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Biomedical subjects

A Ekbom

Publications and source records attributed to A Ekbom.

At least 127 records · Page 7Linked to original sources
PubMed1998

Parity, age at first birth and the risk of carcinoma in situ of the breast.

Epidemiological studies of in situ breast cancer are sparse, and the role of reproductive history, an established risk modifier for invasive breast cancer, remains incompletely investigated. To examine possible associations with parity and age at first birth, we undertook a case-control study nested in a nationwide cohort of Swedish women. The reproductive history of 1,368 women aged 65 or younger with a diagnosis of carcinoma in situ of the breast were compared with that of 6,837 age-matched controls drawn randomly from a population-based Fertility Registry. Statistical analyses were performed by conditional logistic regression. Compared to nulliparous women, ever-parous women were at a reduced risk of carcinoma in situ of the breast. The risk decreased with number of live births, with the estimated risk reduction in the highest parity group (5+), being of the same magnitude as that reported for invasive breast cancer. By contrast, a positive association with increasing age at first birth was somewhat less pronounced than that observed previously in the same data set with respect to invasive breast cancer. Our findings indicate that parity affects the risk of invasive breast cancer and carcinoma in situ similarly, whereas the effect of age at first birth appears to be weaker for the risk of carcinoma in situ.

Adult↗
PubMed1998

Parity and the risk of pancreatic cancer: a nested case-control study.

Smoking is the only generally accepted risk factor for pancreatic cancer. Reproductive history has in recent studies been associated with pancreatic cancer, but with contradictory results. In order to evaluate a possible association between age at first birth and the number of births and pancreatic cancer, we conducted a nested case-control study by linking 2 Swedish nationwide registries: the Cancer Registry and The Fertility Registry. Among women born between 1925 and 1970, 1,015 patients with pancreatic cancer were compared with 5,073 age-matched controls. No association between pancreatic cancer and number of births was found. Age at first birth was inversely related with the risk of pancreatic cancer (OR per 5 years = 0.90; 95% CI 0.83-0.97; p = 0.01), an association mainly confined to women with a diagnosis of pancreatic cancer before 50 years of age (OR per 5 years = 0.85; 95% CI 0.73-1.00; p = 0.04). This trend remained after adjustment for parity, but was less prominent. Young age at first birth and high parity in Sweden are, however, associated with an increased frequency of smoking, thus at least some of the increased risk for pancreatic cancer in women with young age at first birth is likely to be explained by smoking acting as a confounder.

Adolescent↗
PubMed1998

Growing evidence that several human cancers may originate in utero.

Hormone-related cancers may originate in utero. Accumulating evidence is given by animal studies, descriptive epidemiologic data and analytic etiologic studies. Indicators of high levels of endogenous pregnancy hormones, like high birth weight and jaundice in the offspring, are associated with increased risk for breast, prostate, and non-seminoma testicular cancer. Indicators of low levels, like pre-eclampsia, are associated with decreased risk. These results support the hypothesis that the pre- and perinatal periods constitute a 'time window' that is of major importance for future cancer risk.

Breast Neoplasms↗
PubMed1998

Appendectomy in Sweden 1989-1993 assessed by the Inpatient Registry.

We analyzed all appendectomies in Sweden 1989-1993 (n = 60,306) recorded in the national Inpatient Registry. Our focus was on diagnostic accuracy, incidence rate of appendicitis, perforative appendicitis, and length of stay by day of admission and hospital category. The incidence rate of appendectomy decreased by 9.8% in women compared to 4.1% in men. Since the number of patients with an end diagnosis of appendicitis remained almost constant, diagnostic accuracy increased each year. This was more pronounced in women than men, seen in all hospital categories, and was higher for those admitted during periods of low capacity (weekends/ holidays). Perforated appendicitis did not increase. Duration of hospital stay decreased continuously, especially among the oldest. We found no indications of an increased frequency of complications, such as increases in the incidence rate of perforations or in the length of stay.

Adolescent↗
PubMed1998

Trends in colorectal cancer incidence in Sweden 1959-93 by gender, localization, time period, and birth cohort.

OBJECTIVES: This study examined invasive colorectal cancer incidence-rates in Sweden from 1959 through 1993 (n = 134,643 cases). METHODS: Age-standardized rates were calculated using the Swedish population in 1970 as a reference. RESULTS: In right-sided colon cancer (ascending and transverse colon including right and left flexures), male age-standardized rates rose from 8.0 to 15.0 (1.8 percent annually, 95 percent confidence interval [CI] = 1.3-2.4) and female rates increased from 9.1 to 14.4 (1.5 percent annually, CI = 1.0-2.0). For left-sided colon cancer (descending and sigmoid colon), the rates have been stable recently. For rectal cancer, the rates among men rose from 18.8 to 23.0 and among women from 10.7 to 14.7. For both men and women, the relative risk (RR) of right-sided colon cancer had been increasing in successive generations, until leveling-off in those born after 1930. The RR of left-sided colon cancer had been almost constant for cohorts born before 1930 but steadily decreasing in later-born cohorts. The RR of rectal cancer was slightly increasing in successive cohorts. CONCLUSIONS: Changes in lifestyle or carcinogenic exposures during early life probably explain Swedish colorectal cancer incidence-trends better than improved diagnostic activities.

Adult↗
PubMed1998

Smoking and the risk of leukemia, lymphoma, and multiple myeloma (Sweden).

While several epidemiologic studies have indicated a link between smoking and the risk of developing hematolymphoproliferative cancers (chiefly leukemias, lymphomas, and multiple myelomas), in particular myeloid leukemia, the role of tobacco in the etiology of these neoplasms remains unclear. To evaluate the potential impact of tobacco use on development of leukemia, lymphoma, and multiple myeloma, we conducted a cohort study of 334,957 Swedish construction workers using prospectively collected exposure-information with complete long-term follow-up. A total of 1,322 incident neoplasms occurred during the study period, 1971-91. We found no significant association between smoking status, number of cigarettes smoked, or duration of smoking and the risk of developing leukemias, lymphomas, or multiple myeloma. There was a suggestion of a positive association between smoking and the risk of developing Hodgkin's disease, although the rate ratios were not significantly elevated, except for young current smokers. No positive dose-risk trends emerged. Our study provides no evidence that smoking bears any major relationship to the occurrence of leukemias, non-Hodgkin's lymphomas, or multiple myeloma.

Adolescent↗
PubMed1998

Spatial temporal patterns in childhood leukaemia: further evidence for an infectious origin. EUROCLUS project.

The EUROCLUS project included information on residence at diagnosis for 13351 cases of childhood leukaemia diagnosed in the period 1980-89 in defined geographical regions in 17 countries. A formal algorithm permits identification of small census areas as containing case excesses. The present analysis examines spatial-temporal patterns of the cases (n = 970) within these clustered areas. The objectives were, first, to compare these results with those from an analysis conducted for UK data for the period 1966-83, and, second, to extend them to consider infant leukaemias. A modification of the Knox test investigates, within the small areas, temporal overlap between cases in a subgroup of interest at a putative critical time and all other cases at any time between birth and diagnosis. Critical times were specified in advance as follows: for cases of acute lymphoblastic leukaemia aged 2-4 years, the 18-month period preceding diagnosis; for cases of total leukaemia aged 5-14 years, 1 year before to 1 year after birth; and for infant cases (diagnosed < 1 year), 1 year before to 6 months after birth. Each of the analyses found evidence of excess space-time overlap compared with that expected; these were 10% (P = 0.005), 15% (P= 0.0002) and 26% (P= 0.03) respectively. The results are interpreted in terms of an infectious origin of childhood leukaemia.

Adolescent↗
PubMed1998

Spatial clustering of childhood leukaemia: summary results from the EUROCLUS project.

The interpretation of reports of clusters of childhood leukaemia is difficult, first because little is known about the causes of the disease, and second because there is insufficient information on whether cases show a generalized tendency to cluster geographically. The EUROCLUS project is a European collaborative study whose primary objective is to determine whether the residence locations of cases at diagnosis show a general tendency towards spatial clustering. The second objective is to interpret any patterns observed and, in particular, to see if clustering can be explained in terms of either infectious agents or environmental hazards as aetiological agents. The spatial distribution of 13351 cases of childhood leukaemia diagnosed in 17 countries between 1980 and 1989 has been analysed using the Potthoff-Whittinghill method. The overall results show statistically significant evidence of clustering of total childhood leukaemia within small census areas (P=0.03) but the magnitude of the clustering is small (extra-Poisson component of variance (%) = 1.7 with 90% confidence interval 0.2-3.1). The clustering is most marked in areas that have intermediate population density (150-499 persons km[-2]). It cannot be attributed to any specific age group at diagnosis or cell type and involves spatial aggregation of cases of different ages and cell types. The results indicate that intense clusters are a rare phenomenon that merit careful investigation, although aetiological insights are more likely to come from investigation of large numbers of cases. We present a method for detecting clustering that is simple and readily available to cancer registries and similar groups.

Adolescent↗
PubMed1998

Increasing incidence of testicular cancer--birth cohort effects.

The incidence of testicular cancer is rising in most Western populations. A collaborative study between nine population-based cancer registries in countries around the Baltic Sea was utilized in order to analyze in detail geographic variations and temporal trends in the occurrence of testicular cancer. There were 34,309 cases registered up until 1989 starting in Denmark in 1942 and most recently in Latvia in 1977. From the descriptive epidemiology it was obvious that there was a substantial variation in the age-standardized incidence amounting to about a 10-fold difference between the different countries ranging from 0.8 per 100,000 person-years in Lithuania to 7.6 per 100,000 person-years in Denmark. Previous studies have indicated that this increase is due to birth cohort effects. A more detailed analysis was therefore performed in those six countries with a sufficiently long period of cancer registration; Poland, former East Germany, Norway, Finland, Denmark and Sweden. This analysis showed that birth cohort is a more important determinant of testicular cancer risk than year of diagnosis. In Poland, former East Germany and Finland, there was an increasing risk for all birth cohorts. Among men born in Denmark, Norway or Sweden between 1930 and 1945, this increasing trend in risk was interrupted in these birth cohorts but followed thereafter by an uninterrupted increase by birth cohort. In conclusion, life time exposure to environmental factors which are associated with the incidence of testicular cancer appear to be more related to birth cohort than to year of diagnosis. Because testicular cancer typically occurs at an early age, major etiological factors therefore need to operate early in life, perhaps even in utero.

Adult↗
PubMed1998

Is colonoscopic surveillance reducing colorectal cancer mortality in ulcerative colitis? A population based case control study.

BACKGROUND: Colonoscopic surveillance is a standard procedure in many patients with long standing, extensive ulcerative colitis (UC), in order to avoid death from colorectal cancer. No conclusive proof of its benefits has been presented however. AIMS: To evaluate the association between colonoscopic surveillance and colorectal cancer mortality in patients with UC. PATIENTS: A population based, nested case control study comprising 142 patients with a definite UC diagnosis, derived from a study population of 4664 patients with UC, was conducted. METHODS: Colonoscopic surveillance in all patients with UC who had died from colorectal cancer after 1975 was compared with that in controls matched for age, sex, extent, and duration of the disease. Information on colonoscopic surveillance was obtained from the medical records. RESULTS: Two of 40 patients with UC and 18 of 102 controls had undergone at least one surveillance colonoscopy (relative risk (RR) 0.29, 95% confidence interval 0.06 to 1.31). Twelve controls but only one patient with UC had undergone two or more surveillance colonoscopies (RR 0.22, 95% confidence interval 0.03 to 1.74), indicating a protective dose response relation. CONCLUSION: Colonoscopic surveillance may be associated with a decreased risk of death from colorectal cancer in patients with long standing UC.

Adolescent↗
PubMed1997

Risk of second cancers in classical Kaposi's sarcoma.

An association between Kaposi's sarcoma (KS) and malignant lymphoma has been suspected for many years. Both cancers belong to the group of malignancies associated with immune suppression and have been known to occur in the same individual. Accordingly, a common etiology has been suspected. Through linkage within the Nordic cancer registries, we studied the occurrence of cancers in a population-based cohort of 741 patients with classical KS. The relative risk of subsequent malignancies was expressed as the ratio of the observed numbers of cancer to the numbers expected based on age-, sex-, period- and country-specific incidence rates, i.e., the standardized incidence ratio (SIR). A total of 104 cancers was observed during 5,802 person-years of follow-up, which was close to the expected 98.8 cases (SIR, 1.05). During the first year of follow-up, 3 lymphomas were observed, which is in significant excess of the 0.2 lymphomas expected (SIR, 13.0). In contrast, no lymphomas occurred in the period beyond the first year of follow-up vs. 2.3 expected. Cancers of the buccal cavity and pharynx (SIR, 10.6; n = 4) and of the colon (SIR, 2.7; n = 7) occurred in excess among women but not among men. Accordingly, our results indicate that patients with classical KS are not at increased risk of cancer in general. In particular, the overall risk of lymphomas was not significantly increased. The high relative risk of malignant lymphoma immediately after KS was based on a limited number of cases, and this observation is unlikely to indicate a common etiology.

Age Factors↗
PubMed1997

Blood transfusion and non-Hodgkin lymphoma: lack of association.

BACKGROUND: Non-Hodgkin lymphoma is the seventh most commonly diagnosed malignant condition worldwide, and its incidence has increased markedly in recent decades. Blood transfusions have been implicated as a possible risk factor for non-Hodgkin lymphoma. OBJECTIVE: To determine whether blood transfusions are associated with an elevated risk for non-Hodgkin lymphoma. DESIGN: Population-based, nested case-control study. SETTING: Nationwide cohort in Sweden. PATIENTS: 361 patients with non-Hodgkin lymphoma and 705 matched controls, nested within a population-based cohort of 96795 patients at risk for blood transfusion between 1970 and 1983. Prospectively collected information on exposure was retrieved from computerized transfusion registries. MEASUREMENTS: Odds ratios obtained from conditional logistic regression models were used as measures of relative risks. RESULTS: No association was found between blood transfusions and the risk for non-Hodgkin lymphoma when patients who had received transfusions were compared with patients who had not received transfusions (odds ratio, 0.93 [95% CI, 0.71 to 1.23]). A reduction in risk was seen among persons who received transfusion of blood without leukocyte depletion (odds ratio, 0.72 [CI, 0.53 to 0.97]). Risk was not related to number of transfusions, and no interaction was seen with latency after transfusion. CONCLUSION: The findings in this study do not support previous observations of an association between blood transfusions and the risk for non-Hodgkin lymphoma.

Adult↗