# Types of Cancer Statistics

The following are key statistics generally used to assess the impact of cancer in the general population. Use the links on this page to learn more about each statistic type.

- Incidence - the number of newly diagnosed cases during a specific time period
- Mortality - the number of deaths during a specific time period
- Prevalence - new and pre-existing cases for people alive on a certain date
- Survival - the proportion of patients alive at some point subsequent to the diagnosis of their cancer
- Lifetime Risk - the probability of developing or dying of cancer
- Statistics by Race/Ethnicity - a measure of the cancer burden in racial/ethnic minorities and medically underserved populations

**Incidence**

A **cancer incidence rate** is the number of new cancers of a specific site/type occurring in a specified population during a year, usually expressed as the number of cancers per 100,000 population at risk. That is,

**Incidence rate = (New cancers / Population) × 100,000**

The numerator of the incidence rate is the number of new cancers; the denominator is the size of the population. The number of new cancers may include multiple primary cancers occurring in one patient. The primary site reported is the site of origin and not the metastatic site. In general, the incidence rate would not include recurrences. The population used depends on the rate to be calculated. For cancer sites that occur in only one sex, the sex-specific population (e.g., females for cervical cancer) is used.

An age-adjusted rate is a weighted average of the age-specific rates, where the weights are the proportions of persons in the corresponding age groups of a standard population. The potential confounding effect of age is reduced when comparing age-adjusted rates computed using the same standard population.

**Mortality**

A **cancer mortality rate** is the number of deaths, with cancer as the underlying cause of death, occurring in a specified population during a year. Cancer mortality is usually expressed as the number of deaths due to cancer per 100,000 population. That is,

**Mortality Rate = (Cancer Deaths / Population) × 100,000**

The numerator of the mortality rate is the number of deaths; the denominator is the size of the population. The population used depends on the rate to be calculated. For cancer sites that occur in only one sex, the sex-specific population (e.g., females for cervical cancer) is used. The mortality rate can be computed for a given cancer site or for all cancers combined.

**Prevalence**

**Prevalence** is defined as the number or percent of people alive on a certain date in a population who previously had a diagnosis of the disease. It includes new (incidence) and pre-existing cases and is a function of both past incidence and survival. Information on prevalence can be used for health planning, resource allocation, and an estimate of cancer survivorship. Overview of Cancer Prevalence contains a description of the methodology and the types of prevalence statistics.

**Survival**

**Cancer survival statistics** are typically expressed as the proportion of patients alive at some point subsequent to the diagnosis of their cancer. Relative survival is an estimate of the percentage of patients who would be expected to survive the effects of their cancer. Observed survival is the actual percentage of patients still alive at some specified time after diagnosis of cancer. It considers deaths from all causes, cancer or otherwise. Overview of Population-based Cancer Survival Statistics describes the methodologies involved in calculating cancer survival statistics.

**Lifetime Risk**

Statistical models are used to compute the **probability of developing or dying of cancer** from birth or conditional on a certain age. The development of this statistical methodology is described in the following reports:

- Lifetime Risk of Developing Breast Cancer (PDF)
- Estimating Lifetime and Age Conditional Probabilities of Developing Cancer (PDF)

**Statistics by Race/Ethnicity**

The NCI has recognized the need to better define the cancer burden in** racial/ethnic minorities and medically underserved populations** and supports research, applications and surveillance on the full diversity of the United States population. Since its inception in 1973, the the cancer registry system of the SEER Program has included large segments of diverse populations. Subsequent expansions increased the proportions of Hispanics, urban African Americans and Asian and Pacific Islanders in Southern California and the Greater Bay Area, rural African Americans in Georgia, northwestern populations in Seattle, Arizona Indians, and Alaska Natives residing in Alaska. An expansion in 2001 of four areas increased coverage of key populations, such as rural low-income whites, more geographically diverse American Indians, rural African-Americans and other Hispanic groups. This addition – the largest expansion to date – brings SEER coverage to 26% of the U.S. population.

The SEER Program collects and publishes cancer incidence and survival data in order to assemble and report estimates of cancer incidence, survival, mortality, other measures of the cancer burden, and patterns of care in the US. Statistics from the SEER Program routinely include information specific to race/ethnic populations as well as other populations defined by age, gender, and geography.