Distribution and Clustering of Cutaneous T-Cell Lymphoma (CTCL) Cases in Canada During 1992 to 2010

Breaking Down the Barriers for Patients With Cutaneous T-Cell Lymphoma: Current Controversies and Challenges for Radiation Oncologists in 2024

Cutaneous T-cell lymphomas (CTCL) are a rare collection of diseases, frequently associated with diagnostic challenges and complex management dilemmas. The multidisciplinary team is vital for accurate clinico-pathological diagnoses and for collaborative therapeutic decisions throughout the management journey, which frequently involves multiple lines of therapy. Radiotherapy (RT) is a highly effective skin-directed therapy for CTCL, commonly delivered as localised fields or as total skin electron beam therapy (TSEBT). Mycosis fungoides (MF) is the most common of the CTCL, and patients typically experience high rates of morbidity and long natural histories of relapse and progression. Patients with MF typically present with incurable disease; in these patients, RT has an established role in symptom- and disease-control, achieving excellent response rates and proven therapeutic benefits. The role of RT continues to evolve, with modern practices favouring lower doses to reduce toxicity risks and allow for re-irradiation. Less commonly, there are situations where RT has an integral role in the potential cure of patients with MF: firstly, in the setting of unilesional MF where localised RT alone may be curative, and secondly, in the setting of preconditioning prior to curative-intent allogeneic hematopoietic stem cell transplant for patients with advanced MF/Sezary syndrome, where conventional-dose TSEBT is indicated as the most effective single agent for maximal debulking of skin disease. Radiotherapy also has an important role in the management of the less common CTCL, including the curative treatment of localised primary cutaneous anaplastic large cell lymphoma. Despite proven efficacy and quality of life benefits, disparity exists in access to RT and TSEBT. World-wide, stronger multidisciplinary collaborations and greater patient advocacy are required to increase access to RT and improve equity of care for our patients with CTCL.

Cutaneous T-cell Lymphoma

Cutaneous T-cell lymphoma is a group of non-Hodgkin T-cell lymphomas that develop in and affect the skin but can potentially spread to other organs. There are many subtypes, the most common of which are mycosis fungoides, Sezary syndrome, lymphomatoid papulosis, and primary cutaneous anaplastic large cell lymphoma. Cutaneous lymphoma is a common cause of recalcitrant chronic skin rash and notoriously mimics other dermatologic and hematologic conditions, often resulting in diagnostic delays of months to years. This review provides an introduction to cutaneous T-cell lymphoma, with a primary focus on the clinical presentation, diagnosis, immunopathogenesis, and management of the condition.

From Molecules to Microbes: Tracing Cutaneous T-Cell Lymphoma Pathogenesis through Malignant Inflammation

The etiology of CTCL is a subject of extensive investigation. Researchers have explored links between CTCL and environmental chemical exposures, such as aromatic hydrocarbons (eg, pesticides and benzene), as well as infectious factors, including various viruses (eg, human T-lymphotropic virus [HTLV]-I and HTLV-II) and bacteria (eg, Staphylococcus aureus). There has been growing emphasis on the role of malignant inflammation in CTCL development. In this review, we synthesize studies of environmental and infectious exposures, along with research on the aryl hydrocarbon receptor and the involvement of pathogens in disease etiology, providing insight into the pathogenesis of CTCL.

Role of Antigenic Stimulation in Cutaneous T-Cell Lymphomas

Cutaneous T-cell lymphoma (CTCL) involves a clonal expansion of malignant cells accumulating in the skin, a primary barrier site. CTCL has long been hypothesized to be caused or perpetuated by chronic antigen stimulation due to unknown exposures. These antigenic triggers, defined as any element that may cause activation of malignant T cells through TCR signaling, have been hypothesized to range from chemicals to microbes. This review covers current evidence supporting chemical and microbial stimuli that may act as antigenic triggers of CTCL and summarizes novel areas of investigation, in which the potential antigenicity of the exposure is still unknown.

Vitamin D in Cutaneous T-Cell Lymphoma

Cutaneous T-cell lymphoma (CTCL) is characterized by the proliferation of malignant T cells in inflamed skin lesions. Mycosis fungoides (MF)-the most common variant of CTCL-often presents with skin lesions around the abdomen and buttocks ("bathing suit" distribution), i.e., in skin areas devoid of sun-induced vitamin D. For decades, sunlight and vitamin D have been connected to CTCL. Thus, vitamin D induces apoptosis and inhibits the expression of cytokines in malignant T cells. Furthermore, CTCL patients often display vitamin D deficiency, whereas phototherapy induces vitamin D and has beneficial effects in CTCL, suggesting that light and vitamin D have beneficial/protective effects in CTCL. Inversely, vitamin D promotes T helper 2 (Th2) cell specific cytokine production, regulatory T cells, tolerogenic dendritic cells, as well as the expression of immune checkpoint molecules, all of which may have disease-promoting effects by stimulating malignant T-cell proliferation and inhibiting anticancer immunity. Studies on vitamin D treatment in CTCL patients showed conflicting results. Some studies found positive effects, others negative effects, while the largest study showed no apparent clinical effect. Taken together, vitamin D may have both pro- and anticancer effects in CTCL. The balance between the opposing effects of vitamin D in CTCL is likely influenced by treatment and may change during the disease course. Therefore, it remains to be discovered whether and how the effect of vitamin D can be tilted toward an anticancer response in CTCL.

Clusters, crop dusters, and myth busters: a scoping review of environmental exposures and cutaneous T-cell lymphoma

INTRODUCTION

Cutaneous T-cell lymphoma (CTCL) is a heterogenous group of non-Hodgkin lymphomas. Similar presentation to benign conditions, significant genetic variation, and lack of definitive biomarkers contributes to diagnostic delay. The etiology of CTCL is unknown, and environmental exposures, such as geographic, occupational, chemicals, sunlight, and insects have been investigated.

EVIDENCE ACQUISITION

Review of the literature for CTCL and exposures was performed in PubMed and Google Scholar in accordance with the Preferred Reporting Items for Systematic Reviews and Meta-analyses (PRISMA) Extension for Scoping Reviews. This search yielded 193 total results, which were initially screened with defined inclusion and exclusion criteria. The 45 remaining articles were reviewed and classified by exposure type.

EVIDENCE SYNTHESIS

The most frequently investigated CTCL exposure type was geographic (13/45 articles, 29%). Chemical exposures were commonly discussed (10/45 articles, 22%), along with occupational (10/45 articles, 22%). Insect exposures (6/45, 13%) and sun exposure (3/45, 7%) were also reviewed, along with articles describing multiple exposure types (3/45, 7%). Article types ranged from cases to systematic reviews and case-control studies. Evidence linking CTCL and these exposures was mixed. Limitations of this investigation include reliance on patient reporting and frequent speculation on disease association versus causality.

CONCLUSIONS

This investigation synthesizes the current literature on exposures potentially implicated in the pathogenesis of CTCL, while offering guidance on patient history-taking to ensure potential exposures are captured. Awareness of these possible associations may improve understanding of disease pathogenesis and diagnosis. Moreover, these insights may help with public health decision-making and disease mitigation.

Cutaneous T-cell lymphoma developing in surgical scars post cardiac surgery: A case study

Cutaneous T-cell lymphomas are a class of non-Hodgkin lymphomas characterized by the infiltration of malignant T cells into the skin. Their precise pathogenesis remains incompletely understood, but persistent and specific antigen stimulation of skin-homing CD4+ memory T cells by external or internal factors, combined with an inflammatory cytokine-rich tissue microenvironment, may be critical in the development of cutaneous T-cell lymphomas. We present herein a case of primary cutaneous T-cell lymphoma arising in two surgical scars that developed 6 months post-operatively and were successfully treated with external beam radiotherapy. This case highlights the notion that primary cutaneous T-cell lymphoma can develop locally at the site of injury/foreign body within a relatively short time post trauma/surgery. This work contributes to the literature of cutaneous T-cell lymphomas arising after a trauma, surgery, or a foreign body.

Disparities in Cutaneous T-Cell Lymphoma Incidence by Race/Ethnicity and Area-Based Socioeconomic Status

Cutaneous T-cell lymphoma (CTCL) is a rare type of extranodal non-Hodgkin lymphoma (NHL). This study uses population-based data from the New Jersey (NJ) State Cancer Registry to examine geographic variation in CTCL incidence and evaluates whether CTCL risk varies by race/ethnicity and census tract socioeconomic status (SES). The study included 1163 cases diagnosed in NJ between 2006 and 2014. Geographic variation and possible clustering of high CTCL rates were assessed using Bayesian geo-additive models. The associations between CTCL risk and race/ethnicity and census tract SES, measured as median household income, were examined using Poisson regression. CTCL incidence varied across NJ, but there were no statistically significant geographic clusters. After adjustment for age, sex, and race/ethnicity, the relative risk (RR) of CTCL was significantly higher (RR = 1.47, 95% confidence interval: 1.22-1.78) in the highest income quartile than in the lowest. The interactions between race/ethnicity and SES indicated that the income gradients by RR were evident in all groups. Compared to non-Hispanic White individuals in low-income tracts, CTCL risk was higher among non-Hispanic White individuals in high-income tracts and among non-Hispanic Black individuals in tracts of all income levels. Our findings suggest racial disparities and a strong socioeconomic gradient with higher CTCL risk among cases living in census tracts with higher income compared to those living in lower-income tracts.

The Use of Retinoids for the Prevention and Treatment of Skin Cancers: An Updated Review

Retinoids are natural and synthetic vitamin A derivatives that are effective for the prevention and the treatment of non-melanoma skin cancers (NMSC). NMSCs constitute a heterogenous group of non-melanocyte-derived skin cancers that impose substantial burdens on patients and healthcare systems. They include entities such as basal cell carcinoma and cutaneous squamous cell carcinoma (collectively called keratinocyte carcinomas), cutaneous lymphomas and Kaposi’s sarcoma among others. The retinoid signaling pathway plays influential roles in skin physiology and pathology. These compounds regulate diverse biological processes within the skin, including proliferation, differentiation, angiogenesis and immune regulation. Collectively, retinoids can suppress skin carcinogenesis. Both topical and systemic retinoids have been investigated in clinical trials as NMSC prophylactics and treatments. Desirable efficacy and tolerability in clinical trials have prompted health regulatory bodies to approve the use of retinoids for NMSC management. Acceptable off-label uses of these compounds as drugs for skin cancers are also described. This review is a comprehensive outline on the biochemistry of retinoids, their activities in the skin, their effects on cancer cells and their adoption in clinical practice.

Epidemiologic Trends of Cutaneous T-Cell Lymphoma in Arkansas Reveals Demographic Disparities

Accurate demographic data are critical for comprehending and treating cutaneous T-cell lymphoma (CTCL). Our research aimed to determine the demographics and incidence trends of CTCL patients in Arkansas compared to those of the national CTCL population to recognize the underlying disparities. We collected data from 143 CTCL patients at the University of Arkansas for Medical Sciences (UAMS) and national CTCL patient data from the Surveillance, Epidemiology, and End Results (SEER) database. Our analysis revealed that males are affected more than females across all ages and races. CTCL incidence and mortality data show that CTCL has a steady increase at the national level and in Arkansas while disproportionately affecting the young black male population. In Arkansas, more than one-third of black patients presented at an advanced stage (IIB+) compared to one-fifth in the white population, and the mean age of death was more than a decade younger for black (60 years) than for white patients (74.6 years). Nationally, black male patients had the greatest mortality rate (0.5) compared to 0.32 for white males. CTCL is 2.23 and 2.38 times more prevalent in urban versus rural areas in Arkansas and nationally, respectively. Most Arkansas patients reside near major interstates and chemical-emitting sites. In conclusion, our demographic analysis of Arkansas and national CTCL patients verifies recent trends toward more aggressive presentations in young black male patients, and our geographic findings suggest possible environmental risk factors.

Population-Based Study Detailing Cutaneous Melanoma Incidence and Mortality Trends in Canada

Background

Cutaneous melanoma (CM) is one of the most fatal types of skin cancer. Alarmingly, increases in incidence and mortality were noted globally for this malignancy, despite increase in understanding of melanoma pathogenesis and enhanced prevention efforts.

Methods

Data was extracted for CM patients for provinces and territories (except Quebec) using two independent, population-based registries. Analysis was performed using both clinical and pathological characteristics: tumor morphologic classification, age, sex, anatomic site affected and place of residence. Mortality trends were assessed over a 7-year period. Results were compared to prior findings for 1992-2010.

Results

During 2011-2017 39,610 patients were diagnosed with CM, with 5,890 reported deaths. National crude CM incidence was 20.75 (age-standardized incidence: 14.12) cases per 100,000 individuals per year. Females accounted for 45.8% of cases and 37.1% of deaths. While CM incidence rates continue to increase in both sexes, since 2013 the CM mortality is declining. We observed important differences across the provinces/territories, where Nova Scotia, Prince Edward Island, southern Ontario/British Columbia and certain coastal communities of New Brunswick demonstrated higher CM incidence and mortality rates. The observed incidence and mortality trends for 2011-2017 validate and extend earlier observations from 1992 to 2010 for CM.

Conclusion

This population-based study highlights that while melanoma's incidence is increasing in Canada, mortality rates are for the first time decreasing since 2013. We detail regional distribution of this cancer highlighting communities in southern/coastal areas, as being most at risk as well as the latest trends of melanoma incidence by age, sex and anatomic site. In males, melanoma is more common on the head/trunk, while in females on the extremities. Notably, Acral Lentiginous Melanoma was the only CM subtype that was more common in females, which primarily affects hands and feet.

Epidemiologic trends and geographic distribution of patients with gallbladder and extrahepatic biliary tract cancers in Canada

BACKGROUND

Gallbladder and biliary tract cancers are rare malignancies that carry a poor prognosis. Research on their epidemiologic trends is scarce.

METHODS

We performed a retrospective analysis of the data in Canada using population-based cancer registries from 1992 to 2010. The incidence and mortality of gallbladder and extrahepatic bile duct cancers were examined at the levels of provinces/territories, cities, and Forward Sortation Area (FSA) postal codes.

RESULTS

The incidence and mortality rates decreased over the study period. The average national incidence rate of gallbladder and biliary tract cancers was 30.92 cases per million individuals per year. Higher than average incidence rates were observed in Manitoba, Saskatchewan and Québec; there were contiguous regions with high incidence in Saskatchewan and Manitoba that suggest an area of putative case clustering. Higher incidence of gallbladder cancer was observed in women, whereas higher incidence of extrahepatic bile duct cancers was noted in men. Lower socioeconomic status and Hispanic race were found to be risk factors for gallbladder and biliary tract cancers.

CONCLUSION

This is the first study to analyze the burden of gallbladder and biliary tract cancers in Canada. The geographic clustering trends present new avenues for research on environmental triggers.

Geographic clustering of cutaneous T-cell lymphoma in New Jersey: an exploratory analysis using residential histories

PURPOSE

Cutaneous T-cell lymphoma (CTCL) is a rare type of non-Hodgkin lymphoma. Previous studies have reported geographic clustering of CTCL based on the residence at the time of diagnosis. We explore geographic clustering of CTCL using both the residence at the time of diagnosis and past residences using data from the New Jersey State Cancer Registry.

METHODS

CTCL cases (n = 1,163) diagnosed between 2006-2014 were matched to colon cancer controls (n = 17,049) on sex, age, race/ethnicity, and birth year. Jacquez's Q-Statistic was used to identify temporal clustering of cases compared to controls. Geographic clustering was assessed using the Bernoulli-based scan-statistic to compare cases to controls, and the Poisson-based scan-statisic to compare the observed number of cases to the number expected based on the general population. Significant clusters (p < 0.05) were mapped, and standard incidence ratios (SIR) reported. We adjusted for diagnosis year, sex, and age.

RESULTS

The Q-statistic identified significant temporal clustering of cases based on past residences in the study area from 1992 to 2002. A cluster was detected in 1992 in Bergen County in northern New Jersey based on the Bernoulli (1992 SIR 1.84) and Poisson (1992 SIR 1.86) scan-statistics. Using the Poisson scan-statistic with the diagnosis location, we found evidence of an elevated risk in this same area, but the results were not statistically significant.

CONCLUSION

There is evidence of geographic clustering of CTCL cases in New Jersey based on past residences. Additional studies are necessary to understand the possible reasons for the excess of CTCL cases living in this specific area some 8-14 years prior to diagnosis.

Geographic and Socioeconomic Disparity of Gastric Cancer Patients in Canada

Gastric cancer is the 5th most common malignancy worldwide, representing ~5–10% of all new cancer cases. Although its incidence is declining, it is estimated that 1 in 98 Canadians will develop gastric cancer in their lifetime. The epidemiology and distribution of gastric cancer throughout Canada, however, remains poorly understood. A retrospective analysis of demographic data across Canada between 1992 and 2010 was performed using 2 population-based cancer registries. The incidence of gastric cancer was examined at the levels of provinces, cities, and postal codes. In addition, 43,955 patients were diagnosed with gastric cancer in Canada between 1992 and 2010; 66% were male and the average age of diagnosis was 68.4 years. The age-adjusted incidence rate was 5.07 cases per 100,000 individuals per year. The incidence decreased over the study period by 30%. High incidence rates were identified in rural areas of Newfoundland and Labrador, New Brunswick, and Quebec. Our study found a significant association between gastric cancer incidence rates and lower socioeconomic status, as well as Hispanic ethnicity. This is the first study to provide a comprehensive analysis of the incidence of gastric carcinoma in Canada, identifying high-risk populations that may benefit from increased primary and secondary prevention.

Incidence and Mortality of Prostate Cancer in Canada during 1992-2010

In Canada, prostate cancer is the most common reportable malignancy in men. We assessed the temporal trends of prostate cancer to gain insight into the geographic incidence and mortality trends of this disease. Three independent population-based cancer registries were used to retrospectively analyze demographic data on Canadian men diagnosed with prostate cancer and men who died of prostate cancer between the years of 1992 and 2010. The incidence and mortality rates were calculated at the provincial, city, and forward sortation area (FSA) postal code levels by using population counts that were obtained from the Canadian Census of Population. The Canadian average incidence rate was 113.57 cases per 100,000 males. There has been an overall increasing trend in crude prostate cancer incidence between 1992 and 2010 with three peaks, in 1993, 2001, and 2007. However, age-adjusted incidence rates showed no significant increase over time. The national mortality rate was calculated to be 24.13 deaths per 100,000 males per year. A decrease was noted in crude and age-adjusted mortality rates between 1992 and 2010. Several provinces, cities, and FSAs had higher incidence/mortality rates than the national average. Several of the FSA postal codes with the highest incidence/mortality rates were adjacent to one another. Several Canadian regions of high incidence for prostate cancer have been identified through this study and temporal trends are consistent with those reported in the literature. These results will serve as a foundation for future studies that will seek to identify new regional risk factors and etiologic agents.

Hypopigmented Mycosis Fungoides: Loss of Pigmentation Reflects Antitumor Immune Response in Young Patients

Hypopigmented mycosis fungoides (HMF) is a form of cutaneous T-cell lymphoma (CTCL), a heterogeneous group of extranodal non-Hodgkin's lymphomas. HMF has a unique set of defining features that include light colored to achromic lesions, a predilection for darker skin phototypes, an early onset of disease, and predominance of CD8⁺ T-cells, among others. In the current review, we detail the known pathways of molecular pathogenesis for this lymphoma and posit that an active Th1/cytotoxic antitumor immune response in part explains why this variant is primarily seen in children/adolescents and young adults, who do not exhibit signs of immunosenescence. As a result of this potent cytotoxic response, HMF patients experience mostly favorable overall prognosis, while hypopigmentation may in fact represent a useful surrogate marker of cytotoxic immunity targeting the malignant cells. Understanding the molecular processes behind the specific features that define HMF may lead to improved diagnostic accuracy, personalized prognosis by risk stratification, and improved management of HMF. Moreover, improving our knowledge of HMF may aid our further understanding of other cutaneous lymphomas.

Investigating epidemiologic trends and the geographic distribution of patients with anal squamous cell carcinoma throughout Canada

Background

Anal cancer is a rare disease, constituting 0.5% of new cancer cases in the United States. The most common subtype is squamous cell carcinoma (scc). Studies in several developed nations have reported on an increasing incidence of anal cancer in recent decades, and various risk factors pertaining to the pathogenesis of the disease have been identified, including infection with the human papillomavirus, tobacco use, and immunosuppression. The epidemiology and distribution of anal scc throughout Canada remain poorly understood, however.

Methods

Using 3 population-based cancer registries, a retrospective analysis of demographic data across Canada for 1992-2010 was performed. The incidence and mortality for anal scc was examined at the levels of provinces, cities, and the forward sortation area (FSA) component (first 3 characters) of postal codes.

Results

During 1992-2010, 3720 individuals were diagnosed with anal scc in Canada; 64% were women. The overall national incidence rate was 6.3 cases per million population per year, with an average age at diagnosis of 60.4 years. The incidence increased over time, with significantly higher incidence rates documented in British Columbia and Nova Scotia (9.3 cases per million population each). Closer examination revealed clustering of cases in various urban centres and self-identified lgbtq communities in Toronto, Montreal, and Vancouver.

Discussion

This study provides, for the first time, a comprehensive analysis of the burden of anal scc in Canada, identifying susceptible populations and shedding light onto novel avenues of research to lower the incidence of anal cancer throughout the country.

Epidemiology of adult and pediatric Burkitt lymphoma in Canada: sequelae of the HIV epidemic

Background

Although the pathogenesis and epidemiology of endemic Burkitt lymphoma (bl) have been extensively studied, the epidemiologic landscape of sporadic and immunodeficiency-associated bl in North America remains poorly understood.

Methods

We used 3 distinct population-based cancer registries to retrospectively study bl incidence and mortality in Canada. Data for patient sex; age at the time of diagnosis; and reporting province, city, and forward sortation area (fsa, the first three characters of a postal code) were analyzed.

Results

During 1992-2010, 1420 patients with bl in Canada were identified (incidence rate: 2.40 cases per million patient-years), of which 71.1% were male patients. Mean age at diagnosis was 55.5 ± 20.8 years. A bimodal incidence by age distribution was seen in both sexes, with pediatric- and adult-onset peaks. An analysis based on fsas identified select communities with statistically higher rates of adult bl. Several of those fsas were located within the 3 major metropolitan areas (Montreal, Vancouver, Toronto) and within self-identified lgbtq communities. The fsas with a higher socioeconomic status score were associated with lower rates of bl.

Conclusions

Current results highlight the geographic and historic pattern of bl in Canada. The human immunodeficiency virus remains an important risk factor for adult bl.

Current State of Geospatial Methodologic Approaches in Canadian Population Oncology Research

Geospatial analyses are increasingly used in population oncology. We provide a first review of geospatial analysis in Canadian population oncology research, compare to international peers, and identify future directions. Geospatial-focused peer-reviewed publications from 1992-2020 were compiled using PubMed, MEDLINE, Web of Science, and Google Scholar. Abstracts were screened for data derived from a Canadian cancer registry and use of geographic information systems. Studies were classified by geospatial methodology, geospatial unit, location, cancer site, and study year. Common limitations were documented from article discussion sections. Our search identified 71 publications using data from all provincial and national cancer registries. Thirty-nine percent (N = 28) were published in the most recent 5-year period (2016-2020). Geospatial methodologies included exposure assessment (32.4%), identifying spatial associations (21.1%), proximity analysis (16.9%), cluster detection (15.5%), and descriptive mapping (14.1%). Common limitations included confounding, ecologic fallacy, not accounting for residential mobility, and small case/population sizes. Geospatial analyses are increasingly used in Canadian population oncology; however, efforts are concentrated among a few provinces and common cancer sites, and data are over a decade old. Limitations were similar to those documented internationally, and more work is needed to address them. Organized efforts are needed to identify common challenges, develop leading practices, and identify shared priorities.

Epidemiology and Patient Distribution of Oral Cavity and Oropharyngeal SCC in Canada

BACKGROUND

Oral cavity cancers (OCCs) and oropharyngeal cancers (OPCs) continue to be a major source of morbidity and mortality worldwide requiring the shared effort of numerous specialists. Tobacco and alcohol consumption have long been identified as risk factors for both OCC and OPC. In addition, human papilloma virus (HPV) is gaining its position as the main causal agent for OPC.

OBJECTIVE

The objective of this study is to analyze the epidemiology of OCC and OPC in Canada.

METHODS

Data pertaining to the year of diagnosis, the patient's sex, age at the time of diagnosis, province/territory, city and postal code of oral cavity, and oropharyngeal malignancies diagnosed during 1992-2010 were extracted from the Canadian Cancer Registry and Le Registre Québécois du Cancer.

RESULTS

In total, 21 685 OCC cases and 15 965 OPC cases were identified from 1992 to 2010. Of those, 84.97% were oral cavity squamous cell carcinomas (SCCs), 88.10% were oropharyngeal SCCs, and both had a significant male predominance. While oral cavity SCC incidence stabilized over the study period, oropharyngeal SCC continued to increase. Oral cavity SCC incidence increased with age, while oropharyngeal SCC incidence peaked in the 50- to 59-year age group. Detailed geographic distribution analysis of patients at the provincial/territorial, city, and postal code levels identified several patient clusters.

CONCLUSIONS

This work highlights important epidemiological differences in trends between oral and oropharyngeal cancers, identifies high-incidence postal codes for each malignancy, and correlates incidence/mortality with known risk factors including alcohol/tobacco use and HPV infections, therefore providing a comprehensive understanding of epidemiology for these cancers in Canada.

Epidemiology of invasive ocular surface squamous neoplasia in Canada during 1992-2010

BACKGROUND

Ocular surface squamous neoplasia (OSSN) is the most common non-pigmented ocular surface malignancy. It is classified as invasive OSNN (IOSSN) when the underlying stroma are infiltrated by dysplastic squamous epithelial cells through the basement membrane. Here, we present the descriptive epidemiology and geographical distribution of IOSSN in Canada.

METHODS

We determined the incidence and geographical distribution of IOSSN cases diagnosed between 1992 and 2010 using two independent population-based cancer registries: the Canadian Cancer Registry and Le Registre Québécois du Cancer.

RESULTS

The mean annual age-standardised incidence rate (WHO 2000-2025) of IOSSN for 1992-2010 was 0.45 cases per million individuals per year with an average annual percent increase in incidence of 4.5%. IOSSN localisation to the conjunctiva was documented in at least 57% of the reported cases. IOSSN exhibited a male predilection ratio of 3.3:1.0 with a mean age at diagnosis of 69 years. Incidence rates of IOSSN across Canadian provinces and cities showed no significant differences from the crude national average.

CONCLUSIONS

Our results, particularly concerning IOSSN patient age and male predilection, corroborate with data reported from the USA. Additional studies are needed to determine whether the observed increase in incidence rate over the study period (1992-2010) is significant.

Clustering of cutaneous T-cell lymphoma is associated with increased levels of the environmental toxins benzene and trichloroethylene in the state of Georgia

BACKGROUND

Cutaneous T-cell lymphoma (CTCL) is a rare form of non-Hodgkin lymphoma arising in the skin. Geographic clustering of CTCL has recently been reported, but its association with environmental factors is unknown. Benzene and trichloroethylene (TCE) are environmental toxins with carcinogenic properties. The authors investigated associations between geographic clustering of CTCL incidence in the state of Georgia with benzene and TCE exposure.

METHODS

The statewide county-level incidence of CTCL within Georgia was obtained from the Georgia Cancer Registry for the years 1999 to 2015. Standardized incidence ratios (SIRs) were calculated by dividing observed cases by expected cases using national incidence rates by age, sex, and race. Clustering of CTCL was analyzed using spatial analyses. County-level concentrations of benzene and TCE between 1996 and 2014 were collected from the Environmental Protection Agency's National Air Toxics Assessment database. Linear regression analyses on CTCL incidence were performed comparing SIRs with levels of benzene and TCE by county.

RESULTS

There was significant geographic clustering of CTCL in Georgia, particularly around Atlanta, which was correlated with an increased concentration of benzene and TCE exposure. Among the 4 most populous counties in Georgia, CTCL incidence was between 1.2 and 1.9 times higher than the state average, and benzene and TCE levels were between 2.9 and 8.8 times higher.

CONCLUSIONS

The current results demonstrate nonrandom geographic clustering of CTCL incidence in Georgia. To the authors' knowledge, this is the first analysis to identify a correlation between geographic clustering of CTCL and environmental toxic exposures.

Epidemiology of ophthalmic lymphoma in Canada during 1992-2010

BACKGROUND

Ophthalmic lymphoma (OL) is the most common orbital tumour, particularly in older individuals. Little is known about the epidemiology and geographic distribution of OL in Canada. Descriptive demographic statistics are an important first step in understanding OL burden and are necessary to inform comprehensive national cancer prevention programmes.

METHODS

We determined patterns of incidence and geographical distribution of the three major subtypes of OL: extranodal marginal zone B cell lymphoma, follicular lymphoma (FL) and diffuse large B cell lymphoma. Here, we used cases that were diagnosed during 1992-2010 using two independent population-based cancer registries, the Canadian Cancer Registry and Le Registre Québécois du Cancer (LRQC).

RESULTS

The OL mean annual age-standardised incidence rate for 1992-2010 was 0.65 cases per million people per year with an average annual increase in the incidence rate of 4.5% per year. The mean age of diagnosis was 65 years. OL incidence rate was the highest in the cities located along the heavily industrialised Strait of Georgia in British Columbia.

CONCLUSIONS

Our data on patient age, sex and temporal trends showed similarities with data reported in the USA and Denmark. Additional studies are needed to determine whether the observed increase in OL incidence is genuine or spurious.

Penile Invasive Squamous Cell Carcinoma: Analysis of Incidence, Mortality Trends, and Geographic Distribution in Canada

BACKGROUND

Penile invasive squamous cell carcinoma (SCC) is a rare disease with several known risk factors. However, few studies have assessed its incidence, mortality, and temporal trends.

OBJECTIVE

Our objectives are to analyze the epidemiology of penile SCC in Canada and to examine patient distribution with this cancer across Canada in order to elucidate population risk factors.

METHODS

Three independent cancer registries were used to retrospectively analyze demographic data from Canadian men diagnosed with penile invasive SCC between 1992 and 2010. The Canadian Census of Population was used to calculate incidence and mortality rates at the province and Forward Sortation Area levels.

RESULTS

The overall age-adjusted incidence rate was 6.08 cases per million males. Four provinces with statistically significantly higher incidence rates were identified. The national crude incidence rates increased linearly between 1992 and 2010, whereas the age-adjusted incidence rates showed no significant increase during this time period. The overall age-adjusted mortality rate was 1.88 deaths per million males per year. The province of Saskatchewan had significantly higher mortality rates. There was no increase in crude or age-adjusted mortality rates between 1992 and 2010. There was a significant positive correlation between incidence rates and obesity, Caucasian ethnicity, and lower socioeconomic status.

CONCLUSION

This study was able to establish geographic variation for this malignancy at the provincial level. Although there are many established risk factors for penile SCC, our results suggest that the increase in crude incidence rates observed is largely due to the aging population.

Epidemiologic trends and geographic distribution of esophageal cancer in Canada: A national population-based study

Background

Esophageal cancer can be subdivided into two main histological subtypes with significant variability in their etiology and epidemiology. The incidence of esophageal adenocarcinoma (AC) is increasing across the developed countries, whereas the incidence of esophageal squamous cell carcinoma (SCC) is declining. Several risk factors have been identified in the pathogenesis of each subtype, however, their epidemiologic characteristics and distribution throughout Canada remain poorly understood.

Methods

We performed a retrospective analysis of demographic data across Canada from 1992 to 2010 using two independent population‐based cancer registries. The incidence of esophageal cancer, for each subtype, was examined at the levels of provinces/territories, cities, and postal codes.

Results

A total of 19 790 patients were diagnosed with esophageal cancer in Canada between 1992 and 2010; 74% were males. The average national incidence rate was 33.5 cases per million individuals per year. Incidence of esophageal AC increased over time, with notable high‐incidence rates on the Vancouver Island, the coasts of the Great Lakes, and the coasts of the Northumberland Strait in the Maritimes. The overall incidence of esophageal SCC has decreased. However, high incidence of esophageal SCC was detected in the Vancouver city, rural eastern Québec, and in the Maritimes. We also report clustering for each subtype using postal codes, which sheds light onto new avenues of research for potential environmental etiologies.

Conclusions

This study, for the first time, provides a detailed analysis on the burden of esophageal cancer in Canada, revealing important geographic clustering trends.

Analysis of incidence, mortality trends, and geographic distribution of breast cancer patients in Canada

BACKGROUND/PURPOSE

Breast cancer is the malignancy with the highest incidence rate excluding non-melanoma skin cancers, and the second leading cause of cancer-related deaths among Canadian women. Many modifiable risk factors have been linked to the pathogenesis of this disease. The purpose of this study is to analyze the epidemiology of breast cancer in Canada and to examine its geographic distribution to help identify new risk factors for this disease.

METHODS

Three independent population-based cancer registries were used to retrospectively analyze demographic data from Canadian women diagnosed with invasive breast cancer across all provinces and territories between 1992 and 2010. The incidence and mortality rates were assessed at the provincial, city, and forward sortation area (FSA) postal code levels.

RESULTS

The overall age-adjusted incidence rate was 114.4 cases per 100,000 females per year. Six provinces and several groups of FSAs had significantly higher incidence rates. There was a significant increase in incidence and decrease in mortality rates between 1992 and 2010. The overall mortality rate was 31.5 deaths per 100,000 females per year. However, three provinces had significantly higher mortality rates.

CONCLUSION

By identifying high-incidence areas for breast cancer, our study will help identify patient populations that are at higher risk for this malignancy. It will also act as a foundation for future studies to establish novel risk factors for this disease.

Identification of significant geographic clustering of polycythemia vera cases in Montreal, Canada

BACKGROUND

Polycythemia vera (PV) is a chronic myeloproliferative neoplasm associated at times with debilitating symptoms and a significant mortality rate. Understanding the demographics, epidemiology, and geography of this disease may provide further insight into important risk factors associated with its development. The objective of this study was to analyze patient demographics, incidence, and mortality rates, as well as the geographic distribution of PV patients in Canada between 1992 and 2010.

METHODS

This study was achieved by analyzing the Canadian Cancer Registry, Le Registre Québécois du Cancer, and the Canadian Vital Statistics patient databases.

RESULTS

A total of 4645 patients were diagnosed with PV between 1992 and 2010. While the annual incidence rate of this cancer fluctuated in Canada, mortality rate analysis indicated a decreasing trend. Geographically, PV incidence rates were notably elevated in the province of Quebec compared with the Canadian average. Further analysis of high-incidence forward sortation areas indicated a striking clustering of cases in the H4W region encompassing the Côte-Saint-Luc borough of Montreal, with an incidence of 102.97 (95% confidence interval, 75.11-137.79) cases per million per year, which is >13 times the national average.

CONCLUSION

The residential area of Côte-Saint-Luc is an important PV cluster in Canada, with high concentration of retirement homes and geriatric hospices. Also, Jewish residents comprise >60% of the population in this neighborhood. These findings suggest that an older age and, potentially, an inherent genetic predisposition may be implicated in the pathogenesis of this malignancy. This study provides a comprehensive overview of PV burden/geographic distribution of cases in Canada.

Incidence and mortality trends and geographic patterns of follicular lymphoma in Canada

Background

Follicular lymphoma (fl) is the most common indolent lymphoma and the 2nd most common non-Hodgkin lymphoma, accounting for 10%-20% of all lymphomas in the Western world. Epidemiologic and geographic trends of fl in Canada have not been investigated. Our study's objective was to analyze incidence and mortality rates and the geographic distribution of fl patients in Canada for 1992-2010.

Methods

Demographic and geographic patient data for fl cases were obtained using the Canadian Cancer Registry, the Registre québécois du cancer, and the Canadian Vital Statistics database. Incidence and mortality rates and 95% confidence intervals were calculated per year and per geographic area. Rates were plotted using linear regression models to assess trends over time. Overall data were mapped using Microsoft Excel mapping software (Redmond, WA, U.S.A.) to identify case clusters across Canada.

Results

Approximately 22,625 patients were diagnosed with fl during 1992-2010. The age-standardized incidence rate of this malignancy in Canada was 38.3 cases per million individuals per year. Geographic analysis demonstrated that a number of Maritime provinces and Manitoba had the highest incidence rates, and that the provinces of Nova Scotia and Quebec had the highest mortality rates in the nation. Regional data demonstrated clustering of fl within cities or regions with high herbicide use, primary mining, and a strong manufacturing presence.

Conclusions

Our study provides a comprehensive overview of the fl burden and its geographic distribution in Canada. Regional clustering of this disease in concentrated industrial zones strongly suggests that multiple environmental factors might play a crucial role in the development of this lymphoma.

Incidence, Mortality, and Spatiotemporal Distribution of Cutaneous Malignant Melanoma Cases Across Canada

Background:

We recently reported a steady increase in the incidence and mortality of cutaneous malignant melanoma (CMM) in Canada during 1992-2010.

Objectives:

The objective of this article is to examine the distribution of Canadian CMM patients at the level of provinces, cities, and forward sortation area (FSA) postal codes.

Methods:

Using 3 Canadian population-based registries, we conducted an in-depth examination of the incidence and mortality trends for 72 565 Canadian CMM patients over the period 1992-2010.

Results:

We found that among 20- to 39-year-olds, the incidence of CMM in women (7.17 per 100 000 individuals) was significantly higher than in men (4.60 per 100 000 individuals per year). Women age 80 years and older had an incidence of CMM (58.46 cases per 100 000 women per year) more than 4 times greater than the national average (12.29 cases per 100 000 population per year) and a corresponding high mortality rate (20.18 deaths per 100 000 women per year), when compared with the Canadian melanoma mortality of 2.4 deaths per 100 000 per year. In other age groups men had higher incidence and corresponding melanoma mortality rates. We also studied CMM incidence by province, city, and FSA postal codes and identified several high-incidence communities that were located near the coast/waterfronts. In addition, plotting latitude measures for cities and FSAs vs CMM incidence rate confirmed the inverse relationship between geographical latitude and incidence of melanoma in Canada (slope = –0.22 ± 0.05).

Conclusions:

This research may help develop sex-, age- and geographic region-specific recommendations to decrease the future burden of CMM in Canada.

Environmental and Other Extrinsic Risk Factors Contributing to the Pathogenesis of Cutaneous T Cell Lymphoma (CTCL)

The applications of disease cluster investigations in medicine have developed rather rapidly in recent decades. Analyzing the epidemiology of non-random aggregation of patients with a particular disease fostered identification of environmental and external exposures as disease triggers and promoters. Observation of patient clusters and their association with nearby exposures, such as Dr. John Snow's astute mapping analysis in the mid-1800's, which revealed proximity of cholera patients in London to a contaminated water pump infected with Vibrio cholerae, have paved the way for the field of epidemiology. This approach enabled the identification of triggers for many human diseases including infections and cancers. Cutaneous T-cell lymphomas (CTCL) represent a group of non-Hodgkin lymphomas that primarily affect the skin. The detailed pathogenesis by which CTCL develops remains largely unknown. Notably, non-random clustering of CTCL patients was reported in several areas worldwide and this rare malignancy was also described to affect multiple members of the same family. These observations indicate that external factors are possibly implicated in promoting CTCL lymphomagenesis. Here, we review the epidemiology of CTCL worldwide and the clinical characteristics of CTCL patients, as revealed by global epidemiological data. Further, we review the known risk factors including sex, age, race as well as environmental, infectious, iatrogenic and other exposures, that are implicated in CTCL lymphomagenesis and discuss conceivable mechanisms by which these factors may trigger this malignancy.

Multiple myeloma epidemiology and patient geographic distribution in Canada: A population study

BACKGROUND

Multiple myeloma (MM) is a malignancy of mature plasma cells. Environmental risk factors identified for this malignancy, among others, include farming and exposure to pesticides.

METHODS

Using 3 independent population-based databases (the Canadian Cancer Registry, le Registre Québécois du Cancer, and Canadian Vital Statistics), this study analyzed patients' clinical characteristics and the incidence, mortality, and geographic distribution of MM cases in Canada during 1992-2015.

RESULTS

In total, ~32,065 patients were identified, and 53.7% were male. The mean age at the time of diagnosis was 70 ± 12.1 years. The average incidence rate in Canada was 54.29 cases per million individuals per year, and linear regression modeling showed a steady rise in the annual rate of 0.96 cases per million individuals per year. At the provincial level, Quebec and Ontario had significantly higher incidence rates than the rest of Canada. An analysis of individual municipalities and postal codes showed lower incidence rates in large metropolitan areas and in high-latitude regions of the country, whereas high incidence rates were observed in smaller municipalities and rural areas. Land use analysis demonstrated increased density of crop farms and agricultural industries in high-incidence areas. A comparison with the available data from 2011-2015 showed several consistent trends at provincial, municipal, and regional levels.

CONCLUSIONS

These results provide a comprehensive analysis of the MM burden in Canada. Large metropolitan cities as well as high-latitude regions were associated with lower MM incidence. Higher incidence rates were noted in smaller cities and rural areas and were associated with increased density of agricultural facilities.

Retinoblastoma Incidence Trends in Canada: A National Comprehensive Population-Based Study

PURPOSE

To determine the incidence rates and geographic distribution of retinoblastoma in Canada to aid cancer control programs.

METHODS

Patients with retinoblastoma whose data were available from the Canadian Cancer Registry (CCR) and Le Registre Québécois du Cancer (LRQC) were studied. Using third edition International Classification of Diseases for Oncology (ICD-O) codes, the authors examined the incidence rates and geographic distribution of patients with retinoblastoma between 1992 and 2010. Patient data including sex, age, and laterality of the retinoblastoma were analyzed.

RESULTS

Between 1992 and 2010 in Canada, the average annual incidence rate of retinoblastoma was 11.58 cases per 1 million children younger than 5 years (95% CI [confidence interval]: 10.48 to 12.76). The incidence rate was stable over time, with an average age at diagnosis of 2.30 ± 6.85 years and no gender predilection. The laterality of the reported cases was 81.48% for uni-lateral cases and 18.52% for bilateral cases. Provincially, Nova Scotia had twice the national average and the highest incidence rates of retinoblastoma across the Canadian provinces.

CONCLUSIONS

This is the first study to define the disease burden of retinoblastoma and to highlight important longitudinal, geographic, and spatial differences in the distribution of retinoblastoma in Canada between 1992 and 2010. The results of this study indicate continuity of clinical trends between Canada, the United States, and other developed countries. [J Pediatr Ophthalmol Strabismus. 2019;56(2):124-130.].

Analysis of acute myeloid leukemia incidence and geographic distribution in Canada from 1992 to 2010 reveals disease clusters in Sarnia and other industrial US border cities in Ontario

BACKGROUND

Several risk factors have been implicated in acute myeloid leukemia (AML) leukemogenesis. However, the epidemiologic distribution and precise triggers for AML in Canada remain poorly understood.

METHODS

In this study, demographic data for AML patients in Canada from 1992 to 2010 were analyzed using 3 independent population-based cancer registries. The AML incidence and mortality rates were examined at the levels of province/territory, city, and forward sortation area (FSA) postal code.

RESULTS

In total, 18,085 patients were identified. AML incidence was documented to be 30.61 cases per million individuals per year (95% confidence interval [CI], 30.17-31.06) from 1992 to 2010. Five industrial cities in Ontario were identified where incidence rates were significantly higher than the national average: Sarnia, Sault Ste. Marie, Thunder Bay, St. Catharines, and Hamilton. Analysis at the FSA postal code level identified significant patient clusters of AML in these cities. Specifically, FSA N7V in Sarnia, Ontario had an incidence of 106.81 (95% CI, 70.96-161.86) cases per million individuals per year, which is >3 times higher than the national average. The pollution from local oil refineries and chemical plants in Sarnia may be implicated as a risk factor for AML in that city. Analysis of mortality rates at the province and city levels corroborated the findings from the incidence data.

CONCLUSION

These results provide a comprehensive analysis of AML burden in Canada and reveal striking geographic case clustering in industrial Ontario cities and potentially implicate exposure to materials/pollution from these plants as an important risk factor for developing AML in Canada.

Prevalence of human T cell lymphotropic virus 1 infection in Canada

Human T cell lymphotropic virus 1 (htlv-1) is a bloodborne retrovirus that infects at least 5–20 million people around the world [...]

A study of meiomitosis and novel pathways of genomic instability in cutaneous T-cell lymphomas (CTCL)

Genomic instability is a hallmark of cancer and an enabling factor for genetic alterations that drive cancer development and progression. The clashing of mitosis and aberrantly expressed meiosis machineries, which may contribute to genomic instability, has been coined cancer “meiomitosis”. LINE-1 retrotransposition, a process active in germ cells, acts outside of the meiotic machinery to create DNA double strand breaks (DNA DSBs) and has played an important role in the evolution of the human genome. We have previously demonstrated that in CTCL several cancer testis/meiotic genes are expressed. Furthermore, this cancer exhibits extensive and ongoing chromosomal/microsatellite instability. In this study we analyzed immortalized patient-derived cells and primary CTCL patient samples using RT-PCR, western blotting and confocal microscopy and found that proteins critically involved in meiosis and LINE-1 retrotransposition are expressed and are associated with chromosomal instability and DNA DSB formation. Using cell cycle synchronization, we show G1/S phase-transition-specific expression of meiosis proteins. Using the Alu retrotransposition assay, we demonstrate the functional activity of LINE-1 retrotransposon in CTCL. Histone acetyltransferase inhibition results in downregulation of the ectopic germ cell programs and concomitant decrease in DNA DSBs foci formation. Notably, LINE-1 and meiosis genes were expressed across a panel of other solid tumor cell lines. Taken together, our results indicate that malignant cells in culture undergo “cancer meiomitosis” rather than the classic mitosis division. The ectopic expression of meiosis genes and reactivation of LINE-1 may be contributing to genomic instability and represent novel targets for immunotherapy in this and other cancers.

Gene expression profiling and immune cell-type deconvolution highlight robust disease progression and survival markers in multiple cohorts of CTCL patients

CTCL follows different courses depending on the clinical stage at the time of diagnosis. Patients with early stage Mycosis Fungoides (MF) variant of CTCL may experience an indolent course over decades, whereas patients with advanced MF and Sézary Syndrome (SS) disease at diagnosis, often succumb within 5 years. Even within early stage CTCL/MF, a minority of patients will progress to more advanced stages. We recently generated RNA sequencing data on 284 CTCL-relevant genes for 157 patients and identified differentially expressed genes across stages I-IV. In this study, we aim to validate robust molecular markers linked to disease progression and survival. We performed multiple hypothesis testing-corrected analysis of variance (ANOVA) on the expression of individual genes across all CTCL samples and early stage (≤IIA) CTCL/MF patients. We used in silico immune cell-type deconvolution from gene expression data to estimate immune cell populations. Based on the analysis of all CTCL samples, we identified TOX, FYB, and CD52 as predictors of disease progression and poor survival. Among early stage (≤IIA) CTCL/MF patients, these 3 genes, along with CCR4, were valuable to predict disease progression. We validated these 4 genes in 3 independent, external Sézary Syndrome patient cohorts with RNA-Sequencing data. In silico immune cell-type deconvolution revealed that neutrophil infiltration in early stage MF conveyed a higher risk for disease progression. Also, NK cell infiltration in late stage MF/SS correlated with improved survival. TOX, FYB, CCR4 and CD52 are robust disease progression and decreased survival biomarkers in CTCL.