The Ontario Cancer Registry (OCR), maintained by Ontario Health (Cancer Care Ontario), is the main data source for this report. Its goals are to collect, analyze and disseminate timely and high-quality information describing cases of cancer diagnosed among Ontario residents.

The OCR is a dynamic database: new case information and updates to past cases may be added throughout the year. Consequently, the results of analyses vary based on when the data are extracted from the registry. The data in this report were extracted in December 2018.

Ontario Cancer Registry records are created using data collected for purposes other than cancer registration. This information comes from various administrative databases, laboratory reports and clinical records. Four primary sources are used to generate case records in the registry:

• Provincial pathology reports from Ontario’s public hospital laboratories and private laboratories
• Activity-level reporting database, containing data from Ontario’s 14 regional cancer centres and their associated hospitals, for selected systemic therapy and all radiation treatment
• Admission and discharge information from the Canadian Institute of Health Information’s hospital abstracting databases (Discharge Abstract Database, National Ambulatory Care and Reporting System)
• Cause-of-death data from the Office of the Registrar General for Ontario within the Ministry of Government and Consumer Services

Safeguarding confidential information is a guiding principle for Ontario Health (Cancer Care Ontario). All activities – from the initial registration of a new cancer case in the Ontario Cancer Registry, through research and reporting – are governed by the Personal Health Information Protection Act (PHIPA), 2004.^[1] This Ontario law governs the collection and use of data, and the disclosure of personal health information. The Act designates Ontario Health as a prescribed entity, and authorizes the organization to collect, use and disclose personal health information for the purposes of managing and planning Ontario’s health system. See our Statement of Information Practices for details.

Data Quality

Death certificate only and microscopically confirmed cases

Table A.1 shows the percentage of cases in the Ontario Cancer Registry diagnosed based on a death certificate only (DCO) and the percentage microscopically confirmed.

Overall, 1.7% of cases diagnosed in 2016 were DCO. The percentage ranged from a low of 0% for testis cancer to a high of 7.1% for pancreatic cancer.

For all cancers combined, 90.9% of cases were microscopically confirmed. This falls slightly below the Surveillance, Epidemiology and End Results (SEER) Program’s recommendation of at least 93% of cases microscopically confirmed.^[2] The percentage microscopically confirmed varied from a low of 59.2% for liver cancer to a high of 99.0% for thyroid cancer.

Analysis by: Surveillance, Analytics and Informatics, Ontario Health (Cancer Care Ontario)
Data source: Ontario Cancer Registry (December 2018), Ontario Health (Cancer Care Ontario)

Incidence-to-mortality ratio

The age-standardized incidence-to-mortality (I:M) ratio identifies areas of undercoverage within a registry. The I:M ratio for the Ontario Cancer Registry for 2016 was 2.9:1 (Table A.2). This ratio meets the Canadian Partnership Against Cancer’s recommended ratio of at least 2.3:1,^[2] with variation by cancer type. An I:M ratio below the recommended level may indicate incomplete registration of cases.

Abbreviation: I:M ratio is the ratio of the age-standardized incidence rate to the age-standardized mortality rate.
Analysis by: Ontario Cancer Registry, Analytics and Informatics, Ontario Health (Cancer Care Ontario)
Data source: Ontario Cancer Registry (December 2018), Ontario Health (Cancer Care Ontario)

Data element completeness

All the data quality indicators met the minimal requirements from the Canadian Cancer Registry (CCR) guideline, the ‘Gold’ certification standard of the North American Association of Central Cancer Registries (NAACCR), and the Surveillance, Epidemiology and End Results (SEER) Program guideline:

• Stage capture rates overall and for Collaborative Staging achieved the provincial target of 90% for breast, prostate, colorectal, lung and cervical cancers in 2016.
• There were no cases missing information about “age at diagnosis,” “age at death,” or “sex,” thereby meeting NAACCR’s Gold standard of a maximum of 2% or less. Furthermore, 0% of cases were listed as ”alive with current age over 100” and cases listed as ”dead” with missing death date.
• Postal codes were missing for 2% of the cases, under the 5% CCR threshold for this indicator.
• The 2% percent of cases with unknown primary (C809) also met the less than 2.3% threshold of the SEER standard.

In 2016, 89% of discrete synoptic cancer pathology reports had all mandatory elements complete in accordance with the College of American Pathologist’s electronic Cancer Checklist.

There are no standards for the average number of sources or notifications per case or for the percentage of cases with unknown morphology. Cases with a greater number of supporting data sources or notifications are assumed to be considered more complete and credible. The high percentage of unknown morphology raises some concern about data quality and data collection. Table A.3 presents other data quality measures related to completeness of Ontario Cancer Registry case registration.

Symbols:

• †Histology range 8000-8005 (Not Otherwise Specified)
• ‡For lung, female breast, colorectal, cervix and prostate cancers only

Notes:

1. For all malignant cases and in situ bladder.
2. Total number of cases is 81,409 and represents 78,007 individuals.

Analysis by: Ontario Cancer Registry, Analytics and Informatics, Ontario Health (Cancer Care Ontario)
Data source: Ontario Cancer Registry (December 2018), Ontario Health (Cancer Care Ontario)

Population Data

The population used in this report for age standardization is the 2011 Canadian Standard population (Table A.4), based on the 2011 Statistics Canada census.

Cancer Care Ontario surveillance reports published before 2016 used the 1991 Canadian Standard population. We do not recommend comparing age-standardized rates in this report with the rates in these earlier reports.

The 1991 standard population is no longer appropriate because the population age structure has changed considerably since then. Using the 2011 standard population results in age-standardized rates that are closer to the crude rate (i.e., rate unadjusted for age distribution).

Except where otherwise noted, population data used in denominators for cancer projections are from the Ontario Ministry of Finance (spring 2018 release).^[3]

Note: Postcensal estimates are based on the 2011 census counts adjusted for census net undercoverage (CNU) (including adjustment for incompletely enumerated Indian reserves [IEIR]) and the components of demographic growth that took place since that census. Intercensal estimates use counts from 2 consecutive censuses adjusted for CNU (including IEIR and postcensal estimates).

Data source: Statistics Canada. Table 051-0001 – Estimates of population, by age group and sex for July 1, Canada, provinces and territories, annual (persons unless otherwise noted)

Disease Site Grouping

The Ontario Cancer Registry uses disease site groupings based on the third edition of the International Classification of Diseases for Oncology (ICD-O-3).^[4] These disease site groupings are recoded based on the Surveillance, Epidemiology and End Results (SEER) Program groups.^[5]

Cancer deaths are classified according to the 10th edition of the International Classification of Diseases and Related Health Problems (ICD-10).^[6]

The primary cancer groupings used in this report are in Table A.5.

Table A.5 Cancer definitions

Non-Melanoma Skin Cancer

Data in this report exclude cases of basal cell and squamous cell carcinoma of the skin, the most common types of non-melanoma skin cancer.

These tumours are generally not life-threatening and are treated in out-patient settings. Although these cases are captured in pathology reports, their large number poses a challenge for data capture and quality assurance by the Ontario Cancer Registry, a requirement for meaningful surveillance.

Cancer Stage at Diagnosis

Cancer staging is essential for quality care. Stage data are vital for:

• evaluating the effectiveness of screening and treatment programs
• analyzing survival
• research into new treatments
• resource planning for healthcare management

The tumour-node-metastasis (TNM) system is the most widely used classification system for stage at diagnosis. It is recognized as the international standard for describing the anatomic extent of cancers. TNM definitions, now in their eighth edition, are maintained by the Union for International Cancer Control (UICC) and the American Joint Committee on Cancer (AJCC). The stage data in this report are based on the seventh edition of TNM, which was in use at the time of cancer staging by the cancer registry.^[7]

Collaborative staging is a staging approach used by central cancer registries. Collaborative Staging brings together the principles of the following:

• National Cancer Institute (NCI)’s Surveillance, Epidemiology and End Results (SEER) Program Summary Stage
• TNM categories and stage groupings
• SEER Extent of Disease coding structure

Most of the collaborative staging data items have traditionally been collected by some cancer registries. These items include tumour size, extension, lymph node status and metastatic status. Other data, such as site-specific or histology-specific factors (e.g., Gleason score and receptor status), are specific to collaborative staging. The data are used to derive the “best stage” grouping consistent with the AJCC Cancer Staging Manual (in its seventh edition).^[7]

Collaborative Staging values for invasive cancer range from stage 1, which means the disease is in the early phase, to stage 4, which means the cancer has spread (or metastasized) to other organs or places in the body. An “unknown stage” is the result of limited stage work-up, limited documentation in the person’s health record or both. “Not staged” means no attempt at staging has taken place.

Starting with cases diagnosed on January 1, 2005, the Ontario Cancer Registry phased in various versions of collaborative staging by reporting hospital (see the list of contributing hospitals and regional cancer centres below) and selected cancer type. Collaborative Staging was fully implemented for breast, lung, colorectal and prostate cancers in 2010; for ovarian, uterine and cervical cancers and melanoma in 2011; and for thyroid cancer in 2013. Stage data included in this report are for the diagnosis years 2010 to 2016.

Approximately 10% to 20% of breast, colorectal, lung and prostate cancer cases in the Ontario Cancer Registry are missing information on stage at diagnosis and so are excluded from this analysis. Stage at diagnosis may be missing because of inadequate supporting information in a patient’s medical record to support a definitive stage at the time of diagnosis. Stage distributions may not be the same for the cases with missing data.

Contributing facilities to activity-level reporting data used for population-level staging, Ontario

Regional cancer centres

Grand River Regional Cancer Centre
Juravinski Cancer Centre
Cancer Centre of Southeastern Ontario
R.S. McLaughin Durham Regional Cancer Centre
London Regional Cancer Program
Simcoe Muskoka Regional Cancer Centre
Stronach Regional Cancer Centre at Southlake
Northeast Cancer Centre
Odette Cancer Centre
The Ottawa Hospital Regional Cancer Centre
Regional Cancer Care Northwest
Carlo Fidani Peel Regional Cancer Centre
Princess Margaret Hospital
Windsor Regional Cancer Centre

Hospitals

Grand River Hospital
Hamilton Health Sciences
Kingston Health Sciences Centre
Lakeridge Health
London Health Sciences Centre
Royal Victoria Regional Health Centre
Southlake Regional Health Centre
Health Sciences North Sudbury
Sunnybrook Health Sciences Centre
The Ottawa Hospital
Thunder Bay Regional Health Sciences Centre
Trillium Health Partners
University Health Network
Windsor Regional Hospital
Bluewater Health
Cambridge Memorial Hospital
Grey Bruce Health Services
Halton Healthcare Services
Headwaters Health Care Centre
Humber River Regional Hospital
Mackenzie Health (formerly York Central Hospital)
Markham-Stouffville Hospital
The Scarborough Hospital
Sinai Health System
North York General Hospital
Quinte Healthcare Corporation
Rouge Valley Health System
Sault Area Hospital
St. Joseph’s Health Centre
St. Michael’s Hospital
Toronto East General Hospital
William Osler Health Centre

Coding Rules for Multiple Primary Cancers

Different rules exist to determine if a cancer is a new primary cancer or an extension of a previous cancer. Following a recent rebuild, the Ontario Cancer Registry (OCR) adopted the Surveillance, Epidemiology and End Results (SEER) Program’s rules for counting multiple primaries and assigning histology,^[8] similar to other North American cancer registries.

To identify multiple primary cancers, the SEER counting rules take into account histology, site, laterality and time since the initial diagnosis. The SEER rules are more liberal than the rules previously used in the OCR  for counting multiple primaries in their definition of a new primary case.

The SEER rules for multiple primary cancers have been applied to cases in the OCR  diagnosed on or after January 1, 2010.

Cases from the years before SEER adoption (i.e., 1964 to 2009) have been imported into the new OCR from the Ontario Cancer Registry Information System (OCRIS) for continued analytic use. OCRIS applied a modified version of the International Agency for Research on Cancer/International Association of Cancer Registries (IARC/IACR) rules,^[9] which are more conservative than the SEER rules. Under the IARC/IACR rules, only 1 tumour is registered for an organ, irrespective of time, unless there are histological differences.

In this report, data were converted using the IARC/IACR rules when:

• trend analyses span both the OCR (2010 onward) and OCRIS (1983 to 2009) eras
• comparisons are made between data from the 2 registry systems

When data are presented only from 2010 onward, the SEER rules were applied.

Given that the SEER rules are more liberal than the IARC/IACR rules, applying the SEER rules results in an increase in the number of cases included in incidence counts. This is simply a result of using a different methodology and does not reflect an actual increase in the number of people diagnosed with cancer. For 2010 to 2016 in Ontario, an average of 4.2% of new cases were considered as multiple primaries.

Starting with diagnosis year 2019, the registry adopted new SEER solid tumour rules to replace the SEER multiple primary and histology rules. In addition, a new edition of staging was used for new cancer cases diagnosed from 2018 onward. However, these changes in coding and staging systems do not affect this edition of Ontario Cancer Statistics.

Childhood cancer data

The Pediatric Oncology Group of Ontario Networked Information System (POGONIS), maintained by the Pediatric Oncology Group of Ontario (POGO) and funded by the Ontario Ministry of Health, is the data source for the 0 to 14 years age group specifically. POGONIS is a reliable, validated data source used to estimate incidence, inform policy and planning, and provide essential data for research for childhood cancer cases in Ontario.

POGONIS, like the OCR, is a dynamic database. The childhood cancer data used in this report were extracted from POGONIS in October 2019.

POGONIS is a population-based registry and database that captures detailed demographic, diagnostic, treatment and outcome information since 1985 on all children and adolescents diagnosed or treated with cancer in a specialized childhood cancer program in Ontario. Standardized POGONIS data are actively collected by dedicated data managers or clinical research associates at each of the 5 tertiary centres with specialized childhood cancer programs across Ontario. The information comes from comprehensive hospital chart review, internal hospital information systems and direct connections with patients’ healthcare teams. Death information in POGONIS is validated and supplemented via annual record linkage to the OCR and the Ontario Registrar General Death File under a data sharing agreement with Ontario Health (Cancer Care Ontario) to systematically capture deaths in the entire cohort.

POGO is also designated as a prescribed entity under the Personal Health Information Protection Act. POGO has created and operationalized detailed policies and procedures that govern all aspects of the collection, use and disclosure of personal health information, which are detailed in POGO’s Privacy and Data Security Code and its procedures.

Classification

The POGONIS database classifies childhood cancer according to the International Classification of Childhood Cancer, third edition (ICCC-3).^[10] This classification divides childhood cancer into 12 main diagnostic groups and 47 subgroups for additional refinement.

The classification of each case applied in this analysis is true to the timing of the diagnosis and the associated International Classification of Diseases for Oncology (ICD-O) morphology code for that period. Because the ICCC-3 (published in 2005) does not incorporate coding changes made in the updated version of the ICD-O-3 system (ICD-O-3.1, published in 2013), POGO has incorporated changes to the ICD-O-3.1 codes into an updated ICCC classification, based on Ontario clinical and epidemiological expertise. Details of the differences in coding between POGONIS and the ICCC-3 are available in the POGO Surveillance Report.

Population data

Included in incidence, mortality and survival analyses:

• Children diagnosed between 0 to 14 years of age and residents of Ontario, who were treated in a specialized childhood cancer program in Ontario, with a diagnosis included in the POGO updated ICCC-3 classification system

Excluded from incidence, mortality and survival analyses:

• Children who were not residents of Ontario but were diagnosed or treated in a specialized childhood cancer program in Ontario
• Cases not diagnosed and fully treated in a specialized childhood cancer program in Ontario

The population used in this report for age standardization for childhood cancers is the 2011 Canadian Standard population (Table A.4), which is based on the 2011 census conducted by Statistics Canada.

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