Leadership Roles and Activities Among Alumni Receiving Postdoctoral Fellowship Training in Cancer Prevention.

This study was conducted in 2016-2017 to better understand formal and informal leadership roles and activities of alumni from postdoctoral research training programs in cancer prevention. Data were obtained from surveys of 254 employed scientists who completed cancer prevention postdoctoral training within the National Cancer Institute (NCI) Cancer Prevention Fellowship Program, or at US research institutions through NCI-sponsored National Research Service Award (NRSA) individual postdoctoral fellowship (F32) grants, from 1987 to 2011. Fifteen questions categorized under Organizational Leadership, Research Leadership, Professional Society/Conference Leadership, and Broader Scientific/Health Community Leadership domains were analyzed. About 75% of respondents had at least one organizational leadership role or activity during their careers, and 13-34% reported some type of research, professional society/conference, or broader scientific/health community leadership within the past 5 years. Characteristics independently associated with leadership from regression models were being in earlier postdoctoral cohorts (8 items, range for statistically significant ORs = 2.8 to 10.8) and employment sector (8 items, range for statistically significant ORs = 0.4 to 11.7). Scientists whose race/ethnicity was other than white were less likely to report organizational leadership or management responsibilities (OR = 0.4, 95% CI 0.2-0.9). Here, many alumni from NCI-supported cancer prevention postdoctoral programs were involved in leadership, with postdoctoral cohort and employment sector being the factors most often associated with leadership roles and activities. Currently, there is relatively little research on leadership roles of biomedical scientists in general, or in cancer prevention specifically. This study begins to address this gap and provide a basis for more extensive studies of leadership roles and training of scientists.

Colorectal-cancer incidence and mortality with screening flexible sigmoidoscopy.

BACKGROUND: The benefits of endoscopic testing for colorectal-cancer screening are uncertain. We evaluated the effect of screening with flexible sigmoidoscopy on colorectal-cancer incidence and mortality. METHODS: From 1993 through 2001, we randomly assigned 154,900 men and women 55 to 74 years of age either to screening with flexible sigmoidoscopy, with a repeat screening at 3 or 5 years, or to usual care. Cases of colorectal cancer and deaths from the disease were ascertained. RESULTS: Of the 77,445 participants randomly assigned to screening (intervention group), 83.5% underwent baseline flexible sigmoidoscopy and 54.0% were screened at 3 or 5 years. The incidence of colorectal cancer after a median follow-up of 11.9 years was 11.9 cases per 10,000 person-years in the intervention group (1012 cases), as compared with 15.2 cases per 10,000 person-years in the usual-care group (1287 cases), which represents a 21% reduction (relative risk, 0.79; 95% confidence interval [CI], 0.72 to 0.85; P<0.001). Significant reductions were observed in the incidence of both distal colorectal cancer (479 cases in the intervention group vs. 669 cases in the usual-care group; relative risk, 0.71; 95% CI, 0.64 to 0.80; P<0.001) and proximal colorectal cancer (512 cases vs. 595 cases; relative risk, 0.86; 95% CI, 0.76 to 0.97; P=0.01). There were 2.9 deaths from colorectal cancer per 10,000 person-years in the intervention group (252 deaths), as compared with 3.9 per 10,000 person-years in the usual-care group (341 deaths), which represents a 26% reduction (relative risk, 0.74; 95% CI, 0.63 to 0.87; P<0.001). Mortality from distal colorectal cancer was reduced by 50% (87 deaths in the intervention group vs. 175 in the usual-care group; relative risk, 0.50; 95% CI, 0.38 to 0.64; P<0.001); mortality from proximal colorectal cancer was unaffected (143 and 147 deaths, respectively; relative risk, 0.97; 95% CI, 0.77 to 1.22; P=0.81). CONCLUSIONS: Screening with flexible sigmoidoscopy was associated with a significant decrease in colorectal-cancer incidence (in both the distal and proximal colon) and mortality (distal colon only). (Funded by the National Cancer Institute; PLCO ClinicalTrials.gov number, NCT00002540.).

The National Lung Screening Trial: results stratified by demographics, smoking history, and lung cancer histology.

BACKGROUND: The National Lung Screening Trial (NLST), which compared lung cancer screening with low-dose computed tomography (LDCT) versus chest radiography (CXR), demonstrated a statistically significant mortality benefit of LDCT screening. In the current study, the authors performed a post hoc analysis to examine whether the benefit was affected by various baseline factors, including age, sex, and smoking status, and whether it differed by tumor histology. METHODS: Lung cancer death rates were computed as events over person-years of observation; the mortality risk ratio (RR) was defined as the lung cancer death rate in the LDCT versus CXR trial arms. Poisson regression was used to test for interactions of sex, age (< 65 years vs ≥ 65 years), and smoking status (current vs former) with trial arm. Mortality RRs were also computed for specific lung cancer histologies. RESULTS: The overall mortality RR was 0.92 in men and 0.73 in women, with a P value for interaction of .08. RRs were similar for individuals aged < 65 years versus those aged ≥ 65 years (0.82 vs 0.87), and for current versus former smokers (0.81 vs 0.91). By tumor histology, mortality RRs were 0.75 for adenocarcinoma, 0.71 for all non-small cell lung cancers except squamous, 1.23 for squamous cell carcinoma, and 0.90 for small cell carcinoma. RRs were similar for men and women for nonsquamous non-small cell lung cancers (0.71 and 0.70, respectively); women were found to have lower RRs for small cell and squamous cell carcinoma. CONCLUSIONS: A benefit of LDCT did not appear to vary substantially by age or smoking status; there was weak evidence of a differential benefit by sex. A differential benefit across lung cancer histologies may exist.

Who should be included in a clinical trial of screening for bladder cancer?: a decision analysis of data from the Prostate, Lung, Colorectal and Ovarian Cancer Screening Trial.

BACKGROUND: Because of its relatively low incidence, bladder cancer screening might have a better ratio of benefits to harms if it is restricted to a high-risk population. Data from the Prostate, Lung, Colorectal and Ovarian (PLCO) Cancer Screening Trial were used and simple decision analytic techniques were applied to compare different eligibility criteria for a screening trial. METHODS: For a variety of possible eligibility criteria, the percentage of the population aged 55 years to 74 years and classified as being at high risk for developing invasive or high-grade carcinoma, and therefore likely to benefit from screening, was calculated. Regression models were used to calculate a risk score based on age, sex, smoking history, and family history of bladder cancer. The reduction in cases was calculated given hypothetical risk reductions associated with screening. The trade-off between patients screened and tumors avoided was calculated as a net benefit. RESULTS: The 5-year probability of being diagnosed with invasive bladder cancer was 0.24%. Using a risk score > 6 or > 8 as the eligibility criterion for a trial was generally superior to including all older adults. In a typical scenario, a risk score > 6 would result in approximately 25% of the population being screened to prevent 57 invasive or high-grade bladder cancers per 100,000 population; screening the entire population would prevent only an additional 38 cases. CONCLUSIONS: Screening for bladder cancer can be optimized by restricting it to a subgroup of patients considered to be at elevated risk. Different eligibility criteria for a screening trial can be compared rationally using decision-analytic techniques.

Mortality results from a randomized prostate-cancer screening trial.

BACKGROUND: The effect of screening with prostate-specific-antigen (PSA) testing and digital rectal examination on the rate of death from prostate cancer is unknown. This is the first report from the Prostate, Lung, Colorectal, and Ovarian (PLCO) Cancer Screening Trial on prostate-cancer mortality. METHODS: From 1993 through 2001, we randomly assigned 76,693 men at 10 U.S. study centers to receive either annual screening (38,343 subjects) or usual care as the control (38,350 subjects). Men in the screening group were offered annual PSA testing for 6 years and digital rectal examination for 4 years. The subjects and health care providers received the results and decided on the type of follow-up evaluation. Usual care sometimes included screening, as some organizations have recommended. The numbers of all cancers and deaths and causes of death were ascertained. RESULTS: In the screening group, rates of compliance were 85% for PSA testing and 86% for digital rectal examination. Rates of screening in the control group increased from 40% in the first year to 52% in the sixth year for PSA testing and ranged from 41 to 46% for digital rectal examination. After 7 years of follow-up, the incidence of prostate cancer per 10,000 person-years was 116 (2820 cancers) in the screening group and 95 (2322 cancers) in the control group (rate ratio, 1.22; 95% confidence interval [CI], 1.16 to 1.29). The incidence of death per 10,000 person-years was 2.0 (50 deaths) in the screening group and 1.7 (44 deaths) in the control group (rate ratio, 1.13; 95% CI, 0.75 to 1.70). The data at 10 years were 67% complete and consistent with these overall findings. CONCLUSIONS: After 7 to 10 years of follow-up, the rate of death from prostate cancer was very low and did not differ significantly between the two study groups. (ClinicalTrials.gov number, NCT00002540.)

Effect of screening on ovarian cancer mortality: the Prostate, Lung, Colorectal and Ovarian (PLCO) Cancer Screening Randomized Controlled Trial.

CONTEXT: Screening for ovarian cancer with cancer antigen 125 (CA-125) and transvaginal ultrasound has an unknown effect on mortality. OBJECTIVE: To evaluate the effect of screening for ovarian cancer on mortality in the Prostate, Lung, Colorectal and Ovarian (PLCO) Cancer Screening Trial. DESIGN, SETTING, AND PARTICIPANTS: Randomized controlled trial of 78,216 women aged 55 to 74 years assigned to undergo either annual screening (n = 39,105) or usual care (n = 39,111) at 10 screening centers across the United States between November 1993 and July 2001. Intervention The intervention group was offered annual screening with CA-125 for 6 years and transvaginal ultrasound for 4 years. Participants and their health care practitioners received the screening test results and managed evaluation of abnormal results. The usual care group was not offered annual screening with CA-125 for 6 years or transvaginal ultrasound but received their usual medical care. Participants were followed up for a maximum of 13 years (median [range], 12.4 years [10.9-13.0 years]) for cancer diagnoses and death until February 28, 2010. MAIN OUTCOME MEASURES: Mortality from ovarian cancer, including primary peritoneal and fallopian tube cancers. Secondary outcomes included ovarian cancer incidence and complications associated with screening examinations and diagnostic procedures. RESULTS: Ovarian cancer was diagnosed in 212 women (5.7 per 10,000 person-years) in the intervention group and 176 (4.7 per 10,000 person-years) in the usual care group (rate ratio [RR], 1.21; 95% confidence interval [CI], 0.99-1.48). There were 118 deaths caused by ovarian cancer (3.1 per 10,000 person-years) in the intervention group and 100 deaths (2.6 per 10,000 person-years) in the usual care group (mortality RR, 1.18; 95% CI, 0.82-1.71). Of 3285 women with false-positive results, 1080 underwent surgical follow-up; of whom, 163 women experienced at least 1 serious complication (15%). There were 2924 deaths due to other causes (excluding ovarian, colorectal, and lung cancer) (76.6 per 10,000 person-years) in the intervention group and 2914 deaths (76.2 per 10,000 person-years) in the usual care group (RR, 1.01; 95% CI, 0.96-1.06). CONCLUSIONS: Among women in the general US population, simultaneous screening with CA-125 and transvaginal ultrasound compared with usual care did not reduce ovarian cancer mortality. Diagnostic evaluation following a false-positive screening test result was associated with complications. Trial Registration clinicaltrials.gov Identifier: NCT00002540.

Screening by chest radiograph and lung cancer mortality: the Prostate, Lung, Colorectal, and Ovarian (PLCO) randomized trial.

CONTEXT: The effect on mortality of screening for lung cancer with modern chest radiographs is unknown. OBJECTIVE: To evaluate the effect on mortality of screening for lung cancer using radiographs in the Prostate, Lung, Colorectal, and Ovarian (PLCO) Cancer Screening Trial. DESIGN, SETTING, AND PARTICIPANTS: Randomized controlled trial that involved 154,901 participants aged 55 through 74 years, 77,445 of whom were assigned to annual screenings and 77,456 to usual care at 1 of 10 screening centers across the United States between November 1993 and July 2001. The data from a subset of eligible participants for the National Lung Screening Trial (NLST), which compared chest radiograph with spiral computed tomographic (CT) screening, were analyzed. INTERVENTION: Participants in the intervention group were offered annual posteroanterior view chest radiograph for 4 years. Diagnostic follow-up of positive screening results was determined by participants and their health care practitioners. Participants in the usual care group were offered no interventions and received their usual medical care. All diagnosed cancers, deaths, and causes of death were ascertained through the earlier of 13 years of follow-up or until December 31, 2009. MAIN OUTCOME MEASURES: Mortality from lung cancer. Secondary outcomes included lung cancer incidence, complications associated with diagnostic procedures, and all-cause mortality. RESULTS: Screening adherence was 86.6% at baseline and 79% to 84% at years 1 through 3; the rate of screening use in the usual care group was 11%. Cumulative lung cancer incidence rates through 13 years of follow-up were 20.1 per 10,000 person-years in the intervention group and 19.2 per 10,000 person-years in the usual care group (rate ratio [RR]; 1.05, 95% CI, 0.98-1.12). A total of 1213 lung cancer deaths were observed in the intervention group compared with 1230 in usual care group through 13 years (mortality RR, 0.99; 95% CI, 0.87-1.22). Stage and histology were similar between the 2 groups. The RR of mortality for the subset of participants eligible for the NLST, over the same 6-year follow-up period, was 0.94 (95% CI, 0.81-1.10). CONCLUSION: Annual screening with chest radiograph did not reduce lung cancer mortality compared with usual care. TRIAL REGISTRATION: clinicaltrials.gov Identifier: NCT00002540.

Serum prostate-specific antigen hemodilution among obese men undergoing screening in the Prostate, Lung, Colorectal, and Ovarian Cancer Screening Trial.

BACKGROUND: Previous studies have shown an inverse relationship between prostate-specific antigen (PSA) concentration and body mass index (BMI). It has been recently proposed that this relationship may be explained by the larger plasma volume of obese men diluting a fixed amount of PSA (hemodilution effect). We examined this hypothesis in a cohort of men enrolled in the Prostate, Lung, Colorectal, and Ovarian (PLCO) Cancer Screening Trial. METHODS: Of 38,349 men ages 55 to 74 years randomized in PLCO to receive annual PSA and digital rectal examination screening, 28,380 had a baseline PSA, complete demographic information, and no prostate cancer diagnosis within 6 years from baseline. Self-reported height and weight were used to calculate BMI and to estimate plasma volume. PSA mass was estimated as PSA concentration times plasma volume. Multivariable linear regression models were used to investigate the relationship between PSA concentration, plasma volume, PSA mass, and BMI. RESULTS: PSA concentration significantly decreased with increasing BMI (P<0.001); mean PSA values were 1.27, 1.25, 1.18, and 1.07 ng/mL among normal (BMI, 18.5-25), overweight (BMI, 25-30), obese (BMI, 30-35), and morbidly obese (BMI, >35) men, respectively. However, plasma volume also increased with increasing BMI and PSA mass showed no association with BMI, with mean values of 3.78, 3.95, 3.97, and 3.82 microg across the four BMI categories (P=0.10). CONCLUSIONS: This study confirms earlier findings that the inverse relationship between PSA concentration and BMI may be explained by a hemodilution effect. These findings could have implications for prostate cancer screening in large men.

Prostate cancer screening in the Prostate, Lung, Colorectal and Ovarian cancer screening trial: update on findings from the initial four rounds of screening in a randomized trial.

OBJECTIVE: To describe the results of the first four rounds (T0-T3) of prostate cancer screening in the Prostate, Lung, Colorectal and Ovarian (PLCO) cancer screening trial (designed to determine the value of screening in the four cancers), that for prostate cancer is evaluating whether annual screening with prostate-specific antigen (PSA) and a digital rectal examination (DRE) reduces prostate cancer-specific mortality. SUBJECTS AND METHODS: In all, 38 349 men aged 55-74 years were randomized to undergo annual screening with PSA (abnormal >4.0 ng/mL) and a DRE. The follow-up of abnormal screening results was at the discretion of subjects' physicians. PLCO staff obtained records related to diagnostic follow-up of positive screen results. RESULTS: Compliance with screening decreased slightly from 89% at baseline to 85% at T3. Both PSA positivity rates (range 7.7-8.8% at T0-T3) and DRE positivity rates (range 6.8-7.6% at T0-T3) were relatively constant over time. The positive predictive value (PPV) of a PSA level of >4.0 ng/mL decreased from 17.9% at T0 to 10.4-12.3% at T1-T3; the PPV for DRE (in the absence of a positive PSA test) was constant over time (2.9-3.6%). Cancer was diagnosed in 1902 men (4.9%). Screen-detected cancers at T0 (549) were more likely to be clinical stage III/IV (5.8%) and to have a Gleason score of 7-10 (34%) than screen-detected cancers at T1-T3 (1.5-4.2% stage III/IV and 24-27% Gleason score 7-10 among 1054 cases). CONCLUSION: The present findings on serial prostate screening are similar to those reported from other multi-round screening studies. Determining the effect of PSA screening on prostate cancer mortality awaits further follow-up.

Pro-tobacco advertisement exposure among African American smokers: An ecological momentary assessment study.

INTRODUCTION: Many African Americans live in communities with a disproportionately high density of tobacco advertisements compared to Whites. Some research indicates that point-of-sale advertising is associated with impulse purchases of cigarettes and smoking. Ecological Momentary Assessment (EMA) can be used to examine associations between tobacco advertisement exposure and smoking variables in the natural environment. METHODS: Non-treatment seeking African American smokers were given a mobile device for 2weeks (N=56). They were prompted four times per day and responded to questions about recent exposure to tobacco advertisements. Participants were also asked to indicate the number of cigarettes smoked, and if they made any purchase, or an impulse purchase, since the last assessment. Linear mixed models (LMMs) analyzed between- and within-subject associations between exposure and outcomes. RESULTS: Participants reported seeing at least one advertisement on 33% of assessments. Of those assessments, they reported seeing menthol advertisements on 87% of assessments. Between-subject analyses revealed that participants who on average saw more advertisements were generally more likely to report purchasing cigarettes and to purchase cigarettes on impulse. Within-subject analyses revealed that when an individual participant reported seeing more advertisements than usual they were more likely to have reported purchasing cigarettes, making an impulse purchase and smoking more cigarettes during the same period, but not the subsequent time period. CONCLUSIONS: Many African American smokers are frequently exposed to pro-tobacco marketing. Advertisement exposure is cross-sectionally associated with impulse purchases and smoking. Future research should assess prospective associations in more detail.

Career Satisfaction and Perceived Salary Competitiveness among Individuals Who Completed Postdoctoral Research Training in Cancer Prevention.

Studies examining career satisfaction of biomedical scientists are limited, especially in the context of prior postdoctoral training. Here we focused on career satisfaction defined as satisfaction with one's career trajectory and perceived salary competitiveness among a predominantly Ph.D.-trained population of scientists who completed cancer prevention-related postdoctoral training between 1987-2011. National Cancer Institute (NCI) Cancer Prevention Fellowship Program (CPFP) alumni (n = 114), and previous recipients of NCI-sponsored Ruth L. Kirschstein National Research Service Award (NRSA/F32) postdoctoral fellowships (n = 140) completed online surveys. Associations of career satisfaction and perception of salary competitiveness with demographic, training, and employment-related factors were examined using logistic regression. Overall, 61% reported high levels of satisfaction with their career trajectory to-date. Higher salary (odds ratio [OR] = 2.86, 95% confidence interval [95% CI]: 1.07-7.69) and having more leadership roles (OR = 2.26, 95% CI:1.04-4.90) were independently associated with higher career satisfaction. Persons with race/ethnicity other than white (OR = 0.40, 95% CI: 0.20-0.82) or age ≥ 50 (OR = 0.40, 95%CI: 0.17-0.94) had lower career satisfaction levels. There were no statistically significant differences in career satisfaction levels by gender, scientific discipline, or employment sector. 74% perceived their current salary as competitive, but persons with 5-9, or ≥10 years in their current position reported lower levels (OR = 0.31, 95% CI: 0.15-0.65; and OR = 0.37, 95% CI: 0.16-0.87, respectively), as did individuals in government positions (OR = 0.33, 95% CI: 0.11-0.98). These data add to the understanding of career satisfaction of those with advanced training in biomedical research by examining these measures in relation to prior postdoctoral research training and across multiple career sectors.

Comparative effects of DHEA and DHT on gene expression in human LNCaP prostate cancer cells.

BACKGROUND: DHEA is widely used as a dietary supplement in older men. Because DHEA can be converted to androgens or estrogens, such use may promote prostate cancer. In this study, the effects of DHEA were compared with those of DHT using gene expression array profiles in human LNCaP prostate cancer cells. MATERIALS AND METHODS: LNCaP cells were exposed to DHEA (300 nM), DHT (300 nM), or vehicle for 48 h, and mRNA expression was measured using Affymetrix HU-95 gene chips. Gene expression values were sorted in ascending order on the p-values corresponding to the extent of differential RNA expression between control and either hormone treatment. RESULTS: S100 calcium binding protein, neurotensin, 24-dehydrocholesterol reductase, and anterior-gradient 2 homologue were the four most differentially expressed genes (p-values all < 3 x 10(-5)). Nested tests of differential expression revealed lesser effects of DHEA versus DHT treatment (p < 0.01) for the S100 calcium binding protein and neurotensin genes. Microarray findings were confirmed by QRT-PCR. The top 83 genes exhibiting differential expression after DHEA or DHT were used for pathway analysis. DHT decreased expression of more genes involved in intercellular communication, signal transduction, nucleic acid binding and transport, and in structural components, such as myosin and golgin, than DHEA. CONCLUSION: These data revealed consistent, measurable changes in gene expression patterns following treatment of LNCaP prostate cancer cells with DHEA and DHT. Understanding the mechanisms of DHEA versus DHT actions in the prostate may help clarify the separate and interactive effects of androgenic and estrogenic actions in prostate cancer progression.

Serum proteomic profiles suggest celecoxib-modulated targets and response predictors.

Cyclooxygenase-2 is a valid target for cancer prevention and treatment. This has been shown in preclinical and clinical cancer prevention studies by using a cyclooxygenase-2 inhibitor, celecoxib. When used in a randomized cancer prevention clinical trial on patients with the inherited autosomal dominant condition, familial adenomatous polyposis, celecoxib proved efficacious. However, a remarkable heterogeneity in patients' responses to the chemopreventive effects of celecoxib was observed. Proteomic profiling of sera from these patients identified several markers, the expression of which was specifically modulated after treatment with celecoxib. A decision tree algorithm identified classifiers for response to celecoxib with relatively high sensitivity but moderate to low specificity. In particular, a spectral feature at m/z 16,961.4 was identified as a strong discriminator between response and nonresponse to celecoxib at the highest dose.

Ovarian cancer screening in the Prostate, Lung, Colorectal and Ovarian (PLCO) cancer screening trial: findings from the initial screen of a randomized trial.

OBJECTIVE: Ovarian cancer screening with transvaginal ultrasound (TVU) and CA-125 was evaluated in the Prostate, Lung, Colorectal and Ovarian (PLCO) Trial. STUDY DESIGN: This was a randomized controlled trial of screening versus usual care. Baseline screening results are reported. RESULTS: Of 39,115 women randomized to receive screening, 28,816 received at least 1 test. Abnormal TVU was found in 1338 (4.7%), and abnormal CA-125 in 402 (1.4%). Twenty-nine neoplasms were identified (26 ovarian, 2 fallopian, and 1 primary peritoneal neoplasm). Nine were tumors of low malignant potential and 20 were invasive. The positive predictive value for invasive cancer was 3.7% for an abnormal CA-125, 1.0% for an abnormal TVU, and 23.5% if both tests were abnormal. CONCLUSION: The effect of screening on ovarian cancer mortality in the PLCO cohort has yet to be evaluated and will require longer follow-up. Screening identified both early- and late-stage neoplasms, and the predictive value of both tests was relatively low.

Independent Association of Postdoctoral Training with Subsequent Careers in Cancer Prevention.

The purpose of this study was to examine the career paths of alumni from the National Cancer Institute (NCI) Cancer Prevention Fellowship Program (CPFP), a structured in-house postdoctoral training program of 3-4 years duration, and specifically what proportion of the alumni were currently performing cancer prevention-related activities. The analyses here included 119 CPFP alumni and 85 unsuccessful CPFP applicants, all of whom completed postdoctoral training between 1987-2011 and are currently employed. Postdoctoral training experiences and current career outcomes data were collected via online surveys. Differences between groups were assessed using chi-square and Fisher's exact test p-values and subsequent regression analyses adjusted for differences between the groups. Compared to 15.3% of unsuccessful CPFP applicants, 52.1% of CPFP alumni (odds ratio [OR] = 4.99, 95% confidence interval [95% CI): 1.91-13.0) were currently spending the majority of their time working in cancer prevention. Among those doing any cancer prevention-focused work, 54.3% of CPFP alumni spent the majority of their time performing cancer prevention research activities when compared to 25.5% of unsuccessful applicants (OR = 4.26, 95% CI: 1.38-13.2). In addition to the independent effect of the NCI CPFP, scientific discipline, and employment sector were also associated with currently working in cancer prevention and involvement in cancer prevention research-related activities. These results from a structured postdoctoral training program are relevant not only to the cancer prevention community but also to those interested in evaluating alignment of postdoctoral training programs with available and desired career paths more broadly.

Application of the random forest classification algorithm to a SELDI-TOF proteomics study in the setting of a cancer prevention trial.

A thorough discussion of the random forest (RF) algorithm as it relates to a SELDI-TOF proteomics study is presented, with special emphasis on its application for cancer prevention: specifically, what makes it an efficient, yet reliable classifier, and what makes it optimal among the many available approaches. The main body of the paper treats the particulars of how to successfully apply the RF algorithm in a proteomics profiling study to construct a classifier and discover peak intensities most likely responsible for the separation between the classes.

Overview of commonly used bioinformatics methods and their applications.

Bioinformatics, in its broad sense, involves application of computer processes to solve biological problems. A wide range of computational tools are needed to effectively and efficiently process large amounts of data being generated as a result of recent technological innovations in biology and medicine. A number of computational tools have been developed or adapted to deal with the experimental riches of complex and multivariate data and transition from data collection to information or knowledge. These include a wide variety of clustering and classification algorithms, including self-organized maps (SOM), artificial neural networks (ANN), support vector machines (SVM), fuzzy logic, and even hyphenated techniques as neuro-fuzzy networks. These bioinformatics tools are being evaluated and applied in various medical areas including early detection, risk assessment, classification, and prognosis of cancer. The goal of these efforts is to develop and identify bioinformatics methods with optimal sensitivity, specificity, and predictive capabilities.