Zones

On this website, data are shown by cancer reporting zone. These zones have been designed so that they have a minimum population, have similar demographic and socioeconomic characteristics, and are geographically compact (they minimize the distance between different parts of the zone). The minimum population for each zone is 50,000 people.

Incidence rates for California statewide data are taken from the National Cancer Institute's Surveillance, Epidemiology, and End Results (SEER) Program using National Center for Health Statistics annual population estimates. Incidence rates for zones are calculated using data from the California Cancer Registry using 2010 Census population estimates and SEER 2015 census tract estimates by race/origin (controlling to Vintage 2015).

Counties with larger populations (more than 100,000 people) were divided into multiple zones by combining adjacent census tracts. For the rest of the state, adjacent counties and parts of counties were combined to form zones. Three demographic and socioeconomic characteristics were used to determine similarity: the percent minority population (percent of the population who are not non-Hispanic White), percent of the population with incomes below poverty, and the proportion of the population living in urban and rural areas.

We used population data from Census 2010 and Census 2010 tract geographies to construct the zones. Poverty data came from the American Community Survey 2012-2016 5-year data. We used a software zone design program called AZTool to identify aggregations of adjacent tracts and counties that optimize the three objectives: a target population of 50,000, geographic compactness, and similarity in terms of minority population, poverty, and urbanicity characteristics.

Medical Service Study Areas (MSSAs)

As defined by California's Office of Statewide Health Planning and Development (OSHPD) in 2013, "MSSAs are sub-city and sub-county geographical units used to organize and display population, demographic and physician data" (Source). Each census tract in CA is assigned to a given MSSA. The most recent MSSA dataset (2014) was used. Spatial data are available via OSHPD at the California Open Data Portal.

Congressional Districts

111th Congressional districts define the boundaries around areas which are represented by the U.S. House of Representatives (more information at the Census website). California Health Maps uses boundaries for the 111th Congress, happening from 2009-2011 and overlapping in time with the other 2010 data used.

Data reallocation for Congressional Districts

For Congressional Districts, data were transformed from census tract geographies to each of the different geographic area units. Spatial data for each census area unit are available from NHGIS (IPUMS NHGIS, University of Minnesota), and spatial crosswalks used to convert data to each geography from census tracts are available at Missouri Census Data Center (MCDC). The geographic correspondence engine created by MCDC provides a weighting variable based on 2010 census population, which was used to reallocate population numbers and case numbers between disparate but overlapping geographic areas. The reallocated numbers for each census tract were then used to calculate population weighted averages for the larger geography.

Cancer incidence rates

Cancer incidence rates for California statewide data are derived from the National Cancer Institute's Surveillance, Epidemiology, and End Results (SEER) Program using National Center for Health Statistics annual population estimates. Incidence rates for zones, MSSAs, and congressional districts are not available through SEER and were calculated using case counts from the California Cancer Registry and population data from 2010 Census estimates and SEER 2015 census tract estimates by race/origin (controlling to Vintage 2015).

Who developed the census tract aggregation zones?

What are the benefits of using these census tract aggregation zones?

What is Census and American Community Survey data?

Why do some zones not have incidence rates?

Why are data not available for other or more granular racial/ethnic groups (e.g., American Indians, Asian or Latinx ethnic groups) or non-binary genders?

Does my neighborhood influence my cancer risk? What factors in my neighborhood contribute to the cancer incidence rate?

Why are neighborhood data on population sociodemographic factors provided? Do they cause cancer?

What is CHIS?

What is 500 Cities?

Aggregation: Collections of smaller units grouped together for the purposes of statistical reporting. See Methodology for more information.

Age-Adjusted Incidence Rate (AAIR): Age-adjustment is a statistical method that allows comparisons of incidence rates to be made between populations with different age distributions. This is important since the incidence of most cancers increases with age. An age-adjusted cancer incidence (or death) rate is defined as the number of new cancers (or deaths) per 100,000 population that would occur in a certain period of time if that population had a 'standard' age distribution. In the California Health Maps, incidence rates are age-adjusted using the U.S. 2000 Standard Population.

Breast Cancer Screening: Percent of women aged 50-74 years who have received a mammogram in the past 2 years.
Source: 500 Cities/Behavioral Risk Factor Surveillance System, 2018.

Cervical Cancer Screening: Percent of women aged 21–65 years who have not received a hysterectomy and have received a Papanicolaou (Pap) smear within the previous 3 years.
Source: 500 Cities/Behavioral Risk Factor Surveillance System, 2018.

Confidence Interval: A statistical measure of the precision of the observed incidence rate. The lower confidence interval (LCI) and upper confidence interval (UCI) provide a range within which the true rate is thought to be with 95% confidence. Rates based on larger numbers are subject to less variation.

Colorectal Cancer Screening: Percent of adults aged 50–75 years who have received a fecal occult blood test (FOBT) within the past year, a sigmoidoscopy within the past 5 years and a FOBT within the past 3 years, or a colonoscopy within the past 10 years.
Source: 500 Cities/Behavioral Risk Factor Surveillance System, 2018.

Data Suppression: According to California Department of Public Health guidelines, cancer incidence rates cannot be reported if based on fewer than 15 cancer cases and/or 10,000 population counts. Incidence rates with fewer than 15 cases and/or 10,000 population-at-risk for a given cancer site/sex/racial or ethnic group are not shown to ensure confidentiality and stable statistical rates.

Delayed Care: Percent of adults who delayed or did not get medicine/medical services in the past year.
Source: California Health Interview Survey, 2015-2016.

Demographics: Statistical data relating to the population and particular groups within it.

Food Insecure: Percent of adults in low-income households (<200% of the Federal Poverty Line) that are hungry or at risk of hunger.
Source: California Health Interview Survey, 2015-2016.

Foreign Born: Percent of residents who were born outside the United States.
Source: American Community Survey, 2008-2012.

Incidence: The number of new cases of cancer diagnosed over the specified time period.

Over 65: Percent of residents age 65 years and older.
Source: Census 2010.

Obesity: Percent of adults with a body mass index (kilograms/square meter) of 30 or greater.
Source: 500 Cities/Behavioral Risk Factor Surveillance System, 2018; California Health Interview Survey, 2015-2016 (zones only).

Physical Activity: Percent of adults that walked at least 150 minutes in the past week for either leisure or transportation.
Source: California Health Interview Survey, 2015-2016.

Preventive Care: Percent of men or women 65 years and older who have received all of the following: an influenza vaccination in the past year; a pneumococcal vaccination ever; either a fecal occult blood test (FOBT) within the past year, a sigmoidoscopy within the past 5 years and a FOBT within the past 3 years, or a colonoscopy within the previous 10 years; and (for women only) a mammogram in the past 2 years.
Source: 500 Cities/Behavioral Risk Factor Surveillance System, 2018.

Race/Ethnicity: Race/ethnicity is categorized as: All races/ethnicities, Non-Hispanic (NH) White, NH Black, Asian/Pacific Islander, or Hispanic. "All races" includes all of the above, as well as other and unknown race/ethnicity and American Indian/Alaska Native. The latter two groups are not reported separately due to small numbers for many cancer sites.

Racial/Ethnic Composition: Distribution of residents' race/ethnicity (e.g., % Hispanic, % non-Hispanic White, % non-Hispanic Black, % non-Hispanic Asian/Pacific Islander).
Source: US Census, 2010.

Routine Checkups: Percent of adults who report having been to a doctor for a routine checkup (e.g., a general physical exam, not an exam for a specific injury, illness, condition) in the previous year.
Source: 500 Cities/Behavioral Risk Factor Surveillance System, 2018.

Rural: Percent of residents who reside in blocks that are designated as rural.
Source: Census 2010.

Sex: California Cancer Registry defines this field as the sex or gender of the cancer patient, and codes available are male, female, intersex, transsexual, and transgender (natal male, natal female, or not specified). However, categories beyond male and female are not consistently coded by medical reporting facilities, and population estimates for gender categories beyond male and female are not available. Thus, cancer incidence data are reported for only male and female sex at this time.

Smoking: Percent of adults who are current smokers.
Source: California Health Interview Survey, 2015-2016.

Socioeconomic Status (Neighborhood Level): A composite measure of seven indicator variables created by principal component analysis; indicators include: education, blue collar job, unemployment, household income, poverty, rent, and house value. Quintiles based on state distribution, with quintile 1 being the lowest SES and 5 being the highest.
Source: American Community Survey, 2008-2012.

Uninsured: Percent of residents who did not have health insurance.
Source: American Community Survey, 2008-2012.