Clinical and self-reported markers of reproductive function in female survivors of childhood Hodgkin lymphoma.

PURPOSE: To evaluate the impact of treatment for Hodgkin lymphoma (HL) on clinical reproductive markers and pregnancy outcomes. METHODS: This study was embedded within the DCOG LATER-VEVO study; a Dutch, multicenter, retrospective cohort study between 2004 and 2014. Serum anti-Müllerian hormone (AMH), follicle stimulating hormone (FSH), inhibin B, antral follicle count (AFC), and self-reported (first) pregnancy outcomes were evaluated in female childhood HL survivors and controls. RESULTS: 84 HL survivors and 798 controls were included, aged 29.6 and 32.7 years old at time of assessment. Median age at HL diagnosis was 13.4 years. Cyclophosphamide equivalent dose (CED-score) exceeded 6000 mg/m2 in 56 women and 14 survivors received pelvic irradiation. All clinical markers were significantly deteriorated in survivors (odds-ratio for low AMH (< p10) 10.1 [95% CI 4.9; 20.6]; low AFC (< p10) 4.6 [95% CI 2.1; 9.9]; elevated FSH (> 10 IU/l) 15.3 [95% CI 5.7; 41.1], low Inhibin B (< 20 ng/l) 3.6 [ 95% CI 1.7; 7.7], p < 0.001). Pregnancy outcomes were comparable between survivors and controls (± 80% live birth, ± 20% miscarriage). However, survivors were significantly younger at first pregnancy (27.0 years vs 29.0 years, P = 0.04). Adjusted odds-ratio for time to pregnancy > 12 months was 2.5 [95% CI 1.1; 5.6] in survivors, p = 0.031. Adverse outcomes were specifically present after treatment with procarbazine and higher CED-score. CONCLUSION: HL survivors appear to have an impaired ovarian reserve. However, chance to achieve pregnancy seems reassuring at a young age. Additional follow-up studies are needed to assess fertile life span and reproductive potential of HL survivors, in particular for current HL treatments that are hypothesized to be less gonadotoxic.

[Pharmacobezoar in a woman with a clomipramine intoxication]. / Een bezoar bij een vrouw met clomipramine-intoxicatie.

BACKGROUND: Medicines with controlled release can cause a rare phenomenon, known as pharmacobezoar, following overdose of these medications. CASE DESCRIPTION: A case of a 56-year-old women with severe clomipramine intoxication is described. X-ray of the abdomen showed a cluster of tablets in the caecum. Lab results showed severe plasma concentration of clomipramine. Patient was treated with active coal and remained stable. CONCLUSION: It is important to be aware of the presence of pharmacobezoar in intoxication with controlled release medicines. The formation of pharmacobezoar can lead to unpredictable duration of intoxication.

Pregnancy, time to pregnancy and obstetric outcomes among female childhood cancer survivors: results of the DCOG LATER-VEVO study.

PURPOSE: To evaluate pregnancy rates, time to pregnancy (TTP) and obstetric outcomes in female childhood cancer survivors (CCSs) and to identify specific diagnosis- and treatment-related factors associated with these outcomes. METHODS: The study is part of the DCOG LATER-VEVO study, a nationwide multicenter cohort study evaluating fertility among long-term Dutch female CCSs. Data were collected by questionnaire. The current study included 1095 CCSs and 812 controls, consisting of sisters of CCSs and a random sample of women from the general population. RESULTS: Among the subgroup of women who ever had the desire to become pregnant, the chance of becoming pregnant was significantly lower for CCSs than controls (OR 0.5, 95%CI 0.4-0.8). Moreover, TTP was 1.1 times longer for CCSs compared to controls (p = 0.09) and was significantly longer in survivors of CNS and renal tumours. Overall, no differences were found between CCSs and controls regarding the probability of ever having had a miscarriage, still birth, or induced abortion. However, CCSs had a significantly increased risk of delivering preterm (OR 2.2, 95%CI 1.3-3.7) and delivering via caesarean section (OR 1.8, 95%CI 1.2-2.6). Treatment with lower abdominal/pelvic radiotherapy was strongly associated with several adverse obstetric outcomes. CONCLUSION: CCSs are less likely to have ever been pregnant. Among those who do become pregnant, certain subgroups of CCSs are at increased risk of longer TTP. Moreover, as pregnant CCSs, especially those treated with lower abdominal/pelvic radiotherapy, are more likely to develop various adverse obstetric outcomes, appropriate obstetric care is highly advocated.

The distress thermometer provides a simple screening tool for selecting distressed childhood cancer survivors.

AIM: We investigated the value of the distress thermometer, a one-item screening tool, in childhood cancer survivors. METHODS: The participants were 286 childhood cancer survivors who visited an outpatient clinic at Erasmus MC University-Sophia Children's Hospital, Rotterdam, The Netherlands, for the first time from 2001 to 2008 and completed the distress thermometer and Hospital Anxiety and Depression Scale (HADS). Higher scores reflected more distress. A HADS score ≥15 was used as the cut-off point for emotional distress. We calculated the correlation between the HADS and distress thermometer, the relationship between the HADS anxiety and the HADS depression ratings, and the distress score and the sensitivity and specificity for different cut-off scores of the distress thermometer. RESULTS: A moderate correlation was found between the HADS score and the distress thermometer (r: 0.56, p < 0.01, interclass correlation 0.40, p < 0.01). In total, 39% of the variability of distress, as measured by the distress thermometer, could be explained by the HADS anxiety and HADS depression ratings. A cut-off score of at least three on the distress thermometer resulted in a sensitivity of 92% and specificity of 79%. CONCLUSION: The distress thermometer provided a rapid screening tool for identifying distressed childhood cancer survivors who needed further psychological support.

Si amorphization by focused ion beam milling: Point defect model with dynamic BCA simulation and experimental validation.

A Ga focused ion beam (FIB) is often used in transmission electron microscopy (TEM) analysis sample preparation. In case of a crystalline Si sample, an amorphous near-surface layer is formed by the FIB process. In order to optimize the FIB recipe by minimizing the amorphization, it is important to predict the amorphous layer thickness from simulation. Molecular Dynamics (MD) simulation has been used to describe the amorphization, however, it is limited by computational power for a realistic FIB process simulation. On the other hand, Binary Collision Approximation (BCA) simulation is able and has been used to simulate ion-solid interaction process at a realistic scale. In this study, a Point Defect Density approach is introduced to a dynamic BCA simulation, considering dynamic ion-solid interactions. We used this method to predict the c-Si amorphization caused by FIB milling on Si. To validate the method, dedicated TEM studies are performed. It shows that the amorphous layer thickness predicted by the numerical simulation is consistent with the experimental data. In summary, the thickness of the near-surface Si amorphization layer caused by FIB milling can be well predicted using the Point Defect Density approach within the dynamic BCA model.

Longitudinal follow-up in female Childhood Cancer Survivors: no signs of accelerated ovarian function loss.

STUDY QUESTION: Is the long-term decline of ovarian function, as reflected by a decrease in serum anti-Müllerian hormone (AMH) concentration, accelerated over time in female childhood cancer survivors (CCS) as compared to healthy women of the same age? SUMMARY ANSWER: The median decline of AMH levels in long-term female CCS is not accelerated and similar to that observed in healthy controls. WHAT IS KNOWN ALREADY: Gonadal function is compromised in female CCS treated with chemotherapy and/or radiation therapy. Ovarian function is most compromised in survivors treated with total body irradiation, abdominal or pelvic irradiation, stem cell transplantation or high doses of alkylating agents. STUDY DESIGN SIZE, DURATION: Longitudinal single-centre cohort study in 192 CCS in Rotterdam, The Netherlands, between 2001 and 2014. PARTICIPANTS/MATERIALS, SETTING, METHODS: Serum AMH levels of 192 adult female CCS were assessed, at least five years after cessation of treatment and at a follow-up visit with a median of 3.2 years (range: 2.1-6.0) later and were compared to the age-based P50 of AMH in healthy controls. MAIN RESULTS AND THE ROLE OF CHANCE: Median AMH levels were below the P50 at both visit 1 (-0.59 µg/L) and at visit 2 (-0.22 µg/L). In women with a sustained ovarian function (AMH > 1.0 µg/L), the decline in AMH is similar to that in the normal population (difference in decline per year: -0.07 µg/L (range: -2.86 to 4.92), P  = 0.75). None of the treatment modalities was correlated with a significant acceleration of decline of AMH per year. LIMITATIONS REASONS FOR CAUTION: We selected CCS that visited our late effect outpatient clinic and who had two AMH levels available. It is conceivable that women without any apparent late effects of treatment as well as women with extreme late effects, which might be the ones with the largest impact on ovarian function, could be more likely to be lost to follow-up. However, general characteristics did not differ between the included and excluded patients. WIDER IMPLICATIONS OF THE FINDINGS: While prospective longitudinal research is required to strengthen our findings, they may help physicians to counsel female CCS about their expected reproductive lifespan. STUDY FUNDING/COMPETING INTERESTS: A.L.F.v.d.K., M.M.v.d.H.-E. and S.M.F.P. are supported by FP7-PanCare LIFE. J.S.E.L. has received grants from the following companies (in alphabetical order): Ferring, Merck Serono, Merck Sharp and Dome, Organon, Serono, Shering Plough and Shering. The other authors have no conflicts of interest to declare.

Bone mineral density after childhood cancer in 346 long-term adult survivors of childhood cancer.

SUMMARY: More than 45 % of long-term childhood cancer survivors (CCS) were diagnosed with osteopenia. Our data suggest that greater awareness for osteopenia is warranted in long-term CCS, especially in survivors who are older than 30 years, male, and underweight and were treated with cranial-spinal radiotherapy and/or steroids. INTRODUCTION: Osteopenia is a potential complication of childhood cancer treatment, but the magnitude of this problem in survivors is unknown. We examined (determinants of) bone mineral density (BMD) status in long-term survivors of adult childhood cancer. METHODS: This retrospective single-centre cohort study included 346 subjects with the most common types of childhood cancer. Subjects had a median age at diagnosis of 7.0 years (range 0.1-16.8 years), a median age at follow-up of 24.5 years (range 18.0-47.6 years) and a median follow-up time of 16.7 years (range 5.6-39.9 years). Total body BMD (BMDTB) and BMD of the lumbar spine (BMDLS) were measured by dual X-ray absorptiometry. Osteopenia was defined as BMD standardized deviation score (SDS) below -1. RESULTS: Survivors had a lower BMDTB and BMDLS (mean SDS -0.55; p<0.001 and -0.30; p<0.001, respectively) as compared to healthy peers. Osteopenia (BMDTB and/or BMDLS) was present in 45% of the survivors. Multivariate logistic regression analyses identified age at diagnosis<12 years, age>30 years at follow-up, male gender, underweight at follow-up and treatment with cranial-spinal radiotherapy or prednisone as independent prognostic factors for osteopenia. CONCLUSIONS: This large cohort of childhood cancer survivors identified osteopenia in 45% of CCS. This indicates that greater awareness is warranted, especially in survivors who are older than 30 years, male, have underweight and were treated with cranial-spinal radiotherapy and/or steroids.

Gold complexes for focused-electron-beam-induced deposition.

Four gold complexes were tested as a precursor for focused-electron-beam-induced deposition: [ClAu(III)Me2]2, ClAu(I)(SMe2), ClAu(I)(PMe3), and MeAu(I)(PMe3). Complexes [ClAu(III)Me2]2 and MeAu(I)(PMe3) are volatile, have sufficient vapor pressure at room temperature for deposition experiments, and were found to yield deposits that contain gold (29-41 and 19-25 atom %, respectively). Electrons easily remove the Cl ligand from [ClAu(III)Me2]2, and predominantly both methyl ligands are incorporated into the deposit. Electrons remove at least one methyl group from MeAu(I)(PMe3). Complexes ClAu(I)(SMe2) and ClAu(I)(PMe3) are not suitable as a precursor. They dissociate in vacuum, and the only volatile components are Cl, SMe2, and PMe3, respectively.

Fertility studies in female childhood cancer survivors: selecting appropriate comparison groups.

Little information is available on the use of appropriate comparison groups for studies investigating late effects of childhood cancer. Two comparison groups in a nationwide study on reproductive function and ovarian reserve in female childhood cancer survivors were recruited (The Dutch Childhood Oncology Group Long-Term Effects After Childhood Cancer Cohort Study). Experiences of this process are reported. Two types of comparison groups were used: sisters of participating survivors and controls from the general population. A total of 352 out of 580 (61%) of the participating survivors who had a sister gave permission to invite them for the study. The participation rate of sisters was much higher than control participants from the general population (74% versus 21%, respectively), whereas considerably more effort was involved in recruiting controls from the general population. Participants in this group were significantly older and more highly educated than sister controls (P < 0.001 for both groups). No significant differences were observed between both types of comparison groups in several fertility-related characteristics, suggesting minimal bias owing to selective participation. Researchers setting up a study to investigate late effects among survivors of childhood cancer should carefully consider the advantages and disadvantages of using various types of comparison groups.

The dialysis procedure as a trigger for atrial fibrillation: new insights in the development of atrial fibrillation in dialysis patients.

AIMS: Atrial fibrillation (AF) is common in dialysis patients and is associated with increased morbidity and mortality. The pathophysiology may be related to common risk factors for both AF and renal disease or to dialysis-specific factors. The purpose of this study was to determine whether and how AF onset relates to the dialysis procedure itself. METHODS: All dialysis patients enrolled in the implantable cardioverter defibrillator-2 (ICD-2) trial until January 2012, who were implanted with an ICD, were included in this study. Using the ICD remote monitoring function, the exact time of onset of all AF episodes was registered. Subsequently, this was linked to the timing of dialysis procedures. RESULTS: For the current study, a total of 40 patients were included, follow-up was 28 ± 16 months, 80% male, 70 ± 8 years old. A total of 428 episodes of AF were monitored in 14 patients. AF onset was more frequent on the days of haemodialysis (HD) (p<0.001) and specifically increased during the dialysis procedure itself (p=0.04). Patients with AF had a larger left atrium (p<0.001) and a higher systolic blood pressure before and after HD (p<0.001). CONCLUSION: This study provides insight in the exact timing of AF onset in relation to the dialysis procedure itself. In HD patients, AF occurred significantly more often on a dialysis day and especially during HD. These findings might help to elucidate some aspects of the pathophysiology of AF in dialysis patients and could facilitate early detection of AF in these high-risk patients.

Selective functionalization of patterned glass surfaces.

Tailored writing and specific positioning of molecules on nanostructures is a key step for creating functional materials and nano-optical devices, or interfaces for synthetic machines in various applications. We present a novel approach for the selective functionalization of patterned glass surfaces with functional probes of any nature. The presented strategy is optimized for imaging fluorophore labeled nanostructures for (single-molecule) fluorescence microscopy. The first step in the protocol is coating a glass surface, here a microscope cover slide, with a 60 nm thick diamond-like carbon film. Subsequently, the pattern is defined by either writing silicon oxide on the coating with a focused electron beam, or by etching the coating with a focused ion beam to expose the glass surface. Finally, the pattern is silanized and functionalized. We demonstrate the selective binding of organic fluorophores and imaging with high contrast, especially in total-internal-reflection mode. The presented approach is flexible and combines bottom-up assembly with high-resolution lithography on glass cover slides to precisely position and image functional molecules of any type.

Decreased serum anti-Müllerian hormone levels in girls with newly diagnosed cancer.

STUDY QUESTION: Are anti-Müllerian hormone (AMH) levels reduced in girls with newly diagnosed cancer before the start of treatment? SUMMARY ANSWER: AMH levels are already compromised in girls at the time of cancer diagnosis compared with healthy girls. WHAT IS KNOWN ALREADY: In women diagnosed with cancer, evidence of reduced ovarian function has been described even before treatment has started. In girls with newly diagnosed cancer, no data are available. STUDY DESIGN, SIZE, DURATION: We performed an age-matched case-control study in girls with newly diagnosed cancer. PARTICIPANTS/MATERIALS, SETTING, METHODS: We determined serum AMH levels in a cohort of 208 girls with newly diagnosed cancer, up to 18 years of age at diagnosis, and compared them with AMH levels of 250 age-matched healthy girls. The diagnoses included were acute lymphoblastic leukaemia, acute myeloid leukaemia, Hodgkin lymphoma, non-Hodgkin lymphoma, nephroblastoma, sarcoma and neuroblastoma. MAIN RESULTS AND THE ROLE OF CHANCE: The median age was 6.6 years (range 0.0-17.4), comparable with that in the control group (median 6.3 years, range 0.3-18.0). Girls with childhood cancer presented with significantly lower serum AMH levels compared with healthy age-matched controls (standard deviation scores (SDS) -0.8, P < 0.001). Median AMH level in patients was 1.4 µg/l (0.1-10.2) versus 3.0 µg/l (0.1-18.3) in controls. Specifically, 84% of all patients had AMH levels below the 50th percentile of normal AMH levels, and 19% below the 10th percentile. Surrogate markers of general health status (temperature, C-reactive protein and haemoglobin levels at diagnosis) were significantly correlated with AMH SDS. LIMITATIONS, REASONS FOR CAUTION: Some caution is warranted because AMH levels increase with age in healthy children but the cases and controls were age-matched in our study. Although our sample size was large, additional studies are still required in an independent cohort. WIDER IMPLICATIONS OF THE FINDINGS: Our study shows that AMH levels are reduced in girls with newly diagnosed cancer even before the cancer treatment has started. AMH levels correlate with impairment of general health status in girls. Therefore, besides (pre) antral follicle number, other factors may influence serum AMH levels. Longitudinal studies during and after childhood cancer are currently being performed in order to evaluate possible ovarian recovery after discontinuation of treatment. STUDY FUNDING/COMPETING INTEREST(S): W.v.D. is supported by the Paediatric Oncology Centre Society for Research (KOCR), Rotterdam, The Netherlands. J.S.E.L. has received grants from the following companies (in alphabetical order): Ferring, Genovum, Merck Serono, Merck Sharp and Dome, Organon, Serono, Shering Plough and Shering. All other authors have nothing to disclose.

Focused electron beam induced processing and the effect of substrate thickness revisited.

The current understanding in the study of focused electron beam induced processing (FEBIP) is that the growth of a deposit is mainly the result of secondary electrons (SEs). This suggests that the growth rate for FEBIP is affected by the SE emission from the support. Our experiments, with membranes thinner than the SE escape depth, confirm this hypothesis. We used membranes of 1.4 and 4.3 nm amorphous carbon as supports. At the very early stage, the growth is support-dominated and the growth rate on a 4.3 nm thick membrane is three times higher than on a 1.4 nm thick membrane. This is consistent with Monte Carlo simulations for SE emission. The results suggest that SEs are dominant in the dissociation of W(CO)6 on thin membranes. The best agreement between simulations and experiment is obtained for SEs with energies between 3 and 6 eV.With this work we revisit earlier experiments, working at a precursor pressure 20 times lower than previously. Then, despite using membranes thinner than the SE escape depth, we did not see an effect on the experimental growth rate. We explain our current results by the fact that very early in the process, the growth becomes dominated by the growing deposit itself.

Decreased ovarian function is associated with obesity in very long-term female survivors of childhood cancer.

OBJECTIVE: Obesity and gonadal dysfunction are known major side effects of treatment in adult childhood cancer survivors (CCS). In the general population, obesity has a negative influence on female fertility. We aimed to evaluate whether obesity and serum insulin are associated with decreased ovarian reserve markers in CCS. DESIGN: Retrospective single-center cohort study. METHODS: Data of 191 female survivors of childhood cancer were analyzed. Median follow-up time was 18.8 (2.348.8) years. Outcome measures were serum anti-Müllerian hormone (AMH) and total follicle count (FC). Potential risk factors were: BMI; body composition measures, determined by dual-energy X-ray absorptiometry (total fat percentage, lean body mass, and visceral fat percentage); and fasting insulin. RESULTS: Lower serum AMH was found in obese subjects (ß (%) -49, P=0.007) and in subjects with fasting insulin in the highest tertile (ß (%) -43, P=0.039). Total fat percentage tends to be associated with serum AMH (ß (%) -2.1, P=0.06). Survivors in the highest tertile of insulin had significantly lower FC than survivors in the lowest tertile (ß -6.3, P=0.013). BMI and other measures of body composition were not associated with FC. Correlation between serum AMH and antral follicle count (AFC) was ρ=0.32 (P=0.08). CONCLUSIONS: Obesity and insulin resistance are associated with gonadal damage, as reflected by decreased AMH and reduced FC in adult survivors of childhood cancer. In contrast to its highly predictive value for AFC in the healthy female population, serum AMH does not seem to correlate as well with AFC in CCS.

Genetic variation may modify ovarian reserve in female childhood cancer survivors.

STUDY QUESTION: Are genetic polymorphisms, previously identified as being associated with age at menopause in the healthy population, associated with ovarian reserve and predicted age at menopause in adult long-term survivors of childhood cancer? SUMMARY ANSWER: The CT genotype of rs1172822 in the BRSK1 gene is associated with lower serum anti-Müllerian hormone (AMH) levels and a younger predicted age at menopause in adult survivors of childhood cancer. WHAT IS KNOWN ALREADY: Gonadotoxicity is a well-known late side effect of chemotherapy and radiotherapy in adult survivors of childhood cancer. In the healthy population, several genetic polymorphisms are associated with age at natural menopause. Currently, data on the impact of previously identified variants in gene loci associated with ovarian reserve in adult long-term survivors of childhood cancer are lacking. STUDY DESIGN, SIZE, DURATION: We performed a pilot study in a single-centre cohort of adult female Caucasian childhood cancer survivors (n = 176). PARTICIPANTS/MATERIALS, SETTING, METHODS: We determined serum AMH levels (a marker of ovarian reserve) in adult survivors of childhood cancer (n = 176) and studied single nucleotide polymorphisms (SNPs) previously reported to be associated with age at natural menopause: BRSK1 (rs1172822), ARHGEF7 (rs7333181), MCM8 (rs236114), PCSK1 (rs271924), IGF2R (rs9457827) and TNF (rs909253). Association analysis was performed using the additive genetic model. Linear regression was conducted to assess the effect of significant polymorphisms in two previously published menopause prediction models. MAIN RESULTS AND THE ROLE OF CHANCE: The CT genotype of rs1172822 in the BRSK1 (BR serine/threonine kinase 1) gene was negatively associated with serum AMH levels in our cohort (odds ratio: 3.15, 95% confidence interval: 1.35-7.32, P = 0.008) and significantly associated with the predicted age at menopause (P = 0.04). The other five SNPs were not associated with serum AMH levels. LIMITATIONS, REASONS FOR CAUTION: This is a pilot study showing preliminary data which must be confirmed. To confirm our findings and enlarge the project, a nationwide genome-wide association (GWA) project on the ovarian reserve in female survivors of childhood cancer should be performed, including a replication cohort. WIDER IMPLICATIONS OF THE FINDINGS: Our findings support the hypothesis that previously identified genetic polymorphisms associated with age at menopause in healthy women may have an effect on the onset of menopause in female survivors of childhood cancer. Our study highlights a new aspect of the influences on the ovarian reserve after childhood cancer, which should be investigated further in a nationwide GWA study. Eventually, this information can help us to improve counselling on fertility preservation prior to cancer treatment based on genetic factors in individual patients. STUDY FUNDING AND CONFLICT OF INTEREST: W.D. is supported by the Paediatric Oncology Centre Society for Research (KOCR), Rotterdam, The Netherlands. J.S.E.L. has received fees and grant support from the following companies (in alphabetic order): Ferring, Genovum, Merck-Serono, Organon, Schering Plough and Serono. All other authors have nothing to disclose.

Long-term endocrine side effects of childhood Hodgkin's lymphoma treatment: a review.

BACKGROUND Since childhood cancer survival has increased, long-term effects of treatment have gained interest. Childhood Hodgkin's lymphoma has been treated successfully for decades now. We provide an overview of the literature on long-term endocrine side effects, such as gonadal dysfunction and growth retardation, as a result of childhood Hodgkin's lymphoma treatment. METHODS A comprehensive search of the Pubmed database was performed. RESULTS We identified 16 studies (10 studies: 298 male survivors and 6 studies: 230 female survivors) about gonadal dysfunction. In survivors treated with alkylating agents or pelvic radiotherapy, severe gonadal damage is described. Recovery was rarely described. Seven studies (481 survivors) about bone mineral density (BMD) and growth were identified. The effects on BMD appear to be small. Data on growth are scarce, but show that radiotherapy in a dose of >30 Gy including the spine, especially in pre-pubertal children, results in reduced height. We included 10 studies (4012 survivors) about thyroid complications. Hypothyroidism is the most common thyroid disorder after radiotherapy. There is also a significant incidence in thyroid carcinoma after low-dose radiation. In survivors treated with chemotherapy only, hypothyroidism and thyroid cancer have not been reported. CONCLUSIONS The severity of endocrine toxicity after childhood Hodgkin's lymphoma depends on the type of treatment. Gonadal dysfunction seems to be the most severe endocrine long-term effect, especially after treatment with alkylating agents or pelvic radiotherapy. The knowledge obtained in specific follow-up programmes for paediatric cancer survivors will help to find the optimal balance between curability and long-term side effects.

Nanometer-scale lithography on microscopically clean graphene.

Focused-electron-beam-induced deposition, or FEBID, enables the fabrication of patterns with sub-10 nm resolution. The initial stages of metal deposition by FEBID are still not fundamentally well understood. For these investigations, graphene, a one-atom-thick sheet of carbon atoms in a hexagonal lattice, is ideal as the substrate for FEBID writing. In this paper, we have used exfoliated few-layer graphene as a support to study the early growth phase of focused-electron-beam-induced deposition and to write patterns with dimensions between 0.6 and 5 nm. The results obtained here are compared to the deposition behavior on amorphous materials. Prior to the deposition experiment, the few-layer graphene was cleaned. Typically, it is observed in electron microscope images that areas of microscopically clean graphene are surrounded by areas with amorphous material. We present a method to remove the amorphous material in order to obtain large areas of microscopically clean graphene flakes. After cleaning, W(CO)(6) was used as the precursor to study the early growth phase of FEBID deposits. It was observed that preferential adsorption of the precursor molecules on step edges and adsorbates plays a key role in the deposition on cleaned few-layer graphene.

Ultrahigh resolution focused electron beam induced processing: the effect of substrate thickness.

It is often suggested that the growth in focused electron beam induced processing (FEBIP) is caused not only by primary electrons, but also (and even predominantly) by secondary electrons (SEs). If that is true, the growth rate for FEBIP can be changed by modifying the SE yield. Results from our Monte Carlo simulations show that the SE yield changes strongly with substrate thickness for thicknesses below the SE escape depth. However, our experimental results show that the growth rate is independent of the substrate thickness. Deposits with an average size of about 3 nm were written on 1 and 9 nm thick carbon substrates. The apparent contradiction between simulation and experiment is explained by simulating the SE emission from a carbon substrate with platinum deposits on the surface. It appears that the SE emission is dominated by the deposits rather than the carbon substrate, even for deposits as small as 0.32 nm(3).