Two case-control studies of Canadian women aged 40-59 years are reported investigating the relation of cigarette smoking with initial visit (prevalent) and subsequent visit (incident) breast cancer detection, respectively, within the Canadian National Breast Screening Study. The analysis of prevalent breast cancer (1982-1985), which involved 254 cases and 762 controls, showed no evidence of an elevated risk for women with a history of cigarette smoking, with odds ratios of 0.9 (95% confidence interval (Cl) 0.6-1.5) and 1.2 (95% Cl 0.8-1.8) in premenopausal and postmenopausal subjects, respectively. Similarly, in the incident breast cancer analysis (1981-1987) based on 317 cases and 951 controls, women with a history of cigarette smoking had odds ratios of 1.2 (95% Cl 0.8-2.0) and 1.2 (95% Cl 0.9-1.7) in the premenopausal and postmenopausal categories, respectively. No evidence of dose response or of elevated risk in ex-smokers or current smokers was found in either study. These results persisted despite adjustment for several important variables. The present data demonstrate no association between smoking and prevalent or incident breast cancer in either menopausal category, contradicting the authors' previous finding of a positive association with premenopausal prevalent disease earlier in this screening study. The relation of smoking and breast cancer remains controversial. Further study is required to determine whether an association truly does not exist or whether smoking might have both protective and harmful effects that are mediated through different pathways, thus accounting for the paradoxical findings in the literature to date.
To compare demographic characteristics, sexual practices, unprotected receptive and insertive anal intercourse, substance use and rates of HIV-1 seroconversion between two prospective cohorts of HIV-negative men who have sex with men.
Comparative analysis of two independent cohorts.
Between May 1995 and April 1996, 235 HIV-negative Vanguard Project (VP) participants were enrolled and between January and December 1985, 263 HIV-negative participants in the Vancouver Lymphadenopathy AIDS Study (VLAS) completed a follow-up visit. The VP participants were compared with VLAS participants with respect to self-reported demographic variables, sexual behaviors, unprotected sex, substance use and rates of HIV-1 seroconversion during follow-up.
In comparison with the VLAS participants the VP participants were younger (median age, 26 versus 34 years; P
To identify determinants of HIV seroconversion among injection drug users (IDUs) during a period of rising prevalence, a case-control investigation was conducted. Cases were IDUs with a new positive test after 1 January 1994, and a negative test within the prior 18 months. Controls required 2 negative tests during the same period. Subjects completed a questionnaire on demographic, psychosocial, and behavioural factors. Eighty-nine cases and 192 controls were similar with respect to gender, age, ethnicity and inter-test interval. Multivariate analyses of events during the inter-test interval showed borrowing syringes (adj. OR = 2.96; P or = 4 times daily (adj. OR = 1.71; P = 0.06) to be independently associated with seroconversion. Protective associations were demonstrated for sex with opposite gender (adj. OR = 0.36; P = 0.001) and tetrahydrocannabinol use (adj. OR = 0.41; P = 0.001). There is a need to evaluate programmes dealing with addiction, housing and the social underpinnings of risk behaviours in this population.
A case-control study of diet and stomach cancer was conducted during 1979-1982 in Toronto, Winnipeg, and St. John's Canada. Two hundred forty-six histologically verified cancer cases were individually matched by age, sex, and area of residence to 246 randomly selected population controls. Daily nutrient consumption values were calculated from quantitative diet history questionnaire data through use of the US Department of Agriculture Food Composition Data Bank, which was extended and modified for Canadian items. For the analysis, continuous conditional logistic regression methods were used. It was found that consumption of dietary fiber was associated with decreased risk of gastric cancer; the odds ratio estimate of trend was 0.40/10 g average daily intake of fiber (i.e., 0.40(1.5)/15 g, etc.) (p less than 10(-8)). Also, average daily consumption of nitrite, chocolate, and carbohydrate was associated with increasing trends in risk, with odds ratio estimates, respectively, 2.6/mg (p less than 10(-4)), 1.8/10 g (p less than 10(-4)), and 1.5/100 g (p = 0.015). While citrus fruit intake appeared to be somewhat protective (odds ratio = 0.75/100 g daily average, p = 0.0056), vitamin C intake was less so, and vitamin E not at all. Thus, a number of dietary components seem to be implicated in the pathogenesis of stomach cancer.
The health and social conditions of women living in Vancouver's Downtown Eastside has recently been the focus of substantial international attention. Since few studies have examined rates and correlates of death among addicted women in Canada, we have characterized patterns of mortality among female injection drug users (IDUs) in Vancouver. The Vancouver Injection Drug Users Study (VIDUS) is a prospective open cohort study of IDUs. The analyses presented here, were restricted to women enrolled between May 1996 and May 2002 and who were aged 14 years or older. We estimated cumulative mortality rates using Kaplan-Meier methods and Cox regression was used to calculate univariate and adjusted relative hazards. Between May 1996 and May 2002, 520 female IDUs have been recruited from the Vancouver area among whom 68 died during the study period. Elevated rates of mortality were observed among those who reported, baseline sex-trade involvement, those with HIV-infection at baseline, and those who lived in unstable housing at baseline (all log-rank: p
We examined factors associated with the subsequent development of AIDS-related Kaposi's sarcoma in a cohort of 353 homosexual men infected with human immunodeficiency virus (HIV). Cumulative incidence curves for the development of Kaposi's sarcoma and opportunistic infection were stratified over a wide range of variables at enrollment, including those related to demographics, sexual behavior, illicit drug use, and medical history. We found no strong associations between any of these variables and the development of opportunistic infection, but two were related to Kaposi's sarcoma: use of nitrite inhalants (relative risk, 2.3; 95% confidence interval, 1.0-5.0) and high numbers of sexual contacts during the period 1978-1982 in the AIDS epidemic centers of San Francisco, Los Angeles, and/or New York (relative risk, 3.5; 95% confidence interval, 1.6-7.6). The latter variables remained independently associated with risk of Kaposi's sarcoma even after multivariate adjustment for a number of classical HIV risk factors. These results are consistent with the hypothesis that Kaposi's sarcoma is caused by a sexually transmitted cofactor that has remained more prevalent in the original epidemic centers. The effect of nitrites could be due to an independent biological mechanism or to enhancement of transmission of the cofactor.
The contributions of food items and food groups as risk factors in a previously reported case-control study of diet and colo-rectal cancer have been analyzed. The study included 348 patients with colon cancer, 194 with rectal cancer, 542 neighbourhood controls individually matched to the cases on the basis of age and sex and a second control series of 535 surgical hospital controls frequency matched to the cases. For colon cancer, as in the previous analysis, the major risk factor was saturated fat, individual food items or groups failing to make a significant contribution to the risk. In particular there was no protective effect of dietary fibre and, for cruciferous vegetables, only a minor protective effect in females. No individual cruciferous vegetable made an important contribution to this effect. For rectal cancer, on the other hand, a significant effect of saturated fat, independent of other food items or groups, was only found for females in the highest consumption category. For males, consumption of eggs, beef and veal significantly increased risk but not consumption of pork, while for females, there was a non-significant increase in risk with consumption of eggs, no increased risk with consumption of beef or veal and a significantly increased risk with consumption of pork. There was no protective effect of dietary fibre or of cruciferous vegetables for rectal cancer, but in females, there was a significantly increased risk for consumption of beer, though this was somewhat reduced when controlled for consumption of saturated fat. There was no indication of an effect of alcohol in either sex or of beer in males. Thus, these results confirm the previous report in showing a significant effect of saturated fat in increasing risk of colon cancer but suggest a contribution of meats to risk of rectal cancer.
In order to identify socioeconomic characteristics associated with slower progression of HIV infection, we conducted a nested case-control study within a cohort of 729 homosexual men. The study compared non-progressors (defined as subjects who, at a follow-up visit during the period October 1989-December 1990, had been HIV positive for at least 5 years, had a CD4 count > 0.5 x 10(9)/l, had a Karnofsky score of 100%, were at Centers for Disease Control (CDC) Stage III or less, and had never received zidovudine or prophylaxis against Pneumocystis carinii pneumonia) with rapid progressors (defined as those who had developed AIDS other than Kaposi's sarcoma within 6 years of seroconversion, or within 5 years of enrollment if already seropositive). Rapidly progressing subjects were matched to non-progressing subjects on the basis of date of enrollment if seroprevalent and date of seroconversion if seroincident. Socioeconomic data were taken from the questionnaire obtained at enrollment into the cohort during 1982-84. There were 41 subjects in each group. A significantly higher proportion of the non-progressors had annual incomes above $10,000, at enrollment (85 vs 62%; p = 0.019). Similarly, a greater proportion of the non-progressors were more likely to have finished secondary school (100 vs 84%; p = 0.020) than rapid progressors. A higher proportion of non-progressors reported employment in management and professional positions (35 vs 15%). The non-progressing group also had a significantly higher socioeconomic index based on self-reported occupation (45.1 vs 38.3; p = 0.035). The association with higher income persisted even after adjustment for baseline CD4 count and symptoms.(ABSTRACT TRUNCATED AT 250 WORDS)
Young gay and bisexual men may perceive that the consequences of HIV infection have dramatically improved with the availability of highly active antiretroviral therapy. We therefore sought to identify trends in HIV infection rates and associated risk behaviours among young gay and bisexual men in Vancouver.
Prospective cohort study involving gay and bisexual men aged 18-30 years who had not previously tested HIV positive. Subjects were recruited through physicians, clinics and community outreach in Vancouver. Annually participants were tested for HIV antibodies and asked to complete a self-administered questionnaire pertaining to sociodemographic characteristics, sexual behaviours and substance use. Prevalence of HIV infection and risk behaviours were determined for eligible participants who completed a baseline questionnaire and HIV testing as of May 1998. The primary outcome was the proportion of men who reported having protected sex during the year before enrollment and who reported any episode of unprotected sex by the time of the first follow-up visit.
A total of 681 men completed a baseline questionnaire and HIV testing as of May 1998. The median duration between baseline and the first follow-up visit was 14 months. The median age was 25 years. Most of the subjects were white and of high socioeconomic status. The majority (549 [80.6%]) reported having sex only with men; 81 (11.9%) reported bisexual activity. Of the 503 men who had one or more regular male partners, 245 (48.7%) reported at least one episode of unprotected anal sex in the year before enrollment; the corresponding number among the 537 who had one or more casual male partners was 140 (26.1%). The prevalence and incidence of HIV seropositivity were 1.8% (95% confidence interval [CI] 0.8%-2.8%) and 1.7 per 100 person-years [95% CI 0.7-2.7], respectively. Fifty-two (26.5%) of the 196 and 55 (29.7%) of the 185 men with regular partners who reported having practiced protected insertive and receptive anal sex in the year before the baseline visit reported engaging in these activities without a condom at the follow-up visit; the corresponding numbers among the 232 and 242 men with causal partners who had practiced protected insertive and receptive anal sex before the baseline visit were 43 (15.5%) and 26 (9.4%) respectively at follow-up.
The incidence of HIV infection is unacceptably high among this cohort of young gay and bisexual men. Preliminary results suggest a disturbing trend toward increasing levels of unprotected anal intercourse.