Confounding of the association between radiation exposure from CT scans and risk of leukemia and brain tumors by cancer susceptibility syndromes

Recent studies linking radiation exposure from pediatric computed tomography (CT) to increased risks of leukemia and brain tumors lacked data to control for cancer susceptibility syndromes (CSS). These syndromes might be confounders because they are associated with an increased cancer risk and may increase the likelihood of pediatric CT scans. We identify CSS predisposing to leukemia and brain tumors through a systematic literature search and summarize prevalence and risk. Since empirical evidence is lacking in published literature on patterns of CT use for most types of CSS, we estimate confounding bias of relative risks (RR) for categories of radiation exposure based on expert opinion about patterns of CT scans among CSS patients. We estimate that radiation-related RRs for leukemia are not meaningfully confounded by Down syndrome, Noonan syndrome and other CSS. Moreover, tuberous sclerosis complex, von Hippel-Lindau disease, neurofibromatosis type 1 and other CSS do not meaningfully confound RRs for brain tumors. Empirical data on the use of CT scans among CSS patients is urgently needed. Our assessment indicates that associations with radiation exposure from pediatric CT scans and leukemia or brain tumors reported in previous studies are unlikely to be substantially confounded by unmeasured CSS.

Prevalence and risk factors of HSV-1 and HSV-2 antibodies in European HIV infected women

OBJECTIVES

To investigate the prevalence and risk factors of HSV-1 and HSV-2 antibodies in HIV infected women and the association between recurrent genital ulcerations and HIV disease progression in HSV-2 positive women.

METHODS

The presence of HSV antibodies was tested in 276 of the 487 women participating in a European cohort study of HIV infected women. Prevalence rate ratios described the association between HSV infection and its risk factors, using log binomial regression. Generalised estimating equations (GEE) analysis was performed to determine the impact of markers of HIV disease progression on recurrent genital ulcerations.

RESULTS

The prevalence of HSV-1 and HSV-2 antibodies was 76% (95% confidence interval (95% CI): 71-81) and 42% (95% CI: 36-50); 30% (95% CI: 24-35) of the women had antibodies against both HSV-1 and HSV-2. The prevalence of HSV-1 was 86% (95% CI: 80-92) in southern Europe compared with 69% (95% CI: 57-79) and 67% (95% CI: 55-77) in central and northern Europe (p=0.002). This geographical variation remained after adjustment for other risk factors. An increasing number of years of sexual activity (p=0.0002) and a history of prostitution (p=0.0001) were independently associated with HSV-2 prevalence. In HSV-2 positive women, symptomatic cases of HSV infection were minimal, but increased with decreasing CD4 count.

CONCLUSION

In HIV infected women, the prevalence of HSV antibodies is high and symptomatic cases of HSV infection are minimal, but increase with decreasing CD4 count. HSV-2 but not HSV-1 was related to sexual behaviour (that is, a history of prostitution and the number of sexually active years) in this group of HIV infected women.

Application of the steep ramp test for aerobic fitness testing in children with cancer

BACKGROUND

Children with and after cancer are found to have a decreased physical fitness, frequently resulting in decreased physical functioning. The gold standard test for assessing aerobic fitness, a component of physical fitness, is the respiratory gas analyses-based cardiopulmonary exercise test (CPET). However, equipment for gas analysis is often unavailable in local physical therapy centres and non-university hospitals. The steep ramp test (SRT), is a cycle ergometer test with a fast increase in workload, a short duration, and does not require respiratory gas analysis equipment.

AIM

The aim of this study was to compare the results of the CPET and the SRT, in children with cancer, and to assess whether the SRT can be used for aerobic fitness assessment in clinical practice in this population.

DESIGN

This study is a cross-sectional assessment using baseline data of a randomized controlled trial.

SETTING

The study was performed in a hospital setting.

POPULATION

Sixty-one children (mean age 12.9 years; 33 boys) with cancer were included in the analysis; 16 children were on non-intensive chemotherapy treatment, 45 were in the first year thereafter.

METHODS

Participants performed both the SRT and the CPET on a cycle ergometer with respiratory gas analysis. Data of the two tests were compared and regression analyses were performed.

RESULTS

CPET test results revealed a higher impact on the cardiovascular system, as shown by higher peak ventilation (47.8 versus 52.0 Litres per min) and peak heart rates (173 versus 191 beats per min), compared to the SRT. In addition, the test time was significantly longer (90 s versus 390 s). Yet, the primary outcome of the SRT (peak work rate) was able to reliably estimate the peak oxygen uptake of the CPET.

CONCLUSION

The peak oxygen uptake was comparable between the SRT and the CPET, although the peak work rate was significantly higher during the SRT. This study showed that the SRT is a valid instrument to assess aerobic fitness in children with cancer.

CLINICAL REHABILITATION IMPACT

The SRT is less time consuming and can be performed without gas analysis in a non-clinical setting, making it less demanding for children.