|Short description of Indicator
Growth in new cancer cases: the annual number of new cases of cancer diagnosed during a defined period of time attributed to population growth, population aging, and changing cancer rates.
Most common cancers: The number of new cases (and proportion of total cases) diagnosed in Ontario by type of cancer.
Age-standardized incidence rate: the number of new cases of cancer that would occur in a specified population if it had the same age-distribution as a given standard population, per 100,000 population during a defined time period.
|Rationale for measurement
||Cancer incidence is an important measure of cancer burden on the population and on the healthcare system. Monitoring trends in cancer incidence and the distribution of new cases of cancer by cancer type and demographic factors, such as age and sex, assists in informing and evaluating cancer control efforts along several parts of the cancer journey, from prevention (e.g., risk factor reduction) to early detection (i.e., screening) and treatment. Monitoring incidence trends also assists in predicting future cancer burden to help plan for upcoming resource, policy and research needs.
|Evidence/references for rationale
This is a well-established cancer burden indicator, described and reported on by numerous provincial, national and international organizations, including:
|Calculations for the indicator
- Growth in new cancer cases:
- Baseline risk is the number of new cases of cancer observed during the first year of the time period of interest (baseline year).
- The number of cases attributed to changing cancer rates is estimated by multiplying the age-specific rates for each year by the age-specific population of the baseline year.
- The number of cases due to population growth is calculated by assuming that each year has the same age distribution as the baseline year. The age-specific rates for each year are then applied to that year’s population with the modified age structure.
- The number of cases due to population aging is the difference between the observed number of cases and the number attributed to population growth.
- For all cancers, both sexes combined, Ontario, 1981–2018 (projected cases 2014–2018).
- Baseline risk was based on the number of new cases in 1981.
- Most common cancers:
- The number of new cases (and proportion of total cases) diagnosed in Ontario by type of cancer.
- For all cancers, by sex, Ontario, 2013
- Age-standardized incidence rate:
[(∑ age – specific incidence rate in a given age group x standard popn in that age group)/(total population in the standard population)] x 100,000
- For all cancers (ICD-O-3 topography code: C00.0-C80.9), cancer of the female breast (C50.0-C50.9), colorectal (C18.0–C20.9, C26.0), lung (C34.0–C34.9), prostate (C61.9), bladder (C67.0-C67.9) and urothelial cancer (C67: 8020, 8031, 8082, 8120, 8122, 8130, 8131), by sex, Ontario, 1981–2013.
- Rates were standardized using 5-year age groups with the 2011 Canadian population as the standard population.
- Observed incidence rates were based on the National Cancer Institute’s Surveillance, Epidemiology and End Results (NCI SEER) program standards for counting multiple primary cancers, which were adopted by the Ontario Cancer Registry for cases diagnosed in 2010 and beyond.
- Incidence trends were based on incidence rates that have been adjusted to adhere to the International Association of Cancer Registries (IACR) standards for counting multiple primary cancers, to allow for direct comparisons of incidence rates over time. See Considerations for more information.
- Cancer incidence projection:
Details on projection method for Ontario
- Incident cases meeting the IACR multiple primary rules from 1983-2012 were grouped by 5-year age groups and time periods. Population data was also similarly aggregated.
- To obtain projections for all cancer combined, projections were calculated separately for female breast, prostate, colorectal, lung, thyroid, bladder and all other cancers by sex, then summed.
- NORDPRED (https://www.kreftregisteret.no/en/Research/Projects/Nordpred/Nordpred-software/) was used to predict cancer incidence from 2013 to 2032, in four 5-year periods.
- Linear interpolation was used to create annual counts for 2013 to 2029.
- Finally, an inflation factor was applied based on the age-specific increase in multiple primaries due to the SEER rules in 2010-2012.
Details on projection method for LHINs
- All of the steps outlined above for Ontario were re-run for each LHIN. Unlike previous LHIN projections, true LHIN-specific projections were modelled.
- A final year- and age-specific scaling step was added to adjust the LHIN projections so that they now add to the initial Ontario projections.
Details on projection method for prostate
Recent changes in prostate cancer treatment has led to a major drop in incidence rates in the past few years. The age-period-cohort models used for other cancers do not fit for prostate. Instead, an age-only model based on DCO-corrected 2013/14 data has been used for both the Ontario and LHIN-specific projections. As a result, the ASIRs are projected to remain constant over time, while the number of cases will continue to increase due to aging and population growth.
|Standardized Rate Calculation
||Rates were standardized using 5-year age groups with the 2011 Canadian population as the standard population.
- Ontario Cancer Registry, 2016 (Cancer Care Ontario)
- Population data: Ontario Ministry of Finance. Ontario Population Projections (based on the 2011 Census released by Statistics Canada February 2015). Spring 2016 release.
- LHIN population data: Ontario Ministry of Finance. Ontario LHIN Population Projections. Spring 2016 release.
- On Oct. 29, 2014, CCO’s Ontario Cancer Registry Information System (OCRIS) was formally decommissioned and replaced with the new Ontario Cancer Registry (OCR). The new registry brings the OCR in line with current Canadian and U.S. standards for tracking cancer incidence. The OCR now conforms to specific standards as set out by the National Cancer Institute’s Surveillance, Epidemiology and End Results (NCI SEER) program for counting multiple primary cancer sites, which most Canadian provinces and U.S. states now use. The adoption of specific NCI SEER standards with the new OCR has resulted in an increase in the incidence number of certain types of cancer reported in Ontario. However, this change in number is due to how cancers are being counted; it does not mean that more people in Ontario are being diagnosed with cancer or dying of cancer. This change impacts cancer incidence for 2010 and beyond, as such direct comparisons with incidence for 2009 and years prior should not be made.
- Cancers were defined using U.S. Surveillance, Epidemiology and End Results (SEER) Site Recode definitions: http://seer.cancer.gov/siterecode/icdo3_dwhoheme/index.html. Cancer definitions using SEER Site Recode may differ, especially for cancers of the colon and rectum and lung cancer, from definitions in other published analyses.
- For most cancer types (except urinary bladder and kidney), the full site grouping name outlined by the SEER site recode variable definitions was used. Short titles for certain cancers, however, were, used for graphing purposes. Cancer types for which short titles were displayed are as follows:
- Lung and bronchus (ICD-O-3 code C34.0–C34.9): short title “Lung”
- Melanoma of the skin (ICD-O-3 code C44.0 with histology codes 8720–8790): short title “Melanoma”
- Corpus and uterus, NOS (ICD-O-3 code C54.0–C54.9, C55.9): short title “Uterus”
- Colon and rectum (ICD-O-3 code C18.0–C18.9, C19.9, C20.9, C26.0): short title “Colorectal”
- Urinary bladder (ICD-O-3 code C67.0–C67.9): short title “Bladder”
- Kidney and renal pelvis (ICD-O-3 code C64.9, C65.9): short title “Kidney”
- Basal cell carcinoma, squamous cell carcinoma of the skin are not included in any analyses of cancer incidence since the OCR does not collect data on these types of cancer.
- The use of a standard population allows incidence rates to be compared across time periods and jurisdictions by adjusting for differences in the population age distribution over time and across geographic areas. The 2011 Canadian population standard is specified by Statistics Canada.
Because of changes in diagnostic practices or rules of coding and registration, interpretation of temporal trends must be done with caution.
|Data availability & limitations
- Incidence was calculated for cancers diagnosed through 2013, the most recent year for which the Ontario Cancer Registry had received complete data at the time of analysis.
- Projected estimates were calculated for 2014 through 2018.