Irregular screening participation increases advanced stage breast cancer at diagnosis: A population-based study

OBJECTIVE

To evaluate the effect of irregular screening behaviour on the risk of advanced stage breast cancer at diagnosis in Flanders.

METHODS

All women aged 50-69 who were invited to the organized breast cancer screening and diagnosed with breast cancer before age 72 from 2001 to 2018 were included. All prevalent screen and interval cancers within 2 years of a prevalent screen were excluded. Screening behaviour was categorized based on the number of invitations and performed screenings. Four groups were defined: regular, irregular, only-once, and never attenders. Advanced stage cancer was defined as a stage III + breast cancer. The association between screening regularity and breast cancer stage at diagnosis was evaluated in multivariable logistic regression models, taking age of diagnosis and socio-economic status into account.

RESULTS

In total 13.5% of the 38,005 breast cancer cases were diagnosed at the advanced stage. Compared to the regular attenders, the risk of advanced stage breast cancer for the irregular attenders, women who participated only-once, and never attenders was significantly higher with OR_adjusted:1.17 (95%CI:1.06-1.29) and OR_adjusted:2.18 (95%CI:1.94-2.45), and OR_adjusted:5.95 (95%CI:5.33-6.65), respectively.

CONCLUSIONS

In our study, never attenders were nearly six times more likely to be diagnosed with advanced stage breast cancer than regular attenders, which was much higher than the estimates published thus far. An explanation for this is that the ever screened women is a heterogeneous group regarding the participation profiles which also includes irregular and only-once attenders. The benefit of regular screening should be informed to all women invited for screening.

Adiponectin levels do not predict clinical onset of type 1 diabetes in antibody-positive relatives

AIMS/HYPOTHESIS

Insulin resistance has been proposed as a risk factor for type 1 diabetes. We investigated whether adiponectin, an insulin sensitiser, can serve as an additional predictive marker for type 1 diabetes in first-degree relatives of known patients.

METHODS

Adiponectin was followed in 211 persistently islet antibody-positive (Ab+) first-degree relatives of type 1 diabetic patients and in 211 age- and sex-matched persistently antibody-negative relatives, and correlated with antibody status, random proinsulin:C-peptide ratio and HLA-DQ genotype. During follow-up, 37 Ab+ relatives developed type 1 diabetes.

RESULTS

In the group of 422 relatives, baseline adiponectin correlated inversely with age and BMI and was lower in male than in female participants, especially after 15 years of age (p < 0.001). There was no correlation with antibody status or later development of diabetes. In 24 Ab+ relatives sampled fasted, adiponectin levels correlated significantly with homeostasis model assessment of insulin sensitivity (p = 0.006). In Ab+ relatives (n = 211), adiponectin levels could not predict type 1 diabetes nor complement risk assessment based on islet antibodies, HLA-DQ genotype and pancreatic hormones in Cox regression analysis.

CONCLUSIONS/INTERPRETATION

Adiponectin levels do not contribute to the prediction of type 1 diabetes in Ab+ relatives.

Identification of prediabetes in first-degree relatives at intermediate risk of type I diabetes

Prevention trials of type I diabetes are limited by recruitment of individuals at high risk of the disease. We investigated whether demographic and biological characteristics can identify rapid progressors among first-degree relatives of known patients at intermediate (< 10%) 5-year risk. Diabetes-associated antibodies, random proinsulin : C-peptide (PI/C) ratio and HLA DQ genotype were determined (repeatedly) in 258 islet antibody-positive IA-2Antibody-negative (Abpos/IA-2Aneg) normoglycaemic first-degree relatives. During follow-up (median 81 months), 14 of 258 Abpos/IA-2Aneg relatives developed type I diabetes; 13 (93%) of them had persistent antibodies conferring a 12% [95% confidence interval (CI): 5-19%] 5-year risk of diabetes. In Abpos/IA-2Aneg relatives with persistent antibodies (n = 126), the presence of >/= 1 HLA DQ susceptibility haplotype in the absence of a protective haplotype (P = 0.033) and appearance on follow-up of a high PI/C ratio (P = 0.007) or IA-2A-positivity (P = 0.009) were identified as independent predictors of diabetes. In persistently antibody-positive relatives with HLA DQ risk a recurrently high PI/C ratio or development of IA-2A identified a subgroup (n = 32) comprising 10 of 13 (77%) prediabetic relatives and conferred a 35% (95% CI: 18-53%) 5-year risk. Under age 15 years, 5-year progression (95% CI) was 57% (30-84%) and sensitivity 62%. In the absence of IA-2A, the combination of antibody persistence, HLA DQ risk and elevated PI/C ratio or later development of IA-2A and young age defines a subgroup of relatives with a high risk of type I diabetes (>/= 35% in 5 years). Together with initially IA-2A-positive relatives these individuals qualify for standardized beta cell function tests in view of prevention trials.

Sex- and season-dependent differences in C-peptide levels at diagnosis of immune-mediated type 1 diabetes

AIMS/HYPOTHESIS

The incidence of type 1 diabetes varies according to age, sex and season of diagnosis. We investigated whether these and other clinical, biological and anthropometric parameters were correlated with residual beta cell function in newly diagnosed patients, since it is possible that the nature of external and/or genetic disease accelerators may be (partly) reflected in the inaugural disease presentation.

MATERIALS AND METHODS

The correlates of random C-peptide levels sampled shortly after diagnosis (median [interquartile range]: 3 [0-14] days) were studied by multivariate analysis in 1,883 islet-antibody-positive diabetic patients aged <40 years who were diagnosed between 1989 and 2000.

RESULTS

Higher C-peptide levels (above percentile 50 of patients) were associated with older age at diagnosis, female sex, diagnosis in the high-incidence season (October to March), less-decreased BMI (expressed as a standard deviation score), lower insulin requirements after stabilisation, lower prevalence of ketonuria and a less-increased glycaemia at diagnosis (all p < 0.001). C-peptide levels were not correlated with calendar year at diagnosis, duration of symptoms prior to diagnosis, HLA-DQ2/DQ8 genotype or islet antibody status.

CONCLUSIONS/INTERPRETATION

Sex- and season-dependent differences in residual functional beta cell mass and/or insulin resistance have been identified at diagnosis of type 1 diabetes. They may reflect differences in disease-precipitating external or lifestyle factors and should be further investigated longitudinally in prediabetes to further identify putative aetiological factors, which may provide targets for prevention.

Proinsulin levels and the proinsulin:c-peptide ratio complement autoantibody measurement for predicting type 1 diabetes

AIMS/HYPOTHESIS

We investigated whether random proinsulin levels and proinsulin:C-peptide ratio (PI:C) complement immune and genetic markers for identifying relatives at high risk of type 1 diabetes.

MATERIALS AND METHODS

During an initial sampling, random glycaemia, proinsulin, PI:C and HLA DQ genotype were determined in 561 non-diabetic first-degree relatives who had been positive for islet autoantibodies on one or more occasions and in 561 age- and sex-matched persistently antibody-negative relatives.

RESULTS

During follow-up (median 62 months), 46 relatives with antibodies at entry developed type 1 diabetes. At baseline, antibody-positive relatives (n=338) had higher PI:C values (p<0.001) than antibody-negative subjects with (n=223) or subjects without (n=561) later seroconversion. Proinsulin and PI:C were graded according to risk of diabetes as expressed by positivity for (multiple) antibodies or IA-2 antibodies, especially in persons carrying the high-risk HLA DQ2/DQ8 genotype and in prediabetic relatives. In the presence of multiple or IA-2 antibodies, a PI:C ratio exceeding percentile 66 of all antibody-negative relatives at entry (n=784) conferred a 5-year diabetes risk of 50% and 68%, respectively (p<0.001 vs 13% for same antibody status with PI:C<percentile 66). Cox regression analysis confirmed random PI:C as an independent predictor of the risk of diabetes (p< or =0.001).

CONCLUSIONS/INTERPRETATION

Random proinsulin and PI:C represent dynamic markers of the state of beta cell function that complement immune markers in identifying relatives who are at homogeneously high risk of contracting type 1 diabetes and are therefore eligible for secondary prevention trials.

[Early diagnosis and prevention of type 1 diabetes: role of the Belgian Diabetes Registry]

The pathological process of type 1 diabetes starts many years prior to clinical diagnosis and is often accompanied by the appearance of circulating autoantibodies directed against islet cell antigens. Once diagnosed, insulin substitution therapy cannot totally prevent the development of chronic complications of hyperglycaemia. Efficient intervention aims at preventing the development of chronic complications. All antibody-positive subjects do not necessarily develop type 1 diabetes and, in case of progression, the destruction kinetics of beta cells may vary from one individual to another. Therefore, it is important to characterise and follow large representative groups of patients and subjects at risk (e.g. first degree relatives of patients with type 1 diabetes) to define selection criteria for subjects with an homogeneous risk of diabetes (and thus of complications) and consider a prevention strategy. The Belgian Diabetes Registry (BDR) has collected epidemiological, clinical and biological data from more than 4000 patients and more than 7000 first degree relatives. The detection of immune, genetic and hormonal markers allows to identify subjects at risk of rapid destruction of residual beta cells in view of their participation in prevention trials.

Combined positivity for HLA DQ2/DQ8 and IA-2 antibodies defines population at high risk of developing type 1 diabetes

AIMS/HYPOTHESIS

Prevention trials in first-degree relatives of type 1 diabetic patients are hampered by large interindividual differences in progression rate to diabetes. We investigated whether specific combinations of immune and genetic markers can identify subgroups with more homogeneous progression to clinical onset.

METHODS

Antibodies against islet cell cytoplasm (ICA), insulin (IAA), glutamate decarboxylase (GADA) and IA-2 protein (IA-2A) were measured in 790 non-diabetic control subjects and 4,589 first-degree relatives under age 40.

RESULTS

On first sampling, 11.1% of the siblings presented at least one antibody type (p<0.001 vs other relatives). During follow-up (median 52 months) 43 subjects developed type 1 diabetes (31 siblings, ten offspring of a diabetic father, two offspring of a diabetic mother). Using Kaplan-Meier survival analysis and Cox regression, IA-2A conferred the highest 5-year diabetes risk (>50%) irrespective of the number of antibodies present. In initially IA-2A-positive relatives (n=58) progression to hyperglycaemia depended more on HLA DQ status than on type of kinship (84% progression in the presence of DQ2/DQ8 vs 32% in its absence; p<0.003). In IA-2A-negative relatives (n=4,531) 5-year progression to diabetes increased with the number of other antibodies (ICA, GADA and/or IAA) (p<0.001) but overall did not exceed 10% even for two or more antibodies. Among relatives initially positive for one or more antibody type other than IA-2A (n=315), there was significantly more progression to diabetes (overall still <10%) in carriers of DQ2 (p<0.001 vs no DQ2), regardless of DQ8 status.

CONCLUSIONS/INTERPRETATION

These observations suggest that the HLA-DQ-inferred risk of diabetes can proceed through two distinct pathways distinguished by IA-2A status. Combined positivity for DQ2/DQ8 and IA-2A defines a more homogeneous high-risk population for prevention trials than those used so far.

IA-2 autoantibodies predict impending type I diabetes in siblings of patients

AIMS/HYPOTHESIS

Multiple islet autoantibody positivity is currently believed to best predict progression to Type I (insulin-dependent) diabetes mellitus. We compared its predictive value with that of positivity for a particular type of islet autoantibody, directed against the IA-2 antigen.

METHODS

Autoantibodies against islet cell cytoplasm (ICA), insulin (IAA), GAD (GADA) and IA-2 (IA-2A) were measured at initial sampling in 1724 non-diabetic siblings (median age [range]:16 [0-39] years) of Type I diabetic patients with a median follow-up of 50 months.

RESULTS

On initial sampling 11% of siblings were positive for one antibody type or more and 2.1% for three of more types. During follow-up, 27 antibody-positive siblings developed diabetes. Using survival analysis, the risk for clinical onset within 5 years was 34% in subjects positive for three or more types compared with 13% in those with one type or more. Progression to diabetes amounted to 12% within 5 years among siblings positive for IAA, 20% for ICA, 19% for GADA but 59% for IA-2A (p<0.001 vs absence of the respective antibody). IA-2A were detected in 1.7% of all siblings and in 56% of the prediabetic subjects on first sampling. Initial positivity for two or three antibody markers was associated with a higher progression rate in IA-2A positive as compared to IA-2A negative siblings (p=0.001). In absence of IA-2A initial positivity for another antibody (IAA, ICA or GADA) conferred a low (<10% within 5 years) risk of diabetes compared to subjects lacking this antibody.

CONCLUSIONS/INTERPRETATION

In siblings of Type I diabetic patients, IA-2A positivity is a more direct predictor of impending clinical onset than multiple antibody positivity per se. Assessment of IA-2A status allows us to select subjects with homogeneously high risk of diabetes for participation in prevention trials.