagnosed simple cyst. These data support the conclusion that the majority of young women with ovarian cancer have symptoms and/or clinically detectable adnexal masses at the time when medical advice is sought. These studies suggest that diagnosis of ovarian cancer is unlikely in young healthy women lacking subjective symptoms and an adnexal mass upon pelvic examination. In conclusion, programs for the management of simple cysts and development of noninvasive diagnostic methods for ovarian changes found in patients in the reproductive age group are needed in order to reduce the number of patients subjected to operative intervention.
Adolescent↗
Human fertility does not decline: evidence from Sweden.
OBJECTIVE: To assess changes in human fertility over time. DESIGN: Time-trend analyses and age-period-cohort modeling. SETTING: Sweden, 1983-1993. PATIENT(S): All primiparous women aged > or =20 years during the study period. There were 401,653 women who were identified through the nationwide Medical Birth Register. INTERVENTION(S): None. MAIN OUTCOME MEASURE(S): Risk of subfertility, defined as > or =1 year of involuntary childlessness. RESULT(S): Subfertility problems decreased dramatically over successive maternal birth cohorts. Further, the risk of subfertility increased with age and decreased with increasing formal education. CONCLUSION(S): A decrease in male fertility cannot be ruled out on the basis of these results, but if present, it is minor and totally outweighed by other favorable developments. As the main explanation for our findings, we propose a decrease in the prevalence of secondary subfertility as a result of the eradication of gonorrhea.
Adult↗
Early virus infections and inflammatory bowel disease: back to the drawing board?
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Adult↗
Population density and childhood leukaemia: results of the EUROCLUS Study.
The EUROCLUS study assembled incidence data for 13,551 cases of childhood leukaemia (CL) diagnosed between 1980 and 1989 in 17 countries (or regions of countries). These were referenced by location at diagnosis to small census areas of which there were 25,723 in the study area. Population counts, surface area and, hence, population density were available for all these small areas. Previous analyses have shown limited extra-Poisson variation (EPV) of case counts within small areas; this is most pronounced in areas of intermediate population density (150-499 persons/km2). In this study, the data set was examined in more detail for evidence that variations in incidence and EPV of CL are associated with population density. Incidence showed a curvilinear association with population density and was highest in areas which were somewhat more densely populated (500-750 persons/km2), where the incidence rate ratio relative to areas having > or = 1000 persons/km2 was 1.16 (95% confidence interval 1.07-1.26) and the P value for quadratic trend across eight strata of population density was 0.02. Incidence in these areas is uniformly elevated and showed no evidence of heterogeneity (i.e. EPV). Statistically significant evidence of EPV was evident amongst some of the areas previously classified as intermediate density areas (specifically, those with a density of 250-499 persons/km2, P < 0.001 for CL). These results were interpreted in terms of the current aetiological hypotheses for CL which propose that exposure to localised epidemics of one or more common infectious agent may contribute to the development of leukaemia. They suggest that such epidemics arise regularly in moderately densely populated areas and also sporadically in areas which are somewhat less densely populated. Although other interpretations are possible, these results may assist in the identification of characteristics which infectious agents must possess if direct or indirect causes of CL.
Child↗
Maternal pregnancy hormone levels in an area with a high incidence (Boston, USA) and in an area with a low incidence (Shanghai, China) of breast cancer.
Characteristics probably associated with the fetal hormonal milieu have recently been shown to increase (birth size indicators, prematurity, neonatal jaundice) or decrease (pregnancy toxaemia) breast cancer risk in the female offspring. However, it is unknown whether differences in pregnancy hormone levels may contribute to the marked geographical variation in breast cancer incidence. We have compared, in a highly standardized manner, pregnancy hormone levels in a population with high incidence and one with low incidence of breast cancer. Three hundred and four pregnant Caucasian women in Boston and 334 pregnant Chinese women in Shanghai were enrolled from March 1994 to October 1995. Levels of oestradiol, oestriol, prolactin, progesterone, human growth hormone, albumin and sex hormone-binding globulin were measured in maternal blood at weeks 16 and 27 of gestation and compared between the two study sites using non-parametric Wilcoxon's rank-sum test. Demographical, anthropometrical and pregnancy characteristics were ascertained through interview, and relevant variables concerning delivery and the newborn were abstracted from medical records and paediatric charts. During the first visit, median serum levels of all studied hormones were statistically significant, and in most instances substantially, higher among Chinese women, who have a low incidence of breast cancer, compared with American women, who have a high incidence of breast cancer. An analogous pattern was evident during the second visit, although the relative differences tended to be smaller. Further research is needed to identify lifestyle or other exogenous determinants of pregnancy hormone levels, as well as possible mechanisms by which they may influence carcinogenic processes in the breast and possibly other organs.
Adult↗
The safety of proton pump inhibitors in pregnancy.
AIM: To assess the safety of proton pump inhibitors during pregnancy. METHODS: Fifty-one pregnant women exposed to proton pump inhibitors around the time of conception or during pregnancy were compared with 13 327 controls without exposure to any prescribed drug in a population-based study based on The Pharmaco-Epidemiological Prescription Database of North Jutland and the Danish Hospital Discharge Registry. RESULTS: Three babies with malformations were found among 38 women exposed to proton pump inhibitors from 30 days before conception to the end of the first trimester. No cases of stillbirth were recorded. Crude relative risks of malformation, low birth weight and preterm delivery were 1.6 (95% CI: 0.5-5.1), 1.8 (95% CI: 0.2-13.0) and 2.3 (95% CI: 0.9-6.0), respectively. CONCLUSIONS: In this population-based follow-up study, we found no substantially elevated risk in terms of malformations, low birth weight or number of preterm deliveries in pregnancies exposed to proton pump inhibitors. However, further monitoring is warranted in order to establish or rule out a potential association between the use of proton pump inhibitors and increased risk of either cardiac malformations or preterm birth.
Abnormalities, Drug-Induced↗
The sex ratio and rate of reoperation for Dupuytren's contracture in men and women.
We identified all patients treated by local fasciectomy at the Department of Hand Surgery, Uppsala University Hospital between 1965 and 1996. A total of 2375 operations were performed on 1600 patients. We found a male:female ratio of 5.9:1. Women had a higher mean age at first operation (62.4 years) than men (59.8 years). One-third of the men required repeated surgery and one-quarter of the women. Early age at first operation was associated with recurrent disease.
Adolescent↗
Change in the extent of colonoscopic and histological involvement in ulcerative colitis over time.
OBJECTIVE: Colonoscopy has replaced barium enema as the method for determining the extent of disease in patients with ulcerative colitis (UC). Normally, the extent of disease is determined by direct visualization of the mucosa, but biopsies are also used with increasing frequency. Very little is known about the extent to which these two ways of assessing the extent of disease are correlated and whether the correlation differs over time. The aim of this study was to determine the changes in extent of disease assessed by direct visualization and by histological examination of the mucosa at the time of diagnosis and after 1 yr of follow-up in a cohort of incident cases of UC patients. METHODS: All new cases of UC in a defined population were identified during a 4-yr period (496 patients). Of these, 384 patients (78%) were available for follow-up and were subjected to a second colonoscopy with representative biopsies taken from both normal and affected mucosa. RESULTS: After 1 yr there were macroscopical signs of progression in 14%; 22% showed regression, and 30% had a normal colonoscopy. The histological changes from diagnosis until follow-up showed progression in 20%, 24% showed regression, and 24% had normal histological findings. Histological examination showed more extensive disease than did direct visualization in 4% of patients at diagnosis and in 28% at follow-up, whereas direct visualization showed more extensive disease than did histological examination in 18% of patients at diagnosis and 12% at follow-up. The best correlation at both diagnosis and follow-up was seen in pancolitis (99% and 88%, respectively). CONCLUSIONS: With regard to the extent of colonic involvement in the UC patients, we found less agreement between endoscopic and histological evaluation at the follow-up examination than at the start of the study. This could indicate that biopsies represent a better indicator than endoscopical examination for long term prognosis. Further studies are needed to confirm this finding.
Adult↗
Review: substantial coffee consumption was associated with a lower risk of colorectal cancer in the general population.
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Coffee↗
Risk of primary biliary liver cirrhosis in patients with coeliac disease: Danish and Swedish cohort data.
BACKGROUND: Several case reports, but only a few studies, have examined the coexistence of coeliac disease and primary biliary cirrhosis. AIM: To estimate the risk of primary biliary cirrhosis in two national cohorts of patients with coeliac disease in Denmark and Sweden. METHODS: Through record linkage all Danish patients hospitalised with coeliac disease were followed for possible occurrence of primary biliary cirrhosis from 1 January 1977 until 31 December 1992. All patients hospitalised with coeliac disease in Sweden from 1987 to 1996 were also followed in a separate analysis. RESULTS: A total of 896 patients with coeliac disease were identified in Denmark with a median follow up period of 9.1 years for a total of 8040 person-years at risk. Two cases of primary biliary cirrhosis were observed where 0.07 were expected, giving a standardised incidence ratio of 27.6 (95% confidence interval 2.9 to 133.5). A total of 7735 patients with coeliac disease were identified in Sweden with a median follow up period of 5.1 years for a total of 39 284 person-years at risk. Twenty two people with primary biliary cirrhosis were identified compared with 0.88 expected, giving a standardised incidence ratio of 25.1 (95% confidence interval 15.7 to 37.9). CONCLUSION: Patients with coeliac disease are at increased risk of having primary biliary cirrhosis.
Celiac Disease↗
Survival after rectal cancer: differences between hospital catchment areas. A nationwide study in Sweden.
BACKGROUND: The quality of rectal cancer surgery at small units has been debated. No national studies of this issue have been undertaken and most studies have been based on insufficient data to clarify the controversy. It has been claimed that observed differences in outcomes between specialised centres and smaller hospitals are confounded by differences in stage/severity. AIM: To compare survival after rectal cancer between hospital catchment areas. PATIENTS: All patients with rectal cancer notified to the Swedish Cancer Register in 1973-1992 (n = 30 811) were followed up by record linkage to the nationwide Death Register. METHODS: Relative survival-that is, ratio of observed to expected survival-was computed as a measure of excess mortality attributable to rectal cancer. Multivariate analysis was then performed to estimate the independent effects of hospital catchment area categories and age, year of diagnosis, and duration of follow up. RESULTS: One year relative survival among rectal cancer patients residing in catchment areas of large regional hospitals was 76%, compared with 72% for small local hospitals (p<0.001). A difference was already noted after 30 days and remained five years after diagnosis. Relative survival improved considerably overall, but the differences between catchment area categories persisted. These were not reduced by adjustment for age, time after diagnosis, or time period in multivariate models. CONCLUSION: The differences in outcome between catchment area categories could not be explained by differences in age, time period, or duration of follow up after diagnosis. They are unlikely to be explained by differences between catchment area populations with regard to the average stage of the disease at which symptoms lead to diagnosis. The differences may therefore be attributable to different strategies for diagnosing and managing patients with rectal cancer.
Aged↗
Abdominal US for diagnosis of pancreatic tumor: prospective cohort analysis.
PURPOSE: To elucidate the accuracy of abdominal ultrasonography (US) in the diagnosis of pancreatic tumors. MATERIALS AND METHODS: In all patients referred for pancreatic US during 1988-1990, data on malignant disease and survival were analyzed by using the Swedish Death and Cancer Registries. Nine hundred nineteen patients were entered into the analysis. In 140 of them, a clinical diagnosis of tumor in the pancreatic area was confirmed within 1 year after US. These tumors were primary pancreatic tumors (n = 102), common bile duct and duodenal cancers (n = 17), and metastases in the pancreatic area (n = 21). RESULTS: The sensitivity of US in the detection of all tumors in the pancreatic area was 88.6% (124 of 140 patients), which was similar to that for the detection of exocrine pancreatic cancer, 90% (79 of 88 patients). There were nine false-positive US examinations, for a specificity of 98.8% (770 of 779 patients). Systematic sampling of 94 investigations confirmed an association between US accuracy and presence of clinical symptoms of pancreatic cancer. Significant differences in the sensitivity (P < .05) and accuracy (P < .01) of diagnosis were observed between three experienced investigators. CONCLUSION: Study results support the use of US as a first-line diagnostic examination in patients suspected of having pancreatic tumor. Dependency on the investigator's experience with US mandates continuous evaluation of its performance.
Abdomen↗
Epidemiology of inflammatory bowel disease.
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Age Distribution↗
Increased risk for cancer following sarcoidosis.
Little is known about the cancer risk following sarcoidosis. In a retrospective cohort study, we tested the hypothesis of an increased risk for malignant lymphomas, lung cancer as well as cancer in other organs frequently involved in sarcoidosis. Four hundred seventy-four patients from an incidence study 1966-1980 and 8,541 patients identified in the Swedish Inpatient Register (IPR) 1964-1994 were linked to the Cancer Register, the Register of Causes of Death, and the Register of Total Population. Relative risks were estimated using standardized incidence ratios (SIR). The overall relative risks for cancer were similar and elevated in both cohorts (IPR presented), SIR = 1.3; 95% confidence interval (CI) 1.2 to 1.4. For lung cancer and non-Hodgkin's lymphoma, the relative risk was doubled during the first decade of follow-up. Thereafter, the risk for lung cancer was significantly decreased whereas the risk for non-Hodgkin's lymphoma equaled unity. Throughout follow-up, elevated risks were found for melanoma (SIR = 1.6; 95% CI 1.0 to 2.3) and nonmelanoma skin cancer (SIR = 2.8; 95% CI 2.0 to 3.8). An increased risk was also found for liver cancer (SIR = 1.4; 95% CI 0.8 to 2.2). Thus, sarcoidosis appears to be associated with a significantly increased risk for cancer in affected organs. Chronic inflammation is a putative mediator of this risk.
Adult↗
Risk factor patterns for cryptorchidism and hypospadias.
To evaluate the hypothesis of a common etiology for cryptorchidism and hypospadias, we conducted two case-control studies nested in a nationwide cohort in Sweden, using record linkage between the Inpatient and Birth Registries. Cases were 2,782 and 1,220 boys operated for cryptorchidism or hypospadias, respectively. Five matched controls per case were randomly selected. Pregnancy and perinatal data were prospectively recorded in the Birth Registry. Data were modeled through conditional logistic regression. Both cryptorchidism (odds ratio (OR) = 2.22) and hypospadias (OR = 2.75) were positively associated with other congenital malformations and inversely with maternal parity (OR = 0.77 and 0.52, respectively, for parity 4+ compared with primiparae). There is evidence that being born small-for-gestational-age and before the 33rd gestational week have a greater-than-additive effect with respect to both cryptorchidism (OR = 6.19 vs 1.72 expected) and hypospadias (OR = 4.39 vs 2.60 expected) compared with non-small-for-gestational-age boys born at term. Hypospadias was positively associated with severe preeclampsia (OR = 2.11). We conclude that the etiologies of the two conditions are partly shared.
Case-Control Studies↗