Projected estimates of cancer in Canada in 2024.

BACKGROUND: Cancer surveillance data are essential to help understand where gaps exist and progress is being made in cancer control. We sought to summarize the expected impact of cancer in Canada in 2024, with projections of new cancer cases and deaths from cancer by sex and province or territory for all ages combined. METHODS: We obtained data on new cancer cases (i.e., incidence, 1984-2019) and deaths from cancer (i.e., mortality, 1984-2020) from the Canadian Cancer Registry and Canadian Vital Statistics Death Database, respectively. We projected cancer incidence and mortality counts and rates to 2024 for 23 types of cancer, overall, by sex, and by province or territory. We calculated age-standardized rates using data from the 2011 Canadian standard population. RESULTS: In 2024, the number of new cancer cases and deaths from cancer are expected to reach 247 100 and 88 100, respectively. The age-standardized incidence rate (ASIR) and mortality rate (ASMR) are projected to decrease slightly from previous years for both males and females, with higher rates among males (ASIR 562.2 per 100 000 and ASMR 209.6 per 100 000 among males; ASIR 495.9 per 100 000 and ASMR 152.8 per 100 000 among females). The ASIRs and ASMRs of several common cancers are projected to continue to decrease (i.e., lung, colorectal, and prostate cancer), while those of several others are projected to increase (i.e., liver and intrahepatic bile duct cancer, kidney cancer, melanoma, and non-Hodgkin lymphoma). INTERPRETATION: Although the overall incidence of cancer and associated mortality are declining, new cases and deaths in Canada are expected to increase in 2024, largely because of the growing and aging population. Efforts in prevention, screening, and treatment have reduced the impact of some cancers, but these short-term projections highlight the potential effect of cancer on people and health care systems in Canada.

Lifetime probability of developing cancer and dying from cancer in Canada, 1997 to 2020.

Background: The lifetime probabilities of developing (LPdev) cancer and dying (LPdying) from cancer are useful summary statistics that describe the impact of cancer within a population. This study aims to present detailed LPdev and LPdying for cancer by sex and cancer type and to describe changes in these lifetime probabilities over time among the Canadian population. Data and methods: Cancer incidence data (1997 to 2018) were obtained from the Canadian Cancer Registry. All-cause and cancer mortality data (1997 to 2020) were obtained from the Canadian Vital Statistics - Death Database. LPdev and LPdying were calculated using the DevCan software, and trends over time were estimated using Joinpoint. Results: The LPdev for all cancers combined was 44.3% in Canada in 2018, with all results excluding Quebec. At the age of 60, the conditional probability of developing cancer was very similar (44.0% for males and 38.2% for females). The LPdying was 22.5% among the Canadian population in 2020, while the probability of dying from cancer conditional on surviving until age 60 was 25.1% for males and 20.5% for females. Generally, males experienced higher LPdev and LPdying for most specific cancers compared with females. Interpretation: LPdev and LPdying for cancer mirror cancer incidence and mortality rates. Cancer-specific changes in these probabilities over time are indicative of the cancer trends resulting from cancer prevention, screening, detection, and treatment. These changes in LPdev and LPdying provide insight into the shifting landscape of the Canadian cancer burden.

Projected estimates of cancer in Canada in 2022.

BACKGROUND: Regular cancer surveillance is crucial for understanding where progress is being made and where more must be done. We sought to provide an overview of the expected burden of cancer in Canada in 2022. METHODS: We obtained data on new cancer incidence from the National Cancer Incidence Reporting System (1984-1991) and Canadian Cancer Registry (1992-2018). Mortality data (1984-2019) were obtained from the Canadian Vital Statistics - Death Database. We projected cancer incidence and mortality counts and rates to 2022 for 22 cancer types by sex and province or territory. Rates were age standardized to the 2011 Canadian standard population. RESULTS: An estimated 233 900 new cancer cases and 85 100 cancer deaths are expected in Canada in 2022. We expect the most commonly diagnosed cancers to be lung overall (30 000), breast in females (28 600) and prostate in males (24 600). We also expect lung cancer to be the leading cause of cancer death, accounting for 24.3% of all cancer deaths, followed by colorectal (11.0%), pancreatic (6.7%) and breast cancers (6.5%). Incidence and mortality rates are generally expected to be higher in the eastern provinces of Canada than the western provinces. INTERPRETATION: Although overall cancer rates are declining, the number of cases and deaths continues to climb, owing to population growth and the aging population. The projected high burden of lung cancer indicates a need for increased tobacco control and improvements in early detection and treatment. Success in breast and colorectal cancer screening and treatment likely account for the continued decline in their burden. The limited progress in early detection and new treatments for pancreatic cancer explains why it is expected to be the third leading cause of cancer death in Canada.

Continued increasing incidence of malignant appendiceal tumors in Canada and the United States: A population-based study.

BACKGROUND: To the authors' knowledge, there are limited data regarding the epidemiology of malignant appendiceal tumors. It remains unknown whether the previously reported trends are occurring in different countries and/or continuing in recent years and/or whether they are possibly due to increasing rates of appendectomies. In the current study, the authors investigated the patterns and time trends of malignant appendiceal tumor diagnosis by age group, sex, stage of disease, and histology in Canada and the United States and concomitant rates of appendectomies in Canada. METHODS: The Canadian Cancer Registry and the US Surveillance, Epidemiology, and End Results incidence databases were used to identify incident patients of malignant appendiceal tumors in the 2 countries between 1992 and 2016. The Canadian national hospitals Discharge Abstract Database was used to identify appendectomies performed between 2004 and 2015. Joinpoint regression analyses were performed to determine time trends. RESULTS: There was an overall increase in the incidence of malignant appendiceal tumors of 232% in the United States and 292% in Canada between 2000 and 2016. The increase was noted for malignant adenocarcinomas and neuroendocrine appendiceal tumors in both countries. The increase occurred across all age groups, sexes, and stages of disease. The highest rate of increase was noted for appendiceal neuroendocrine malignant tumors diagnosed among the youngest age groups. The rate of appendectomies was stable in the recent time periods, resulting in a decreasing rate of appendectomies per malignant appendiceal tumor diagnosis. CONCLUSIONS: The incidence of malignant appendiceal tumor is continuing to increase, which is not likely due to the increasing diagnosis of asymptomatic tumors at the time of appendectomies.

Projected estimates of cancer in Canada in 2020.

BACKGROUND: Cancer projections to the current year help in policy development, planning of programs and allocation of resources. We sought to provide an overview of the expected incidence and mortality of cancer in Canada in 2020 in follow-up to the Canadian Cancer Statistics 2019 report. METHODS: We obtained incidence data from the National Cancer Incidence Reporting System (1984-1991) and Canadian Cancer Registry (1992-2015). Mortality data (1984-2015) were obtained from the Canadian Vital Statistics - Death Database. All databases are maintained by Statistics Canada. Cancer incidence and mortality counts and age-standardized rates were projected to 2020 for 23 cancer types by sex and geographic region (provinces and territories) for all ages combined. RESULTS: An estimated 225 800 new cancer cases and 83 300 cancer deaths are expected in Canada in 2020. The most commonly diagnosed cancers are expected to be lung overall (29 800), breast in females (27 400) and prostate in males (23 300). Lung cancer is also expected to be the leading cause of cancer death, accounting for 25.5% of all cancer deaths, followed by colorectal (11.6%), pancreatic (6.4%) and breast (6.1%) cancers. Incidence and mortality rates will be generally higher in the eastern provinces than in the western provinces. INTERPRETATION: The number of cancer cases and deaths remains high in Canada and, owing to the growing and aging population, is expected to continue to increase. Although progress has been made in reducing deaths for most major cancers (breast, prostate and lung), there has been limited progress for pancreatic cancer, which is expected to be the third leading cause of cancer death in Canada in 2020. Additional efforts to improve uptake of existing programs, as well as to advance research, prevention, screening and treatment, are needed to address the cancer burden in Canada.

Projection du fardeau du cancer au Canada en 2024.

CONTEXTE: Les données de surveillance du cancer sont essentielles pour mieux comprendre les lacunes et les progrès réalisés dans la lutte contre le cancer. Nous avons cherché à résumer les répercussions prévues du cancer au Canada en 2024, en effectuant des projections sur les nouveaux cas de cancer et les décès par cancer, par sexe et par province ou territoire, pour tous les âges confondus. MÉTHODES: Nous avons obtenu les données sur les nouveaux cas de cancer (c.-à-d., l'incidence, 1984­2019) et les décès par cancer (c.-à-d., la mortalité, 1984­2020) du Registre canadien du cancer et de la Base canadienne de données de l'état civil ­ Décès, respectivement. Nous avons projeté les chiffres et les taux d'incidence du cancer et de mortalité jusqu'en 2024 pour 23 types de cancer, par sexe et par province ou territoire. Nous avons calculé des taux normalisés selon l'âge au moyen de données de la population type canadienne de 2011. RÉSULTATS: En 2024, les nombres de nouveaux cas de cancer et de décès causés par le cancer devraient atteindre 247 100 et 88 100, respectivement. Le taux d'incidence normalisé selon l'âge (TINA) et le taux de mortalité normalisé selon l'âge (TMNA) devraient diminuer légèrement par rapport aux années précédentes, tant chez les hommes que chez les femmes, avec des taux plus élevés chez les hommes (TINA de 562,2 pour 100 000, et TMNA de 209,6 pour 100 000 chez les hommes; TINA de 495,9 pour 100 000 et TMNA de 152,8 pour 100 000 chez les femmes). Les TINA et les TMNA de plusieurs cancers courants devraient continuer à diminuer (p. ex., cancer du poumon, cancer colorectal et cancer de la prostate), tandis que ceux de plusieurs autres cancers devraient augmenter (p. ex., cancer du foie et des voies biliaires intrahépatiques, cancer du rein, mélanome et lymphome non hodgkinien). INTERPRÉTATION: Bien que l'incidence globale du cancer et la mortalité connexe sont en déclin, il devrait y avoir une augmentation des nouveaux cas et des décès au Canada en 2024, en grande partie en raison de la croissance et du vieillissement de la population. Les efforts en matière de prévention, de dépistage et de traitement ont atténué les répercussions de certains cancers, mais ces projections à court terme soulignent l'effet potentiel du cancer sur les gens et les systèmes de soins de santé au Canada.

Risk of colorectal cancer after the diagnosis of prostate cancer: A population-based study.

BACKGROUND: A rigorous assessment of the risk of colorectal cancer (CRC) among prostate cancer (PC) survivors that controls for important confounding factors and competing risks is necessary to determine the risk of CRC in this population and to inform screening guidelines. METHODS: With data from Manitoba, Canada, subjects diagnosed with PC as their first cancer between 1987 and 2009 were age-matched with up to 5 men with no history of invasive cancer on the PC diagnosis date. Subjects were followed to the date of diagnosis of CRC or another cancer, death, emigration, or the study endpoint (December 31, 2009). Competing risk proportional hazards models were used to compare the CRC incidence between those with PC and those without PC with the following model covariates: history of lower gastrointestinal endoscopy, frequency of health care visits, diabetes, and socioeconomic status. Mutually exclusive competing outcomes included CRC, another primary cancer, and death. RESULTS: For a total of 559,081 person-years, 14,164 men with PC and 69,051 men without PC were followed. Men diagnosed with PC had an increased risk of a subsequent diagnosis of CRC (all CRC: hazard ratio [HR], 1.14; 95% confidence interval [CI], 1.02-1.27; rectal cancer: HR, 1.36; 95% CI, 1.09-1.71). The treatment of PC with radiation was associated with an increased risk for rectal cancer (HR, 2.06; 95% CI, 1.42-2.99) in comparison with PC cases not treated with radiation. CONCLUSIONS: The risk of CRC is increased after a diagnosis of PC and is highest for rectal cancer among those treated with radiation. CRC screening should be considered soon after the diagnosis of PC, especially for men planning for radiotherapy.

Longitudinal Rates of Colon Cancer Screening Use in Winnipeg, Canada: The Experience of a Universal Health-Care System with an Organized Colon Screening Program.

OBJECTIVES: We examined trends in colorectal cancer (CRC) screening (fecal occult blood test (FOBT), colonoscopy, and flexible sigmoidoscopy (FS)) and differences in CRC screening by income in a population with an organized CRC screening program and universal health-care coverage. METHODS: Individuals who had an FOBT, colonoscopy, or FS were identified from the provincial Physician Claims database and the population-based colon cancer screening registry. Trends in age-standardized rates were determined. Logistic regression was performed to explore the association between CRC screening and income quintiles by year. RESULTS: Up-to-date CRC screening (FOBT, colonoscopy, or FS) increased over time for men and women, all age groups, and all income quintiles. Up-to-date CRC screening was very high among 65- to 69- and 70- to 74-year-olds (70% and 73%, respectively). There was a shift toward the use of an FOBT for CRC screening for individuals in the lower income quintiles. The disparity in colonoscopy/FS coverage by income quintile was greater in 2012 than in 1995. Overall, there was no reduction in disparities by income in up-to-date CRC screening nor did the rate of increase in up-to-date CRC screening or FOBT use change after the introduction of the organized provincial CRC screening program. CONCLUSIONS: CRC screening is increasing over time for both men and women and all age groups. However, a disparity in up-to-date CRC screening by income persisted even with an organized CRC screening program in a universal health-care setting.

Effect of changes in treatment practice on survival for cervical cancer: results from a population-based study in Manitoba, Canada.

BACKGROUND: Results from clinical trials in the 1990s led to changes in the recommended treatment for the standard therapy for stage IIB-IVA cervical cancer from radiotherapy alone to chemo-radiotherapy. We conducted the first population-based study in Canada to investigate temporal treatment patterns for cervical cancer and long-term survival in relation to these changes in the treatment guidelines. METHODS: Detailed information on stage and treatment for 1085 patients diagnosed with cervical cancer in 1984-2008 and identified from the population-based Manitoba Cancer Registry (MCR) in Canada was obtained from clinical chart review and the MCR. Factors associated with receiving guideline treatment were identified using logistic regression. All cause and cervical cancer specific survival were compared in patients who were and were not treated as recommended in the guidelines, using Cox proportional hazards models. RESULTS: The median follow-up time was 6.4 years (range: 0.05-26.5 years). The proportion of women who received guideline treatment was 79 % (95 % confidence interval [CI]: 76-81 %). However, the likelihood of being treated according to the guidelines over time was modified by age (p < 0.0001) and tumour stage at diagnosis (p = 0.002). Women who were treated according to the guidelines after the change in recommended clinical practice (1999-2008) had a significantly lower risk of death from all causes and from cervical cancer. This was driven by lower mortality rates in cases with stage IIB-IVA tumours (all causes of death: hazard ratio [HR] = 0.60, 95 % CI: 0.43-0.82, p = 0.002; cervical cancer related death: HR = 0.64, 95 % CI: 0.44-0.93, p = 0.02). CONCLUSIONS: The management of cervical cancer patients in Manitoba, Canada was in good agreement with treatment guidelines although reasons for departure from the guideline recommendations could not be examined further due to lack of data. Treatment of stage IIB-IVA cervical cancers with recommended concurrent chemo-radiotherapy, which is now standard practice, was associated with substantially increased survival, although the effect of changes in clinical practice including maintenance of haemoglobin levels on improved survival cannot be ruled out as a contributing factor.

Mammography rates for breast cancer screening: a comparison of First Nations women and all other women living in Manitoba, Canada, 1999-2008.

INTRODUCTION: First Nations (FN) women historically have low rates of preventive care, including breast cancer screening. We describe the frequency of breast cancer screening among FN women living in Manitoba and all other Manitoba (AOM) women after the introduction of a provincial, organized breast screening program and explore how age, area of residence, and time period influenced breast cancer screening participation. METHODS: The federal Indian Registry was linked to 2 population-based, provincial data sources. A negative binomial model was used to compare breast cancer screening for FN women with screening for AOM women. RESULTS: From 1999 through 2008, 37% of FN and 59% of AOM women had a mammogram in the previous 2 years. Regardless of area of residence, FN women were less likely to have had a mammogram than AOM women (relative rate [RR] = 0.69 in the north, RR = 0.55 in the rural south, and RR = 0.53 in urban areas). CONCLUSIONS: FN women living in Manitoba had lower mammography rates than AOM women. To ensure equity for all Manitoba women, strategies that encourage FN women to participate in breast cancer screening should be promoted.

Progress in cancer control leads to a substantial number of cancer deaths avoided in Canada.

It is currently not known how many more cancer deaths would have occurred among Canadians if cancer mortality rates were unchanged following various modern human interventions. The objective of this study was to estimate the number of cancer deaths that have been avoided in Canada since the age-standardized overall cancer mortality rate peaked in 1988. We applied the age-specific overall cancer mortality rates from 1988 to the Canadian population for all subsequent years to estimate the number of expected deaths. Avoided cancer deaths were estimated as the difference between the observed and expected number of cancer deaths for each year. Since 1988, there have been 372 584 (standardized mortality ratio = 0.77) and 120 045 (standardized mortality ratio = 0.90) avoided cancer deaths in males and females, respectively (492 629 total). Nearly half a million cancer deaths have been avoided in Canada since the overall cancer mortality rate peaked, which demonstrates the exceptional progress made in modern cancer control in Canada.

Increased risk of nonmelanoma skin cancers among individuals with inflammatory bowel disease.

BACKGROUND & AIMS: There are limited data on the risk of nonmelanoma skin cancer (NMSC) among individuals with inflammatory bowel disease (IBD), including those with or without exposure to immunosuppressant medications. METHODS: Individuals with IBD (n = 9618) were identified from the University of Manitoba IBD Epidemiology Database and matched with randomly selected controls (n = 91,378) based on age, sex, and postal area of residence on the date of IBD diagnosis (index date). Groups were followed up from the index date until a diagnosis of any invasive cancer (including NMSC), death, migration from the province, or the end of the study (December 31, 2009), whichever came first. Cox regression analysis was performed to calculate the relative risk of NMSC among the individuals with IBD, adjusting for frequency of ambulatory care visits and socioeconomic status. RESULTS: Of the individuals followed, 1696 were diagnosed with basal cell skin cancer (BCC) and 341 were diagnosed with squamous cell skin cancer (SCC). Individuals with IBD had an increased risk for BCC, compared with controls (hazard ratio, 1.20; 95% confidence interval [CI], 1.03-1.40). Among patients with IBD, use of thiopurines increased the risk of SCC (hazard ratio, 5.40; 95% CI, 2.00-14.56), compared with controls. Use of thiopurines also was associated with SCC in a case-control, nested analysis of individuals with IBD (odds ratio, 20.52; 95% CI, 2.42-173.81). CONCLUSIONS: The risk of BCC could be increased among individuals with IBD. Use of thiopurines increases the risk of SCC among individuals with IBD.

Update on cancer incidence trends in Canada, 1984 to 2017. / Le point sur les tendances de l'incidence du cancer au Canada (1984-2017).

This paper highlights findings on cancer trends from the Canadian Cancer Statistics 2021 report. Trends were measured using annual percent change (APC) of age-standardized incidence rates. Overall, cancer incidence rates are declining (-1.1%) but the findings are specific to the type of cancer and patient sex. For example, in males, the largest decreases per year were for prostate (-4.4%), colorectal (-4.3%), lung (-3.8%), leukemia (-2.6%) and thyroid (-2.4%) cancers. In females, the largest decreases were for thyroid (-5.4%), colorectal (-3.4%) and ovarian (-3.1%) cancers.

Overall, cancer incidence is declining at a rate of −1.1% per year. In males, the two largest decreases were for prostate (−4.4% per year) and colorectal (−4.3% per year) cancer. In females, they were for thyroid (−5.4% per year) and colorectal (−3.4% per year) cancer. Melanoma (males: 2.2% per year; females: 2.0% per year) and multiple myeloma (males: 2.5% per year; females: 1.6% per year) rates are increasing. Cancer trends in Canada are dynamic and type-specific. The decreases for prostate and thyroid cancer underscore the importance of updating testing practices based on best evidence.

Dans l'ensemble, l'incidence du cancer diminue à un taux de −1,1 % par année. Les deux plus fortes baisses ont été observées chez les hommes pour le cancer de la prostate (−4,4 % par année) et le cancer colorectal (−4,3 % par année) et, chez les femmes, pour le cancer de la thyroïde (−5,4 % par année) et le cancer colorectal (−3,4 % par année). Les taux de mélanome sont en hausse (hommes : 2,2 % par année; femmes : 2,0 % par année) ainsi que ceux de myélome multiple (hommes : 2,5 % par année; femmes : 1,6 % par année). Les tendances en matière de cancer au Canada sont dynamiques et elles dépendent de chaque type de cancer. La diminution de l'incidence du cancer de la prostate et du cancer de la thyroïde souligne l'importance de mettre à jour les pratiques de dépistage à partir des meilleures données probantes.

The reduction in colorectal cancer mortality after colonoscopy varies by site of the cancer.

BACKGROUND & AIMS: There are limited data on mortality from colorectal cancer (CRC) among patients who have received colonoscopy examinations. We sought to determine CRC mortality among persons undergoing colonoscopies compared with the general population. METHODS: We identified all individuals who had a colonoscopy as their first lower gastrointestinal endoscopy from April 1, 1987, to September 30, 2007 (24,342 men and 30,461 women), based on information from Manitoba's provincial physicians' billing claims database. Patients were followed until March 31, 2008, death, or migration out of the province (310,718 person-years). Individuals less than 50 years of age or more than 80 years of age at the index colonoscopy or those with prior sigmoidoscopy, inflammatory bowel disease, resective colorectal surgery, or CRC were excluded. CRC mortality after the index colonoscopy was compared with that of the general population by standardized mortality ratios (SMRs). Stratified analyses were performed to determine CRC mortality for different age groups at index colonoscopy and sex, duration of follow-up, medical specialty of the endoscopist, and site of CRC. RESULTS: There was a 29% reduction in overall CRC mortality (SMR, 0.71; 95% confidence interval [CI], 0.61-0.82], a 47% reduction in mortality from distal CRC (SMR, 0.53; 95% CI, 0.42-0.67), and no reduction in mortality from proximal CRC (SMR, 0.94; 95% CI, 0.77-1.17). The reduction in mortality from distal CRC remained significant for follow-up beyond 10 years (SMR, 0.53; 95% CI, 0.31-0.84). CONCLUSIONS: In Manitoba, colonoscopies significantly reduce mortality from CRC, but the benefit is not uniform for colorectal tumors that arise in different areas of the colon.

Risk of cervical abnormalities in women with inflammatory bowel disease: a population-based nested case-control study.

BACKGROUND & AIMS: We evaluated the risk of cervical abnormalities in women with inflammatory bowel disease (IBD) in a population-based, nested, case-control study. METHODS: Cases with abnormal Papanicolaou (Pap) smears or cervical biopsies were matched with up to 3 controls (normal Pap smears) by year of birth, year of first health care coverage, and number of Pap smears in the preceding 5 years. A diagnosis of IBD before the index date was identified from the University of Manitoba IBD Epidemiology Database. Exposures to immunosuppressant drugs and corticosteroids were determined from the provincial drug prescription database. Analyses were adjusted for socioeconomic status and exposure to oral contraceptives and nonsteroidal anti-inflammatory drugs. RESULTS: 19,692 women with cervical cytologic and/or histologic abnormalities were matched with 57,898 controls with normal Pap smears. There was no association between cervical abnormalities and ulcerative colitis (odds ratio [OR], 1.03; 95% confidence interval [CI], 0.77-1.38). The increase in risk in women with Crohn's disease was limited to those exposed to 10 or more prescriptions of oral contraceptives (OR, 1.66; 95% CI, 1.08-2.54). The combined exposure to corticosteroids and immunosuppressants was associated with increased risk of cervical abnormalities (OR, 1.41; 95% CI, 1.09-1.81). There was no interaction between the effect of IBD and corticosteroids and/or immunosuppressants. CONCLUSIONS: These findings do not support an association between IBD itself and the risk of developing cervical abnormalities. An increased risk in patients given a combination of corticosteroids and immunosuppressants should be considered in managing women with IBD.

Rate and predictors of early/missed colorectal cancers after colonoscopy in Manitoba: a population-based study.

OBJECTIVES: Many of the colorectal cancers (CRCs) diagnosed within 3 years after a colonoscopy are likely because of lesions missed on the initial colonoscopy. In this population-based study, we investigated the rate and predictors of CRCs diagnosed within 3 years of a colonoscopy. METHODS: We identified individuals 50-80 years of age diagnosed with CRC between 1992 and 2008 from the provincewide Manitoba Cancer Registry. Performance of colonoscopy and history of co-morbidities was determined by linkage to the provincial universal health care insurance provider's physician billing claims and hospital discharges databases. CRCs diagnosed within 6 months of a colonoscopy were categorized as detected CRCs and those 6-36 months after a colonoscopy as early/missed CRCs. Logistic regression analysis was performed to identify the patient, endoscopist, colonoscopy, and CRC factors associated with early/missed CRCs. RESULTS: Of the 4,883 CRCs included in the study, 388 (7.9%) were early/missed CRCs, with a range of 4.5% of rectum/rectosigmoid cancers in men to 14.4% of transverse colon/splenic flexure cancers in women. Independent risk factors associated with early/missed CRCs included prior colonoscopy, performance of index colonoscopy by family physicians, recent year of CRC diagnosis, and proximal site of CRC. CONCLUSIONS: This study suggests that approximately 1 in 13 CRCs may be an early/missed CRC, diagnosed after an index colonoscopy in usual clinical practice. Women are more likely to have early/missed CRC. It is unclear if this relates to differences in procedure difficulty, bowel preparation issues, or tumor biology between men and women.

Predictors of colorectal cancer after negative colonoscopy: a population-based study.

OBJECTIVES: A higher proportion of colorectal neoplasia among women occurs in the proximal colon, which might be more frequently missed by colonoscopy. There are no data on predictors of developing colorectal cancer (CRC) after a negative colonoscopy in usual clinical practice. We evaluated gender differences and predictors of CRC occurring after a negative colonoscopy. METHODS: All individuals 40 years or older with negative colonoscopy were identified from Manitoba's provincial physicians' billing claims database. Individuals with less than 5 years of coverage by the provincial health plan, earlier CRC, inflammatory bowel disease, resective colorectal surgery, or lower gastrointestinal endoscopy were excluded. CRC risk after negative colonoscopy was compared to that in the general population by standardized incidence ratios. Cox regression analysis was performed to determine the independent predictors of CRC occurring after negative colonoscopy. RESULTS: A total of 45,985 individuals (18,606 men; 27,379 women) were followed up for 229,090 person-years. After a negative colonoscopy, men had a 40-50% lower risk of CRC diagnosis through most of the follow-up time. Risk among women was similar to that of women in the general population in the first 3 years and then was 40-50% lower. Older subject age and performance of index colonoscopy by non-gastroenterologists were independent predictors for early/missed CRC (cancers occurring within 3 years of negative colonoscopy). CONCLUSIONS: Women may have a higher rate of missed/early CRCs after negative colonoscopy. Predictors of missed/early CRCs after negative colonoscopy include older age and performance of index colonoscopy by a non-gastroenterologist.

Long-term use of statins and risk of colorectal cancer: a population-based study.

OBJECTIVES: We conducted a population-based cohort study to determine the effect of long-term regular use of statins on the risk of colorectal cancer (CRC). METHODS: Individuals who were dispensed statins regularly were identified from Manitoba's population-based prescription drug database and followed up until diagnosis of CRC, migration out of province, death, or December 2005. The incidence of CRC in this group was compared with that among individuals who were never dispensed statins. Stratified analysis was performed to determine the risk after 5 years of regular statin use. Multivariate Poisson regression models were used to adjust for potential confounding by age, sex, and history of diabetes, inflammatory bowel disease, coronary heart disease, lower gastrointestinal endoscopy, resective colorectal surgery, use of nonsteroidal anti-inflammatory drugs, hormone replacement therapy (among women), and median household income. The dose effect was evaluated in defined daily dose units. RESULTS: In total, 35,739 individuals were dispensed statins regularly. In all, 10,287 (49% males; 51% females) long-term (>or=5 years) regular statin users were followed up for up to 5 additional years. In multivariate analysis, the incidence rate ratio (IRR) of CRC among those dispensed statins regularly compared with those who were never dispensed statins (n=377,532) was 1.13 (95% confidence interval (CI): 1.02-1.25). The CRC risk among the long-term regular statin users was similar to that for individuals never dispensed statins (IRR, 0.89; 95% CI: 0.70-1.13). A statistically nonsignificant risk reduction was observed among high-dose long-term regular statin users. CONCLUSIONS: These findings suggest that long-term regular use of statins for the current clinical indications does not protect against CRC. The benefit of high-dose long-term statin use needs further evaluation.

Twenty-year trends in the incidence and prevalence of diagnosed anogenital warts in Canada.

BACKGROUND: A vaccine has recently been licensed in many countries that protects against the human papillomavirus types 6, 11, 16, and 18. Types 6 and 11 account for approximately 90% of anogenital warts (AGWs). We describe the 20-year trends in the incidence and prevalence of AGWs in Manitoba, Canada. METHODS: We used linked population-based hospital and physician databases for Manitoba for 1984 to 2004. Cases were identified using tariff (billing) and ICD codes. A case was considered to be incident if it was preceded by a 12-month interval free period of AGWs care. Otherwise, it was deemed to be prevalent. An episode was considered over once a 12-month interval had elapsed without an AGW claim. RESULTS: Approximately 25,000 Manitobans were diagnosed with AGWs between 1985 and 2004. The annual age-standardized incidence rates peaked in 1992 (men, 149.9/100,000; women 170.8/100,000). In recent years, the rates have been increasing again, particularly for men. The male:female incidence rate ratio increased from 0.76 in 1985 to 1.25 in 2004. The highest incidence rate tended to be in those aged 20 to 24 years. Trends in prevalence were similar. Prevalence in 2004 was 165.2/100,000 for men and 128.4/100,000 for women. CONCLUSIONS: These population-based findings suggest that AGWs are a substantial burden to Manitobans and that their pattern has changed over time, with incidence and prevalence becoming higher in men than women. Monitoring the future trends in AGWs will provide an early marker of the effectiveness and duration of protection of human papillomavirus vaccination at a population level.

Incidence and anatomic presentation of cutaneous malignant melanoma in central Canada during a 50-year period: 1956 to 2005.

BACKGROUND: Incidence rates of cutaneous malignant melanoma (CMM) have increased worldwide. Long-term studies examining rates and anatomic site-specific incidence on a population-based level are infrequent. OBJECTIVE: We sought to examine the historical changes in the incidence and anatomic site presentation of CMM during a 50-year period in Manitoba, Canada. METHODS: Using population-based data, all first diagnoses of CMM reported between 1956 and 2005 were identified. Age-specific rates, age-standardized incidence rates, and anatomic sites were recorded. RESULTS: Incidence rates of CMM slowed for each sex beginning in 1981 for female patients and 1992 for male patients. Annual percent change revealed decreasing rates among male patients younger than 40 years (1992-2005: -5.3% [P = .03]) and female patients younger than 40 years (1987-2005: -1.8% [P = .15]). Similarly, middle-aged individuals (age 40-59 years) also had diminished annual percent change (men 1992-2005: 0.6% [P = .65]; women 1983-2005: -0.3% [P = .68]). The annual percent change for older men and women (60-79 and > or =80 years) continued to increase. Anatomic site-specific analyses revealed that the trunk was the most frequent site of CMM for young male patients (<60 years) whereas the lower extremities were the most common among young female patients (<60 years). Incidence rates for each site, however, are slowing. Among those aged 60 years and older, the rates for each anatomic site increased. LIMITATIONS: Determining changes in tumor thickness would have been useful in determining whether the nature of tumors have changed over time; however, this is not recorded in our registry. CONCLUSION: The rates of CMM are slowing; however, this change is confined to younger individuals. Anatomic site-specific CMMs are changing; rates among older individuals continue to increase for both sexes.