Determinants of active surveillance uptake in a diverse population-based cohort of men with low-risk prostate cancer: The Treatment Options in Prostate Cancer Study (TOPCS).

BACKGROUND: Active surveillance (AS) is the preferred strategy for low-risk prostate cancer (LRPC); however, limited data on determinants of AS adoption exist, particularly among Black men. METHODS: Black and White newly diagnosed (from January 2014 through June 2017) patients with LRPC ≤75 years of age were identified through metro-Detroit and Georgia population-based cancer registries and completed a survey evaluating factors influencing AS uptake. RESULTS: Among 1688 study participants, 57% chose AS (51% of Black participants, 61% of White) over definitive treatment. In the unadjusted analysis, patient factors associated with initial AS uptake included older age, White race, and higher education. However, after adjusting for covariates, none of these factors was significant predictors of AS uptake. The strongest determinant of AS uptake was the AS recommendation by a urologist (adjusted prevalence ratio, 6.59, 95% CI, 4.84-8.97). Other factors associated with the decision to undergo AS included a shared patient-physician treatment decision, greater prostate cancer knowledge, and residence in metro-Detroit compared with Georgia. Conversely, men whose decision was strongly influenced by the desire to achieve "cure" or "live longer" with treatment and those who perceived their LRPC diagnosis as more serious were less likely to choose AS. CONCLUSIONS: In this contemporary sample, the majority of patients with newly diagnosed LRPC chose AS. Although the input from their urologists was highly influential, several patient decisional and psychological factors were independently associated with AS uptake. These data shed new light on potentially modifiable factors that can help further increase AS uptake among patients with LRPC.

Prediagnostic circulating markers of inflammation and risk of oesophageal adenocarcinoma: a study within the National Cancer Institute Cohort Consortium.

OBJECTIVE: Cross-sectional data indicate that systemic inflammation is important in oesophageal adenocarcinoma. We conducted a prospective study to assess whether prediagnostic circulating markers of inflammation were associated with oesophageal adenocarcinoma and to what extent they mediated associations of obesity and cigarette smoking with cancer risk. DESIGN: This nested case-control study included 296 oesophageal adenocarcinoma cases and 296 incidence density matched controls from seven prospective cohort studies. We quantitated 69 circulating inflammation markers using Luminex-based multiplex assays. Conditional logistic regression models estimated associations between inflammation markers and oesophageal adenocarcinoma, as well as direct and indirect effects of obesity and smoking on risk of malignancy. RESULTS: Soluble tumour necrosis factor receptor 2 (sTNFR2) (ORsquartile 4 vs 1=2.67, 95% CI 1.52 to 4.68) was significantly associated with oesophageal adenocarcinoma. Additional markers close to the adjusted significance threshold included C reactive protein, serum amyloid A, lipocalin-2, resistin, interleukin (IL) 3, IL17A, soluble IL-6 receptor and soluble vascular endothelial growth factor receptor 3. Adjustment for body mass index, waist circumference or smoking status slightly attenuated biomarker-cancer associations. Mediation analysis indicated that sTNFR2 may account for 33% (p=0.005) of the effect of waist circumference on oesophageal adenocarcinoma risk. Resistin, plasminogen activator inhibitor 1, C reactive protein and serum amyloid A were also identified as potential mediators of obesity-oesophageal adenocarcinoma associations. For smoking status, only plasminogen activator inhibitor 1 was a nominally statistically significant (p<0.05) mediator of cancer risk. CONCLUSION: This prospective study provides evidence of a link between systemic inflammation and oesophageal adenocarcinoma risk. In addition, this study provides the first evidence that indirect effects of excess adiposity and cigarette smoking, via systemic inflammation, increase the risk of oesophageal adenocarcinoma.

The extrema of circulating miR-17 are identified as biomarkers for aggressive prostate cancer.

MicroRNAs (miRNAs) constitute short non-coding RNAs that can post-transcriptionally modulate the expression of many oncogenes and tumor suppressor genes engaged in key cellular processes. Deregulated serum miRNA signatures have been detected in various solid cancers including prostate cancer, suggesting that circulating miRNAs could function as non-invasive biomarkers of tumor emergence and progression. To determine whether serum miRNA expression levels are different between patients with aggressive and non-aggressive prostate cancer, we analyzed a panel of miRNAs from the blood of African American (AA) prostate cancer patients using a new recursive partitioning method that allows hypothesis testing of each split. We observed that both extrema of circulating miR-17, i.e. upregulation and downregulation, are associated with aggressive prostate cancer. A similar effect was observed in tumor samples from a separate dataset representing a different population of prostate cancer patients and in AA prostate cancer samples from the TCGA. The dual effect is consistent with the contradictory findings on the role of miR-17 in prostate cancer progression, whereby it controls important oncogenic and tumor-suppressive genes.

Renal cell carcinoma risk associated with lower intake of micronutrients.

Kidney cancer incidence in African Americans (AA) is higher than among European Americans (EA); reasons for this disparity are not fully known. Dietary micronutrients may have a protective effect on renal cell carcinoma (RCC) development by inhibiting oxidative DNA damage and tumor growth. We evaluated whether any micronutrient associations differed by race in the US Kidney Cancer Study. 1142 EA and AA RCC cases and 1154 frequency-matched controls were enrolled in a population-based case-control study between 2002 and 2007. Dietary micronutrient intake was derived from an interviewer-administered diet history questionnaire. RCC risk associated with micronutrient intake was estimated using adjusted odds ratios from logistic regression comparing lower to highest quartiles of intake and sample weighting. Inverse associations with RCC risk were observed for α-carotene, ß-carotene, lutein zeaxanthin, lycopene, vitamin A, folate, thiamin, vitamin C, α-tocopherol, ß-tocopherol, γ-tocopherol, and selenium. A trend for ß-cryptoxanthin was suggested among EA but not AA or the total sample (P-interaction = .04). Otherwise, findings did not differ by race, gender, age, or smoking status. The increase in RCC risk associated with lower micronutrient intake is similar within AA and EA populations. A diet rich in sources of micronutrients found in fruits, vegetables, and nuts may help to reduce the overall risk of RCC.

A study of circulating microRNAs identifies a new potential biomarker panel to distinguish aggressive prostate cancer.

Prostate cancer is one of the most common cancers in men worldwide. Currently available diagnostic and prognostic tools for this disease, such as prostate specific antigen, suffer from lack of specificity and sensitivity, resulting in over- and misdiagnosis. Hence, there is an urgent need for clinically relevant biomarkers capable of distinguishing between aggressive and nonaggressive forms of prostate cancer to aid in stratification, management and therapeutic decisions. To address this unmet need, we investigated the patterns of expression of a panel of 68 plasma-derived microRNAs (miRNAs) in a cohort of African American (AA) and European American (EA) prostate cancer patients (n = 114). miRNA qPCR results were analyzed using in-depth statistical methods, and a bioinformatics analysis was conducted to identify potential targets of the differentially expressed miRNAs. Our data demonstrate that a new previously unreported circulating miRNA signature consisting of a combination of interacting miRNAs (miR-17/miR-192) and an independent miRNA (miR-181a) are capable of segregating aggressive and nonaggressive prostate cancer in both AA and EA patients. The interacting miRNAs outperformed independent miRNAs in identifying aggressiveness. Our results suggest that these circulating miRNAs may constitute novel biomarkers of prostate cancer aggressiveness in both races and warrant further investigation.

The effect of genetic variants on the relationship between statins and breast cancer in postmenopausal women in the Women's Health Initiative observational study.

PURPOSE: Statins have been postulated to have chemopreventive activity against breast cancer. We evaluated whether germline genetic polymorphisms modified the relationship between statins and breast cancer risk using data from the Women's Health Initiative. We evaluated these interactions using both candidate gene and agnostic genome-wide approaches. METHODS: To identify candidate gene-statin interactions, we tested interactions between 22 SNPS in nine candidate genes implicated in the effect of statins on lipid metabolism in 1687 cases and 1687 controls. We then evaluated statin use interaction with the remaining 30,380 SNPs available in this sample from the CGEMS GWAS study. RESULTS: After adjusting for multiple comparisons, no SNP interactions with statin usage and risk of breast cancer were statistically significant in either the candidate genes or genome-wide approaches. CONCLUSIONS: We found no evidence of SNP interactions with statin usage for breast cancer risk in a population of 3374 individuals. These results suggest that genome-wide common genetic variants do not moderate the association between statin usage and breast cancer in the population of women in the Women's Health Initiative.

Family history of prostate and colorectal cancer and risk of colorectal cancer in the Women's health initiative.

BACKGROUND: Evidence suggests that risk of colorectal and prostate cancer is increased among those with a family history of the same disease, particularly among first-degree relatives. However, the aggregation of colorectal and prostate cancer within families has not been well investigated. METHODS: Analyses were conducted among participants of the Women's Health Initiative (WHI) observational cohort, free of cancer at the baseline examination. Subjects were followed for colorectal cancer through August 31st, 2009. A Cox-proportional hazards regression modeling approach was used to estimate risk of colorectal cancer associated with a family history of prostate cancer, colorectal cancer and both cancers among first-degree relatives of all participants and stratified by race (African American vs. White). RESULTS: Of 75,999 eligible participants, there were 1122 colorectal cancer cases diagnosed over the study period. A family history of prostate cancer alone was not associated with an increase in colorectal cancer risk after adjustment for confounders (aHR =0.94; 95% CI =0.76, 1.15). Separate analysis examining the joint impact, a family history of both colorectal and prostate cancer was associated with an almost 50% increase in colorectal cancer risk (aHR = 1.48; 95% CI = 1.04, 2.10), but similar to those with a family history of colorectal cancer only (95% CI = 1.31; 95% CI = 1.11, 1.54). CONCLUSIONS: Our findings suggest risk of colorectal cancer is increased similarly among women with colorectal cancer only and among those with both colorectal and prostate cancer diagnosed among first-degree family members. Future studies are needed to determine the relative contribution of genes and shared environment to the risk of both cancers.

Interaction between Nonsteroidal Anti-inflammatory Drugs and Low-fat Dietary Intervention on Colorectal Cancer Incidence; the Women's Health Initiative (WHI) Dietary Modification Trial.

BACKGROUND: The Women's Health Initiative (WHI) Dietary Modification (DM) trial did not show that reductions in dietary fat accompanied by increases in vegetable and fruit consumption decrease the incidence of colorectal cancer. Secondary analyses suggested that aspirin use may modify the intervention effects of DM on colorectal cancer development, although a recent reanalysis including the postintervention period confirmed no main effect of the intervention on reducing colorectal cancer incidence Methods: We analyzed data from 48,834 postmenopausal women who were randomized into the low-fat DM (N = 19,540) or comparison (N = 29,294) group for an average 8.1 years and followed for an additional 9.4 years through August 31, 2014. Exposure to specific class(es) or strength(s) of nonsteroidal anti-inflammatory drugs (NSAIDs) was modeled at baseline and as time-dependent use through the 9-year clinic visit. A Cox proportional hazard model was employed to assess the association of the DM, medication use, and their interaction with colorectal cancer events. RESULTS: A total of 906 incident cases of colorectal cancer were identified during the intervention and postintervention periods. By both exposure models, we found that colorectal cancer incidence was not different in the DM from the comparison group among any type of NSAID users. None of the interactions with any category of NSAID use was statistically significant; however there was most modest evidence for an interaction (p = 0.07) with aspirin use at baseline (hazard ratio [HR] = 0.81, 95% confidence interval [CI], 0.60-1.11 for users; HR = 1.12, 95% CI, 0.97-1.30 for nonusers). Strength and duration of aspirin use at baseline did not alter the associations. CONCLUSION: Extended follow-up of women in the WHI DM trial did not confirm combined protective effects of aspirin and low-fat diet on colorectal cancer risk among the postmenopausal women.

A Meta-analysis of Multiple Myeloma Risk Regions in African and European Ancestry Populations Identifies Putatively Functional Loci.

BACKGROUND: Genome-wide association studies (GWAS) in European populations have identified genetic risk variants associated with multiple myeloma. METHODS: We performed association testing of common variation in eight regions in 1,318 patients with multiple myeloma and 1,480 controls of European ancestry and 1,305 patients with multiple myeloma and 7,078 controls of African ancestry and conducted a meta-analysis to localize the signals, with epigenetic annotation used to predict functionality. RESULTS: We found that variants in 7p15.3, 17p11.2, 22q13.1 were statistically significantly (P < 0.05) associated with multiple myeloma risk in persons of African ancestry and persons of European ancestry, and the variant in 3p22.1 was associated in European ancestry only. In a combined African ancestry-European ancestry meta-analysis, variation in five regions (2p23.3, 3p22.1, 7p15.3, 17p11.2, 22q13.1) was statistically significantly associated with multiple myeloma risk. In 3p22.1, the correlated variants clustered within the gene body of ULK4 Correlated variants in 7p15.3 clustered around an enhancer at the 3' end of the CDCA7L transcription termination site. A missense variant at 17p11.2 (rs34562254, Pro251Leu, OR, 1.32; P = 2.93 × 10-7) in TNFRSF13B encodes a lymphocyte-specific protein in the TNF receptor family that interacts with the NF-κB pathway. SNPs correlated with the index signal in 22q13.1 cluster around the promoter and enhancer regions of CBX7 CONCLUSIONS: We found that reported multiple myeloma susceptibility regions contain risk variants important across populations, supporting the use of multiple racial/ethnic groups with different underlying genetic architecture to enhance the localization and identification of putatively functional alleles. IMPACT: A subset of reported risk loci for multiple myeloma has consistent effects across populations and is likely to be functional. Cancer Epidemiol Biomarkers Prev; 25(12); 1609-18. ©2016 AACR.

Female chromosome X mosaicism is age-related and preferentially affects the inactivated X chromosome.

To investigate large structural clonal mosaicism of chromosome X, we analysed the SNP microarray intensity data of 38,303 women from cancer genome-wide association studies (20,878 cases and 17,425 controls) and detected 124 mosaic X events >2 Mb in 97 (0.25%) women. Here we show rates for X-chromosome mosaicism are four times higher than mean autosomal rates; X mosaic events more often include the entire chromosome and participants with X events more likely harbour autosomal mosaic events. X mosaicism frequency increases with age (0.11% in 50-year olds; 0.45% in 75-year olds), as reported for Y and autosomes. Methylation array analyses of 33 women with X mosaicism indicate events preferentially involve the inactive X chromosome. Our results provide further evidence that the sex chromosomes undergo mosaic events more frequently than autosomes, which could have implications for understanding the underlying mechanisms of mosaic events and their possible contribution to risk for chronic diseases.

Antioxidant micronutrients and the risk of renal cell carcinoma in the Women's Health Initiative cohort.

BACKGROUND: Renal cell carcinoma (RCC) is the eighth leading cancer among women in incidence and commonly is diagnosed at a more advanced stage. Oxidative stress has been considered to play an important role in the pathogenesis of RCC. Various dietary micronutrients have antioxidant properties, including carotenoids and vitamins C and E; thus, diets rich in these nutrients have been evaluated in relation to RCC prevention. The objective of this study was to explore the correlation between antioxidant micronutrients and the risk of RCC. METHODS: In total, 96,196 postmenopausal women who enrolled in the Women's Health Initiative (WHI) between 1993 and 1998 and were followed through July 2013 were included in this analysis. Dietary micronutrient intake was estimated from the baseline WHI food frequency questionnaire, and data on supplement use were collected using an interview-based inventory procedure. RCC cases were ascertained from follow-up surveys and were centrally adjudicated. The risks for RCC associated with intake of α-carotene, ß-carotene, ß-cryptoxanthin, lutein plus zeaxanthin, lycopene, vitamin C, and vitamin E were analyzed using Cox proportional hazards regression adjusted for confounders. RESULTS: Two hundred forty women with RCC were identified during follow-up. Lycopene intake was inversely associated with RCC risk (P = .015); compared with the lowest quartile of lycopene intake, the highest quartile of intake was associated with a 39% lower risk of RCC (hazard ratio, 0.61; 95% confidence interval, 0.39-0.97). No other micronutrient was significantly associated with RCC risk. CONCLUSIONS: The current results suggest that further investigation into the correlation between lycopene intake and the risk of RCC is warranted.

Genome-wide scan of 29,141 African Americans finds no evidence of directional selection since admixture.

The extent of recent selection in admixed populations is currently an unresolved question. We scanned the genomes of 29,141 African Americans and failed to find any genome-wide-significant deviations in local ancestry, indicating no evidence of selection influencing ancestry after admixture. A recent analysis of data from 1,890 African Americans reported that there was evidence of selection in African Americans after their ancestors left Africa, both before and after admixture. Selection after admixture was reported on the basis of deviations in local ancestry, and selection before admixture was reported on the basis of allele-frequency differences between African Americans and African populations. The local-ancestry deviations reported by the previous study did not replicate in our very large sample, and we show that such deviations were expected purely by chance, given the number of hypotheses tested. We further show that the previous study's conclusion of selection in African Americans before admixture is also subject to doubt. This is because the FST statistics they used were inflated and because true signals of unusual allele-frequency differences between African Americans and African populations would be best explained by selection that occurred in Africa prior to migration to the Americas.

Gene-environment interactions between JAZF1 and occupational and household lead exposure in prostate cancer among African American men.

PURPOSE: A single nucleotide polymorphism, rs10486567, in JAZF1 has consistently been associated with increased risk of prostate cancer. The physical interaction of zinc finger proteins, such as JAZF1, with heavy metals may play a role in carcinogenesis. This study assessed potential gene-environment statistical interactions (G×E) between rs10486567 and heavy metals in prostate cancer. METHODS: In a case-only study of 228 African American prostate cancer cases, G×E between rs10486567 and sources of cadmium and lead (Pb) were assessed. Unconditional logistic regression was used to estimate interaction odds ratios (IORs), and generalized estimating equations were used for models containing nested data. Case-control validation of IORs was performed, using 82 controls frequency matched to cases on age-race. RESULTS: Among cases, a potential G×E interaction was observed between rs10486567 CC genotype and living in a Census tract with a high proportion of housing built before 1950, a proxy for household Pb exposure, when compared to CT or TT carriers (OR 1.81; 95% CI 1.04-3.16; p = 0.036). A stronger G×E interaction was observed when both housing and occupational Pb exposure were taken into account (OR 2.62; 95% CI 1.03-6.68; p = 0.04). Case-control stratified analyses showed the odds of being a CC carrier were higher in cases compared to controls among men living in areas with older housing (OR 2.03; CI 0.99-4.19; p = 0.05) or having high occupational Pb exposure (OR 2.50; CI 1.01-6.18; p = 0.05). CONCLUSIONS: In African American men, the association between JAZF1 rs10486567 and prostate cancer may be modified by exposure to heavy metals such as Pb.

Reducing prostate cancer racial disparity: evidence for aggressive early prostate cancer PSA testing of African American men.

BACKGROUND: There is continuing controversy about prostate cancer testing and the recent American Urological Association guidelines. We hypothesize that the reduction and elimination of racial survival disparity among African American men (AAM; high-risk group) compared with European American men (EAM; intermediate-risk group) during the PSA testing era compared with the pre-PSA era strongly supports the use of PSA testing in AAM. METHODS: We used Surveillance, Epidemiology, and End Results (SEER) data to investigate relative survival disparities between AAM and EAM. To evaluate pre-PSA testing era, we selected malignant first primary prostate cancer in AAM and EAM, all stages, diagnosed during 1973-1994. To evaluate relative survival disparities in the current PSA testing era, we selected malignant first primary local, regional, and distant stage prostate cancers diagnosed during 1998-2005 to calculate 5-year relative survival rates. RESULTS: Age-adjusted 5-year relative survival of prostate cancer diagnosed during 1973-1994 in the national SEER data revealed significantly shorter survival for AAM compared with EAM (P < 0.0001). The SEER-based survival analysis from 1995 to 2005 indicated no statistical difference in relative survival rates between AAM and EAM by year of diagnosis of local, regional, or distant stage prostate cancer. CONCLUSION: We conclude that the elimination of prostate cancer racial disparity of local, regional, and metastatic prostate cancer relative survival in the current PSA testing era compared with pre-PSA era as an endpoint to test PSA efficacy as a marker for prostate cancer diagnosis is evidence for aggressive testing of AAM. IMPACT: Evidence for screening AAM.

Case-only gene-environment interaction between ALAD tagSNPs and occupational lead exposure in prostate cancer.

BACKGROUND: Black men have historically had higher blood lead levels than white men in the U.S. and have the highest incidence of prostate cancer in the world. Inorganic lead has been classified as a probable human carcinogen. Lead (Pb) inhibits delta-aminolevulinic acid dehydratase (ALAD), a gene recently implicated in other genitourinary cancers. The ALAD enzyme is involved in the second step of heme biosynthesis and is an endogenous inhibitor of the 26S proteasome, a master system for protein degradation and a current target of cancer therapy. METHODS: Using a case-only study design, we assessed potential gene-environment (G × E) interactions between lifetime occupational Pb exposure and 11 tagSNPs within ALAD in black (N = 260) and white (N = 343) prostate cancer cases. RESULTS: Two ALAD tagSNPs in high linkage disequilibrium showed significant interaction with high Pb exposure among black cases (rs818684 interaction odds ratio or IOR = 2.73, 95% CI 1.43-5.22, P = 0.002; rs818689 IOR = 2.20, 95% CI 1.15-4.21, P = 0.017) and an additional tagSNP, rs2761016, showed G × E interaction with low Pb exposure (IOR = 2.08, 95% CI 1.13-3.84, P = 0.019). Further, the variant allele of rs818684 was associated with a higher Gleason grade in those with high Pb exposure among both blacks (OR 3.96, 95% CI 1.01-15.46, P = 0.048) and whites (OR 2.95, 95% CI 1.18-7.39, P = 0.020). CONCLUSIONS: Genetic variation in ALAD may modify associations between Pb and prostate cancer. Additional studies of ALAD, Pb, and prostate cancer are warranted and should include black men. Prostate 74:637-646, 2014. © 2014 Wiley Periodicals, Inc.

A meta-analysis identifies new loci associated with body mass index in individuals of African ancestry.

Genome-wide association studies (GWAS) have identified 36 loci associated with body mass index (BMI), predominantly in populations of European ancestry. We conducted a meta-analysis to examine the association of >3.2 million SNPs with BMI in 39,144 men and women of African ancestry and followed up the most significant associations in an additional 32,268 individuals of African ancestry. We identified one new locus at 5q33 (GALNT10, rs7708584, P = 3.4 × 10(-11)) and another at 7p15 when we included data from the GIANT consortium (MIR148A-NFE2L3, rs10261878, P = 1.2 × 10(-10)). We also found suggestive evidence of an association at a third locus at 6q16 in the African-ancestry sample (KLHL32, rs974417, P = 6.9 × 10(-8)). Thirty-two of the 36 previously established BMI variants showed directionally consistent effect estimates in our GWAS (binomial P = 9.7 × 10(-7)), five of which reached genome-wide significance. These findings provide strong support for shared BMI loci across populations, as well as for the utility of studying ancestrally diverse populations.

Genes associated with prostate cancer are differentially expressed in African American and European American men.

BACKGROUND: Despite more aggressive screening across all demographics and gradual declines in mortality related to prostate cancer (PCa) in the United States, disparities among populations persist. A substantial proportion of African American men (AAM) have a higher overall incidence, earlier age of onset, increased proportion of clinically advanced disease, and increased bone metastases and mortality from PCa compared to European American men (EAM). Limited early evidence indicates that underlying causes for disparities may be observed in tumor-specific gene expression programs. METHODS: This study used microarray-based methods to measure expression levels for 517 genes that were previously associated with PCa in archived formalin-fixed paraffin embedded (FFPE) specimens; testing the hypothesis that gene expression features of functional consequence to cancer distinguish PCa from AAM and EAM. A t test was conducted comparing AAM to EAM expression levels for each probe on the array. RESULTS: Analysis of 639 tumor samples (270 AAM, 369 EAM) showed that 95 genes were overexpressed specifically in PCa from AAM relative to EAM and 132 were overexpressed in PCa from EAM relative to AAM. Furthermore, systems-level analyses highlight the relevant signaling pathways and functions associated with the EAM- or AAM-specific overexpressed gene sets, for example, inflammation and lipid metabolism. CONCLUSIONS: Results here bring further understanding to the potential for molecular differences for PCa in AAM versus EAM. IMPACT: The results support the notion that therapeutic benefits will be realized when targeted treatments are designed to acknowledge and address a greater spectrum of PCa subtypes and molecular distinctions.

Detectable clonal mosaicism and its relationship to aging and cancer.

In an analysis of 31,717 cancer cases and 26,136 cancer-free controls from 13 genome-wide association studies, we observed large chromosomal abnormalities in a subset of clones in DNA obtained from blood or buccal samples. We observed mosaic abnormalities, either aneuploidy or copy-neutral loss of heterozygosity, of >2 Mb in size in autosomes of 517 individuals (0.89%), with abnormal cell proportions of between 7% and 95%. In cancer-free individuals, frequency increased with age, from 0.23% under 50 years to 1.91% between 75 and 79 years (P = 4.8 × 10(-8)). Mosaic abnormalities were more frequent in individuals with solid tumors (0.97% versus 0.74% in cancer-free individuals; odds ratio (OR) = 1.25; P = 0.016), with stronger association with cases who had DNA collected before diagnosis or treatment (OR = 1.45; P = 0.0005). Detectable mosaicism was also more common in individuals for whom DNA was collected at least 1 year before diagnosis with leukemia compared to cancer-free individuals (OR = 35.4; P = 3.8 × 10(-11)). These findings underscore the time-dependent nature of somatic events in the etiology of cancer and potentially other late-onset diseases.