Intentional tanning among adolescents in seven Canadian provinces: Provincial comparisons (CRAYS 2015).

This report explores intentional tanning behaviors among Canadian high school students in light of provincial restrictions on UV tanning device use among youth. Data are from the Cancer Risk Assessment in Youth Survey (CRAYS), collected from January to December 2015, at randomly selected high schools in 7 provinces. Relevant variables were: tanning methods ever used, demographics, and location and refusal of UV tanning device (beds, lamps) use in the past 12 months. Data were weighted so total survey weights by male/female, grade and province equal actual enrolments in these groups. Analyses were conducted in SAS, mostly for grades 10 and 11. Rao-Scott chi squared tests and p-values were calculated. Among 6803 grade 10 and 11 participants, 82% tanned intentionally, mostly by being/playing outside, or laying in the sun. Spray/self-tanners were used by 15% of participants. UV tanning device use was uncommon (4.4%), lowest in Ontario (2.7%) and British Columbia (3.8%), which have legislation against use among youth. Of 202 who used UV tanning devices in the past 12 months, most did at salons/studios (85%), 35% at home and 30% at a gym. Two hundred and forty-nine participants (3.4%) were refused use of UV tanning devices in the past 12 months. While legislation appears to deter UV tanning device use, it appears to have no impact on UV exposure among high school students overall. Greater prevention efforts are required to deter intentional tanning among high school students.

Tanning among Ontario adolescents pre-legislation: Prevalence and beliefs.

To establish adolescent tanning beliefs and behaviors, prevalence and location of UV tanning device (beds/lamps) use, awareness of risk and restriction signage, and frequency of tanning service refusal, noting differences by grade and sex, prior to a ban on UV tanning device use among those under 18 in Ontario, Canada. Data were collected May 5 to 20 of 2014. Children in grades 7 to 12, and under age 18 completed an on-line questionnaire that asked their age, sex, grade, methods used to tan, frequency, length and location of UV tanning device use, if services were refused and why, awareness and content of signs/warning labels, tanning beliefs and knowledge, and use of eye protection. Of 1561 participants (10% response rate), 49% were male, 51% female. There were significant differences between the sexes regarding tanning behaviors (e.g. not tanning, tanning outside). Seven percent (108) had 'ever' used UV tanning devices, females more than males (p=0.0026). Over half (57%) of the 104 using UV tanning devices in the past 12months noticed warning signs/labels, of which most noticed that UV tanning devices can cause cancer (65%), and that UV exposure can contribute to premature aging (67%). While most (66%) tanned at tanning salons/studios and beauty salons/studios, gyms/fitness clubs (35%) and home use were common (25%). A relatively low proportion of adolescents used UV tanning devices prior to the ban, with use more common among females and those in higher grades.

Sociodemographic factors associated with cervical cancer screening coverage and follow-up of high grade abnormal results in a population-based cohort.

INTRODUCTION: A cervical cytology based screening program is effective if there is regular screening of the 'at risk' population and close follow-up of those labeled abnormal. METHODS: This is a population cohort study of women between 20-69 year old who were eligible in Ontario from 2008-2010. We used administrative data to evaluate the rates of cervical cancer screening and follow-up of high grade Pap tests. Variation in cervical cytology coverage and follow-up of high grade abnormal results are associated with age, area level income and health region. Multivariate logistic regression was used to identify independent factors associated with screening and followup. RESULTS: 3.7million women were eligible for screening of which 72% had a Pap smear in the prior 3years. These rates varied by age, income and region (p<0.0001). Women residing in the lowest income neighborhoods were half as likely to be screened (p<0.0001). 83% of those with an high grade intraepithelial lesion Pap test result had follow-up with colposcopy or treatment within 6months and this varied by year, age, income and region (p<0.0001). CONCLUSIONS: Despite universal health coverage, cervical cancer screening rates are suboptimal with older and low income women being at greatest risk. Follow-up among women with high grade abnormal tests is mediocre at 3months and acceptable at 6months. Novel models of cervical cancer screening program implementation are needed to address these inadequacies.

Cancer survival in Australia, Canada, Denmark, Norway, Sweden, and the UK, 1995-2007 (the International Cancer Benchmarking Partnership): an analysis of population-based cancer registry data.

BACKGROUND: Cancer survival is a key measure of the effectiveness of health-care systems. Persistent regional and international differences in survival represent many avoidable deaths. Differences in survival have prompted or guided cancer control strategies. This is the first study in a programme to investigate international survival disparities, with the aim of informing health policy to raise standards and reduce inequalities in survival. METHODS: Data from population-based cancer registries in 12 jurisdictions in six countries were provided for 2·4 million adults diagnosed with primary colorectal, lung, breast (women), or ovarian cancer during 1995-2007, with follow-up to Dec 31, 2007. Data quality control and analyses were done centrally with a common protocol, overseen by external experts. We estimated 1-year and 5-year relative survival, constructing 252 complete life tables to control for background mortality by age, sex, and calendar year. We report age-specific and age-standardised relative survival at 1 and 5 years, and 5-year survival conditional on survival to the first anniversary of diagnosis. We also examined incidence and mortality trends during 1985-2005. FINDINGS: Relative survival improved during 1995-2007 for all four cancers in all jurisdictions. Survival was persistently higher in Australia, Canada, and Sweden, intermediate in Norway, and lower in Denmark, England, Northern Ireland, and Wales, particularly in the first year after diagnosis and for patients aged 65 years and older. International differences narrowed at all ages for breast cancer, from about 9% to 5% at 1 year and from about 14% to 8% at 5 years, but less or not at all for the other cancers. For colorectal cancer, the international range narrowed only for patients aged 65 years and older, by 2-6% at 1 year and by 2-3% at 5 years. INTERPRETATION: Up-to-date survival trends show increases but persistent differences between countries. Trends in cancer incidence and mortality are broadly consistent with these trends in survival. Data quality and changes in classification are not likely explanations. The patterns are consistent with later diagnosis or differences in treatment, particularly in Denmark and the UK, and in patients aged 65 years and older. FUNDING: Department of Health, England; and Cancer Research UK.

Dietary fat intake and risk of epithelial ovarian cancer.

BACKGROUND: Evidence exists that dietary fat may be a contributory factor in the development of hormone-related cancers such as ovarian cancer. Previous studies have demonstrated significantly higher circulating-estrogen levels among nonvegetarian women than among vegetarian women; the increase correlated directly with consumption of saturated fat. However, the contribution that dietary fat plays in the development of hormone-related cancers remains unresolved. PURPOSE: Our purpose was to evaluate whether saturated fat intake increases the risk of ovarian cancer development. METHODS: Population-based sampling was used to acquire cases and controls over a 3-year period from the study area, which included the highly populated region surrounding the western end of Lake Ontario, Canada. From the Ontario Cancer Registry, all histologically confirmed, primary malignant or borderline malignant epithelial ovarian tumors first diagnosed from November 1989 through October 1992 among study-area residents aged 35-79 years were determined. In total, 631 eligible case subjects were identified, of whom 450 (71.3%) were interviewed concerning reproduction and diet; 564 randomly selected population control subjects were similarly interviewed. From the quantitative diet-history information, average daily intakes of macronutrients and micronutrients were calculated. Unconditional continuous logistic regression methods were used for analysis, with adjustment for age at interview, number of full-term pregnancies, years of oral contraceptive use, and total daily caloric intake. RESULTS: Saturated fat consumption was associated with increasing risk of ovarian cancer (odds ratio [OR] = 1.20 for each 10 g/day of intake; 95% confidence interval [CI] = 1.03-1.40; one-sided P = .0082). No relationship was seen with intake of unsaturated fats. Egg consumption also appeared related to increased risk (OR = 1.42 for each 100 mg of egg cholesterol per day; 95% CI = 1.18-1.72; two-sided P = .0002), though this association may have resulted from disease-related changes in the dietary practices of case subjects prior to diagnosis. Consumption of vegetable fiber (but not fruit or cereal fiber) was associated with decreased risk (OR = 0.63 for each 10 g/day; 95% CI = 0.49-0.80; two-sided P = .0001). All three nutrients (saturated fat, egg cholesterol, and vegetable fiber) remained statistically significant when included in the same regression model. CONCLUSION: Diet may contribute to risk of ovarian cancer development. IMPLICATION: If confirmed in further studies, this association may allow women to appreciably lower their risk of ovarian cancer through dietary modifications: reducing the intake of saturated fats and eating more vegetables.

Bladder tumor incidence among workers exposed to benzidine: a thirty-year follow-up.

Linkage with records of the Connecticut Tumor Registry was used to determine cancer incidence in a cohort of workers (n = 984) at a benzidine manufacturing facility. Compared to the findings for the Connecticut population, there was a statistically significant excess of bladder tumor among male cohort members [standardized incidence ratio (SIR) = 343; 95% confidence limits (CL) = 148, 676; n = 830], which was confined to those with the highest estimated level of benzidine exposure (SIR = 1,303; CL = 479, 2,839; n = 105). No significantly elevated risks were found for cancers at other anatomic sites in men or at any anatomic sites in women; nor was there any pattern of increasing risk with increasing benzidine exposure for sites other than bladder. In addition, the elevated bladder cancer risk was greater for men first employed during the earliest years of the plant, namely, 1945-49 (SIR = 976; CL = 262, 2,498) as compared to those first employed in 1950-54 (SIR = 213; CL = 3, 1,184) after equalization of duration of follow-up. These results suggest that the major preventive measures instituted around 1950 may have reduced bladder cancer risk in this plant.

Changing cigarette habits and bladder cancer risk: a case-control study.

With the use of data from the 8,764 subjects in the National Bladder Cancer Study, the separate contribution of various aspects of a person's cigarette smoking history to his increased risk of bladder cancer was estimated. These estimates have not been previously available, owing to the smaller sizes of earlier studies. Our data indicated that people who have only smoked unfiltered cigarettes have higher risks than those who have only smoked filtered cigarettes but that people who have switched from unfiltered to filtered have experienced no reduction in risk. Our data also indicated that smoking cessation substantially reduced the risk. The former smoker appeared to benefit both because he stopped adding to the burden of irreversible damage and because he ceased being exposed to some reversible hazard. Thus the former smoker had a lower risk than the current smoker even though they had smoked the same number of cigarettes daily for the same number of years, but the former smoker's risk remained higher than the risk of a person who never smoked. Our data suggest that one-half of the bladder cancer occurring among men in the United States and one-third of that among women is caused by cigarette smoking.

Bladder cancer, drinking water source, and tap water consumption: a case-control study.

Data from a population-based case-control interview study of incident bladder cancer in 10 areas of the United States were used to estimate relative risks among white men (2,116 cases, 3,892 controls) and women (689 cases, 1,366 controls) according to beverage intake level and type of water source. Individual year-by-year profiles of water source and treatment were developed by linking lifetime residential information with historical water utility data from an ancillary survey. Risk of bladder cancer increased with intake level of beverages made with tap water. The odds ratio (OR) for the highest vs. lowest quintile of tap water consumption was 1.43 [95% confidence interval (CI) = 1.23, 1.67; chi 2 for trend = 26.3, P less than .001]. The risk gradient with intake was restricted to persons with at least a 40-year exposure to chlorinated surface water and was not found among long-term users of nonchlorinated ground water. The ORs for the highest vs. lowest quintiles of tap water intake were 1.7 and 2.0, respectively, among subjects with 40-59 and greater than or equal to 60 years' exposure. Duration of exposure to chlorinated surface water was associated with bladder cancer risk among women and nonsmokers of both sexes. Among non-smoking respondents with tap water consumption above the population median, the OR increased with exposure duration to a level of 3.1 (CI = 1.3, 7.3; chi 2 for trend = 6.3, P = .01) for greater than or equal to 60 years of residence at places served by chlorinated surface water (vs. non-chlorinated ground water users). These results extend findings of earlier epidemiologic studies and are consistent with environmental chemistry and toxicologic data demonstrating the presence of genotoxic by-products of chlorine disinfection in treated surface waters.

Use of hair dyes and risk of bladder cancer.

The relation between use of hair dyes and risk of bladder cancer was assessed using data from a case-control study of bladder cancer. Incident cases (2982) and general population controls (5782) were interviewed. The overall estimate of relative risk of bladder cancer for users of hair dyes was 1.0 (95%) confidence interval, 0.9 to 1.2) compared to nonusers. No consistent pattern of association was detected between bladder cancer risk and various indices of timing or intensity of exposure to hair dyes. Various explanations of the lack of association are discussed.

Case-control study of colon and rectal cancers and chlorination by-products in treated water.

This population-based case-control study was conducted in southern Ontario, Canada from 1992 to 1994 to assess the relationship between chlorination by-products in public water supplies and cancers of the colon and rectum. Interviews providing residence and water source histories were completed by 76% of eligible cancer cases and 72% of eligible controls. Supplemental data from municipal water supplies were used to estimate individual exposure to water source, chlorination status, and by-product levels as represented by trihalomethanes (THMs) during the 40-year period before the interview. The analyses included 767 colon cases, 661 rectal cases, and 1545 controls with exposure information for at least 30 of these years (75% of subjects with completed interviews). Among males, colon cancer risk was associated with cumulative exposure to THMs, duration of exposure to chlorinated surface water, and duration of exposure to a THM level > or = 50 microg/liter and 75 microg/liter. Males exposed to chlorinated surface water for 35-40 years had an increased risk of colon cancer compared with those exposed for < 10 years (odds ratio, 1.53; 95% confidence interval, 1.13-2.09). Males exposed to an estimated THM level of 75 microg/liter for > or = 35 years had double the risk of those exposed for < 10 years (odds ratio, 2.10; 95% confidence interval, 1.21-3.66). In contrast, these relationships were not observed among females. No relationship was observed between rectal cancer risk and any of the measures of exposure to chlorination by-products. The results of this study should be interpreted with caution because they are only partially congruent with the limited amount of literature addressing this issue.

Cancer incidence registration and trends in Ontario.

The Ontario Cancer Registry (OCR) contains information on the incidence, mortality and survival of cancer in Ontario. The OCR refers to the population of Ontario, which is currently more than 9 million people. Cancer registration is accomplished by the computerised linkage of records collected routinely for other purposes. Incidence data are available from the OCR beginning in 1964. Incidence rates, age-standardised to the World Standard Population, are presented for Ontario in two recent 5-year periods (1979-1983 and 1984-1988). Age-specific rates are also presented for selected sites. The most common cancer sites, in terms of Ontario incidence rates, were similar to those reported from other registries. In males, these were cancers of the lung, prostate, colon, bladder and rectum. In females, these were cancers of the breast, lung, colon, body of the uterus and ovary. The potential effects of changes in medical services, screening practices and risk factor prevalence on the incidence rates and trends are discussed.

The effect on response rates of offering a small incentive with a mailed questionnaire.

To determine whether response rates to a mailed questionnaire sent to population control subjects could be increased through offer of a small incentive, half of the control subjects (n = 477) in a case-control study of renal cell carcinoma were randomly selected to receive a contact letter offering a lottery ticket if a completed questionnaire was returned; the remaining subjects (n = 477) received the same letter but with no mention of a lottery ticket. Overall response rates did not differ between the two groups (72.6% versus 74.4%), although a higher percentage of those offered a lottery ticket responded without follow-up (24.4% versus 18.5%). Binomial regression modeling of the effect of the lottery ticket offer, sex, age, and percent of urban dwellers on response indicated a significant effect only for percent of urban dwellers, the rate of response increasing with a decreasing percentage of urban dwellers. The effect of sex was of borderline significance (P = 0.05), with females having the higher rate of response.

Reliability of interviewer and subject assessments of nevus counts in a study of melanoma.

Several types of data are presented concerning the reliability of counting or estimating the density of nevi (moles), a major risk factor for melanoma, using methods typically employed in epidemiologic studies. First, interviewer-derived counts of nevi on the arm produced estimates of inter-observer, inter-subject, temporal and random variability, and their interactions. Second, interviewer-derived arm counts and respondent self-reports of whole body nevus density were compared. Finally, we compared male and female cases and controls with respect to their reported rates of having a relative with a malignant mole. Overall, the intra-observer reliability ranged from 55 to 81%, and was better for observers with more experience. The correlation between the interviewer counts and respondents' self-reported estimates was 0.41. The data on malignant moles in relatives suggest higher reporting rates in male cases and lower reporting in male controls relative to their female counterparts, but there is little difference by sex in the reporting of one's own nevus density.

An application of capture-recapture methods to the estimation of completeness of cancer registration.

Completeness of cancer registration has not been consistently ascertained across different registries. This report describes how capture-recapture methods have been used to estimate completeness at the Ontario Cancer Registry. The method was applied in two fashions; first, using three data sources in a modeling approach: and second, using two data sources and standard, simple capture-recapture methods. The modeling approach is more flexible, since several variables that influence cancer registration can be considered and can be used to identify reporting patterns of different data sources. In the present analysis, estimates of completeness of the registry as a whole were remarkably similar using either two or three data sources, and site-specific comparisons differed by at most 7%. Because of the advantages of capture-recapture methods-estimation of level of completeness, possible comparability of estimates across different registries, and versatility to consider other determinants of cancer registration-a plea for greater use of these methods in cancer registration is made.

Do larger people have more naevi? Naevus frequency versus naevus density.

BACKGROUND: It is unclear which of the number or the density of naevi on the skin is the more appropriate measure of risk of melanoma. Furthermore, the relationship between the number of naevi and their density in an individual has not been explored. Thus, for example, it is unknown if larger people tend to have more naevi by virtue of having a larger skin area, or if the density of naevi is similar in people of different body sizes. In this study, we explored the relationship between the number and the density of naevi in a sample of adolescents. SUBJECTS AND METHODS: A sample survey of naevi in 472 grade 9 secondary school students (aged 14-15 years) was conducted in Tasmania, Australia during 1992, and a subset of these individuals was followed up in 1997. Counts of naevi of various sizes were taken on the arm, leg, and back. Naevus density was estimated by using an algorithm to estimate body surface area from the height and weight of an individual. More general relationships of the naevus counts to height and weight were also explored. Finally, we considered whether the relationship between naevus density and the anthropometric variables could be confounded by exposure to ultraviolet radiation. RESULTS: The mean number of naevi was very similar in the two samples. Naevus density was slightly lower in the 1997 sample, mainly because of increasing body size in the cohort. The numbers of naevi were only weakly related to height and weight in males, and there was essentially no relationship in females. Regression analysis showed significant relationships of weight to the back naevus counts in males in 1992 and 1997, and to the arm naevus count in males in 1997; otherwise, none of the regression coefficients for height and weight were statistically significant. This picture did not change following adjustment for potentially confounding variables indicating time spent outdoors or in the sun. Furthermore, there was no evidence that time spent in the sun was related to the body mass index. CONCLUSIONS: It appears that the number and density of naevi in an individual are unrelated. Accordingly, with the present state of knowledge concerning the risk of melanoma, both the number and density of naevi should be considered as equally valid in future studies as markers of the risk of melanoma, and in studies on the natural history of naevi. If the disease mechanism is systemic, and not related to particular naevi, naevus density might form the better marker of risk. However, if the disease mechanism is related to effects on particular naevi, then the risk would vary in proportion to the number of naevi.

Association of cutaneous malignant melanoma with intermittent exposure to ultraviolet radiation: results of a case-control study in Ontario, Canada.

BACKGROUND: Although solar radiation is well established as a risk factor for melanoma, it is less clear how the pattern and timing of exposure to ultraviolet (UV) radiation might be important. The particular objective of this study was to evaluate the association of melanoma risk with various measures of intermittent and chronic exposures to UV radiation, and to assess how these exposures interact with other risk factors such as skin type. METHODS: Data were analysed from a large case-control study (583 cases, 608 controls) of malignant melanoma, carried out in southern Ontario, Canada. RESULTS: Significant risk increases were identified with several measures of intermittent exposure, including beach vacations in adolescence and in the past 5 years, previous sunburn, and use of sunbeds and sunlamps. Chronic exposure, indicated by days of outdoor activity during adolescence and by occupation in recent adult life, was associated with significantly reduced risk. Subgroup analyses showed: no major risk differences by body site of melanoma; stronger association of lentigo maligna melanoma with intermittent exposure; more pronounced effects of beach vacations and sunburn in younger subjects; and consistently higher risks for intermittent exposures among subjects with skin more susceptible to burning. CONCLUSIONS: The data lend limited support to the hypothesis of increased risk associated with intermittent UV exposure. The findings suggest that future studies should take age at diagnosis, host susceptibility and histological subtype into account.

Coffee and tea consumption and cancers of the bladder, colon and rectum.

Coffee has been observed to be associated weakly or not at all with bladder cancer risk, inversely with colon cancer risk, and inconsistently with rectal cancer risk. The association between these cancers and consumption of coffee and tea was examined in a single case-control study conducted in Ontario, Canada from 1992 to 1994. A questionnaire was filled out by 927 bladder cancer cases, 991 colon cancer cases, 875 rectal cancer cases, and 2118 population controls. Although bladder cancer risk was not associated with coffee or tea, risk estimates associated with coffee among subjects who had never smoked were non-significantly increased. Colon cancer risk was inversely associated with coffee. Relative to those drinking less than 1 cup of coffee per day, the odds ratios (OR) for those drinking 1-2 cups was 0.9 (95% CI 0.8-1.1), for those drinking 3-4 cups was 0.8 (95% CI 0.7-1.0), and for those drinking 5 or more cups was 0.7 (95% CI 0.5-0.9); these ORs decreased linearly (P = 0.008). The reduced risk estimates were more pronounced with cancer of the proximal colon than the distal colon. Rectal cancer risk was not associated with either coffee or tea. Coffee consumption was observed to have a different relationship for each of the cancer sites and tea consumption was not related to any cancer site.

Parental occupational exposure and the risk of testicular cancer in Ontario.

The incidence of germ cell testicular cancer is increasing, but its etiology remains largely unknown. Initiation may occur in a parental germ cell. In a case-control study in Ontario, jobs and industries of mothers (before and during pregnancy) and fathers (before pregnancy) of 343 case subjects and 524 control subjects were analyzed. Significantly increased risk was associated with fathers who were wood processors (odds ratio [OR] = 10.46; 95% confidence interval [CI], 1.20 to 91.14), metalworkers (OR = 3.28; 95% CI, 1.03 to 10.52), stationary engineers (OR = 1.05; 95% CI, 1.05 to 11.87), or employees of the food products (OR = 2.79; 95% CI, 1.34 to 5.79), metal products (OR = 5.77, 95% CI, 1.53 to 21.77), or food and beverage services (OR = 4.36; 95% CI, 1.50 to 12.63) industries. There was little evidence of risk associated with maternal employment. Paternal employment before conception in jobs related particularly to metal or food and beverages may be related to testicular cancer risk in sons.

Occupation and risk of germ cell testicular cancer by histologic type in Ontario.

Incidence of both major histologic subgroups of germ cell testicular cancer, seminoma and nonseminoma, is increasing, but the etiology is largely unknown. Occupational clusters have been observed. In a case-control study in Ontario with 495 incident cases and 974 population control subjects, jobs and industries were coded and analyzed. There is little evidence of occupational risk for all cases or for seminoma. Significantly increased risk of nonseminoma was associated with: miners (odds ratio [OR] = 12.39; 95% confidence interval [CI], 2.22 to 69.27), food and beverage processors (OR = 3.20; 95% CI, 1.39 to 7.35), utilities employees (OR = 3.15; 95% CI, 1.15 to 8.61), and other service workers (OR = 1.05; 95% CI, 1.05 to 4.56). Leather-industry employees had elevated risk of nonseminoma (OR = 4.60; 95% CI, 0.75 to 28.28) consistent with a leather tannery cluster. Increased risk of nonseminoma among some workers can be explained if an additional event is required for converting seminoma to nonseminoma.

An analysis of the geographic variation in cancer incidence and its determinants in Ontario.

Cancer incidence data for the Ontario Public Health Units in 1980-91 were examined to investigate regional patterns and the existence of outlier values after adjustment for known risk factors. Candidate risk factors were derived from the Ontario Health Survey and the census. Weighted regressions were fit to the data, and the spatial pattern of the residuals was analyzed. The number of outlier data points with significant elevations or reductions in risk was close to that expected by chance. They were dispersed geographically, and occurred in a variety of cancer types. We conclude that, in general, most of the geographic variation in cancer risk can be associated with variation in known risk factors, and that there appear to be no broad regional effects remaining after adjustment for these factors. A few cancer sites provide limited evidence of regional effects that may warrant further investigation.