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Biomedical subjects

R K Ross

Publications and source records attributed to R K Ross.

At least 127 records · Page 7Linked to original sources
PubMed1992

Cigarette smoking and cancers of the renal pelvis and ureter.

A population-based case-control study of renal pelvis and ureter cancers (502 cases, 496 controls) conducted in three areas of the United States found cigarette smoking to be associated with a 3.1-fold increase in risk, with long-term (greater than 45 years) smokers having a 7.2-fold increased risk. Statistically significant dose-response associations were observed for both cancer sites and in both sexes regardless of the measure used: cigarettes per day, duration of use, or pack years. A significant decreasing trend in risk with increasing years quit smoking was also demonstrated for these cancers. Attributable risk estimates indicate that approximately 7 of 10 cancers of the renal pelvis and ureter among men and almost 4 of 10 among women are caused by smoking. The results of this study, the largest to date, confirm that cigarette smoking is the major cause of cancers of the renal pelvis and ureter, and that cessation of smoking could eliminate a large proportion of these tumors.

Carcinoma, Transitional Cell↗
PubMed1992

Dietary beta-carotene, cigarette smoking, and lung cancer in men.

A cohort of 5,080 men living in a retirement community in California (United States) and initially free from lung cancer were followed from June 1981 to December 1989. At recruitment, each study participant completed a mailed questionnaire which requested information on the subject's medical history, use of cigarettes, and usual consumption frequencies during the preceding 12 months of 44 vegetable and fruit items. Men who had never smoked had the highest mean daily intake of beta-carotene (8,505 micrograms), followed by past smokers (7,761 micrograms) and then by current smokers (6,178 micrograms). beta-Carotene intake of the subject's wife was correlated significantly with that of the husband in the 4,018 spouse pairs (r = 0.46; P = 0.0001). Among men with similar smoking habits, dietary beta-carotene intake significantly decreased with the spouse's smoking habit: never, past, and current smokers (P = 0.004; test for linear trend). During 31,477 person-years of follow-up, 125 incident cases of lung cancer were observed among the cohort of 5,080 men. Age-adjusted relative risks for lung cancer were below unity (i.e., demonstrating a reduced risk) for higher relative to lower consumption of beta-carotene, of all vegetables and fruits, and of yellow vegetables alone. However, these relative risks approached or crossed the null value when adjusted for personal smoking.

Aged↗
PubMed1992

Towards a model of acidification effects on waterfowl in Eastern Canada.

Data from 212 lakes in central Ontario were used to examine the relationship between presence of breeding waterfowl and loons and the following lake characteristics: pH, presence of fish, lake area, dissolved organic carbon (DOC) and total phosphorus (TP) concentration. In univariate analyses, the two fish-eating species preferred large, high pH lakes with fish, while insectivorous species showed little consistent pattern of lake association. Logistic regression analyses confirmed that large lake size and presence of fish were important determinants of presence of piscivores, though the residual effect of pH differed between the two species. Broods of three of the four insectivorous species avoided lakes with fish, and independently showed a positive response to pH. By calculating the probability that fish will be present on a lake of given area and pH, it is possible to estimate the net effect of pH change on these waterfowl. Relationships such as those presented here can, with some assumptions, be linked to models of lake acidification to estimate response of waterfowl to predicted changes in acidic deposition.

Journal Article↗
PubMed1992

Stage and delay in breast cancer diagnosis by race, socioeconomic status, age and year.

Information on 23,567 Non-Hispanic White, 2,539 Black, and 2,380 Hispanic breast cancer cases diagnosed between 1977 and 1985 was used to evaluate the risk of late stage diagnosis and long duration of symptoms prior to diagnosis in relation to ethnicity, socioeconomic status, age and year of diagnosis. All data were collected by the University of Southern California Cancer Surveillance Program, the comprehensive population-based incidence registry of Los Angeles County. The results indicate that lower socioeconomic status, Black or Hispanic ethnicity, younger age, and earlier year of diagnosis are risk factors for late stage diagnosis and long duration of symptoms. The effect of ethnicity was not explained by lower SES levels among Black or Hispanic women. After controlling for duration of symptoms, race and SES remained significantly predictive of more advanced stage. More recent diagnosis across the 9 year time frame was not associated with improved stage for those of low SES. These results suggest that increased efforts are needed to reach low SES and Black and Hispanic women with campaigns to improve the stage at which breast cancer is detected.

Adult↗
PubMed1992

Intake of vegetables, fruits, beta-carotene, vitamin C and vitamin supplements and cancer incidence among the elderly: a prospective study.

A cohort of 11,580 residents of a retirement community initially free from cancer were followed from 1981 to 1989. A total of 1,335 incident cancer cases were diagnosed during the period. Relative risks of cancer were calculated for baseline consumption of vegetables, fruits, beta-carotene, dietary vitamin C, and vitamin supplements. After adjustment for age and smoking, no evidence of a protective effect was found for any of the dietary variables in men. However, an inverse association was observed between vitamin C supplement use and bladder cancer risk. In women, reduced cancer risks of all sites combined and of the colon were noted for combined intake of all vegetables and fruits, fruit intake alone, and dietary vitamin C. Supplemental use of vitamins A and C showed a protective effect on colon cancer risk in women. There was some suggestion that beta-carotene intake and supplemental use of vitamin A, C, and E were associated with reduced risk of lung cancer in women, but none of these results were statistically significant. These inverse associations observed in women seem to warrant further investigation, although there was inconsistency in results between the sexes.

Aged↗
PubMed1992

Lp(a) lipoprotein: relationship to cardiovascular disease risk factors, exercise, and estrogen.

OBJECTIVE: Lp(a) lipoprotein is a distinct lipoprotein particle that recently has been found to be associated with cardiovascular disease. A study was conducted to assess the influence of cardiovascular disease risk factors on levels of Lp(a) and to evaluate the effects of age, exercise, and estrogen on these levels. STUDY DESIGN: Two studies, a cross-sectional study of older men (n = 105) and women (n = 75) (mean age 76 years) and a prospective study of younger postmenopausal women (mean age 48 years), were carried out. Lp(a) and other lipoproteins were measured in the two studies and differences were sought by statistical analysis. RESULTS: In the cross-sectional study, serum Lp(a) was similar in men and women and was not influenced by age. Lp(a) levels in men and women were higher when there was more than one cardiovascular disease risk factor present (p less than 0.028). We could not demonstrate such a relationship with other lipid and lipoprotein measurements. In the prospective study exercise alone had no influence on Lp(a) levels. Oral estrogen decreased Lp(a) levels marginally (p = 0.08). The decrease in Lp(a) with oral estrogen was associated with increases in triglycerides (p less than 0.01) and very-low-density lipoprotein (p less than 0.06). CONCLUSIONS: These data confirm that elevated Lp(a) levels are an independent risk factor for cardiovascular disease. Lp(a) levels are primarily influenced by genetic factors and it appears estrogen may have a minor influence on its hepatic synthesis.

Aging↗
PubMed1992

Relationship of hormone use to cancer risk.

Exogenous hormones are widely prescribed in the United States, primarily as oral contraceptives and hormone-replacement therapy. Each of these frequently used categories of drugs has important potential for altering risk of several major human cancers. The efficacy of oral contraceptives in preventing ovarian cancer and endometrial cancer is well established. There remains controversy about the relationship between oral-contraceptive use and breast cancer risk, but most studies show that use in the postmenarcheal and perimenopausal periods is associated with an increased risk of breast cancer in a duration-dependent manner. As with oral contraceptives, the relationship between estrogen-replacement therapy and breast cancer risk is controversial, but several well-designed studies showed a moderate increased risk after long-term use. Estrogen-replacement therapy is a major cause of endometrial cancer. Combination hormone-replacement therapy will probably reduce some of the excess risk of endometrial cancer, but few epidemiological data exist on this relationship. The sparse data suggest that combination therapy may enhance breast cancer risk. As with endometrial and ovarian cancers, hormonal chemoprevention of breast cancer is also feasible. We review two such strategies, ie, gonadotropin-releasing hormone agonists and the antiestrogenic drug tamoxifen.

Adolescent↗
PubMed1991

Toward the primary prevention of cancer.

This is the threshold of an era when many of the most prevalent human cancers can, to a significant extent, be prevented through life-style changes or medical interventions. For lung cancer, the leading cause of cancer deaths in the United States, the major cause, cigarette smoking, is known and strategies for reducing smoking are slowly succeeding. Dietary changes can reduce the risk of developing large bowel cancer, the second most common cancer overall. The etiology of the major cancer in women, cancer of the breast, is sufficiently well understood that large-scale medical intervention trials are imminent. Recent changes in the incidence and mortality of these and the other major human cancers are reviewed with a brief explanation as to why these changes have occurred, followed by a summary of the state of knowledge regarding the major causes of cancer.

Diet↗
PubMed1991

From gene to carcinogen: a rapidly evolving field in molecular epidemiology.

Chemical and physical carcinogens leave footprints of their activities on DNA because of the patterns of base changes they induce. Additionally, the conversion of 5-methylcytosine to thymine in CpG sequences leads to a characteristic mutation which can be used to estimate the contribution of endogenous processes to human mutations. Knowledge of the pattern mutations found in genes commonly mutated in human cancer, such as the p53 tumor suppressor gene, allows for predictions to be made on the likelihood of an exogenous DNA-damaging agent being involved. Working from gene to carcinogen is likely to have a profound impact on our understanding of the origins of human cancer.

Carcinogens↗
PubMed1991

Age at menarche and estrogen concentrations of adult women.

It has recently been reported that women with a recorded early menarche had approximately two-fold greater follicular phase serum E2 (estradiol) levels than women with menarche at age 13 or later. We have evaluated E1 (estrone) and E2 concentrations in the blood, and estrogen concentrations in the urine, in two groups of premenopausal women (mean ages 33 and 38 years) for categories of age at menarche. Study subjects were 106 Caucasian women in the United States (assessed for E1, E2, and urinary estrogens) and 39 women from Shanghai, China (assessed for E2). US subjects were classified according to whether their recalled menarche occurred before age 12, at age 12, or at age 13 or older. The mean age at recalled menarche of the Shanghai subjects was considerably older, and their ages at menarche were classified as less than age 15, age 15, and age 16 or older. We found little evidence in these premenopausal women in their thirties of an effect of age at menarche on estrogen levels. A large-scale study of women in the age range 20-40 years is necessary to investigate this important issue more thoroughly.

Adult↗
PubMed1991

Cancers of the prostate and breast among Japanese and white immigrants in Los Angeles County.

Using age-adjusted incidence rates and proportional incidence ratios, the risks of prostate cancer and breast cancer in three racial/ethnic groups - Spanish-surnamed whites, other whites and Japanese - were studied in Los Angeles County native residents and compared with those in immigrants and representative 'homeland' populations. An algorithm based on social security numbers was developed and utilised to estimate age at immigration for non-US-born Los Angeles County cancer patients. For prostate cancer, the incidence rates in Los Angeles County were much higher than those in the homelands for each racial/ethnic group. However, prostate cancer rates of immigrants were similar to those of US-born patients in the Spanish-surnamed white and Japanese populations, regardless of age at immigration. For breast cancer, the incidence rates in Los Angeles County were also high compared with those in the homelands. However, the timing of immigration to the US was important in determining breast cancer risk. When social security numbers indicated that migration occurred later in life, rates for breast cancer were substantially lower than when migration occurred early, although they were still much higher than in the homeland populations. These findings suggest that environmental factors in early life rather than in later life are important in the etiology of breast cancer and that later life events can substantially impact the likelihood of developing clinically detectable prostate cancer.

Age Factors↗
PubMed1991

Epidemiology of adenocarcinomas of the small intestine: is bile a small bowel carcinogen?

Using pathology reports and other data from the Cancer Surveillance Program, the population-based cancer registry of Los Angeles County, we evaluated demographic characteristics and the detailed subsite distribution of adenocarcinomas of the small intestine for the period 1972-1985. The most striking finding was the great preponderance of these tumours in the duodenum, especially in comparison with other histologic types of small bowel cancers. Fifty percent of all small intestinal adenocarcinomas occurred at this location, even though the duodenum comprises just 4% of the entire length of the small bowel. Furthermore, after excluding those cases occurring in the duodenum but with indeterminate subsite, 57% of these duodenal primaries could be mapped to the 2nd portion of the duodenum, a six to seven centimeter segment containing the Ampulla of Vater. We could pinpoint the location for 48 of the 77 tumours (62%) occurring in this segment, specifically to areas adjacent to the Ampulla. We also confirmed the high male to female ratio of small bowel adenocarcinomas in blacks and non-Latino whites, but could find no evidence of such an effect in Latinos or Asians; however, the number of cases was not large in these latter two racial-ethnic groups.

Adenocarcinoma↗
PubMed1991

Exercise and other factors in the prevention of hip fracture: the Leisure World study.

As part of a prospective study begun in 1981, we evaluated 8,600 postmenopausal women and 5,049 men residing in a southern California retirement community for risk factors for hip fracture. Incidence rates were twice as high in women as in men, but in both sexes the rates nearly doubled every 5 years between 70 and 90 years. Active exercise was strongly and negatively associated with hip fracture risk in both sexes; the age-adjusted relative risk was 0.6 and 0.5 for females and males, respectively, for 1 or more hours of exercise per day compared with less than 1/2 hour of exercise. A high body mass index (upper tertile of weight divided by height squared) was associated with a strong reduction in hip fracture risk for females (RR = 0.5). Current cigarette smokers had a significantly increased risk (RR = 1.8 and RR = 2.2 for females and males, respectively) compared with never-smokers, but the risk for past smokers was not different from that of lifetime nonsmokers. Other factors related to reduced hip fracture risk in women were high parity, late age at menarche, and long menstrual cycle length. These age-adjusted relative risk estimates did not change materially in multivariate analysis when adjusted simultaneously for age, active exercise, body mass, smoking, and, for women, age at menarche and number of children. Among estrogen users, the lowest risk of hip fracture was observed for recent users (RR = 0.8), while users who had stopped estrogen use 15 or more years ago had a relative risk of 1.1, suggesting that the protective effect of estrogen dissipates after many years since cessation of estrogen therapy.

Age Factors↗
PubMed1991

Possible underestimation of the incidence rate of prostate cancer in Japan.

We adjusted the prostate cancer incidence rate in Japan for differences between Japan and the US in the proportion of latent prostate carcinoma identified at autopsy and of localized tumors among all carcinomas of the prostate. The adjusted incidence rate of prostate cancer in Japanese in Japan by this method is estimated to be between 24.9 and 33.3 per 100,000 population, based on incidence rates from the population-based cancer registries of Miyagi, Japan, and Los Angeles and Hawaii, USA. The rate estimated here is almost 3-4 times greater than the rate reported previously. The difference in the incidence rates of prostate cancer between Japanese in Japan and the US (32.2-49.8 per 100,000) may therefore be substantially smaller than previously thought.

Humans↗
PubMed1991

Decreased mortality in users of estrogen replacement therapy.

In a prospective study of 8881 postmenopausal female residents of a retirement community in southern California, we evaluated in detail the relationship between estrogen use and overall mortality. After 7 1/2 years of follow-up, there had been 1447 deaths. Women with a history of estrogen use had 20% lower age-adjusted, all-cause mortality than lifetime nonusers (95% confidence interval, 0.70 to 0.87). Mortality decreased with increasing duration of use and was lower among current users than among women who used estrogens only in the distant past. Current users with more than 15 years of estrogen use had a 40% reduction in their overall mortality. Among oral estrogen users, relative risks of death could not be distinguished by specific dosages of the oral estrogen taken for the longest time. Women who had used estrogen replacement therapy had a reduced mortality from all categories of acute and chronic arteriosclerotic disease and cerebrovascular disease. This group of women had a reduced mortality from cancer, although this reduction was not statistically significant. The mortality from all remaining causes combined was the same in estrogen users and lifetime nonusers.

Aged↗