Estimating the hazard rate difference from case-cohort studies.

The case-cohort design, among many two-phase sampling designs, substantially reduces the cost of an epidemiological study by selecting more informative participants within the full cohort for expensive variable measurements. Despite their benefits, additive hazards models, which estimate hazard differences, have rarely been used for the analysis of case-cohort studies due to the lack of software and application examples. In this paper, we describe a newly developed estimation method that fits the additive hazards models to general two-phase sampling studies along with the R package addhazard that implements it. It allows for missing covariates among cases, cohort stratification, robust variances, and the incorporation of auxiliary information from the full cohort to enhance inference precision. We demonstrate the use of this tool to estimate the association of the risk of coronary heart disease (CHD) with biomarkers high-sensitivity C-reactive protein (hs-CRP) and Lipoprotein-associated phospholipase A2 (Lp-PLA2) by analyzing the Atherosclerosis Risk in Communities Study, which adopted a two-phase sampling design for studying these two biomarkers. We show that the use of auxiliary variables from the full cohort based on calibration techniques improves the precision of the hazard difference being estimated. We observe a synergistic effect of the two biomarkers among participants with lower LDL cholesterol (LDL-C): the CHD hazard rate attributable to the combined action of high hs-CRP and high Lp-PLA2 exceeded the sum of the CHD hazard rate attributable to each one independently by 11.58 (95% CI 2.16-21.01) cases per 1000 person-years. With higher LDL-C, we observe the CHD hazard rate attributable to the combined action of high hs-CRP and medium Lp-PLA2 was less than the sum of their individual effects by 13.42 (95% CI 2.44-24.40) cases per 1000 person-years. This demonstration serves the dual purposes of illustrating analysis techniques and providing insights about the utility of hs-CRP and Lp-PLA2 for identifying the high-risk population of CHD that the traditional risk factors such as the LDL-C may miss. Epidemiologists are encouraged to use this new tool to analyze other case-cohort studies and incorporate auxiliary variables embedded in the full cohort in their analysis.

Z-estimation and stratified samples: application to survival models.

The infinite dimensional Z-estimation theorem offers a systematic approach to joint estimation of both Euclidean and non-Euclidean parameters in probability models for data. It is easily adapted for stratified sampling designs. This is important in applications to censored survival data because the inverse probability weights that modify the standard estimating equations often depend on the entire follow-up history. Since the weights are not predictable, they complicate the usual theory based on martingales. This paper considers joint estimation of regression coefficients and baseline hazard functions in the Cox proportional and Lin-Ying additive hazards models. Weighted likelihood equations are used for the former and weighted estimating equations for the latter. Regression coefficients and baseline hazards may be combined to estimate individual survival probabilities. Efficiency is improved by calibrating or estimating the weights using information available for all subjects. Although inefficient in comparison with likelihood inference for incomplete data, which is often difficult to implement, the approach provides consistent estimates of desired population parameters even under model misspecification.

Individual prediction of heart failure among childhood cancer survivors.

PURPOSE: To create clinically useful models that incorporate readily available demographic and cancer treatment characteristics to predict individual risk of heart failure among 5-year survivors of childhood cancer. PATIENTS AND METHODS: Survivors in the Childhood Cancer Survivor Study (CCSS) free of significant cardiovascular disease 5 years after cancer diagnosis (n = 13,060) were observed through age 40 years for the development of heart failure (ie, requiring medications or heart transplantation or leading to death). Siblings (n = 4,023) established the baseline population risk. An additional 3,421 survivors from Emma Children's Hospital (Amsterdam, the Netherlands), the National Wilms Tumor Study, and the St Jude Lifetime Cohort Study were used to validate the CCSS prediction models. RESULTS: Heart failure occurred in 285 CCSS participants. Risk scores based on selected exposures (sex, age at cancer diagnosis, and anthracycline and chest radiotherapy doses) achieved an area under the curve of 0.74 and concordance statistic of 0.76 at or through age 40 years. Validation cohort estimates ranged from 0.68 to 0.82. Risk scores were collapsed to form statistically distinct low-, moderate-, and high-risk groups, corresponding to cumulative incidences of heart failure at age 40 years of 0.5% (95% CI, 0.2% to 0.8%), 2.4% (95% CI, 1.8% to 3.0%), and 11.7% (95% CI, 8.8% to 14.5%), respectively. In comparison, siblings had a cumulative incidence of 0.3% (95% CI, 0.1% to 0.5%). CONCLUSION: Using information available to clinicians soon after completion of childhood cancer therapy, individual risk for subsequent heart failure can be predicted with reasonable accuracy and discrimination. These validated models provide a framework on which to base future screening strategies and interventions.

Shift work and breast cancer among women textile workers in Shanghai, China.

PURPOSE: Although night-shift work has been associated with elevated risk of breast cancer in numerous epidemiologic studies, evidence is not consistent. We conducted a nested case-cohort study to investigate a possible association between shift work including a night shift and risk of breast cancer within a large cohort of women textile workers in Shanghai, China. METHODS: The study included 1,709 incident breast cancer cases and 4,780 non-cases. Data on historical shift work schedules were collected by categorized jobs from the factories, where the study subjects had worked, and then were linked to the complete work histories of each subject. No jobs in the factories involved exclusively night-shift work. Therefore, night shift was evaluated as part of a rotating shift work pattern. Hazard ratios and 95 % confidence intervals were calculated using Cox proportional hazards modeling adapted for the case-cohort design for years of night-shift work and the total number of nights worked. Additionally, analyses were repeated with exposures lagged by 10 and 20 years. RESULTS: We observed no associations with either years of night-shift work or number of nights worked during the entire employment period, irrespective of lag intervals. Findings from the age-stratified analyses were very similar to those observed for the entire study population. CONCLUSIONS: The findings from this study provide no evidence to support the hypothesis that shift work increases breast cancer risk. The positive association between shift work and breast cancer observed in Western populations, but not observed in this and other studies of the Chinese population, suggests that the effect of shift work on breast cancer risk may be different in Asian and Caucasian women.

Breast cancer in female survivors of Wilms tumor: a report from the national Wilms tumor late effects study.

BACKGROUND: The standard treatment of pulmonary metastases in patients with Wilms tumor (WT) includes 12-gray radiotherapy (RT) to the entire chest. To the authors' knowledge, the risk of breast cancer (BC) in a large cohort of female survivors of WT has not previously been reported. METHODS: A total of 2492 female participants in National Wilms Tumor Studies 1 through 4 (1969-1995) were followed from age 15 years through the middle of 2013 for incident BC. The median age at the time of last contact was 27.3 years. The authors calculated cumulative risk at age 40 years (CR40), hazard ratios (HR) by Cox regression, standardized incidence ratios (SIRs) relative to US population rates, and 95% confidence intervals (95% CIs). RESULTS: The numbers of survivors with invasive BC divided by the numbers at risk were 16 of 369 (CR40, 14.8% [95% CI, 8.7-24.5]) for women who received chest RT for metastatic WT, 10 of 894 (CR40, 3.1% [95% CI, 1.3-7.41]) for those who received only abdominal RT, and 2 of 1229 (CR40, 0.3% [95% CI, 0.0-2.3]) for those who received no RT. The SIRs for these 3 groups were 27.6 (95% CI, 16.1-44.2) based on 5010 person-years (PY) of follow-up, 6.0 (95% CI, 2.9-11.0) based on 13,185 PY of follow-up, and 2.2 (95% CI, 0.3-7.8) based on 13,560 PY of follow-up, respectively. The risk was high regardless of the use of chest RT among women diagnosed with WT at age ≥10 years, with 9 of 90 women developing BC (CR40, 13.5% [95% CI, 5.6-30.6]; SIR, 23.6 [95% CI, 10.8-44.8] [PY, 1463]). CONCLUSIONS: Female survivors of WT who were treated with chest RT had a high risk of developing early BC, with nearly 15% developing invasive disease by age 40 years. Current guidelines that recommend screening only those survivors who received ≥20 Gy of RT to the chest might be reevaluated.

Outcome of patients with Stage II/favorable histology Wilms tumor with and without local tumor spill: a report from the National Wilms Tumor Study Group.

BACKGROUND: Intra-operative tumor spill increases the risk of local recurrence of Wilms tumor, and adversely impacts relapse-free (RFS) and overall survival (OS) rates. METHODS: Surgical checklists, operative notes, institutional pathology reports, central pathology review and flow sheets of 602 patients registered between August 1986 and September 1994 on National Wilms Tumor Study-4 as randomized, followed or switched and coded as Final Stage II, favorable histology (FH) were reviewed. RFS and OS were estimated using the Kaplan-Meier method. Hazard ratios (HRs) were estimated using the Cox model and tested for statistical significance by the log-rank test. RESULTS: Four hundred ninety-nine patients were found after review to have Stage II, FH Wilms tumor. The 8-year RFS percentages were 85.0% (95% confidence interval (CI): 81.1%, 88.1%) for those with no spill compared to 75.7% (65.8%, 83.2%) for those with spill. The 8-year OS percentages were 95.6% (93.1%, 97.3%) for those with no spill compared to 90.3% (82.2%, 94.9%) for those with spill. The HR for relapse among those with spill was 1.55 ((95%CI: 0.97,2.51), P = 0.067) and the HR for death was 1.94 ((0.92,4.09), P = 0.077). CONCLUSIONS: RFS and OS were lower for patients who had intra-operative tumor spill. The majority of NWTS Stage II, FH patients with intra-operative tumor spill have an overall excellent outcome when treated with two drug chemotherapy (vincristine and actinomycin D) and no abdominal irradiation.

Using the Whole Cohort in the Analysis of Case-Control Data: Application to the Women's Health Initiative.

Standard analyses of data from case-control studies that are nested in a large cohort ignore information available for cohort members not sampled for the sub-study. This paper reviews several methods designed to increase estimation efficiency by using more of the data, treating the case-control sample as a two or three phase stratified sample. When applied to a study of coronary heart disease among women in the hormone trials of the Women's Health Initiative, modest but increasing gains in precision of regression coefficients were observed depending on the amount of cohort information used in the analysis. The gains were particularly evident for pseudo- or maximum likelihood estimates whose validity depends on the assumed model being correct. Larger standard errors were obtained for coefficients estimated by inverse probability weighted methods that are more robust to model misspecification. Such misspecification may have been responsible for an important difference in one key regression coefficient estimated using the weighted compared with the more efficient methods.

Occupational exposure to magnetic fields and breast cancer among women textile workers in Shanghai, China.

Exposure to magnetic fields (MFs) is hypothesized to increase the risk of breast cancer by reducing production of melatonin by the pineal gland. A nested case-cohort study was conducted to investigate the association between occupational exposure to MFs and the risk of breast cancer within a cohort of 267,400 female textile workers in Shanghai, China. The study included 1,687 incident breast cancer cases diagnosed from 1989 to 2000 and 4,702 noncases selected from the cohort. Subjects' complete work histories were linked to a job-exposure matrix developed specifically for the present study to estimate cumulative MF exposure. Hazard ratios and 95% confidence intervals were calculated using Cox proportional hazards modeling that was adapted for the case-cohort design. Hazard ratios were estimated in relation to cumulative exposure during a woman's entire working years. No association was observed between cumulative exposure to MFs and overall risk of breast cancer. The hazard ratio for the highest compared with the lowest quartile of cumulative exposure was 1.03 (95% confidence interval: 0.87, 1.21). Similar null findings were observed when exposures were lagged and stratified by age at breast cancer diagnosis. The findings do not support the hypothesis that MF exposure increases the risk of breast cancer.

Pulmonary disease after treatment for Wilms tumor: a report from the national wilms tumor long-term follow-up study.

PURPOSE: This study was undertaken to evaluate the incidence of pulmonary disease among patients treated with radiation therapy (RT) for pulmonary metastases (PM) from Wilms tumor (WT). PATIENTS AND METHODS: We reviewed records of 6,449 patients treated on National Wilms Tumor Studies-1, -2, -3, and -4 whose flow sheets or annual status reports documented one of several pulmonary conditions. Cases were fully evaluable if pulmonary function test (PFT) results were available, pulmonary fibrosis was identified on a chest radiograph or was listed as the primary or a contributing factor to death. Partially evaluable cases were those for whom PFT results could not be obtained. We evaluated the relationship between RT factors and the occurrence of pulmonary disease using hazard ratios (HRs) and cumulative incidence, treating death as a competing risk. RESULTS: Sixty-four fully evaluable and 16 partially evaluable cases of pulmonary disease were identified. The cumulative incidence of pulmonary disease at 15 years since WT diagnosis was 4.0% (95% confidence interval [CI] 2.6-5.4%) among fully evaluable and 4.8% (95% CI 3.3-6.4%) among fully and partially evaluable patients who received lung RT for PM at initial diagnosis. Rates of pulmonary disease were substantially higher among those who received lung RT for PM present at initial diagnosis or relapse compared to those who received no RT or only abdominal RT (HR 30.2, 95% CI 16.9-53.9). CONCLUSION: The risk of pulmonary disease must be considered in evaluating the risk:benefit ratio of lung RT for the management of PM from WT.

Clinicopathologic findings predictive of relapse in children with stage III favorable-histology Wilms tumor.

PURPOSE: Stage III designation in NWTS-5 (National Wilms Tumor Study-5) was determined by four pathologic criteria: positive lymph nodes (LNs), peritoneal implants, residual disease, and tumor rupture. The objective of this study was to determine the prognostic significance of each of the stage III criteria. PATIENTS AND METHODS: Children with stage III Wilms tumor (WT) treated in NWTS-5 were assessed for event-free (EFS) and overall survival (OS). Sites of relapse and molecular status of tumors are reported. EFS and OS are reported 8 years after diagnosis. RESULTS: There were 569 patients with local stage III favorable-histology (FH) WT in this analysis, of whom 109 had overall stage IV disease. LN involvement alone was the most frequent criterion for stage III designation (38%), followed by microscopic residual disease alone (20%), microscopic residual disease and LN involvement (14%), and spill or soilage alone (9%). The 8-year EFS and OS estimates for all patients with local stage III FHWT were 82% and 91%, respectively. Multivariate analysis demonstrated that both LN involvement (relative risk, 1.89; P = .005) and microscopic residual disease (relative risk, 1.87; P = .007) were predictive of EFS, and OS results were similar. There was no apparent difference in pattern of relapse according to stage III subtype. The rate of loss of heterozygosity was higher (6%) for those with positive LNs than for those without (2%; P = .05). CONCLUSION: LN involvement and microscopic residual are the stage III criteria highly predictive of EFS and OS for patients with stage III FHWT. It is possible that in future studies, patients with different stage III criteria may receive different therapies.

Clinically relevant subsets identified by gene expression patterns support a revised ontogenic model of Wilms tumor: a Children's Oncology Group Study.

Wilms tumors (WT) have provided broad insights into the interface between development and tumorigenesis. Further understanding is confounded by their genetic, histologic, and clinical heterogeneity, the basis of which remains largely unknown. We evaluated 224 WT for global gene expression patterns; WT1, CTNNB1, and WTX mutation; and 11p15 copy number and methylation patterns. Five subsets were identified showing distinct differences in their pathologic and clinical features: these findings were validated in 100 additional WT. The gene expression pattern of each subset was compared with published gene expression profiles during normal renal development. A novel subset of epithelial WT in infants lacked WT1, CTNNB1, and WTX mutations and nephrogenic rests and displayed a gene expression pattern of the postinduction nephron, and none recurred. Three subsets were characterized by a low expression of WT1 and intralobar nephrogenic rests. These differed in their frequency of WT1 and CTNNB1 mutations, in their age, in their relapse rate, and in their expression similarities with the intermediate mesoderm versus the metanephric mesenchyme. The largest subset was characterized by biallelic methylation of the imprint control region 1, a gene expression profile of the metanephric mesenchyme, and both interlunar and perilobar nephrogenic rests. These data provide a biologic explanation for the clinical and pathologic heterogeneity seen within WT and enable the future development of subset-specific therapeutic strategies. Further, these data support a revision of the current model of WT ontogeny, which allows for an interplay between the type of initiating event and the developmental stage in which it occurs.

Treatments and outcomes for end-stage renal disease following Wilms tumor.

BACKGROUND: Little is known about treatment outcomes for children who have end-stage renal disease (ESRD) after treatment for Wilms tumor (WT). METHODS: Time-to-transplant, graft failure, and survival outcomes were examined for 173 children enrolled on the National Wilms Tumor Study who developed ESRD. RESULTS: Fifty-five patients whose ESRD resulted from progressive bilateral WT (PBWT) experienced high early mortality from WT that limited their opportunity for transplant (47% at 5 years) and survival (44% at 10 years) in comparison to population controls. The 118 patients whose ESRD was due to other causes (termed "chronic kidney disease"), many of whom had WT-associated congenital anomalies, had transplant (77% at 5 years) and survival (73% at 10 years) outcomes no worse than those for population controls. Graft failure following transplant was comparable for the two groups. Minority children had twice the median time to transplant as non-Hispanic whites and twice the mortality rates, also reflecting population trends. CONCLUSIONS: In view of the continuing high mortality in patients with ESRD, and the dramatic improvement in outlook following kidney transplantation, re-evaluation of current guidelines for a 2-year delay in transplant following WT treatment may be warranted.

Clinical significance of pulmonary nodules detected by CT and Not CXR in patients treated for favorable histology Wilms tumor on national Wilms tumor studies-4 and -5: a report from the Children's Oncology Group.

BACKGROUND: Metastatic lung disease in Wilms tumor (WT) patients was traditionally identified by chest radiograph (CXR). It is unclear whether patients with small lesions, detectable only by computed tomography ("CT-only" lesions), require the more intensive therapy, including doxorubicin and lung irradiation, given to patients with metastases detectable by CXR. PROCEDURES: This study involved 417 patients with favorable histology WT and isolated lung metastases (detected by CXR or CT) who were registered on National Wilms tumor Study (NWTS)-4 or -5. Outcomes by method of detection (CXR vs. CT-only), use of lung radiation, and 2- or 3-drug chemotherapy (dactinomycin and vincristine ± doxorubicin) were determined and compared using the log-rank test. RESULTS: There were 231 patients with lung lesions detected by CXR and 186 by CT-only. Of the patients with CT-only nodules, 37 received only 2 drugs and 101 did not receive lung radiation. Five-year event-free survival (EFS) was greater for patients receiving three drugs (including doxorubicin) with or without lung radiation than for those receiving two drugs (80% vs. 56%; P = 0.004). There was no difference seen in 5-year overall survival (OS) between the 3- and 2-drug subsets (87% vs. 86%; P = 0.91). There were no significant differences in EFS (82% vs. 72%; P = 0.13) or OS (91% vs. 83%; P = 0.46) for patients with CT-only nodules whether they received lung radiation or not. CONCLUSIONS: Our results suggest that patients with CT-only lung lesions may have improved EFS but not OS from the addition of doxorubicin but do not appear to benefit from pulmonary radiation.

Risk factors for end stage renal disease in non-WT1-syndromic Wilms tumor.

PURPOSE: We assessed risk factors for end stage renal disease in patients with Wilms tumor without known WT1 related syndromes. We hypothesized that patients with characteristics suggestive of a WT1 etiology (early onset, stromal predominant histology, intralobar nephrogenic rests) would have a higher risk of end stage renal disease due to chronic renal failure. We predicted a high risk of end stage renal disease due to progressive bilateral Wilms tumor in patients with metachronous bilateral disease. MATERIALS AND METHODS: End stage renal disease was ascertained in 100 of 7,950 nonsyndromic patients enrolled in a National Wilms Tumor Study during 1969 to 2002. Risk factors were evaluated with cumulative incidence curves and proportional hazard regressions. RESULTS: The cumulative incidence of end stage renal disease due to chronic renal failure 20 years after Wilms tumor diagnosis was 0.7%. For end stage renal disease due to progressive bilateral Wilms tumor the incidence was 4.0% at 3 years after diagnosis in patients with synchronous bilateral Wilms tumor and 19.3% in those with metachronous bilateral Wilms tumor. For end stage renal disease due to chronic renal failure stromal predominant histology had a HR of 6.4 relative to mixed (95% CI 3.4, 11.9; p<0.001), intralobar rests had a HR of 5.9 relative to no rests (95% CI 2.0, 17.3; p=0.001), and Wilms tumor diagnosis at less than 24 months had a HR of 1.7 relative to 24 to 48 months and 2.8 relative to greater than 48 months (p=0.003 for trend). CONCLUSIONS: Metachronous bilateral Wilms tumor is associated with high rates of end stage renal disease due to surgery for progressive Wilms tumor. Characteristics associated with a WT1 etiology markedly increased the risk of end stage renal disease due to chronic renal failure despite the low risk in non-WT1 syndromic cases overall.

Pregnancy outcome after treatment for Wilms tumor: a report from the national Wilms tumor long-term follow-up study.

PURPOSE: This study was undertaken to evaluate the effect of prior treatment with radiation therapy or chemotherapy for unilateral Wilms tumor (WT) diagnosed during childhood on pregnancy complications, birth weight, and the frequency of congenital malformations in live-born offspring. PATIENTS AND METHODS: We reviewed pregnancy outcomes among female survivors and partners of male survivors of WT treated on National Wilms Tumor Studies 1, 2, 3, and 4 by using a maternal questionnaire and a review of both maternal and offspring medical records. RESULTS: We received reports of 1,021 pregnancies with duration of 20 weeks or longer, including 955 live-born singletons, for whom 700 sets of maternal and offspring medical records were reviewed. Rates of hypertension complicating pregnancy (International Classification of Diseases [ICD] code 642), early or threatened labor (ICD-644) and malposition of the fetus (ICD-652) increased with increasing radiation dose in female patients. The percentages of offspring weighing less than 2,500 g at birth and of those having less than 37 weeks of gestation also increased with dose. There was no significant trend with radiation dose in the number of congenital anomalies recorded in offspring of female patients. CONCLUSION: Women who receive flank radiation therapy as part of the treatment for unilateral WT are at increased risk of hypertension complicating pregnancy, fetal malposition, and premature labor. The offspring of these women are at risk for low birth weight and premature (ie, < 37 weeks gestation) birth. These risks must be considered in the obstetrical management of female survivors of WT.

Long-term outcomes for infants with very low risk Wilms tumor treated with surgery alone in National Wilms Tumor Study-5.

OBJECTIVE: To determine the event-free survival (EFS) and overall survival (OS) of children with very low risk Wilms tumor (VLRWT) treated with surgery only. BACKGROUND: Previous studies suggested that postoperative chemotherapy had not improved the prognosis of children with VLRWT. A total of 77 children <24 months of age with small (<550 g) Stage I favorable histology Wilms tumors were treated with surgery only. This study was closed based on stopping rules to ensure that the 2-year EFS was > or =90%. METHODS: A total of 77 children were assessed for EFS and OS. Of these patients, 21 enrolled at the time of closure were recalled, treated with dactinomycin and vincristine (regimen EE4A), and censored for analysis thereafter. About 111 children subsequently treated with EE4A were available for comparison. RESULTS: Median follow-up of surviving patients was 8.2 years for surgery only (range, 1.9-11.8 years) and 5.2 years for the EE4A group (range, 1.6-8.9 years). The estimated 5-year EFS for surgery only was 84% (95% confidence interval [CI]: 73%, 91%); for the EE4A patients it was 97% (95% CI: 92%, 99%, P = 0.002). One death was observed in each treatment group. The estimated 5-year OS was 98% (95% CI: 87%, 99%) for surgery only and 99% (95% CI: 94%, 99%) for EE4A (P = 0.70). CONCLUSION: The surgery-only EFS was lower than anticipated but, coupled with a much higher than anticipated salvage rate of the chemotherapy naive patients whose disease recurred, led to an observed long-term OS equivalent to that seen with 2-drug chemotherapy. This approach to the treatment of patients with VLRWT eliminates the toxic side-effects of chemotherapy for a large majority of patients. A follow-up study is underway to confirm these findings.

Intraoperative spillage of favorable histology wilms tumor cells: influence of irradiation and chemotherapy regimens on abdominal recurrence. A report from the National Wilms Tumor Study Group.

PURPOSE: We undertook this study to determine (1) the frequency with which spilled tumor cells of favorable histology produced intra-abdominal disease in patients treated with differing chemotherapy regimens and abdominal radiation therapy (RT) and (2) the patterns of relapse and outcomes in such patients. METHODS AND MATERIALS: The influence of RT dose (0, 10, and 20 Gy), RT fields (flank, whole abdomen), and chemotherapy with dactinomycin and vincristine (2 drugs) vs. added doxorubicin (three drugs) on intra-abdominal tumor recurrence rates was analyzed by logistic regression in 450 patients. Each patient was considered at risk for two types of failure: flank and subdiaphragmatic beyond-flank recurrence, with the correlation between the two outcomes accounted for in the analyses. RESULTS: The crude odds ratio for the risk of recurrence relative to no RT was 0.35 (0.15-0.78) for 10Gy and 0.08 (0.01-0.58) for 20Gy. The odds ratio for the risk of recurrence for doxorubicin to two drugs after adjusting for RT was not significant. For Stage II patients (NWTS-4), the 8-year event rates with and without spillage, respectively, were 79% and 87% for relapse-free survival (p = 0.07) and 90% and 95% for overall survival (p = 0.04). CONCLUSIONS: Irradiation (10 Gy or 20 Gy) reduced abdominal tumor recurrence rates after tumor spillage. Tumor spillage in Stage II patients reduced relapse-free survival and overall survival, but only the latter was of statistical significance. These data provide a basis for assessing the risks vs. benefits when considering treatment for children with favorable histology Wilms tumor and surgical spillage.

Portal hypertension in children with Wilms' tumor: a report from the National Wilms' Tumor Study Group.

PURPOSE: This analysis was undertaken to determine the cumulative risk of and risk factors for portal hypertension (PHTN) in patients with Wilms' tumor (WT). METHODS AND MATERIALS: Medical records were reviewed to identify cases of PHTN identified with late liver/spleen/gastric toxicities in a cohort of 5,195 patients treated with National Wilms' Tumor Studies (NWTS) protocols 1 to 4. A nested case control study (5 controls/case) was conducted to determine relationships among doxorubicin, radiation therapy (RT) dose to the liver, patient gender, and PHTN. Conditional logistic regression was used to estimate adjusted hazard ratios (HR) of PHTN associated with these factors. RESULTS: Cumulative risk of PHTN at 6 years from WT diagnosis was 0.7% for patients with right-sided tumors vs. 0.1% for those with left-sided tumors (p = 0.002). Seventeen of 19 cases were evaluable for RT. The majority of cases (16/17 [94%]) received right-flank RT either alone or as part of whole-abdomen RT and received >15 Gy to the liver. Fifteen of 17 (88%) patients received a higher dose to the liver than they would have with modern WT protocols. Controlling for RT dose, the HR was 3.0 for patients who received doxorubicin (p = 0.32) and 2.8 for females (p = 0.15). Controlling for doxorubicin, the 95% lower confidence bound on the HR associating PHTN with a minimum liver RT dose of >15 Gy vs. 15 Gy vs. 15 Gy) and the development of PHTN among WT patients.