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Biomedical subjects

R K Peters

Publications and source records attributed to R K Peters.

48 records · Page 3Linked to original sources
PubMed1986

Increased frequency of adenocarcinoma of the uterine cervix in young women in Los Angeles County.

By hypothesizing that oral contraceptives (OC's) might have a carcinogenic effect on glandular cells of the cervix if given during periods of active metaplasia (e.g., postmenarchal adolescence), an increasing rate of cervical adenocarcinoma was predicted in young women who had been teenagers when OC's were introduced roughly 20 years ago. Secular trends for cervical carcinomas in non-Hispanic whites were examined by age, histologic type, and social class by using data from the Los Angeles County population-based tumor registry. Between 1972 and 1982, the frequency of invasive cervical adenocarcinoma in women under 35 years of age increased from about 2 to about 5 annually, amounting to an average rate of change of 8% per year (P less than .01). There was essentially no trend for women over 35 years old; the frequency of other invasive carcinomas (and of squamous carcinoma in situ) decreased at average rates of about 3% per year in women under 35 years of age and decreased more rapidly in older women. The increase in adenocarcinoma, unlike risk from cervical cancer generally, was most striking among young women residing in middle-to-upper income neighborhoods, who were the first to use OC's; in this subgroup the average rate of increase was 16% per year (P less than .05). These findings are compatible with our hypothesis and merit further study.

Adenocarcinoma↗
PubMed1986

Risk factors for invasive cervical cancer among Latinas and non-Latinas in Los Angeles County.

A case-control study among white women in Los Angeles County was conducted to investigate etiologic factors that might explain the high rates of invasive cervical cancer among Latinas. Two hundred patients with invasive squamous cell carcinoma of the uterine cervix and matched (age, sex, preferred language, and neighborhood) controls were interviewed, 98 pairs in English and 102 pairs in Spanish. Seven factors were found to contribute independently and significantly (P less than .01) to risk, each after adjustment for the other six: years since last Pap smear, years of education (protective), frequency-years douching, pack-years of smoking, years of barrier contraceptive use (protective), number of sexual partners before age 20, and recognized episodes of genital warts. An eighth variable, interval in years between menarche and first intercourse, was the second variable to enter the stepwise logistic regression analysis but lost its statistical significance when sexual partners before age 20 entered the model. Together, these eight variables accounted for almost 99% of the risk. There were no significant interactions between any of these variables and age, language of interview, or birth in a Latin country. There was no increased risk associated with use of oral contraceptives, either before or after adjustment for the other significant factors. Compared to English-speaking controls, Spanish-speaking controls smoked less, douched less, had fewer sexual partners before 20, and had essentially the same average interval between menarche and first intercourse and the same average number of episodes of genital warts; however, they had had a longer interval since their last Pap smear, fewer years of barrier contraceptive use, and fewer years of education. Education, presumably a correlate of an inadequately measured etiologic risk factor (possibly papillomavirus infection), was responsible for the greatest difference in risk between the Spanish- and English-speaking cases.

Adolescent↗
PubMed1984

Parallels in the epidemiology of selected anogenital carcinomas.

Characteristics of Los Angeles, Calif., residents in whom carcinomas of the cervix, vulva, vagina, anus, and penis were diagnosed during the period 1972-81 were compared with those of all residents and with those in whom any cancer was diagnosed during the same period. At all five sites, risks for squamous and transitional cell carcinomas generally increased with decreasing social class, were low among Jews (not explained by social class), and were elevated among persons who were separated or divorced at diagnosis compared to married persons. Single men had a striking excess of anal but not penile carcinomas. The five sites represent contiguous and histologically similar tissues, and the clinical literature suggests common risk factors, e.g., sexually transmitted infections and other forms of chronic irritation. These observations are all consistent with the hypothesis that tumors at these sites have common or similar etiologic elements.

Adenocarcinoma↗
PubMed1983

Physical fitness and subsequent myocardial infarction in healthy workers.

Physical work capacity (PWC), a measure of physical fitness, was assessed by bicycle ergometry on 2,779 healthy men younger than 55 years who were subsequently followed up for an average of 4.8 years for symptomatic myocardial infarction (MI). There were 36 MIs. The relative risk (RR) of MI for below median PWC, adjusted for conventional risk factors for heart disease, was 2.2 (95% confidence limits, 1.1 and 4.7). This increased risk appeared to be limited to men with certain other risk factors present simultaneously: above-median cholesterol level, smoking, above-median systolic BP, or a combination of these. Among men with at least two of these factors, the adjusted RR for below-median PWC was 6.6 (95% confidence limits, 2.3 and 27.8). Poor physical fitness may be an important risk factor for heart disease, especially when conventional risk factors are also present.

Adult↗
PubMed1983

Patterns of anal carcinoma by gender and marital status in Los Angeles County.

Marital status and other characteristics of 970 residents of Los Angeles County in whom cancer of the anus (including perianal skin) was diagnosed during the period 1972-1981 were compared with those of all county residents and all other persons in whom cancer was diagnosed during the same period. The incidence rate of anal cancer for single males was 6.1 times that for married males (P less than 0.001). This excess was limited to squamous and transitional cell carcinomas and was reasonably consistent by age, stage, subsite, social class and race. Single women were not at increased risk, but separated and divorced persons of both sexes were at increased risk compared to married persons. Anal cancers were more common in males under the age of 35, after which there was a substantial female predominance. This relative excess in older women occurred at all stages, subsites, and social classes of whites and also in blacks, but not in Hispanics, among whom women had lower overall incidence rates compared to both whites and blacks. The findings were consistent with the hypothesis that sexual activity involving the anus is related to anal cancer. We could not rule out the possibility that anal cancer is related to the acquired immune-deficiency syndrome (AIDS) since the incidence in young single men appears to have increased in 1980 and 1981.

Adenocarcinoma↗
PubMed1978

Mortality among Boston firefighters, 1915--1975.

Although the nature of firefighting involves particular health hazards, previous mortality and morbidity studies of firemen have produced inconsistent evidence for an increased risk of mortality from cardiovascular disease, respiratory disease, cancer and accidents. Mortality experience since 1915 has been examined in 5655 Boston firefighters, comprising all male members of the city fire department with three or more years of service. The observed cause of death as stated on the death certificates of 2470 deceased firefighters has been compared with the numbers expected based on rates for the male population of Massachusetts and of the United States of America. Among all firefighters, deaths from all causes were 91% of expected. The standardised mortality ratio (SMR) was markedly reduced (less than 50) for infectious disease, diabetes, rheumatic heart disease, chronic nephritis, blood diseases and suicide. The SMR was 86 for cardiovascular deaths, 83 for neoplastic deaths, and 93 for respiratory deaths. The SMR for accidents was 135 for active firefighters. The results suggest that the survival experience of firefighters is strongly influenced by strict entry selection procedures, ethnic derivation, and sociocultural attributes of membership. While excessive morbidity has been demonstrated in firefighters, there does not appear to be a strong association between occupation and cause-specific mortality.

Accidents, Occupational↗
PubMed1977

Daily relaxation response breaks in a working population: I. Effects on self-reported measures of health, performance, and well-being.

An experiment conducted at the corporate offices of a manufacturing firm investigated the effects of daily relaxation breaks on five self-reported measures of health, performance, and well-being. For 12 weeks, 126 volunteers filled out daily records and reported bi-weekly for additional measurements. After four weeks of baseline monitoring, they were divided randomly into three groups: Group A was taught a technique for producing the relaxation response; Group B was instructed to sit quiety; Group C received no instructions. Groups A and B were asked to take two 15-minute relaxation breaks daily. After an eight-week experimental period, the greatest mean improvements on every index occurred in Group A; the least improvements occurred in Group C; Group B was intermediate. Differences between the mean changes in Groups A vs C reached statistical significance (p < 0.05) on four of the five indices: Symptoms, Illness Days, Performance, and Sociability-Satisfaction. Improvements on the Happiness-Unhappiness Index were not significantly different among the three groups. The relationship between amount of change and rate of practicing the relaxation response was different for the different indices. While less than three practice periods per week produced little change on any index, two daily sessions appeared to be more practice than was necessary for many individuals to achieve positive changes. Somatic symptoms and performance responded with less practice of the relaxation response than did behavioral symptoms and measures of well-being. (Am. J. Public Health 67:946-953,1977)

Adult↗
PubMed1977

Daily relaxation response breaks in a working population: II. Effects on blood pressure.

A 12-week randomized experiment investigated the effects of daily relaxation breaks on office workers with "normal" blood pressure. Blood pressures of 126 volunteers from the corporate offices of a manufacturing firm were measured biweekly. After four weeks of baseline monitoring,volunteers were divided randomly into three groups: Group A was taught a technique for producing the relaxation response; Group B was "taught" to sit quietly; and Group C was taught nothing. Groups A and B were asked to take two 15-minute relaxation breaks daily. During the baseline period, mean systolic blood pressures (SBP) were 119.7, 118.4, and 114.2 for Groups A, B and C respectively; mean diastolic pressures (DBP) were 78.7 and 75.7 Between the first and last measurements, mean changes in SBP were -11.6, -6.5, and +0.4 mm Hg in Groups A, B, and C; mean DBP decreased by 7.9, 3.1, and 0.3. Between the fourweek baseline period and last four weeks of the experimental period, mean SBP and DBP, mean changes in Group A were significantly greater than those in Group B (p < 0.05) and in Group C (p < 0.001). The same pattern of changes among the three groups was exhibited by both sexes, all ages, and at all initial levels of blood pressure. However, in general, within Group A, the higher the initial blood pressure, the greater the decrease. (Am. J. Public Health 67;954-959, 1977)

Adult↗
PubMedDate not supplied

Temporal stability and overlap of behavioral and questionnaire assessments of type A behavior in coronary patients.

To examine the temporal stability of the Type A behavior pattern (TABP) after a cardiac event, both a Videotaped Clinical Interview (VCI) (formerly known as the Videotaped Structured Interview) and the Jenkins Activity Survey (JAS) were administered to 81 male and 19 female patients three times during the first year after hospitalization for an initial myocardial infarction, coronary artery bypass graft, or both. There was no intervention other than the usual treatment provided by the medical care system. The test-retest reliability coefficients were moderately high for all measures of TABP. The JAS provided the most reliable scores in both sexes. The Hard Driving and Competitive component of the JAS decreased significantly throughout the year in both men (p less than 0.001) and women (p less than 0.01), but in men all three overall indices of TABP and their components (other than Hard Driving and Competitive) decreased spontaneously between 1 and 3 months, and then increased again by 1 year to nearly the original levels. In women, there were no consistent changes over time among the indices other than that for the Hard Driving and Competitive component of the JAS. Intercorrelations among the indices demonstrate the failure of the JAS to assess the Hostility component of the TABP and the possibility that the Speed and Impatience subscale of the JAS measures different things in men and women. The newest method of scoring the VCI appeared to provide the best index for measuring TABP in male coronary patients, while the original scoring was more reliable for women.

Adult↗
PubMedDate not supplied

Computer-assisted rescreening of clinically important false negative cervical smears using the PAPNET Testing System.

OBJECTIVE: To investigate the efficacy of the PAPNET Testing System and its ability to detect significant areas on clinically important false negative gynecologic smears. STUDY DESIGN: Sixty-two gynecologic smears that had been obtained from women studied in a previous case-control investigation, completed in 1987, and had originally been interpreted as negative were rescreened by two independent, blind cytotechnologist-cytopathologist teams. Twenty-nine of these "negative" smears were from 19 women who had been subsequently diagnosed with invasive squamous cell carcinoma and had self-reported a history of only negative gynecologic smears. Thirty-three smears were from 33 control women who did not develop cervical cancer. One team, at the University of Southern California (USC), manually rescreened the smears as part of the original study. The other team, at the University of California at Los Angeles (UCLA), recently used the PAPNET Testing System to rescreen the same smears. This computer-assisted system utilizes neural network technology to recognize and select potentially abnormal cell scenes on a conventionally prepared gynecologic smear. The PAPNET-selected scenes are displayed for review by trained cytologists, who ultimately diagnose the smear. RESULTS: Manual reevaluation of the smears by the USC team in 1987 resulted in the reclassification of 9 of the 29 case smears (31%) and 2 of 33 control smears (6%) as class II to V (atypical squamous cells of undetermined significance to invasive carcinoma). Using the PAPNET System to scan and review the same smears, the cytotechnologist at UCLA referred 24 case smears to the cytopathologist, who ultimately reclassified 12 of the 29 case smears (41%) and 5 of the 33 control smears (15%) as abnormal. CONCLUSION: This study supports the use of the PAPNET System as an effective, routine rescreener for the detection of clinically significant false negative gynecologic smears.

Case-Control Studies↗
PubMedDate not supplied

Wood-dust exposures and cancer of the colon.

Previous studies of workers exposed to wood dusts have shown a decreased risk of cancer of the colon in these workers. However, none of these studies adequately controlled for potential confounders, such as physical activity, diet, and family history of colorectal cancer. The purpose of this case-control study was to evaluate the association between exposure to wood dust and risk for colon cancer after adjusting for potential confounders. Four hundred nineteen male cases of adenocarcinoma of the colon, identified from the Los Angeles County Cancer Surveillance Program, were individually matched to neighborhood controls based on gender and date of birth. Exposure to wood dust was associated with reduced risk of colon cancer that was partially masked before adjustment for confounders, and was limited to workers with frequent exposures that had begun at least 30 years before diagnosis [unadjusted and adjusted ORs, respectively, to exposures 5+ times a week beginning 30+ years before diagnosis = 0.63 (95% CI 0.36-1.13) and 0.39 (95% CI 0.20-0.77)]. This study provides additional evidence that heavy exposure to wood dusts may be associated with reduced risk of colon cancer in males after adjustment for other known causes of colon cancer.

Adenocarcinoma↗