# Ontario Cancer Statistics 2022 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 in that year. An age-standardized rate gives the rate that would occur if the population of interest had the same age distribution as a given standard population. ln this report, the standard population is the 2011 Canadian Standard 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 in that year. An age-standardized rate gives the rate that would occur if the population of interest had the same age distribution as a given standard population. ln this report, the standard population is the 2011 Canadian Standard population.

**Annual percent change (APC):** A measure to assess the rate of change over time of a rate (e.g., incidence or mortality rate). It represents the percentage increase or decrease per year in a specified time interval.

**Average annual percent change (AAPC):** Represents the weighted average of the annual percent changes, 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 from cancer during a specific period in a population.

**Cancer prevalence:** The number of people newly diagnosed with cancer, as well as people previously diagnosed with cancer and who are still alive.

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

**Complete prevalence:** The number of people alive on a certain date (called an index date) who were diagnosed with cancer, regardless of when their diagnoses were made.

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

**Death certificate only (DCO):** Cases that only have a death certificate as their data source. These cases are excluded from survival analyses.

**International Cancer Survival Standards (ICSS):** 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 that has a greater emphasis on morphology than the classification of cancers for adults.

**International Classification of Diseases for Oncology (ICD-0):** 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 and 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 from cancer):** The chance someone has over the course of their lifetime (from birth to death) of being diagnosed with or dying from cancer.

**Limited-duration prevalence: **Describes the number of people alive on a certain date (called the index date) who were diagnosed with cancer within a specified number of years (e.g., 2 years, 5 years, 10 years, 30 years).

**Look-back period:** Describes how far back in time the prevalence is estimated for in limited-duration prevalence. For example, a 15-year limited-duration prevalence in 2018 has a 15-year look-back period, and considers people diagnosed from 2003 to 2018 and still alive in 2018.

**Median age (at diagnosis):** Age at which half of the cancer cases reported are older and half are 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:** In this report, the 4 most commonly diagnosed cancers in Ontario are breast, prostate, lung and colorectal.

**Multiple primary and histology coding rules:** A set of rules that guide and standardize the process of determining the number of primary cancers. The histology rules contain detailed histology coding instructions for cancer registrars.

**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. May also be referred to as observed survival.

**Population aging:** An increasing proportion of people age 65 and older in the population.

**Prevalence and Incidence Analysis Model (PIAMOD):** A statistical method that can be used for estimating and projecting prevalence statistics from cancer registry incidence and survival data (Verdecchia et al., 2002).

**Prevalence proportion:** The number of people alive who have had a cancer diagnosis for every 100,000 people in the general population as of the index date.

**Primary cancer:** The original, or first, tumour in the body. Cancer cells from a primary cancer may spread to other parts of the body and form new, or secondary, tumours.

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

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

**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 2 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.

**Solid tumour coding rules:** The new multiple primary and histology (MPH) rules that replaced the 2007 Surveillance, Epidemiology and End Results multiple primary and histology coding rules. They are used for cases diagnosed from 2018 onward in the Ontario Cancer Registry. Stage at diagnosis: Refers to how much a cancer has spread at the time of diagnosis.

**Stage at diagnosis:** Refers to how much a cancer has spread at the time of diagnosis.

**Standard population**: The age distribution used as weights to create age-standardized (i.e., age-adjusted) statistics.

**Subsite: **An anatomical part of a body site, such as an organ.

**Subtype:** The histological type of a cancer.

**TNM classification of malignant tumours: **The recognized standard for classifying how much a cancer has spread.