# Ontario Cancer Statistics 2020 Glossary

**Age-standardized incidence rate (ASIR):** A weighted average (based on a standard population) of the number of new cases of cancer per 100,000 people in a 5-year age group (0 to 4, 5 to 9, …, 85 and older) diagnosed during a year divided by the total number of people in that age group that year. Age-standardized rates give the rate that would occur if the population of interest had the same age distribution as a given standard population. In this report, the standard population is the 2011 Canadian population.

**Age-standardized mortality rate (ASMR):** A weighted average (based on a standard population) of the number of deaths from cancer per 100,000 people in a 5-year age group (0 to 4, 5 to 9, …, 85 and older) that occurred during a year divided by the number of people in that age group that year. Age-standardized rates give the rate that would occur if the population of interest had the same age distribution as a given standard population. In this report, the standard population is the 2011 Canadian population.

**Annual percent change (APC):** A measure to assess the rate of change over time of an incidence or mortality rate. It is calculated by fitting a linear model to the annual rates after applying a logarithmic transformation. The estimated slope is then transformed back to represent a percentage increase or decrease per year. The method allows for a series of straight-line segments with different slopes to be fitted to long-term trend data.

**Average annual percent change (AAPC):** Represents the weighted average of the annual percent changes from the joinpoint model, where the weight is the length (i.e., number of years) of the APC interval.

**Cancer incidence:** The number of new cancer cases diagnosed during a specific period in a population.

**Cancer mortality:** The number of deaths due to cancer during a specific period in a population.

**Canproj:** A statistical cancer projection method based on age, period, and/or cohort statistical modelling.

**Conditional survival:** The probability of surviving a certain number of years given that a patient has already survived “x” years after their diagnosis. In this report, 5-year conditional survival looks at the chance of surviving at least 5 years, given that a person has already survived 1,2,3 or 4 years from the time of their initial diagnosis.

**Death certificate only (DCO):** Cases for which the only data source is a death certificate. Such cases are excluded from survival analyses.

**International Cancer Survival Standards:** An internationally accepted population weighting method for age standardizing survival ratios.

**International Classification of Childhood Cancer (ICCC):** A diagnostic classification scheme for childhood cancer based on tumour morphology and primary site, with a greater emphasis on morphology as compared to the classification of cancers for adults.

**International Classification of Diseases for Oncology (ICD-O):** An international standard for classifying a cancer using a topographical code, which describes the anatomical site of origin (or organ system) of the tumour, and a morphological code, which describes the cell type (or histology) of the tumour, together with the behaviour (malignant or benign).

**Lead-time bias:** The length of time between the early detection of cancer and the time of its usual clinical presentation and diagnosis.

**Lifetime probability (of developing or dying):** The chance a person has, over the course of his or her lifetime (from birth to death), of being diagnosed with or dying from cancer.

**Median age (at diagnosis):** Age at which half of the cancer cases reported were older and half were younger.

**Microscopically confirmed:** Percentage of cases that were diagnosed on the basis of microscopic verification of a tissue specimen, including histologically confirmed cases, cases diagnosed on the basis of cytology specimens, and cases of leukemia diagnosed on the basis of hematological examination.

**Most common cancers: **For the purpose of this report, refers to the 4 most commonly diagnosed cancers in Ontario, namely breast, prostate, lung and colorectal cancers.

**Multiple primary and histology rule:** Tumours are considered multiple primary malignancies if arising in different sites and/or are of a different histology or morphology group in an individual.

**Overall Survival Proportion:** An estimate of the probability of surviving all causes of death for a specified time interval (e.g., 5 years) following diagnosis of cancer from a cohort of cancer cases. May also be referred to as Observed Survival.

**Population aging:** Refers to an increasing proportion of people 65 years of age or older in the population.

**Prevalence:** The number of people still alive who have ever been diagnosed with cancer in a given population and at a specific time or any point in time.

**Prognosis:** The probable outcome or course of cancer.

**Projection:** An estimate or forecast of a future cancer incidence or mortality based on current and historical data.

**Rare cancer:** A cancer with an incidence rate of less than 6 new cases per 100,000 people per year.

**Recurrence:** The reappearance of cancer at the same site or in another location after remission.

**Relative change (in projected rates):** The difference in projected rates of two periods compared to the rate in the earlier period, expressed as a percentage (i.e., [rate in period 2 minus rate in period 1] divided by rate in period 1)

**Relative survival ratio (RSR):** The proportion of people surviving for a certain amount of time (e.g., 5 years) compared with the expected survival of similar people (based on age, sex and time) in the general population.

**Remission:** The reduction or disappearance of the signs and symptoms of cancer.

**Stage at diagnosis:** Refers to the extent of spread of cancer at the time the cancer diagnosis is made.

**Standard population:** Often referred to as standard million, is the age distribution used as weights to create age-standardized (i.e., age-adjusted) statistics.

**TNM classification of malignant tumours:** The recognized standard for classifying the extent of spread of cancer.

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