Influence of human papillomavirus type 16 (HPV-16) E2 polymorphism on quantification of HPV-16 episomal and integrated DNA in cervicovaginal lavages from women with cervical intraepithelial neoplasia

Integrated human papillomavirus type 16 (HPV-16) viral loads are currently estimated by quantification with real-time PCR of HPV-16 E6 (RT-E6 and HPV-16 PG) and E2 (RT-E2-1) DNA. We assessed the influence of HPV-16 E2 polymorphism on quantification of integrated HPV-16 DNA in anogenital specimens. HPV-16 E2 was sequenced from 135 isolates (123 from European and 12 from non-European lineages). An assay targeting conserved HPV-16 E2 sequences (RT-E2-2) was optimized and applied with RT-E6 and RT-E2-1 on 139 HPV-16-positive cervicovaginal lavages collected from 74 women [58 human immunodeficiency virus (HIV)-seropositive and 16 HIV-seronegative]. Ratios of HPV-16 copies measured with RT-E2-2 and RT-E2-1 obtained with African 2 (median=3.23, range=1.92-3.49) or Asian-American (median=3.78, range=1.47-37) isolates were greater than those obtained with European isolates (median=1.02, range=0.64-1.80; P<0.02 for each comparison). The distribution of HPV-16 E2 copies measured in 139 samples with RT-E2-2 (median=6150) and RT-E2-1 (median=8960) were different (P<0.0001). The risk of high-grade cervical intraepithelial neoplasia (CIN-2,3) compared with women without CIN was increased with higher HPV-16 total [odds ratio (OR)=2.17, 95 % confidence interval (CI)=1.11-4.23], episomal (OR=2.14, 95 % CI=1.09-4.19), but not for HPV-16 integrated viral load (OR=1.71, 95 % CI=0.90-3.26), after controlling for age, race, CD4 count, HIV and HPV-16 polymorphism. The proportion of samples with an E6/E2 ratio >2 in women without squamous intraepithelial lesion (7 of 35) was similar to that of women with CIN-2,3 (5 of 11, P=0.24) or CIN-1 (5 of 14, P=0.50). HPV-16 E2 polymorphism was a significant factor that influenced measures of HPV-16 integrated viral load.

Selected class I and class II HLA alleles and haplotypes and risk of high-grade cervical intraepithelial neoplasia

Human leukocyte antigens (HLAs) present foreign antigens to the immune system and may be important determinants of cervical neoplasia. Previously published associations between HLA and cervical neoplasia exhibit considerable variation in findings. The biomarkers of cervical cancer risk (BCCR) case-control study addressed the role of specific HLA alleles as cofactors in the development of high-grade cervical intraepithelial neoplasia (HG-CIN) based on the most consistent evidence from published literature. Cases (N = 381) were women with histologically-confirmed HG-CIN attending colposcopy clinics and controls (N = 884) were women from outpatient clinics with normal cytological screening smears. Subjects were mainly of French-Canadian descent. Cervical specimens were tested for human papillomavirus (HPV) DNA and HLA genotypes by PGMY L1 consensus primer PCR and a PCR sequence-specific primer method, respectively. Unlike other studies, the DQB1*03 and DRB1*13 allele groups were not associated with risk of HG-CIN. The B7-DRB1*1501-DQB1*0602 haplotype was associated with a 41% overall reduction in HG-CIN risk (odds ratio [OR] = 0.59; 95% confidence interval [CI]: 0.36-0.96), and an 83% reduction in risk of HG-CIN among HPV 16 or HPV 18-positive subjects (OR = 0.17; 95%CI: 0.05-0.54). Paradoxically, however, the same haplotype was associated with HPV 16/18 infection risk among controls (OR = 8.44, 95%CI: 1.12-63.73). In conclusion, the B7-DRB1*1501-DQB1*0602 haplotype was protective against HG-CIN, especially in individuals infected with oncogenic HPV, but the mechanism of the association seems to involve multiple steps in the natural history of HPV and CIN.

Meat consumption and cancer risk

The authors review the key studies on the association between meat intake and cancer risk, including a new prospective cohort study by Amanda Cross and colleagues published inPLoS Medicine.

Fruits, Vegetables, and Colon Cancer Risk in a Pooled Analysis of 14 Cohort Studies

BACKGROUND

Fruit and vegetable intakes have been associated with a reduced risk of colon cancer; however, in more recent studies associations have been less consistent. Statistical power to examine associations by colon site has been limited in previous studies.

METHODS

Fruit and vegetable intakes in relation to colon cancer risk were examined in the Pooling Project of Prospective Studies of Diet and Cancer. Relative risks (RRs) and 95% confidence intervals (CIs) were estimated separately in 14 studies using Cox proportional hazards model and then pooled using a random-effects model. Intakes of total fruits and vegetables, total fruits, and total vegetables were categorized according to quintiles and absolute cutpoints. Analyses were conducted for colon cancer overall and for proximal and distal colon cancer separately. All statistical tests were two-sided.

RESULTS

Among 756,217 men and women followed for up to 6 to 20 years, depending on the study, 5838 were diagnosed with colon cancer. The pooled multivariable RRs (95% CIs) of colon cancer for the highest versus lowest quintiles of intake were 0.91 (0.82 to 1.01, P(trend) = .19) for total fruits and vegetables, 0.93 (0.85 to 1.02, P(trend) = .28) for total fruits, and 0.94 (0.86 to 1.02, P(trend) = .17) for total vegetables. Similar results were observed when intakes were categorized by identical absolute cut points across studies (pooled multivariable RR = 0.90, 95% CI = 0.77 to 1.05 for 800 or more versus <200 g/day of total fruits and vegetables, P(trend) = .06). The age-standardized incidence rates of colon cancer for these two intake categories were 54 and 61 per 100,000 person-years, respectively. When analyzed by colon site, the pooled multivariable RRs (95% CIs) comparing total fruit and vegetable intakes of 800 or more versus less than 200 g/day were 0.74 (0.57 to 0.95, P(trend) = .02) for distal colon cancers and 1.02 (0.82 to 1.27, P(trend) = .57) for proximal colon cancers. Similar site-specific associations were observed for total fruits and total vegetables.

CONCLUSION

Fruit and vegetable intakes were not strongly associated with colon cancer risk overall but may be associated with a lower risk of distal colon cancer.

Haptoglobin phenotype and risk of cervical neoplasia: a case-control study

BACKGROUND

Haptoglobin is an acute-phase glycoprotein that influences host response to infections and tumours. The haptoglobin locus is polymorphic with 2 classes of alleles (Hp(1) and Hp(2)) yielding 3 phenotypes: Hp1-1, Hp2-2, and Hp2-1 with structurally and functionally distinct protein products, suggesting that haptoglobin polymorphism may influence susceptibility to infections and cancers.

METHODS

We examined the relation between haptoglobin phenotype and high-grade cervical intraepithelial neoplasia (CIN) in a hospital-based case-control study. Cases (n = 307) were women with biopsy-confirmed CIN-2 or CIN-3. Controls (n = 358) were a random sample of women with normal cytology. The PGMY polymerase chain reaction and reverse line blot methods were used for HPV detection and genotyping. Haptoglobin phenotype was determined by polyacrylamide gel electrophoresis.

RESULTS

Among controls, phenotype distribution corresponded to allele frequencies of 0.39 for Hp(1) and 0.61 for Hp(2) with no significant deviation from the Hardy-Weinberg equilibrium (p=0.66). With all women included in the analysis, the Hp1-1 phenotype was associated with increased risk of CIN (OR contrasting Hp1-1 vs. Hp2-2 = 1.0; 95% CI: 0.6-1.5). However, in analyses restricted to HPV-positive participants, the Hp1-1 phenotype was associated with 2.7-fold (95% CI: 1.0-7.2) higher risk of CIN.

CONCLUSIONS

If confirmed, these findings indicate an increased risk of CIN among women with the Hp1-1 phenotype.

Nonsynonymous polymorphisms in genes in the one-carbon metabolism pathway and associations with colorectal cancer

The Ala(222)Val single nucleotide polymorphism (SNP) in the gene for 5,10-methylenetetrahydrofolate reductase (MTHFR), a critical enzyme in one-carbon metabolism, has been associated with colorectal cancer risk. Many enzymes are involved in one-carbon metabolism, and SNPs in the corresponding genes may play a role in colorectal carcinogenesis. We examined 24 nonsynonymous SNPs in 13 genes involved in the one-carbon metabolism pathway in relation to the risk of colorectal cancer in a case-control study nested in the Nurses' Health Study and the Health Professionals Follow-up Study cohorts. Among 376 men and women with colorectal cancer and 849 controls, a reduced risk of colorectal cancer was observed for Val/Val versus Ala carriers of MTHFR Ala(222)Val [odds ratio (OR), 0.66; 95% confidence interval (CI), 0.43-1.00]. An increased risk was suggested for the variant carrier genotypes versus homozygous wild-type for betaine hydroxymethyltransferase Arg(239)Gln (OR, 1.40; 95% CI, 1.07-1.83) and two linked SNPs in methionine synthase reductase, Ser(284)Thr (OR, 1.85; 95% CI, 1.05-3.27) and Arg(415)Cys (OR, 2.03; 95% CI, 1.15-3.56). The other SNPs were not associated with colorectal cancer risk. Also, none of the SNPs were associated with risk in subgroups of dietary methyl status or were jointly associated with colorectal cancer risk in combination with another SNP, except possibly SNPs in methionine synthase and transcobalamin II. However, these analyses of gene-diet interactions were limited in statistical power. Our results corroborate previous findings for MTHFR Ala(222)Val and suggest that other genes involved in one-carbon metabolism, particularly those that affect DNA methylation, may be associated with colorectal cancer risk.

Insulin-like Growth Factor-I and Risk of High-Grade Cervical Intraepithelial Neoplasia

Insulin-like growth factors (IGF) and their binding proteins (IGFBP) have been implicated in the risk of several epithelial or glandular tumors, including prostate cancer, breast cancer, and colon cancer. Cervical cancer, which is also of epithelial origin, has been shown to overexpress receptors for IGF-I, and plasma levels of IGF-I have been positively associated with cervical cancer precursors in one epidemiologic study. In this case-control study, we investigated plasma levels of IGF-I and IGFBP-3 in relation to the risk of histologically confirmed high-grade cervical intraepithelial neoplasia (HGCIN) and the risk of human papillomavirus (HPV) infection. Included in this analysis were 329 cases and 621 controls recruited from clinics affiliated with two Montréal-area hospital centers. We observed a reduced risk of HGCIN for increasing levels of IGF-I, with an adjusted odds ratio (OR) of 0.40 (95% confidence interval, 0.19-0.87) for the highest quartile relative to the lowest quartile of IGF-I. No association was observed between IGFBP-3 levels and HGCIN. Among controls, IGF-I was associated with a decreased risk of being positive for HPV-16 or HPV-18, with an adjusted odds ratio of 0.20 (95% confidence interval, 0.05-0.87) for the highest quartile relative to the lowest quartile of IGF-I. There was no association observed between IGFBP-3 levels and HPV infection status. IGF-I-mediated effects seemed to predominate among women <30 years of age. In contrast to the previously reported study, our results suggest that levels of IGF-I in young women may be inversely associated with HGCIN, a precursor to cervical cancer.

Viral load of episomal and integrated forms of human papillomavirus type 33 in high-grade squamous intraepithelial lesions of the uterine cervix

The association between total and integrated HPV-33 DNA loads and high-grade squamous intraepithelial lesions (HSIL) of the uterine cervix was investigated. Of 5,347 women recruited in 4 studies, 89 (64 without SIL, 7 low-grade SIL (LSIL), 15 HSIL, 3 unknown grade) were infected by HPV-33. HPV-33 E6, HPV-33 E2 and beta-globin DNA were measured with real-time PCR that allowed to assess total (E6), episomal (E2) and integrated (E6-E2) HPV-33 viral loads. HPV-33 E6/E2 ratios >/=>/=2.0 suggesting the presence of integrated HPV-33 were obtained for 28.6% (n = 18) of women without SIL and 21.4% (n = 3) of women with HSIL (p = 0.74). Although median viral loads were similar, there was a trend toward having a greater proportion of women with HSIL in the fourth quartile (>/=>/=10(6.69) copies/mug DNA) of total HPV-33 viral loads compared to normal women. Controlling for age, site, ethnicity and LCR polymorphism by logistic regression, HPV-33 total loads in the fourth quartile {odds ratio (OR) 4.5 [95% confidence interval (CI) 1.2-17.3]; p = 0.03} and episomal loads in the fourth quartile (>/=>/=10(6.64) copies/mug DNA) [OR 3.9 (95% CI 1.1-13.2); p = 0.05] but not integrated HPV-33 load in the fourth quartile [OR 1.0 (95% CI 0.3-3.3); p = 0.50] were associated with HSIL. Controlling for age, study site and SIL grade, HPV-33 episomal load [OR 0.2 (95% CI 0.1-0.5), p = 0.0004] was associated with the presence of HPV-33 integration. High episomal loads in HSIL and the presence of integration in women without SIL are likely to weaken the usefulness of HPV load of integrated forms in clinical practice.

p53 Arg72Pro polymorphism and risk of colorectal adenoma and cancer

A single nucleotide polymorphism (SNP) at codon 72 of the p53 gene (Arg72Pro) alters the p53 protein structure and affects its activity. We investigated this SNP in relation to colorectal adenoma and cancer among men and women from case-control studies nested within the Nurses' Health Study, the Health Professionals Follow-up Study and the Physicians' Health Study. Among 856 colorectal adenoma cases and 1,184 controls, we observed a modest association with p53 Arg72Pro genotype (multivariate odds ratio (OR) = 1.25, 95% confidence interval (CI) = 1.04-1.50 for Arg/Pro and Pro/Pro vs. Arg/Arg). This association did not vary by colorectal site or by sex. Among 442 colorectal cancer cases and 904 controls, we observed no significant overall association between p53 Arg72Pro genotype and colorectal cancer (multivariate OR = 1.14, 95% CI = 0.90-1.45). However, when colorectal site and sex was accounted for, the Pro carrier genotypes compared to Arg/Arg were associated with an increased risk of proximal colon cancers in women (multivariate OR = 2.59, 95% CI = 1.49-4.52) though not with distal colon or rectal cancers, while among men the same genotypes were associated with an increased risk of distal colon cancers (multivariate OR = 2.09, 95% CI = 1.28-3.40) but not proximal colon or rectal cancers. Our results suggest that Arg72Pro may play a role in the early stages of colorectal neoplasia and possibly in progression to invasive disease, depending on site and sex.

Human Papillomavirus Type 33 Polymorphisms and High‐Grade Squamous Intraepithelial Lesions of the Uterine Cervix

BACKGROUND

We investigated the association between polymorphisms of human papillomavirus (HPV)-33 and squamous intraepithelial lesions (SILs).

METHODS

Endocervical specimens from 89 women infected with HPV-33, out of a total of 5347 recruited for 2 case-control and 2 cohort studies, were further analyzed by polymerase chain reaction sequencing of the long control region (LCR), E6, and E7.

RESULTS

Of the 89 samples, 64 were normal, 7 had low-grade SILs (including 3 determined by histopathologic analysis), 15 had high-grade SILs (HSILs, including 14 determined by histopathologic analysis), and 3 had an unknown diagnosis. Non-prototype-like LCR variants were significantly associated with HSILs (age- and study site-adjusted odds ratio [OR], 9.2 [95% confidence interval {CI}, 1.8-45.9]). The C7732G variation, which results in the loss of a putative binding site for the cellular upstream stimulatory factor, was associated with HSILs (age- and site-adjusted OR, 8.0 [95% CI, 1.5-42.8]). E6 and E7 polymorphisms were not associated with HSILs. Samples collected at 6-month intervals from 14 participants contained the same variant. The HPV-33 MT 1-0-0 variant carrying the G7584A variation was detected more frequently in women from Brazil (7/20 [35%]) than in women from Canada (1/65 [1.5%]; P=.001).

CONCLUSION

Intratypic LCR variants of HPV-33 seem to vary geographically and to differ with respect to their oncogenic potential.

Intake of the major carotenoids and the risk of epithelial ovarian cancer in a pooled analysis of 10 cohort studies

Carotenoids, found in fruits and vegetables, have the potential to protect against cancer because of their properties, including their functions as precursors to vitamin A and as antioxidants. We examined the associations between intakes of alpha-carotene, beta-carotene, beta-cryptoxanthin, lutein/zeaxanthin and lycopene and the risk of invasive epithelial ovarian cancer. The primary data from 10 prospective cohort studies in North America and Europe were analyzed and then pooled. Carotenoid intakes were estimated from a validated food frequency questionnaire administered at baseline in each study. Study-specific relative risks (RR) were estimated using the Cox proportional hazards model and then combined using a random-effects model. Among 521,911 women, 2,012 cases of ovarian cancer occurred during a follow-up of 7-22 years across studies. The major carotenoids were not significantly associated with the risk of ovarian cancer. The pooled multivariate RRs (95% confidence intervals) were 1.00 (0.95-1.05) for a 600 microg/day increase in alpha-carotene intake, 0.96 (0.93-1.03) for a 2,500 microg/day increase in beta-carotene intake, 0.99 (0.97-1.02) for a 100 microg/day increase in beta-cryptoxanthin intake, 0.98 (0.94-1.03) for a 2,500 microg/day increase in lutein/zeaxanthin intake and 1.01 (0.97-1.05) for a 4,000 microg/day increase in lycopene intake. These associations did not appreciably differ by study (p-values, tests for between-studies heterogeneity >0.17). Also, the observed associations did not vary substantially by subgroups of the population or by histological type of ovarian cancer. These results suggest that consumption of the major carotenoids during adulthood does not play a major role in the incidence of ovarian cancer.

Dairy products and ovarian cancer: a pooled analysis of 12 cohort studies

BACKGROUND

Dairy foods and their constituents (lactose and calcium) have been hypothesized to promote ovarian carcinogenesis. Although case-control studies have reported conflicting results for dairy foods and lactose, several cohort studies have shown positive associations between skim milk, lactose, and ovarian cancer.

METHODS

A pooled analysis of the primary data from 12 prospective cohort studies was conducted. The study population consisted of 553,217 women among whom 2,132 epithelial ovarian cases were identified. Study-specific relative risks and 95% confidence intervals were calculated by Cox proportional hazards models and then pooled by a random-effects model.

RESULTS

No statistically significant associations were observed between intakes of milk, cheese, yogurt, ice cream, and dietary and total calcium intake and risk of ovarian cancer. Higher lactose intakes comparing > or = 30 versus <10 g/d were associated with a statistically significant higher risk of ovarian cancer, although the trend was not statistically significant (pooled multivariate relative risk, 1.19; 95% confidence interval, 1.01-1.40; P(trend) = 0.19). Associations for endometrioid, mucinous, and serous ovarian cancer were similar to the overall findings.

DISCUSSION

Overall, no associations were observed for intakes of specific dairy foods or calcium and ovarian cancer risk. A modest elevation in the risk of ovarian cancer was seen for lactose intake at the level that was equivalent to three or more servings of milk per day. Because a new dietary guideline recommends two to three servings of dairy products per day, the relation between dairy product consumption and ovarian cancer risk at these consumption levels deserves further examination.

Fruits and Vegetables and Ovarian Cancer Risk in a Pooled Analysis of 12 Cohort Studies

Because fruits and vegetables are rich in bioactive compounds with potential cancer-preventive actions, increased consumption may reduce the risk of ovarian cancer. Evidence on the association between fruit and vegetable intake and ovarian cancer risk has not been consistent. We analyzed and pooled the primary data from 12 prospective studies in North America and Europe. Fruit and vegetable intake was measured at baseline in each study using a validated food-frequency questionnaire. To summarize the association between fruit and vegetable intake and ovarian cancer, study-specific relative risks (RR) were estimated using the Cox proportional hazards model, and then combined using a random-effects model. Among 560,441 women, 2,130 cases of invasive epithelial ovarian cancer occurred during a maximum follow-up of 7 to 22 years across studies. Total fruit intake was not associated with ovarian cancer risk-the pooled multivariate RR for the highest versus the lowest quartile of intake was 1.06 [95% confidence interval (95% CI), 0.92-1.21; P value, test for trend = 0.73; P value, test for between-studies heterogeneity = 0.74]. Similarly, results for total vegetable intake indicated no significant association (pooled multivariate RR, 0.90; 95% CI, 0.78-1.04, for the highest versus the lowest quartile; P value, test for trend = 0.06; P value, test for between-studies heterogeneity = 0.31). Intakes of botanically defined fruit and vegetable groups and individual fruits and vegetables were also not associated with ovarian cancer risk. Associations for total fruits and vegetables were similar for different histologic types. These results suggest that fruit and vegetable consumption in adulthood has no important association with the risk of ovarian cancer.

The p53 codon 72 polymorphism and risk of high-grade cervical intraepithelial neoplasia

BACKGROUND

The Arg/Arg genotype versus Arg/Pro or Pro/Pro at codon 72 of the p53 gene has been implicated in increasing susceptibility of the cervix to human papillomavirus (HPV) infection and thus altering cancer risk. However, research on this topic has been contentious, which prompted us to carry out a case-control study in the Montreal area.

METHODS

Cases were women with histologically-confirmed high-grade cervical intraepithelial neoplasia (HGCIN). Controls were women without a history of cervical abnormalities. From each woman, we obtained a cervical specimen for HPV testing and p53 genotyping, and a questionnaire was completed. DNA sequencing was used to minimize genotype misclassification. A subsample of specimens was also genotyped using the TaqMan assay.

RESULTS

There were 357 cases and 760 controls recruited between February 2001 and December 2003. The distribution of Arg/Arg, Arg/Pro and Pro/Pro was 55.2, 36.4 and 8.4%, respectively, among cases, and 52.1, 38.7 and 9.2%, among controls, corresponding to an odds ratio (OR) adjusted for ancestral origin of 1.16 (95% confidence interval (CI): 0.9-1.5) for Arg/Arg versus other genotypes. When restricted to high-risk HPV-positive women, the adjusted ORs were 1.40 (CI: 0.9-2.1) and 2.12 (CI: 1.1-4.2), for Arg/Arg versus other genotypes and versus Pro/Pro, respectively. The findings were comparable with analyses of genotype results that agreed between DNA sequencing and TaqMan.

CONCLUSIONS

In this study, we attempted to minimize selection bias, population stratification and genotype misclassification. The results suggest that the role of the p53 codon 72 polymorphism on HGCIN is weak at best. Further research may reveal if the polymorphism has a stronger influence on the risk of invasive cervical cancer.

p53 Codon 72 Polymorphism and Cervical Neoplasia: A Meta-Analysis Review

The Arg/Arg genotype versus Arg/Pro or Pro/Pro at codon 72 of the p53 gene has been implicated as a risk marker in cervical neoplasia. However, research on this topic has produced controversial results. We reviewed the published literature to summarize the association and to identify methodological features that may have contributed to the heterogeneity. Information on specific methodological features of studies addressing this topic published between 1998 and 2002 were obtained. Study-specific odds ratios (ORs) were combined in a meta-analysis, assuming random effects. To identify characteristics that significantly contributed to heterogeneity, we used meta-regression analysis. We identified 50 articles, of which 45 were included in the meta-analyses and regressions. No evidence of association or heterogeneity was detected for preinvasive lesions. For invasive cervical cancer with undefined histology, the Arg/Arg genotype was not found to affect risk (OR, 1.1; 95% confidence interval (CI), 0.9-1.3). However, a slightly increased risk was observed for squamous cell carcinoma (OR, 1.5; 95% CI, 1.2-1.9) and adenocarcinoma (OR, 1.7; 95% CI, 1.0-2.7). Meta-regression analysis identified that the most important factor contributing to heterogeneity among results for invasive lesions was departures from Hardy-Weinberg equilibrium in the control group. Summary ORs for studies in equilibrium were essentially null. A possible susceptibility role by the p53 codon 72 polymorphism at a late carcinogenetic stage in cervical cancer cannot be ruled out. However, various methodological features can contribute to departures from Hardy-Weinberg equilibrium and consequently to less than ideal circumstances for the examination of this polymorphism. Future investigations require appropriate attention to design and methodological issues.

Screening for diabetic retinopathy in James Bay, Ontario: a cost-effectiveness analysis

BACKGROUND

Retinopathy is a common complication of diabetes mellitus that if detected early by regular retinal examinations can be treated; thus, blindness can be delayed or prevented. Providing high-quality retinal screening is difficult, especially in rural and remote areas. Canada's First Nations population has a higher prevalence of diabetes and is, in general, more geographically isolated than the broader Canadian population. We modelled the cost-effectiveness of retinopathy screening by travelling retina specialists versus retinal photography with a portable digital camera in an isolated First Nations cohort with diabetes.

METHODS

The 2 screening programs were modelled to run concurrently for 5 years, with outcomes evaluated over 10 years. To construct economic models for the population of Cree individuals living in the western James Bay area of northern Ontario, we used available data on the prevalence of diabetes in the area and estimates of the incidence of retinopathy derived from the published literature. We compared the screening models and calculated total costs, visual outcome, costs per sight-year saved and costs per quality-adjusted life year (QALY). We also estimated the costs of implementing a screening program for all First Nations individuals in Ontario with diabetes and no access to an ophthalmologist.

RESULTS

From the perspective of the health care system the camera program was preferable to the specialist-based program. Over 10 years, 67 v. 56 sight years were saved, compared with no screening, at costs of 3900 Canadian dollars v. 9800 Canadian dollars per sight year and 15,000 Canadian dollars v. 37,000 Canadian dollars per QALY. Generalizing these results to the province of Ontario, the camera system could allow most isolated First Nations people with diabetes to be screened for 5 years for approximately 1.2 million Canadian dollars.

INTERPRETATION

A portable retinal camera is a cost-effective means of screening for diabetic retinopathy in isolated communities of at-risk individuals.

Herpes simplex virus type II is not a cofactor to human papillomavirus in cancer of the uterine cervix

OBJECTIVE

Cells that were cotransfected with herpes simplex virus-16 and the herpes simplex virus type 2 Xho -2 DNA induce tumors in nude mice. In a cross-sectional study, we investigated the role of herpes simplex virus type 2 as a cofactor to human papillomavirus in cervical cancer.

STUDY DESIGN

Cervical cells that were obtained with an endocervical Cytobrush brush (Medscand) from 439 women (50 women with cancer lesions, 65 women with high-grade squamous intraepithelial lesions, 80 women with low-grade squamous intraepithelial lesions, 244 healthy subjects) and DNA that was extracted from 150 cervical cancer biopsy specimens were analyzed with polymerase chain reaction for herpes simplex virus type 2 Xho -2 and Bgl IIC transforming DNA sequences.

RESULTS

All 439 cervical samples and 150 cervical cancer biopsy specimens tested negative for herpes simplex virus type 2 Xho -2 and Bgl IIC DNA by polymerase chain reaction. Overall, none of 200 samples (0%) from women with invasive cervical cancer contained herpes simplex virus type 2 Xho -2 or Bgl IIC DNA (95% CI, 0.0-1.8).

CONCLUSION

Although herpes simplex virus type 2 Bgl IIN transforms epithelial cells in vitro, it was not detected in cervical cancer specimens.

Detection of human herpes virus type 6 DNA in precancerous lesions of the uterine cervix

Human herpes virus type 6 (HHV-6) DNA has been suggested to be a cofactor to human papillomavirus (HPV) in cervical cancer. In a cross-sectional study, we investigated the association between HHV-6 DNA detected in cervical brushings and high-grade squamous intraepithelial lesions (HSIL), while controlling for genital infection with 27 genotypes of HPV. Of the 320 women recruited from an oncologic gynecology clinic, 50 had invasive cervical cancer, 65 had HSIL, 80 had low-grade squamous intraepithelial lesions (LSIL), and 125 were normal. Four of the seven HHV-6-positive women had HSIL. HHV-6 was associated with HSIL after adjusting for age and socioeconomic status (odds ratio [OR] of 10.9, 95% confidence interval [CI]: 1.1-107.1). This association was no longer significant after controlling for HPV (OR = 6.4, 95% CI = 0.3-128.5). HHV-6 was detected in cervical samples from women with precancerous and cancerous lesions of the cervix, but not significantly more frequently than in normal women.

Risk factors for diabetic retinopathy in the Cree of James Bay

BACKGROUND

The purpose of this project was to evaluate risk factors for diabetic retinopathy in the Cree population of James Bay, Ontario.

METHODS

A retrospective cohort design was employed. The cohort was made up of all known individuals who had previously been diagnosed with diabetes in the communities of Moose Factory and Moosonee, Ontario. Hypertension, body-mass index, serum lipid levels, renal function status, and hemoglobin A1C were the main exposures of interest. Values for these variables were determined from a retrospective chart review and were sought for each individual for a five-year interval beginning one year following the diagnosis of diabetes. Relative risks for the association of these variables with diabetic retinopathy were determined through both univariate and multivariate Poisson regression. The main outcome of interest in this study was the presence or absence of any diabetic retinopathy in either eye, as determined by a retinal specialist.

RESULTS

Significant univariate risks for the development of retinopathy included duration of diabetes, body-mass index, hemoglobin A1C, fasting blood glucose, insulin treatment, and serum cholesterol levels. In multivariate analyses, predictors of diabetic retinopathy included body-mass index, insulin treatment, and serum cholesterol levels. An increase in body-mass index reduced the risk of diabetic retinopathy (Relative Risk [RR] 0.64 per five kg/m( 2), 95% Confidence Interval [CI] 0.04 to 1.00). Insulin therapy was associated with an increased risk of retinopathy when compared to individuals on dietary therapy alone (Relative Risk [RR] 4.71, 95% Confidence Interval [CI] 1.16 to 19.16). For individuals with serum cholesterol levels above the average for the cohort, 5.2 mmol/L, the risk of retinopathy was increased (Relative Risk [RR] 2.38, 95% Confidence Interval [CI] 0.98 to 5.79).

INTERPRETATION

Elevated serum cholesterol, lower body-mass index and insulin treatment were all associated with an increased risk of diabetic retinopathy in the Cree of James Bay, Ontario.

Factors associated with missed eye examinations in a cohort with diabetes

BACKGROUND

The diabetes screening program in Moosonee and Moose Factory, Ontario was evaluated to explore which factors may be associated with individuals who had/had not attended screening examinations for diabetic retinopathy.

METHODS

Exposure data were collected from patient charts for basic demographic and medical history data. The main outcome of interest was the absence of a retinal examination in the two years preceding data collection.

RESULTS

There were 248 subjects identified with diabetes who had complete data for the variables of interest. On univariate analysis, younger age and shorter duration of diabetes were significantly associated with not having an eye examination. On multivariate analysis, younger age, residence in Moosonee, and shorter duration of diabetes remained in the final model.

INTERPRETATION

Screening programs for diabetic retinopathy in the James Bay Cree should consider targeting younger individuals with diabetes of less than 5 years duration since this sub-group is not as likely to attend eye examinations.

An ecologic study of childhood leukemia and population mixing in Ontario, Canada

OBJECTIVE

To examine the association between population mixing and the incidence of childhood leukemia, specifically the acute lymphocytic leukemia (ALL) subtype among young children.

METHODS

This ecologic study was based on incidence rates of leukemia in children aged 0-14 years. The Ontario Cancer Registry was used to identify the residence of 1394 leukemia cases between 1978 and 1992. Ecologic units were composed of census subdivisions in a 5-year period. Percent population change, determined from the Census of Canada, was employed as a measure of population mixing. The relationship between population mixing and childhood leukemia was examined separately after stratifying by the level of geographic isolation, defined according to urban-rural status. Analyses were also conducted separately in specific age groups and for the ALL subtype.

RESULTS

Population growth in rural areas was associated with an increased incidence of leukemia, particularly for the ALL subtype in children aged 0-4 years (rate ratio = 1.8, 95% confidence interval 1.1-2.8, for a greater than 20% population change relative to no increase in population). In contrast, an elevated risk due to population mixing was not observed in urban areas.

CONCLUSIONS

Results from this study are consistent with results from similar studies conducted in the United Kingdom, which are suggestive of a role for an infectious agent in the etiology of childhood leukemia, as proposed in the Kinlen hypothesis.

Estimation of youth smoking behaviours in Canada

This study estimated the prevalence of current smoking and smoking initiation among Canadian youth. Logistic regression was used to relate socio-demographic predictors to the occurrence of the smoking indicators among youth (15-24 years) in the 1994/95 National Population Health Survey (NPHS). Models were then applied to provincial youth populations in the 1996/97 NPHS and the 1996 census of Canada. Model-generated estimates were compared with direct estimates obtained from NPHS data. The models accurately predicted provincial rates of current youth smoking for 1994/95. When applied to the 1996/97 NPHS, the current smoking models performed reasonably well, but were less predictive when applied to 1996 census data. Modelling of youth smoking initiation was not successful. This suggests that although simple estimation models of youth smoking can be derived, these models may not be portable across different populations or time periods.