Reproductive variables and risk of uterine cervical cancer in Norwegian registry data

The influence of reproductive variables on cervical cancer incidence, controlling for other sociodemographic factors, was estimated in Norwegian register and census data, using Poisson regression models. Among the 1.3 million women under observation, a total of 2,870 cases of cervical cancer were diagnosed. According to models restricted to parous women, parity level had no independent impact on cervical cancer incidence, but a clear effect of age at first birth was noted. It was most pronounced in the squamous cell carcinomas, where the incidence was reduced by 48 percent from age at first birth <21 years to age at first birth 27+years. Women without children had the same cervical cancer incidence as parous women with a first birth after age 24. The sociodemographic variables controlled for exerted a strong net effect on the cervical cancer incidence. Educational level was related inversely to the cancer risk. Moreover, an increased risk was seen for women who had given birth when they were still single (never married) and for those who were divorced/separated at the time of the last previous census. A fairly small excess risk was found to be associated with living in non-rural compared with rural areas.Dr Bjørge is with the Cancer Registry of Norway, Oslo, Norway. Dr Kravdal is with the Section for Demography, Department of Economics, University of Oslo, Oslo, Norway. Address correspondence to Dr Bjørge, the Cancer Registry of Norway, Institute for Epidemiological Cancer Research, Montebello, N-0310 Oslo, Norway. This work was supported by grant no. 95034/001 from the Norwegian Cancer Society.     

A cancer survival model that takes sociodemographic variations in "normal" mortality into account: comparison with other models

STUDY OBJECTIVES: Sociodemographic differentials in cancer survival have occasionally been studied by using a relative survival approach, where all cause mortality among persons with a cancer diagnosis is compared with that among similar persons without such a diagnosis ("normal" mortality). One should ideally take into account that this "normal" mortality not only depends on age, sex, and period, but also various other sociodemographic variables. However, this has very rarely been done. A method that permits such variations to be considered is presented here, as an alternative to an existing technique, and is compared with a relative survival model where these variations are disregarded and two other methods that have often been used. DESIGN, SETTING, AND PARTICIPANTS: The focus is on how education and marital status affect the survival from 12 common cancer types among men and women aged 40-80. Four different types of hazard models are estimated, and differences between effects are compared. The data are from registers and censuses and cover the entire Norwegian population for the years 1960-1991. There are more than 100 000 deaths to cancer patients in this material. MAIN RESULTS AND CONCLUSIONS: A model for registered cancer mortality among cancer patients gives results that for most, but not all, sites are very similar to those from a relative survival approach where educational or marital variations in "normal" mortality are taken into account. A relative survival approach without consideration of these sociodemographic variations in "normal" mortality gives more different results, the most extreme example being the doubling of the marital differentials in survival from prostate cancer. When neither sufficient data on cause of death nor on variations in "normal" mortality are available, one may well choose the simplest method, which is to model all cause mortality among cancer patients. There is little reason to bother with the estimation of a relative-survival model that does not allow sociodemographic variations in "normal" mortality beyond those related to age, sex, and period. Fortunately, both these less data demanding models perform well for the most aggressive cancers.     

Parenthood after cancer - a population-based study

Many cancer forms today have good prognosis, and parenthood after cancer diagnosis and treatment has become a central research topic. Previous research has mainly focused on reproductive cancers, and few population-based studies exist.The effect of several cancer forms on fertility at a population level was explored. Discrete-time hazard regression models were used to analyse register and census data for complete Norwegian birth cohorts. Men and women 17-44 years in the period 1965-2001 were included. Models for first- and higher-order birth rates, for men and women, were estimated.Overall, first-birth rates among persons with cancer were reduced by only about 25% when compared with the general population. Male cancer survivors' second- and third-birth rates were similarly reduced, whereas higher-order birth rates for females were 36% below those of the general population. Significant decreases in cancer survivors' fertility disadvantage relative to the general population were seen from 1965 to 2001.Reductions in fertility were most pronounced for reproductive cancer forms, presumably related to subfecundity. However, also cancer forms unrelated to reproductive function led to reduced fertility, perhaps suggesting underlying social mechanisms. This is further supported by the difference in probability between first and subsequent births observed for women.     

Diagnostic utility of a single-epitope sandwich B-type natriuretic peptide assay in stable coronary artery disease: Data from the Akershus Cardiac Examination (ACE) 1 Study

ObjectivesTo assess the merit of a novel single-epitope sandwich (SES) assay specific to the stable part of BNP in patients with reversible myocardial ischemia as post-translational modifications of BNP may influence assay performance.Design and methodsWe measured BNP concentration by a conventional assay and the SES-BNP assay in 198 patients referred for myocardial perfusion imaging (MPI). BNP concentration was determined before and immediately after exercise stress testing, and 1.5 and 4.5 h later. Patients were categorized according to MPI results.ResultsBNP concentration was higher with both assays at all time points in patients with reversible myocardial ischemia (n = 19) compared to the other patients (n = 179). Measuring BNP after stress testing or calculating the changes in BNP concentration did not improve diagnostic accuracy compared to baseline measurements: SES-BNP: AUC 0.71 (95% CI 0.58–0.84) vs. conventional BNP: 0.71 (0.59–0.83), p = 0.96. By linear regression analysis, reversible myocardial ischemia was significantly associated with baseline SES-BNP concentration (p = 0.043), but not with measurements by the conventional assay (p = 0.089). In multivariate logistic regression models, only baseline measurement with the SES-BNP assay was significantly associated with reversible myocardial ischemia: odds ratio [logarithmical transformed BNP] 2.00 (95% CI 1.16–3.47), p = 0.013. The SES-BNP assay, but not the conventional BNP assay, reclassified a significant proportion of the patients towards their correct category on top of the best clinical model of our data set: NRI = 0.47, p = 0.04.ConclusionsThe SES-BNP assay was significantly associated with reversible myocardial ischemia as assessed by several statistical indices, while a conventional BNP assay was not.     

Cardiac troponin T levels and exercise stress testing in patients with suspected coronary artery disease: the Akershus Cardiac Examination (ACE) 1 study

Whether reversible ischaemia in patients referred for exercise stress testing and MPI (myocardial perfusion imaging) is associated with changes in circulating cTn (cardiac troponin) levels is controversial. We measured cTnT with a sensitive assay before, immediately after peak exercise and 1.5 and 4.5 h after exercise stress testing in 198 patients referred for MPI. In total, 19 patients were classified as having reversible myocardial ischaemia. cTnT levels were significantly higher in patients with reversible myocardial ischaemia on MPI at baseline, at peak exercise and after 1.5 h, but not at 4.5 h post-exercise. In patients with reversible ischaemia on MPI, cTnT levels did not change significantly after exercise stress testing [11.1 (5.2-14.9) ng/l at baseline compared with 10.5 (7.2-16.3) ng/l at 4.5 h post-exercise, P=0.27; values are medians (interquartile range)]. Conversely, cTnT levels increased significantly during testing in patients without reversible myocardial ischaemia [5.4 (3.0-9.0) ng/l at baseline compared with 7.5 (4.6-12.4) ng/l, P<0.001]. In conclusion, baseline cTnT levels are higher in patients with MPI evidence of reversible myocardial ischaemia than those without reversible ischaemia. However, although cTnT levels increase during exercise stress testing in patients without evidence of reversible ischaemia, this response appears to be blunted in patients with evidence of reversible ischaemia. Mechanisms other than reversible myocardial ischaemia may play a role for acute exercise-induced increases in circulating cTnT levels.