Incidence of childhood cancer in Canada during the COVID-19 pandemic.

BACKGROUND: The COVID-19 pandemic has had a major impact on access to health care resources. Our objective was to estimate the impact of the COVID-19 pandemic on the incidence of childhood cancer in Canada. We also aimed to compare the proportion of patients who enrolled in clinical trials at diagnosis, presented with metastatic disease or had an early death during the first 9 months of the COVID-19 pandemic compared with previous years. METHODS: We conducted an observational study that included children younger than 15 years with a new diagnosis of cancer between March 2016 and November 2020 at 1 of 17 Canadian pediatric oncology centres. Our primary outcome was the monthly age-standardized incidence rates (ASIRs) of cancers. We evaluated level and trend changes using interventional autoregressive integrated moving average models. Secondary outcomes were the proportion of patients who were enrolled in a clinical trial, who had metastatic or advanced disease and who died within 30 days. We compared the baseline and pandemic periods using rate ratios (RRs) and 95% confidence intervals (CIs). RESULTS: Age-standardized incidence rates during COVID-19 quarters were 157.7, 164.6, and 148.0 per million, respectively, whereas quarterly baseline ASIRs ranged between 150.3 and 175.1 per million (incidence RR 0.93 [95% CI 0.78 to 1.12] to incidence RR 1.04 [95% CI 0.87 to 1.24]). We found no statistically significant level or slope changes between the projected and observed ASIRs for all new cancers (parameter estimate [ß], level 4.98, 95% CI -15.1 to 25.04, p = 0.25), or when stratified by cancer type or by geographic area. Clinical trial enrolment rate was stable or increased during the pandemic compared with baseline (RR 1.22 [95% CI 0.70 to 2.13] to RR 1.71 [95% CI 1.01 to 2.89]). There was no difference in the proportion of patients with metastatic disease (RR 0.84 [95% CI 0.55 to 1.29] to RR 1.22 [0.84 to 1.79]), or who died within 30 days (RR 0.16 [95% CI 0.01 to 3.04] to RR 1.73 [95% CI 0.38 to 15.2]). INTERPRETATION: We did not observe a statistically significant change in the incidence of childhood cancer, or in the proportion of children enrolling in a clinical trial, presenting with metastatic disease or who died early during the first 9 months of the COVID-19 pandemic, which suggests that access to health care in pediatric oncology was not reduced substantially in Canada.

Childhood cancer incidence in Canada: demographic and geographic variation of temporal trends (1992-2010). / Incidence du cancer chez les enfants au Canada : variations démographiques et géographiques des tendances (1992-2010).

INTRODUCTION: Surveillance of childhood cancer incidence trends can inform etiologic research, policy and programs. This study presents the first population-based report on demographic and geographic variations in incidence trends of detailed pediatric diagnostic groups in Canada. METHODS: The Canadian Cancer Registry data were used to calculate annual age-standardized incidence rates (ASIRs) from 1992 to 2010 among children less than 15 years of age by sex, age and region for the 12 main diagnostic groups and selected subgroups of the International Classification of Childhood Cancer (ICCC), 3rd edition. Temporal trends were examined by annual percent changes (APCs) using Joinpoint regression. RESULTS: The ASIRs of childhood cancer among males increased by 0.5% (95% confidence interval (CI) = 0.2-0.9) annually from 1992 to 2010, whereas incidence among females increased by 3.2% (CI = 0.4-6.2) annually since 2004 after an initial stabilization. The largest overall increase was observed in children aged 1-4 years (APC = 0.9%, CI = 0.4-1.3). By region, the overall rates increased the most in Ontario from 2006 to 2010 (APC = 5.9%, CI = 1.9-10.1), and increased non-significantly in the other regions from 1992 to 2010. Average annual ASIRs for all cancers combined from 2006 to 2010 were lower in the Prairies (149.4 per million) and higher in Ontario (170.1 per million). The ASIRs increased for leukemias, melanoma, carcinoma, thyroid cancer, ependymomas and hepatoblastoma for all ages, and neuroblastoma in 1-4 year olds. Astrocytoma decreased in 10-14 year olds (APC = -2.1%, CI = -3.7 to -0.5), and among males (APC = -2.4%, CI = -4.6 to -0.2) and females (APC = -3.7%, CI = -5.8 to -1.6) in Ontario over the study period. CONCLUSION: Increasing incidence trends for all cancers and selected malignancies are consistent with those reported in other developed countries, and may reflect the changes in demographics and etiological exposures, and artefacts of changes in cancer coding, diagnosis and reporting. Significant decreasing trend for astrocytoma in late childhood was observed for the first time.

INTRODUCTION: La surveillance des tendances de l'incidence du cancer chez les enfants peut éclairer la recherche, les politiques et les programmes en matière d'étiologie. Cette étude donne lieu au premier rapport sur les variations démographiques et géographiques des tendances de l'incidence de groupes diagnostiques détaillés chez les enfants de la population générale au Canada. MÉTHODOLOGIE: Les données du Registre canadien du cancer ont servi à calculer les taux d'incidence normalisés selon l'âge (TINA) annuels de 1992 à 2010 chez les enfants de moins de 15 ans selon le sexe, l'âge et la région pour les 12 principaux groupes et certains sous­groupes diagnostiques de la 3e édition de la Classification internationale du cancer chez les enfants (CICE). Les tendances temporelles ont été examinées à partir des variations annuelles en pourcentage (VAP) au moyen d'une régression Joinpoint. RÉSULTATS: Les TINA annuels du cancer chez les enfants ont augmenté de 0,5 % (intervalle de confiance [IC] à 95 % = 0,2 à 0,9) chez les garçons chaque année entre 1992 et 2010, tandis que l'incidence chez les filles a augmenté de 3,2 % (IC = 0,4 à 6,2) chaque année depuis 2004 après une stabilisation initiale. L'augmentation globale la plus importante a été observée chez les enfants de 1 à 4 ans (VAP = 0,9 %, IC = 0,4 à 1,3). Par région, c'est en Ontario entre 2006 et 2010 que les taux globaux ont le plus augmenté (VAP = 5,9 %, IC = 1,9 à 10,1) et ils ont augmenté de façon non significative dans les autres régions entre 1992 et 2010. On a mesuré en 2006-2010 les TINA annuels moyens de tous les cancers confondus les plus faibles dans les Prairies (149,4 pour 1 million) et les plus élevés en Ontario (170,1 pour 1 million). Les TINA des leucémies, du mélanome, des carcinomes, du cancer de la thyroïde, des épendymomes et de l'hépatoblastome ont augmenté dans tous les groupes d'âge, et les TINA du neuroblastome ont augmenté chez les enfants de 1 à 4 ans. L'incidence de l'astrocytome a diminué chez les enfants de 10 à 14 ans (VAP = −2,1 %, IC = −3,7 à −0,5) ainsi que chez les garçons (VAP = −2,4 %, IC = −4,6 à −0,2) et les filles (VAP = −3,7 %, IC = −5,8 à −1,6) en Ontario au cours de la période étudiée. CONCLUSION: Les tendances à la hausse de l'incidence de tous les cancers confondus et de certaines tumeurs malignes correspondent aux tendances signalées dans d'autres pays développés. Elles sont explicables par des variations démographiques, par des variations de l'exposition aux facteurs étiologiques ou par des changements apportés aux méthodes de codification, de diagnostic et de déclaration du cancer. Une baisse significative de la tendance de l'astrocytome chez les 10 à 14 ans a été observée pour la première fois.

Invasive cervical cancer incidence and mortality among canadian women aged 15 to 29 and the impact of screening.

OBJECTIVE: The utility of screening young women for cervical cancer is questionable given the likelihood of pre-cancer regression and the potential harm of the intervention. Our objective was to determine the incidence and mortality rates of invasive cervical cancer (ICC) in women aged 15 to 29 years and to assess changes in rates since the uptake of screening. METHODS: The incidence of ICC cases from 1970 to 2007 was obtained from records in the Canadian Cancer Registry and from the National Cancer Incidence Reporting System. Mortality rates in women with ICC for the same time period were obtained from the Canadian Vital Statistics Death Database. Data were classified by age group and year at diagnosis or death, assessed at five-year intervals. The incidence was further analyzed according to histology. RESULTS: ICC among 15- to 19-year-olds is rare and has remained relatively constant from 1970-1974 to 2005-2007. From 1975-1979 to 2005-2007, the incidence in 20- to 24-year-olds declined from 3.2 to 1.2 per 100 000. From 1980-1984 to 2005-2007, the incidence in 25- to 29-year-olds declined from 11.1 to 6.3 per 100 000. Deaths among 15- to 19-year-olds and 20- to 24-year-olds are rare, but in 25- to 29-year-olds mortality declined from 0.9 to 0.5 per 100 000 between 1975-1979 and 2005-2007. Among 20- to 24-year-olds, rates of all cervical cancers and squamous cell carcinomas declined, while adenocarcinomas and unknown types were rare. In 25- to 29-year-olds there was a decline in all cervical cancers and squamous cell cancers and an apparent increase in adenocarcinoma. CONCLUSIONS: ICC in adolescents is rare and does not justify population-based screening. Screening appears to have affected the incidence of ICC in 20- to 24-year olds and incidence and mortality from ICC in 25- to 29-year-olds.

Reduced cervical cancer incidence and mortality in Canada: national data from 1932 to 2006.

BACKGROUND: High levels of participation in cervical screening are reported in Canada from the 1970's as a result of early uptake of the Pap smear and universal Medicare. Despite recommendations to the contrary, the programs have featured early age of initiation of screening and frequent screening intervals. Other countries have achieved successful outcomes without such features. We analyzed national data to better understand mortality and incidence trends, and their relationships to screening. METHODS: The Canadian Cancer Registry, National Cancer Incidence Reporting System, and the Canadian Vital Statistics Database were used to measure mortality and incidence rates. Cases and deaths from invasive cervical cancer were classified by 5 year age groups at diagnosis and death (15 to 19 years through to 80 to 84 years), year of diagnosis (1972 to 2006), and year of death (1932 to 2006). Probabilities of developing and dying from cervical cancer were calculated for age-specific mortality and incidence. The proportion of women reporting a timely Pap test was estimated for 1978 to 2006. RESULTS: Cervical cancer mortality has declined steadily from a peak of 13.5 to 2.2 per 100,000 (83%,) between 1952 and 2006, and 71% between 1972 and 2006. Incidence of invasive cervical cancer has declined by 58% since 1972. These declines have occurred more among older age groups than younger. Invasive cervical cancer incidence and mortality is less in each successive birth cohort of women. Participation rates in screening are high especially in women under age 50. CONCLUSIONS: Despite increasing risk factors for cervical cancer, both incidence and mortality have declined over time, across age groups, and across birth cohorts. Earlier increasing mortality (1932 - 1950) was likely related to improved classification of cancers and the early subsequent reduction (1950 - 1970) to improved treatment. Recent improvements in incidence and mortality are likely due to high rates of screening. For women under age 30 years there are low rates of disease but lesser improvement related to screening.

Increases in antihypertensive prescriptions and reductions in cardiovascular events in Canada.

The Canadian Hypertension Education Program, an extensive professional education program to improve the management of hypertension, was started in 1999. There were very large increases in diagnosis and treatment of hypertension in the first 4 years after initiation of the program. The purpose of this study was to examine the association between the changes in antihypertensive therapy with changes in hospitalization and death from major hypertension-related cardiovascular diseases in Canada between 1992 and 2003. Using various national databases, Canadian standardized yearly mortality and hospitalization rates per 1000 for stroke, heart failure, and acute myocardial infarction were calculated for individuals aged >or=20 years and regressed against antihypertensive prescription rates. Changes in rates were examined in a time series analysis. There were significant reductions (P<0.0001) in the rate of death from stroke, heart failure, and myocardial infarction starting in 1999. There was also a reduction in hospitalization rate from stroke (P<0.0001) and heart failure (P<0.0001) but not myocardial infarction in 1999. The changes in death (P<0.001 for all 3 diseases) and hospitalization (P<0.0001 for stroke and heart failure; P=0.018 for acute myocardial infarction) were associated with the increases in antihypertensive prescriptions. This study demonstrates that the reduction in cardiovascular death and hospitalization rates is associated with an increase in antihypertensive prescriptions and that it coincides with the introduction of the Canadian Hypertension Education Program. The Canadian Hypertension Education Program educational model for improving health care could be adopted by other countries with well-developed professional and scientific societies.

Why some adult Canadians do not have blood pressure measured.

Regular blood pressure (BP) measurements are required to identify people with hypertension and to optimally manage their cardiovascular risk. Analyses of data from the 2000-2001 Canadian Community Health Survey showed that most adult Canadians have had a BP assessment in the previous 2 years and few have never had one. Large numbers of persons without BP recordings were observed, however, among persons who were younger, were male, who did not have either a regular doctor or physician contact in the previous year, who were recent immigrants or visible minorities (nonwhite and non-Aboriginal), and who spoke neither French nor English. Common reasons reported for not having a BP assessment included believing it was not necessary and simply not getting around to it. Education programs targeting those at risk as well as more convenient BP screening may improve awareness and testing.

Large increases in hypertension diagnosis and treatment in Canada after a healthcare professional education program.

This study was conducted to compare the self-reported prevalence and treatment of hypertension in adult Canadians before and subsequent to the implementation of the Canadian Hypertension Education Program in 1999. Data were obtained from 5 cycles of the Canadian Health Surveys between 1994 and 2003 on respondents aged > or = 20 years. Piecewise linear regression was used to calculate the average annual increase in rates, before and after 1999. Between 1994 and 2003, the percentage of adult Canadians aware of being diagnosed with hypertension increased by 51% (from 12.37% to 18.74%; P<0.001), and the percentage prescribed antihypertensive drugs increased by 66% (from 9.57% to 15.86%; P<0.001). After 1999, there was approximately a doubling of the annual rate of increase in the diagnosis of hypertension (from 0.52% of the population per year before 1999 to 1.03% per year after 1999; P<0.001) and the percentage prescribed antihypertensive drugs (from 0.54% of the population per year before 1999 versus 0.98% per year after 1999; P<0.001). The proportion of those aware of the diagnosis of hypertension but not being treated with drugs was reduced by half between 1994 and 2003 (from 31.47% untreated to 15.34% untreated; P<0.001). There was a greater increase in awareness of hypertension and use of antihypertensive drugs among men compared with women after 1999. The large increase in the diagnosis and treatment of hypertension in Canada between 1994 and 2003 is consistent with an overall beneficial effect of the Canadian Hypertension Education Program, including a reduced gender gap in hypertension care.

Lifetime and recent prostate specific antigen (PSA) screening of men for prostate cancer in Canada.

BACKGROUND: In spite of national guidelines which do not recommend prostate specific antigen (PSA) screening for prostate cancer or are inconclusive, Canadian men may be accessing the screening test. METHODS: For the purpose of informing prostate screening policy, cross-sectional self-reported data from the Canadian Community Health Survey (2000-2001) were analyzed to determine the lifetime and recent PSA screening prevalence of Canadian men aged 50 and older with no prostate cancer, and to explore the socio-demographic characteristics associated with ever being screened. Multivariate binomial regression analyses were used to calculate prevalence rate ratios as a measure of association between respondents' characteristics and PSA screening behaviour. RESULTS: Almost half of Canadian men over the age of 50 years (47.5%; 95% CI=46.4-48.5) reported receiving PSA screening during their lifetime. Seventy-two percent (71.8%) of PSA screening was performed within one year prior to the survey or recently. Lifetime prevalence was highest among men aged 60-69 (53.1%; 95% CI=51.1-55.1). Next to advanced age, having a family doctor was the most predictive of screening behaviour (PRR=1.83, p<0.01). Black ethnicity, a risk factor for prostate cancer, failed to be predictive of screening (PRR=1.04, NS). Not speaking French or English was strongly associated with not obtaining a PSA screen (PRR=0.66, p< or =0.01). INTERPRETATION: Our finding that Canadian men commonly reported PSA screening for prostate cancer is not congruent with national guidelines. While we wait for randomized controlled trial evidence of the effectiveness of PSA screening in reducing mortality due to prostate cancer, PSA screening has emerged as a public health issue.

The Outcomes Research Task Force and the Canadian Hypertension Education Program.

The present report is an update on the contribution of the Canadian Hypertension Education Program's (CHEP) Outcomes Research Task Force to the surveillance and monitoring efforts surrounding hypertension and hypertension-related conditions in Canada. Components of the program include advocating national physical measures surveys of blood pressure; analysis of national cross-sectional and longitudinal population-based health surveys that assess hypertension diagnosis and treatment; assessment of national and regional pharmacotherapy patterns using existing commercial databases; assessment of national and regional trends in hypertensive complications (stroke, myocardial infarction and congestive heart failure); development of a national system based on provincial administrative data to assess the incidence, prevalence and management of diagnosed hypertension; and assessing some aspects of CHEP implementation. Preliminary data support a large increase in the diagnosis and treatment of hypertension corresponding to the initiation of CHEP.

The distribution and predictive validity of the stages of change for mammography adoption among Canadian women.

OBJECTIVE: To examine the predictive validity of the transtheoretical model (TTM) stages of change for mammography participation in Canadian women. METHOD: We examined the association between baseline TTM stage of mammography adoption and subsequent mammography participation in a representative sample of 3,125 Canadian women aged 40 and older from the longitudinal Canadian National Population Health Survey. RESULTS: The likelihood of having a mammogram at follow-up (1998/1999) increased with progressive stages of change at baseline (1996/1997) even after adjusting for potential confounders. Relative to women in maintenance, women in precontemplation, relapse, contemplation, relapse risk, and action were significantly less likely to report a recent mammogram during follow-up (adjusted RR of 0.41, 0.50, 0.63, 0.75, and 0.92, respectively; P(trend) < 0.01). This pattern held for women within and outside of the 50-69 target age range, and for urban and to a lesser degree rural-dwelling women. CONCLUSION: Our findings support the predictive validity of the TTM stages of mammography adoption construct and the inclusion of both relapse and relapse risk categories to improve the sensitivity of the predictive model. Interventions to promote the eventual maintenance of mammography screening should also benefit from further research that aims to understand the variables that promote progressive movement through the stages.

Organized breast screening programs in Canada: effect of radiologist reading volumes on outcomes.

PURPOSE: To examine retrospectively the relationship between radiologist screening program reading volumes and interpretation results. MATERIALS AND METHODS: This research project was reviewed by the University of British Columbia Research Ethics Board. Informed patient consent was not required. Data were requested from Canadian provincial screening programs for the period 1988-2000. Cancer detection rates, abnormal interpretation rates, and positive predictive values (PPVs) were calculated for individual radiologists in those programs. Multivariate Poisson mixed regression models were used to examine the effect of patient age, screening examination sequence (first or subsequent screening examination), province, radiologist reading volume, and interradiologist differences on cancer detection rate, abnormal interpretation rate, and PPV. RESULTS: The results of the interpretation of 1406678 screening mammograms by 304 radiologists from seven provincial programs were analyzed. Cancer detection rate, abnormal interpretation rate, and PPV all varied according to age of woman screened and screening sequence and across the sample of radiologists. None of the rates varied by province. Neither the cancer detection rate nor the abnormal interpretation rate varied by reading volume, but the average PPV was increased by 34% for volumes over 2000 mammograms versus volumes of 480-699 mammograms per year. There was no evidence that the magnitude of variability around the average, for radiologists reading the same volume of mammograms, varied across different volume groups for any of the outcome measures. CONCLUSION: Cancer detection did not vary with reading volume. The average PPV for individual radiologists increased as reading volume rose up to 2000 mammograms per year; it stabilized at higher volumes.

Mammography utilization in Canadian women aged 50 to 69: identification of factors that predict initiation and adherence.

OBJECTIVE: To identify factors that predict initiation of mammography and adherence with biennial screening among Canadian women aged 50-69 years. METHODS: Using data from a longitudinal panel of Canadian women interviewed in the National Population Health Survey (NPHS) in 1994/95 and 2 and 4 years later, we estimated the relative risks (RR) of mammography initiation and adherence according to socio-demographic, health and lifestyle characteristics. RESULTS: Among 505 women with no history of mammography use at baseline, 23.0% and 41.4% initiated mammography by 2 and 4 years, respectively. Urban residence (RR = 2.85) was most strongly associated with initiation by 2 years; younger age (50-54) and lower education also predicted initiation by 2 years. Younger age, birthplace outside Canada, and having a recent (< 2 years) blood pressure check were associated with initiation by 4 years. Among 873 women reporting a recent (< 2 years) mammogram at baseline, 88.7% also reported a recent mammogram within 2 years while 73.0% reported one at both the 2- and 4-year follow-up. Being a non-smoker was the strongest predictor of maintaining adherence both at the 2- (RR = 1.18) and the 4-year (RR = 1.37) follow-up. INTERPRETATION: Previously identified underserved groups of Canadian women (e.g., those with lower educational levels or born outside of Canada) were most likely to initiate mammography. Approximately 1 in 6 women aged 50 to 69 years remained never-users during follow-up, and fewer than half reported recent mammograms at all three survey cycles, suggesting the need to reinforce regular screening participation.

The influence of breast self-examination on subsequent mammography participation.

OBJECTIVES: We evaluated whether breast self-examination (BSE) influences subsequent mammography participation. METHODS: We evaluated associations between BSE and subsequent mammography participation, adjusting for baseline screening behaviors and sociodemographic, health, and lifestyle characteristics, among women aged 40 years and older using data from the longitudinal Canadian National Population Health Survey. RESULTS: Regular performance of BSE at baseline was not associated with receipt of a recent mammogram at follow-up among all women (adjusted odds ratio [OR]=1.01; 95% confidence interval [CI]= 0.75, 1.35) or with mammography uptake among the subgroup of women reporting never use at baseline (adjusted OR=0.78; 95% CI=0.50, 1.22). CONCLUSIONS: The lack of association between performance of BSE and subsequent mammography participation suggests that not recommending BSE is unlikely to influence mammography participation.

Report of the 2003 pan-Canadian forum on cervical cancer prevention and control.

OBJECTIVE: To develop evidence-based consensus recommendations on the delivery of cervical cancer screening, human papillomavirus (HPV) education, HPV testing, and the optimal tool for cervical cytology within the Canadian health system. PARTICIPANTS: Leading up to a forum held in Ottawa on November 21 and 22, 2003, 254 registrants reviewed position papers through a Web-based discussion group. Experts in program management, clinical practice, epidemiology, public health, economics, and women's health, representing 48 organizations, then participated in the 2-day forum to develop consensus recommendations. EVIDENCE: Writing groups prepared position papers on optimal methods for cervical cytology; education concerning HPV; HPV testing in primary screening; HPV testing as a triage tool in cytopathology; and delivery mechanisms for cervical screening. Systematic reviews were the primary source of evidence supplemented by literature searches. CONSENSUS PROCESS: Feedback from Web-based discussions was incorporated into consecutive drafts of position papers. At the forum, recommendations and supporting evidence were presented, further debated in small-group sessions, and discussed in a plenary session. Despite divergent professional mandates and opinions, consensus was achieved on 15 recommendations across all areas. Final recommendations were posted to the Web for further input and circulated for written consensus by participants. CONCLUSIONS: The recommendations cover the use of new evidence and technologies in cervical cancer prevention in Canada and provide a framework for provision of HPV education, planning the implementation of new cervical screening technologies in Canada, the development of evaluation plans, and new research areas.