Inference on the Genetic Architecture of Breast Cancer Risk.

BACKGROUND: What are the major determinants of women's breast cancer risk? Rare mutations such as those in the BRCA1/2 genes, polygenic scores of common alleles identified by genome-wide association studies, or nongenetic factors? METHODS: The population-based Nordic Twin Study of Cancer, with 3,933 breast cancer cases among 21,054 monozygotic (MZ) and 30,939 dizygotic (DZ) female twin pairs, provides three key clues to this question: (i) the average lifetime risk, approximately 8%, does not differ by twin zygosity; (ii) the mean time interval between diagnoses when both twins develop disease (i.e., disease concordance) also does not differ by zygosity; but, (iii) conditioning on one twin having developed disease, the incidence rate in the co-twin is approximately 1% per year if the pair is MZ and 0.5% per year if DZ. RESULTS: Assuming that nongenetic risk factors are shared similarly between twins regardless of zygosity, we can draw two conclusions from (i) to (iii). CONCLUSIONS: First, (i) and (iii) imply that the chief determinant of risk is in the germline DNA, because the conditional incidence rate is several-fold higher than the average risk (8% lifetime) in MZ twins but only half as much in DZ twins. Second, the seeming inconsistency between the two-fold conditional incidence rate (iii) and the equality of the mean inter-twin disease intervals in disease concordance (ii) can be resolved if the risk factors in the germline DNA are rare variants, not common variants. IMPACT: This paper details simple deductive reasoning for these conclusions and draws a critical inference regarding breast cancer etiology. See related In the Spotlight, p. 1477.

Clinical Assessment of Late Health Outcomes in Survivors of Wilms Tumor.

OBJECTIVES: We aimed to clinically characterize the health, neurocognitive, and physical function outcomes of curative treatment of Wilms tumor. METHODS: Survivors of Wilms tumor (n = 280) participating in the St. Jude Lifetime Cohort, a retrospective study with prospective follow-up of individuals treated for childhood cancer at St. Jude Children's Research Hospital, were clinically evaluated and compared to age and sex-matched controls (n = 625). Health conditions were graded per a modified version of the National Cancer Institute's Common Terminology Criteria for Adverse Events. Standardized neurocognitive testing was graded by using age-adjusted z-scores. Impaired physical function was defined by age- and sex-matched z-scores >1.5 SD below controls. Modified Poisson regression was used to compare the prevalence of conditions and multivariable logistic regression to examine treatment associations. RESULTS: Median age at evaluation was similar between survivors and controls (30.5 years [9.0-58.0] and 31.0 [12.0-70.0]). Therapies included nephrectomy (100%), vincristine (99.3%), dactinomycin (97.9%), doxorubicin (66.8%), and abdominal (59.3%) and/or chest radiation (25.0%). By age 40 years, survivors averaged 12.7 (95% confidence interval [CI] 11.7-13.8) grade 1-4 and 7.5 (CI: 6.7-8.2) grade 2 to 4 health conditions, compared to 4.2 (CI: 3.9-4.6) and 2.3 (CI: 2.1-2.5), respectively, among controls. Grade 2 to 4 endocrine (53.9%), cardiovascular (26.4%), pulmonary (18.2%), neurologic (8.6%), neoplastic (7.9%), and kidney (7.2%) conditions were most prevalent. Survivors exhibited neurocognitive and physical performance impairments. CONCLUSIONS: Wilms tumor survivors experience a threefold higher burden of chronic health conditions compared to controls and late neurocognitive and physical function deficits. Individualized clinical management, counseling, and surveillance may improve long-term health maintenance.

Health-related and cancer risk concerns among siblings of childhood cancer survivors: a report from the Childhood Cancer Survivor Study (CCSS).

OBJECTIVE: To characterize the prevalence and predictors of concerns regarding future health and cancer risk among siblings of childhood cancer survivors. METHODS: This study reports longitudinal data (baseline and follow-up) from 3969 adult siblings (median age = 29 [range 18-56] years) of long-term survivors of childhood cancer (median time since diagnosis 19.6 [9.6-33.8] years). Self-reported future health and cancer risk concerns (concerned vs not concerned) were assessed. Demographics and health data reported by both the siblings and their matched cancer survivors were examined as risk factors for health concerns using multivariable logistic regression. RESULTS: Percentage of siblings reporting future health and cancer risk concerns, respectively, decreased across decade of survivors' diagnosis: 1970s (73.3%; 63.9%), 1980s (67.2%; 62.6%), and 1990s (45.7%; 52.3%). Risk factors associated with future health concerns included sibling chronic health conditions (grade 2 Odds Ratio [OR]=1.57, 95% CI: 1.12-2.20; grades 3-4 OR=1.86, 95% CI: 1.18-2.94; compared to less than grade 2). Risk factors associated with future cancer concerns included sibling chronic health conditions (grade 2 OR=1.43, 95% CI: 1.05-1.94; grades 3-4 OR=1.64, 95% CI: 1.09-2.47; compared to less than grade 2). CONCLUSIONS: Sibling concerns regarding future health and cancer have diminished in recent decades. There are subgroups of siblings that are at-risk for future health and cancer risk concerns. IMPLICATIONS FOR CANCER SURVIVORS: Routine screening of concerns in at-risk siblings of survivors of childhood cancer may benefit the siblings of cancer survivors. These individuals may benefit from early interventions during diagnosis and treatment of their siblings.

SMARTp: A SMART design for nonsurgical treatments of chronic periodontitis with spatially referenced and nonrandomly missing skewed outcomes.

This paper proposes dynamic treatment regimes (DTRs) as effective individualized treatment strategies for managing chronic periodontitis. The proposed DTRs are studied via SMARTp-a two-stage sequential multiple assignment randomized trial (SMART) design. For this design, we propose a statistical analysis plan and a novel cluster-level sample size calculation method that factors in typical features of periodontal responses such as non-Gaussianity, spatial clustering, and nonrandom missingness. Here, each patient is viewed as a cluster, and a tooth within a patient's mouth is viewed as an individual unit inside the cluster, with the tooth-level covariance structure described by a conditionally autoregressive structure. To accommodate possible skewness and tail behavior, the tooth-level clinical attachment level (CAL) response is assumed to be skew-t, with the nonrandomly missing structure captured via a shared parameter model corresponding to the missingness indicator. The proposed method considers mean comparison for the regimes with or without sharing an initial treatment, where the expected values and corresponding variances or covariance for the sample means of a pair of DTRs are derived by the inverse probability weighting and method of moments. Simulation studies are conducted to investigate the finite-sample performance of the proposed sample size formulas under a variety of outcome-generating scenarios. An R package SMARTp implementing our sample size formula is available at the Comprehensive R Archive Network for free download.

Does Medicaid Coverage Modify the Relationship between Glycemic Status and Teeth Present in Older Adults?

Understanding the relationships among diabetes, teeth present, and dental insurance is essential to improving primary and oral health care. Participants were older adults who attended senior centers in northern Manhattan (New York, N.Y.). Sociodemographic, health, and health care information were obtained via intake interviews, number of teeth present via clinical dental examinations, and glycemic status via measurement of glycosylated hemoglobin (HbA1c). Complete data on dental insurance coverage status for 785 participants were available for analysis (1,015 after multiple imputation). For participants with no dental insurance and any private/other dental insurance, number of teeth present is less for participants with diabetes than for participants without diabetes; however, for participants with Medicaid coverage only, the relationship is reversed. Potential explanations include the limited range of dental services covered under the Medicaid program, inadequate diabetes screening and monitoring of Medicaid recipients, and the poor oral and general health of Medicaid recipients.

Preece-Baines Model 1 to Estimate Height and Knee Height Growth in Boys and Girls From Merida, Mexico.

BACKGROUND: Height and body segments in children have differential pubertal growth characteristics. Lower leg length is a sensitive indicator of child's nutritional status. OBJECTIVE: The purpose of this study was to estimate differential timing and tempo of height and knee height (KH) growth in 9- to 17-year-old boys (n = 475) and girls (n = 500) from Merida, Mexico. METHODS: In this cross-sectional study, the Preece-Baines growth curves-model 1 (PB 1) was fitted to the anthropometric data for height and KH. RESULTS: Based on the PB 1 model, KH had earlier age at maximum increment than height in boys (height = 12.37 years, KH = 11.54 years) and girls (height = 11.01 years, KH = 10.93 years). Peak velocity of these 2 dimensions was different in both sexes (boys: height = 7.11 cm/yr, KH = 2.25 cm/yr; girls: height = 5.14 cm/yr, KH = 1.45 cm/yr). Differences ( P <.001) by sex were also observed for the estimated size at peak velocity and final size of height and KH. CONCLUSIONS: When compared to height, KH was shown to have earlier adolescent growth spurt and a smaller difference between final size and the size at maximum (peak) velocity indicating an earlier age for achieving adult size. Overall, the studied boys and girls had short estimated final size, an earlier age at maximum increment, and a lower peak velocity in height than urban Guatemalan peers, the only regional reference available.