Showing papers by "Olof Nyrén published in 1998"
TL;DR: A large increase in the risk for diagnosis of virtually all cancers is found at the time of VTE or in the first year afterwards, and in subsequent years, a persistent 30% increase in risk remains.
497 citations
452 citations
TL;DR: There was a positive association between the questionnaire retrieval rate and partial nonresponse (missing answers in retrieved questionnaires), and marginal losses due to the latter did not cancel the gains by optimized mailing routines.
Abstract: Although self-administered questionnaires are major sources of information in epidemiology, comparatively little has been done to study practical aspects of design and mailing. The objective of this study was to evaluate various measures taken to increase the response rate. A questionnaire was mailed in July 1995 to a random sample (n = 2,000) of the Swedish population aged 20-79 years. Using a randomized factorial study design, the questionnaire and mailing procedures were changed in three ways: preliminary notification, length of the questionnaire, and mention of telephone contact. The overall questionnaire retrieval rate was 49%. Preliminary notification (adjusted odds ratio of receiving a completed questionnaire = 1.30, 95% confidence interval (CI) 1.08-1.56 relative to the absence of preliminary notification) and short length of the questionnaire (odds ratio = 1.24, 95% CI 1.04-1.48 relative to a long questionnaire) were both independently associated with a higher retrieval rate. Of eight possible combinations, the one comprising preliminary notification, a short questionnaire, and no mention of telephone contact gave the highest retrieval rate, 56%. The lowest retrieval rate, 40%, was observed for the combination of no preliminary notification, a long questionnaire, and mention of telephone contact. Young age, male sex, and urban residence significantly lowered the retrieval rate. Although there was a positive association between the questionnaire retrieval rate and partial nonresponse (missing answers in retrieved questionnaires), the marginal losses due to the latter did not cancel the gains by optimized mailing routines. Old age was the strongest determinant of partial nonresponse. The data provide evidence that design and mailing strategies, as well as demographic characteristics, may greatly influence the response rate of mailed epidemiologic questionnaires.
211 citations
TL;DR: This large nationwide cohort study of all women in the Swedish national inpatient registry who underwent breast augmentation surgery with artificial implants during 1964-93 shows no evidence of association between breast implants and connective tissue disease.
Abstract: OBJECTIVE: To examine the relation between connective tissue disease and related conditions and breast implants. DESIGN: Retrospective cohort study of all women in the Swedish national inpatient registry who underwent breast augmentation surgery with artificial implants during 1964-93, compared with women who underwent breast reduction surgery during the same period. SETTING: Sweden. SUBJECTS: 7442 women with implants for cosmetic reasons or for reconstruction after breast cancer surgery and 3353 women with breast reduction surgery. MAIN OUTCOME MEASURES: Subsequent hospitalisation for definite connective tissue diseases (rheumatoid arthritis, systemic lupus erythematosus, systemic sclerosis, dermatomyositis, and Sjogren's syndrome) or related disorders. RESULTS: 29 women with implants were hospitalised for definite connective tissue disease compared with 25.5 expected based on general population rates (standardised hospitalisation ratio 1.1 (95% confidence interval 0.8 to 1.6)). There were no diagnoses of systemic sclerosis, and no significant excess in risk for polymyalgia rheumatica, fibromyalgia, and several related disorders. Among women who underwent breast reduction surgery, 14 were hospitalised for definite connective tissue disease compared with 10.5 expected (standardised hospitalisation ratio 1.3 (0.7 to 2.2)). Compared with the breast reduction group, women with breast implants showed a slight reduction for all definite connective tissue disease (relative risk 0.8 (95% confidence interval 0.5 to 1.4)). CONCLUSIONS: This large nationwide cohort study shows no evidence of association between breast implants and connective tissue disease.
126 citations
TL;DR: This study provides no evidence that smoking bears any major relationship to the occurrence of leukemias, non-Hodgkin's lymphomas, or multiple myeloma, and there was a suggestion of a positive association between smoking and the risk of developing Hodgkin's disease.
Abstract: While several epidemiologic studies have indicated a link between smoking and the risk of developing hematolymphoproliferative cancers (chiefly leukemias, lymphomas, and multiple myelomas), in part ...
87 citations
Journal Article•
TL;DR: The Swedish data did not provide any support for the hypothesis of a role of sex hormones in the etiology of esophageal adenocarcinoma, and analysis by latency intervals after prostate cancer diagnosis revealed no clear trend toward increasing or decreasing risk over time.
Abstract: The striking male predominance in patients with adenocarcinoma of the esophagus (male:female ratio = 6:1) is not explained by known risk factors. We hypothesized that sex hormones could be responsible for this sex imbalance. If the hypothesis is correct, treatment that increases the estrogen level and/or decreases the testosterone level in males might reduce the risk of developing esophageal adenocarcinoma. To test our hypothesis, we performed a population-based, retrospective cohort study among all patients given a diagnosis of prostate cancer in Sweden between 1958 and 1992. The vast majority had received prolonged antiandrogenic treatment, typically with estrogens. A total of 100,215 patients were followed up for an average of 4 years. The standardized incidence ratio, the ratio of the observed to the expected number of incident cancers, was used as a measure of relative risk, with the expected number derived from the entire Swedish population. We observed 14 adenocarcinomas of the esophagus during follow-up in the cohort, compared to the 16 expected, yielding a relative risk close to unity (standardized incidence ratio = 0.9; 95% confidence interval = 0.5-1.5). Analysis by latency intervals after prostate cancer diagnosis revealed no clear trend toward increasing or decreasing risk over time. In conclusion, our Swedish data did not provide any support for our hypothesis of a role of sex hormones in the etiology of esophageal adenocarcinoma.
69 citations
TL;DR: In this article, the authors studied risk for endometrial cancer in relation to physical activity at work in a large cohort of Swedish women identified in the nationwide censuses in 1960 and 1970, with jobs that could be consistently classified into one of four levels of physical demands.
Abstract: Notwithstanding its biologic plausibility, the association between physical activity and endometrial cancer has been analyzed in only a few epidemiological studies. Retrospective assessment of exposure and small sample size often hampers interpretation of published data. We studied risk for endometrial cancer in relation to physical activity at work in a large cohort of Swedish women identified in the nationwide censuses in 1960 and 1970, with jobs that could be consistently classified into one of 4 levels of physical demands. Follow-up from 1971 through 1989 was accomplished through record linkages. Multivariate Poisson regression models were used to estimate relative risk. The risk for endometrial cancer increased regularly with decreasing level of occupational physical activity (p for trend < 0.001), and was associated more strongly with activity in 1970 than in 1960. In multivariate analyses, adjusted for age at follow-up, place of residence, calendar year of follow-up, and social class, the relative risk among women with the same physical activity level in 1960 and in 1970 was 30% higher for sedentary as compared with high/very high activity level; (p for trend=0.04). The protective effect of physical activity appeared to be confined to women aged 50 to 69, among whom sedentary work was associated with a 60% higher risk than that observed among women estimated to be physically most active. The excess seemed to disappear within 10 years after a change in physical activity level. Although confounding cannot be ruled out in our data, occupational physical activity appears to reduce the risk for endometrial cancer.
68 citations
TL;DR: Diagnostic accuracy increased each year, more pronounced in women than men, seen in all hospital categories, and was higher for those admitted during periods of low capacity (weekends/ holidays), and length of stay by day of admission and hospital category.
64 citations
TL;DR: Risks of renal pelvis/ureter cancer and bladder cancer among patients with an associated diagnosis of urinary tract infection were more than double those among patients without such infection, although the risks were significantly elevated in both groups.
62 citations
TL;DR: The results indicate that information bias is not likely to explain the discrepancy between the results of observational studies and of randomized‐intervention trials, and suggests that fruit and vegetable consumption is inversely related to stomach cancer.
Abstract: Observational studies, primarily of a case-control design, have shown an inverse association of fruit and vegetable consumption with the risk of stomach cancer, a finding tentatively attributed to anti-oxidant vitamins. Ensuing randomized-intervention trials of these vitamins, however, have been mostly negative. Therefore, the seemingly protective effect of fruit and vegetables in case-control studies is suspected to be influenced by the information bias inherent in the retrospective assessment of exposure, particularly since pre-conceptions about the wholesome effects of these foods are common among the public. Our aim was to examine the association of fruit and vegetable intake with the risk of stomach cancer in a prospective cohort study. Fruit and vegetable consumption was assessed in 1967 in 11,546 individuals in the Swedish Twin Registry, along with a wide range of potentially confounding factors. Complete follow-up through 1992 was attained through record linkage to the National Cancer and Death Registers. The relative risk of stomach cancer was estimated in proportional hazards models, with confidence intervals (CIs) adjusted for correlated outcomes. The risk of stomach cancer was inversely related to fruit and vegetable consumption. Controlling for potentially confounding factors, the relative risk among subjects with the lowest compared to those with the highest intake was 5.5 (95% CI 1.7-18.3) with a statistically significant dose-risk trend (p < 0.05). Our results indicate that information bias is not likely to explain the discrepancy between the results of observational studies and of randomized-intervention trials.
61 citations
TL;DR: The results provide no support for the conjecture that breast implants cause neurologic disease, as measured by measures of the risk of neurologic diseases among women with implants.
Abstract: Objective: To examine the risk of neurologic disorders among women with breast implants. Background: Case reports in the literature have raised concern about a possible link between silicone breast implants and some types of neurologic disorders, but there is a dearth of epidemiologic studies in this area. Methods: Through the nationwide Swedish hospital discharge register, we identified a population-based cohort of 7433 women with breast implants. A similarly identified cohort of 3351 women who underwent breast reduction surgery served as a comparison. The women were followed from 1972 (or date of breast surgery if it occurred later) through 1993 by means of record linkages and review of inpatient medical records. Ratios of observed to expected numbers, and relative risks (RR) with 95% confidence intervals (CI), were calculated as measures of the risk of neurologic diseases among women with implants. Results: A direct comparison of the exposed (implant) versus comparison (breast reduction) groups, after exclusion of patients with pre-existing disease or incorrect neurologic diagnoses, showed no excess risk among implant patients(RR = 0.8; 95% CI = 0.5 to 1.4). When external rates derived from the background population were used as comparison, we found a small, statistically nonsignificant excess of neurologic disorders both in the breast implant (RR = 1.3; 95% CI = 0.9 to 1.9) and the breast reduction (RR = 1.5; 95% CI = 0.9 to 2.4) cohorts. Conclusion: Our results provide no support for the conjecture that breast implants cause neurologic disease.
TL;DR: Findings from a large national systematic follow-up of women in Sweden who received cosmetic breast implants add to a growing consensus that the risk of breast cancer among women with silicone breast implants is not increased and may in fact be decreased.
Abstract: Concerns about cancer risk after implantation of silicone devices in the human body have resulted from reports of sarcomas in silicone-exposed experimental animals and case reports of breast and other cancers in women with breast implants(1). Epidemiologic data during the past few years, however, have shown no generalized increase of cancer(1). In fact, the most consistent pattern observed from the investigations conducted to date has been a decreased risk of breast cancer (1,2). To further evaluate the occurrence of cancers of the breast and other organs, we present findings from a large national systematic follow-up of women in Sweden who received cosmetic breast implants. This study includes a considerable increase in the number of patients and extends the follow-up time of our earlier report (3). Table 1 shows characteristics of women in the cohort who received breast implants. There were 3473 women with implants enrolled in the follow-up. As indicated in the table, the women in the cohort tended to be young (median age at cosmetic breast implant surgery was 30 years). The average duration of follow-up was 10 years, with a maximum follow-up of 29 years and a median follow-up of 9 years. Overall, the number of women who developed cancer among implant recipients was nearly the same as expected based on national cancer rates of Swedish women of the same age over the same time period (Table 2). In total, 74 women were diagnosed with some form of cancer subsequent to implant surgery versus 70.3 expected (standardized incidence ratio [SIR]4 1.1; 95% confidence interval [CI]4 0.8–1.3). The most common was breast cancer, which occurred less often than expected (SIR 4 0.7; 95% CI4 0.4–1.1), followed by cervical cancer (SIR4 1.9; 95% CI4 0.9–3.5). The only statistically significant departure from expectation was for lung cancer (SIR4 2.7; 95% CI4 1.1– 5.6). There was no significant excess of lymphoproliferative/hematopoietic cancers, with one non-Hodgkin’s lymphoma, one multiple myeloma, and three leukemias observed. One connective tissue cancer (an abdominal hemangiosarcoma) was diagnosed versus 0.6 expected. We observed no consistent trends in risk over time for lung, cervix, or breast cancers (data not shown). These data add to a growing consensus that the risk of breast cancer among women with silicone breast implants is not increased and may in fact be decreased(1,2). Reasons for a deficit (though not statistically significant) of breast cancer incidence are not clear, although several explanations are plausible. An anticarcinogenic effect of silicone has been postulated (2), since silicone has been reported to retard in vitro growth of human breast cancer cells and to inhibit nitrosourea-induced breast tumors in rats (6–9).More likely explanations, however, may relate to the characteristics of women with breast implants, for example, to their typically smaller breast size and less glandular tissue mass, which have been linked to a lower risk of breast cancer in some (10), but not other(11), studies. Furthermore, in the United States(12) and in Denmark (13), women with breast implants have been reported to have earlier ages at the birth of their first child, a protective factor for breast cancer (14). We had no information, however, on the pregnancy, menstrual, or other histories of the women in the cohort, and thus could not adjust for potential confounding factors. A clinical study(1) has suggested that breast implants may interfere with tumor detection, thus shifting diagnosis to a more advanced stage, but several cohort studies(2,13,15)have found no difference in the stages of breast cancer among implant recipients compared with those in the general population. The Swedish Cancer Register does not obtain information on stage of disease
TL;DR: It is analyzed to what extent such potential relief would affect the subsequent risk of lung cancer in patients who had had a vagotomy for peptic ulcer disease, compared with patients with the disease who were treated without surgery.
Abstract: Smoking increases the risk of peptic ulcer disease and also adversely affects its course.1 Both pharmacological and surgical treatments will lead to a relief from the symptoms of the disease.23 We analysed to what extent such potential relief would affect the subsequent risk of lung cancer in patients who had had a vagotomy for peptic ulcer disease, compared with patients with the disease who were treated without surgery.
TL;DR: Current evidence of a strong causal link between H. pylori infection and gastric cancer in humans has become less convincing, and recent studies seem to indicate that the strength of the association may vary with type of H.pylori strain, and possibly presence of effect-modifying co-factors in the host and/or the environment.
TL;DR: It is of paramount importance that people are given a realistic, honest, and understandable account of both benefits and risks/disadvantages before they decide to participate in a chemoprevention trial.
Abstract: The idea of preventing cancer with a pill sounds attractive to most people. But several ethical issues need to be addressed before a chemoprevention trial is started. Undue fear of cancer-not only among the participants-may be triggered if the information to the public is not formulated with great care. Since prolonged treatment is typically required, the participants' quality of life may become impaired; they may even perceive themselves as already sick. The ethical implications of placebo treatment for many years need careful consideration. The investigators must also have a plan for how to take care of the participants after the study. The benefits of the intervention are small and not noticeable for the individual, who will never know whether he/she would otherwise have developed cancer. But participants who get cancer despite their efforts to comply with the study protocol will likely feel double disappointment. It is of paramount importance that people are given a realistic, honest, and understandab...