Hein Putter

Persistent epigenetic differences associated with prenatal exposure to famine in humans

Extensive epidemiologic studies have suggested that adult disease risk is associated with adverse environmental conditions early in development. Although the mechanisms behind these relationships are unclear, an involvement of epigenetic dysregulation has been hypothesized. Here we show that individuals who were prenatally exposed to famine during the Dutch Hunger Winter in 1944–45 had, 6 decades later, less DNA methylation of the imprinted IGF2 gene compared with their unexposed, same-sex siblings. The association was specific for periconceptional exposure, reinforcing that very early mammalian development is a crucial period for establishing and maintaining epigenetic marks. These data are the first to contribute empirical support for the hypothesis that early-life environmental conditions can cause epigenetic changes in humans that persist throughout life.

Surgical treatment of gastric cancer: 15-year follow-up results of the randomised nationwide Dutch D1D2 trial

BACKGROUND Historical data and recent studies show that standardised extended (D2) lymphadenectomy leads to better results than standardised limited (D1) lymphadenectomy. Based on these findings, the Dutch D1D2 trial, a nationwide prospectively randomised clinical trial, was undertaken to compare D2 with D1 lymphadenectomy in patients with resectable primary adenocarcinoma of the stomach. The aim of the study was to assess the effect of D2 compared with D1 surgery on disease recurrence and survival in patients treated with curative intent. METHODS Between August, 1989, and July, 1993, patients were entered and randomised at 80 participating hospitals by means of a telephone call to the central data centre of the trial. The sequence of randomisation was in blocks of six with stratification for the participating centre. Eligibility criteria were a histologically proven adenocarcinoma of the stomach without evidence of distance metastasis, age younger than 85 years, and adequate physical condition for D1 or D2 lymphadenectomy. Patients were excluded if they had previous or coexisting cancer or had undergone gastrectomy for benign tumours. Strict quality control measures for pathological assessment were implemented and monitored. Analyses were by intention to treat. This study is registered with the NCI trial register, as DUT-KWF-CKVO-8905, EU-90003. FINDINGS A total of 1078 patients were entered in the study, of whom 996 were eligible. 711 patients underwent the randomly assigned treatment with curative intent (380 in the D1 group and 331 in the D2 group) and 285 had palliative treatment. Data were collected prospectively and all patients were followed up for a median time of 15.2 years (range 6.9-17.9 years). Analyses were done for the 711 patients treated with curative intent and were according to the allocated treatment group. Of the 711 patients, 174 (25%) were alive, all but one without recurrence. Overall 15-year survival was 21% (82 patients) for the D1 group and 29% (92 patients) for the D2 group (p=0.34). Gastric-cancer-related death rate was significantly higher in the D1 group (48%, 182 patients) compared with the D2 group (37%, 123 patients), whereas death due to other diseases was similar in both groups. Local recurrence was 22% (82 patients) in the D1 group versus 12% (40 patients) in D2, and regional recurrence was 19% (73 patients) in D1 versus 13% (43 patients) in D2. Patients who had the D2 procedure had a significantly higher operative mortality rate than those who had D1 (n=32 [10%] vs n=15 [4%]; 95% CI for the difference 2-9; p=0.004), higher complication rate (n=142 [43%] vs n=94 [25%]; 11-25; p<0.0001), and higher reoperation rate (n=59 [18%] vs n=30 [8%]; 5-15; p=0.00016). INTERPRETATION After a median follow-up of 15 years, D2 lymphadenectomy is associated with lower locoregional recurrence and gastric-cancer-related death rates than D1 surgery. The D2 procedure was also associated with significantly higher postoperative mortality, morbidity, and reoperation rates. Because a safer, spleen-preserving D2 resection technique is currently available in high-volume centres, D2 lymphadenectomy is the recommended surgical approach for patients with resectable (curable) gastric cancer. FUNDING Dutch Health Insurance Funds Council and The Netherlands Cancer Foundation.

DNA methylation differences after exposure to prenatal famine are common and timing- and sex-specific

Prenatal famine in humans has been associated with various later-life consequences, depending on the gestational timing of the insult and the sex of the exposed individual. Epigenetic mechanisms have been proposed to underlie these associations. Indeed, animal studies and our early human data on the imprinted IGF2 locus indicated a link between prenatal nutritional and DNA methylation. However, it remains unclear how common changes in DNA methylation are and whether they are sex- and timing-specific paralleling the later-life consequences of prenatal famine exposure. To this end, we investigated the methylation of 15 loci implicated in growth and metabolic disease in individuals who were prenatally exposed to a war-time famine in 1944-45. Methylation of INSIGF was lower among individuals who were periconceptionally exposed to the famine (n = 60) compared with their unexposed same-sex siblings (P = 2 x 10(-5)), whereas methylation of IL10, LEP, ABCA1, GNASAS and MEG3 was higher (all P < 10(-3)). A significant interaction with sex was observed for INSIGF, LEP and GNASAS. Next, methylation of eight representative loci was compared between 62 individuals exposed late in gestation and their unexposed siblings. Methylation was different for GNASAS (P = 1.1 x 10(-7)) and, in men, LEP (P = 0.017). Our data indicate that persistent changes in DNA methylation may be a common consequence of prenatal famine exposure and that these changes depend on the sex of the exposed individual and the gestational timing of the exposure.

Preoperative radiotherapy combined with total mesorectal excision for resectable rectal cancer: 12-year follow-up of the multicentre, randomised controlled TME trial

BACKGROUND The TME trial investigated the value of preoperative short-term radiotherapy in combination with total mesorectal excision (TME). Long-term results are reported after a median follow-up of 12 years. METHODS Between Jan 12, 1996, and Dec 31, 1999, 1861 patients with resectable rectal cancer without evidence of distant disease were randomly assigned to TME preceded by 5 × 5 Gy radiotherapy or TME alone (ratio 1:1). Randomisation was based on permuted blocks of six with stratification according to centre and expected type of surgery. The primary endpoint was local recurrence, analysed for all eligible patients who underwent a macroscopically complete local resection. FINDINGS 10-year cumulative incidence of local recurrence was 5% in the group assigned to radiotherapy and surgery and 11% in the surgery-alone group (p<0·0001). The effect of radiotherapy became stronger as the distance from the anal verge increased. However, when patients with a positive circumferential resection margin were excluded, the relation between distance from the anal verge and the effect of radiotherapy disappeared. Patients assigned to radiotherapy had a lower overall recurrence and when operated with a negative circumferential resection margin, cancer-specific survival was higher. Overall survival did not differ between groups. For patients with TNM stage III cancer with a negative circumferential resection margin, 10-year survival was 50% in the preoperative radiotherapy group versus 40% in the surgery-alone group (p=0·032). INTERPRETATION For all eligible patients, preoperative short-term radiotherapy reduced 10-year local recurrence by more than 50% relative to surgery alone without an overall survival benefit. For patients with a negative resection margin, the effect of radiotherapy was irrespective of the distance from the anal verge and led to an improved cancer-specific survival, which was nullified by an increase in other causes of death, resulting in an equal overall survival. Nevertheless, preoperative short-term radiotherapy significantly improved 10-year survival in patients with a negative circumferential margin and TNM stage III. Future staging techniques should offer possibilities to select patient groups for which the balance between benefits and side-effects will result in sufficiently large gains. FUNDING The Dutch Cancer Society, the Dutch National Health Council, and the Swedish Cancer Society.

Vaginal brachytherapy versus pelvic external beam radiotherapy for patients with endometrial cancer of high-intermediate risk (PORTEC-2): an open-label, non-inferiority, randomised trial

BACKGROUND After surgery for intermediate-risk endometrial carcinoma, the vagina is the most frequent site of recurrence. This study established whether vaginal brachytherapy (VBT) is as effective as pelvic external beam radiotherapy (EBRT) in prevention of vaginal recurrence, with fewer adverse effects and improved quality of life. METHODS In this open-label, non-inferiority, randomised trial undertaken in 19 Dutch radiation oncology centres, 427 patients with stage I or IIA endometrial carcinoma with features of high-intermediate risk were randomly assigned by a computer-generated, biased coin minimisation procedure to pelvic EBRT (46 Gy in 23 fractions; n=214) or VBT (21 Gy high-dose rate in three fractions, or 30 Gy low-dose rate; n=213). All investigators were masked to the assignment of treatment group. The primary endpoint was vaginal recurrence. The predefined non-inferiority margin was an absolute difference of 6% in vaginal recurrence. Analysis was by intention to treat, with competing risk methods. The study is registered, number ISRCTN16228756. FINDINGS At median follow-up of 45 months (range 18-78), three vaginal recurrences had been diagnosed after VBT and four after EBRT. Estimated 5-year rates of vaginal recurrence were 1.8% (95% CI 0.6-5.9) for VBT and 1.6% (0.5-4.9) for EBRT (hazard ratio [HR] 0.78, 95% CI 0.17-3.49; p=0.74). 5-year rates of locoregional relapse (vaginal or pelvic recurrence, or both) were 5.1% (2.8-9.6) for VBT and 2.1% (0.8-5.8) for EBRT (HR 2.08, 0.71-6.09; p=0.17). 1.5% (0.5-4.5) versus 0.5% (0.1-3.4) of patients presented with isolated pelvic recurrence (HR 3.10, 0.32-29.9; p=0.30), and rates of distant metastases were similar (8.3% [5.1-13.4] vs 5.7% [3.3-9.9]; HR 1.32, 0.63-2.74; p=0.46). We recorded no differences in overall (84.8% [95% CI 79.3-90.3] vs 79.6% [71.2-88.0]; HR 1.17, 0.69-1.98; p=0.57) or disease-free survival (82.7% [76.9-88.6] vs 78.1% [69.7-86.5]; HR 1.09, 0.66-1.78; p=0.74). Rates of acute grade 1-2 gastrointestinal toxicity were significantly lower in the VBT group than in the EBRT group at completion of radiotherapy (12.6% [27/215] vs 53.8% [112/208]). INTERPRETATION VBT is effective in ensuring vaginal control, with fewer gastrointestinal toxic effects than with EBRT. VBT should be the adjuvant treatment of choice for patients with endometrial carcinoma of high-intermediate risk. FUNDING Dutch Cancer Society.

Impact of short-term preoperative radiotherapy on health-related quality of life and sexual functioning in primary rectal cancer: report of a multicenter randomized trial.

BACKGROUND Few prospective studies have been performed about the impact of preoperative radiotherapy (PRT) or total mesorectal excision (TME) on health-related quality of life (HRQL) and sexual functioning in patients with resectable rectal cancer. This report describes the HRQL and sexual functioning of 990 patients who underwent TME and were randomly assigned to short-term PRT (5 x 5 Gy). PATIENTS AND METHODS The Rotterdam Symptom Check List supplemented with additional items was used with questionnaires before treatment and at 3, 6, 12, 18, and 24 months after surgery. Patients without a recurrence the first 2 years were analyzed (n = 990). RESULTS Few differences were found in HRQL between patients treated with or without PRT. Daily activities were significantly less for PRT patients 3 months postoperatively. Irradiated patients recovered slower from defecation problems than TME-only patients (P = .006). PRT had a negative effect on sexual functioning in males (P = .004) and females (P < .001). Irradiated males had more ejaculation disorders (P = .002), and erectile functioning deteriorated over time (P < .001). PRT had similar effects in patients who underwent a low anterior resection (LAR) versus an abdominoperineal resection (APR). Patients with an APR scored better on the physical (P = .004) and psychologic dimension (P = .007) than LAR patients, but worse on voiding (P = .0007). CONCLUSION Short-term PRT leads to more sexual dysfunction, slower recovery of bowel function, and impaired daily activity postoperatively. However, this does not seriously affect HRQL. The comparison between LAR and APR patients demonstrates that the existence of a permanent stoma is not the only determinant of HRQL.

Competing risks in epidemiology: possibilities and pitfalls

BACKGROUND In studies of all-cause mortality, the fundamental epidemiological concepts of rate and risk are connected through a well-defined one-to-one relation. An important consequence of this relation is that regression models such as the proportional hazards model that are defined through the hazard (the rate) immediately dictate how the covariates relate to the survival function (the risk). METHODS This introductory paper reviews the concepts of rate and risk and their one-to-one relation in all-cause mortality studies and introduces the analogous concepts of rate and risk in the context of competing risks, the cause-specific hazard and the cause-specific cumulative incidence function. RESULTS The key feature of competing risks is that the one-to-one correspondence between cause-specific hazard and cumulative incidence, between rate and risk, is lost. This fact has two important implications. First, the naïve Kaplan-Meier that takes the competing events as censored observations, is biased. Secondly, the way in which covariates are associated with the cause-specific hazards may not coincide with the way these covariates are associated with the cumulative incidence. An example with relapse and non-relapse mortality as competing risks in a stem cell transplantation study is used for illustration. CONCLUSION The two implications of the loss of one-to-one correspondence between cause-specific hazard and cumulative incidence should be kept in mind when deciding on how to make inference in a competing risks situation.

The bootstrap: a tutorial

Abstract Bootstrap methods have gained wide acceptance and huge popularity in the field of applied statistics. The bootstrap is able to provide accurate answers in cases where other methods are simply not available, or where the usual approximations are invalid. The number of applications in chemistry, however, has been rather limited. One possible cause for this is the overwhelming number of techniques available. This tutorial aims to introduce the basic concepts of bootstrap methods, provide some guidance as to what bootstrap methods are appropriate in different situations, and illustrate several potential application areas in chemometrics by worked examples.

Adjuvant tamoxifen and exemestane in early breast cancer (TEAM): a randomised phase 3 trial

BACKGROUND Aromatase inhibitors improved disease-free survival compared with tamoxifen when given as an initial adjuvant treatment or after 2-3 years of tamoxifen to postmenopausal women with hormone-receptor-positive breast cancer. We therefore compared the long-term effects of exemestane monotherapy with sequential treatment (tamoxifen followed by exemestane). METHODS The Tamoxifen Exemestane Adjuvant Multinational (TEAM) phase 3 trial was conducted in hospitals in nine countries. Postmenopausal women (median age 64 years, range 35-96) with hormone-receptor-positive breast cancer were randomly assigned in a 1:1 ratio to open-label exemestane (25 mg once a day, orally) alone or following tamoxifen (20 mg once a day, orally) for 5 years. Randomisation was by use of a computer-generated random permuted block method. The primary endpoint was disease-free survival (DFS) at 5 years. Main analyses were by intention to treat. The trial is registered with ClinicalTrials.gov, NCT00279448, NCT00032136, and NCT00036270; NTR 267; Ethics Commission Trial27/2001; and UMIN, C000000057. FINDINGS 9779 patients were assigned to sequential treatment (n=4875) or exemestane alone (n=4904), and 4868 and 4898 were analysed by intention to treat, respectively. 4154 (85%) patients in the sequential group and 4186 (86%) in the exemestane alone group were disease free at 5 years (hazard ratio 0·97, 95% CI 0·88-1·08; p=0·60). In the safety analysis, sequential treatment was associated with a higher incidence of gynaecological symptoms (942 [20%] of 4814 vs 523 [11%] of 4852), venous thrombosis (99 [2%] vs 47 [1%]), and endometrial abnormalities (191 [4%] vs 19 [<1%]) than was exemestane alone. Musculoskeletal adverse events (2448 [50%] vs 2133 [44%]), hypertension (303 [6%] vs 219 [5%]), and hyperlipidaemia (230 [5%] vs 136 [3%]) were reported more frequently with exemestane alone. INTERPRETATION Treatment regimens of exemestane alone or after tamoxifen might be judged to be appropriate options for postmenopausal women with hormone-receptor-positive early breast cancer. FUNDING Pfizer.

Variation, patterns, and temporal stability of DNA methylation: considerations for epigenetic epidemiology

The prospect of finding epigenetic risk factors for complex diseases would be greatly enhanced if DNA from existing biobanks, which is generally extracted from whole blood, could be used to perform epigenetic association studies. We characterized features of DNA methylation at 16 candidate loci, 8 of which were imprinted, in DNA samples from the Netherlands Twin Register biobank. Except for un‐methylated or fully methylated sites, CpG methylation varied considerably in a sample of 30 unrelated individuals. This variation remained after accounting for the cellular heterogeneity of blood. Methylation of CpG sites was correlated within loci and, for 4 imprinted loci, across chromosomes. In 34 additional individuals, we investigated the DNA methylation of 8 representative loci in 2 longitudinal blood and 2 longitudinal buccal cell samples (follow‐up 11–20 and 2–8 yr, respectively). Five of 8 loci were stable over time (ρ>0.75) in both tissues, indicating that prospective epigenetic studies may be possible. For 4 loci, the DNA methylation in blood (mesoderm) correlated with that in the buccal cells (ectoderm) (ρ>0.75). Our data suggest that epigenetic studies on complex diseases may be feasible for a proportion of genomic loci provided that they are carefully designed.—Talens, R. P., Boomsma, D. I., Tobi, E. W., Kremer, D., Jukema, J. W., Willemsen, G., Putter, H., Slagboom, P. E., Heijmans, B. T. Variation, patterns, and temporal stability of DNA methylation: considerations for epigenetic epidemiology. FASEB J. 24, 3135–3144 (2010). www.fasebj.org