Cancer Incidence Statistics Dataset Details

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Source of Cancer Registry Data

The Colorado Central Cancer Registry is the statewide cancer surveillance program of the Colorado Department of Public Health and Environment. The program's goal is to reduce death and illness due to cancer by informing citizens and health professionals through statistics and reports on incidence, treatment and survival, and deaths due to cancer.

The Registry is mandated by Colorado law and a regulation (pdf file) passed by the Colorado Board of Health. Information is collected from all Colorado hospitals, pathology labs, outpatient clinics, physicians solely responsible for diagnosis and treatment, and state Vital Statistics. Pertinent data is registered on all malignant tumors, except basal and squamous cell carcinomas of the skin. All individual patient, physician, and hospital information is confidential as required by Colorado law.
Colorado Central Cancer Registry data are used in a variety of ways:

1. To educate health professionals and citizens regarding specific cancer risks,
2. To answer public questions about cancer statistics,
3. To help focus cancer control activities in the state,
4. To monitor the occurrence of cancer,
5. To aid in research studies,
6. To monitor the effectiveness of treatment, and
7. To help develop health services and screening programs.

Registry statistics are used by physicians and other health professionals, hospital administrators and planners, the general public, legislators, government agencies including local and county health departments, epidemiologists, students, researchers, and the news media.

Contact Information: cdphe.pscaregistry@state.co.us

Colorado Department of Public Health and Environment
Prevention Services Division
Colorado Central Cancer Registry
4300 Cherry Creek Drive South
PSD-CR-A5
Denver, CO 80246-1530
303-692-2540

Clarifications on Cancer Registry Data

County of Residence

Geographical choices include county of residence at the time the cancer was diagnosed. Through a constitutional amendment, residents of the City of Broomfield organized to become Colorado's 64th county. Annexing portions of Adams, Boulder, Jefferson, and Weld counties, the City of Broomfield became the City and County of Broomfield on 11/15/01. Residents of Broomfield County diagnosed with cancer starting in 2002 were coded to Broomfield County.

Diagnosis Year

The year is defined as the year the cancer was diagnosed. Choices for years will be updated as a new complete year of data are available.

Race/Ethnicity

Race and ethnicity (defined as Hispanic or not) are determined by information reported to the Cancer Registry by medical facilities. Additional assignment of Hispanic ethnicity is done at the Registry by checking a U.S. Census list of Hispanic surnames. Six race/ethnicity choices are available in COHID: all races combined, white/non-Hispanic, white/Hispanic, Black, Asian/Pacific Islander, and American Indian/Native Alaskan.

Age-Adjusted Incidence Rates

Incidence rates measure the number of new invasive cancer diagnoses per 100,000 population during a defined time period. According to methodology used throughout the country, incidence rates for all cancer sites exclude in situ stage cancers, except bladder cancer, which includes in situ tumors. Stage of disease at the time of cancer diagnosis is typically defined by size and containment or spread of the tumor. One of the schemes for staging, SEER summary stage, which allows for general historical comparisons over time includes the categories of in situ, localized, regional, or distant spread. The pre-invasive stage of a malignant tumor is called in situ and is usually highly curable. In the earliest invasive stage of cancer, the localized stage, the tumor is confined to the organ of origin. Regional spread is to adjacent organs or lymph nodes, and distant (metastatic) stage refers to a tumor that has spread to distant organs or lymph nodes. The length of survival is typically increased the earlier a cancer can be diagnosed. Summary stage 1977 rules govern staging for cases diagnosed before 2001; summary stage 2000 rules govern staging for cases diagnosed 2001 and after. These two sets of rules are not completely consistent; for a discussion of possible effects on historical trends, see http://www.naaccr.org/index.asp?Col_SectionKey=11&Col_ContentID=397.

Age standardization, often referred to as "age-adjustment,” is used to eliminate the confounding effects of differences in the age composition among different populations or across time, which allows for statistical comparisons of rates in these different populations and over different time periods.

The age-adjusted incidence rate is defined as the incidence rate that would occur if the observed age-specific incidence rates were present in a population with an age distribution equal to a standard population. The age-adjusted incidence rate is calculated by multiplying each age-specific rate by the standard population weight and summing the weighted age-specific incidence rates. Because each population or time period shares a common age distribution represented by the age-specific standard population weights, the effects of variation in the age distribution are eliminated.
The age-adjusted cancer incidence rates presented here are adjusted to the 2000 U.S. standard population, which is a procedure adopted by all federal and state agencies to reflect age changes in the population and to move toward a single age-adjustment standard for all diseases. Comparisons of these rates with previous reports should not be done due to a change in the standard year for age-adjusting rates. All printed publications of the Cancer Registry before 2002 have age-adjusted rates based on the 1970 U.S. standard population. Starting with publications released in 2002, rates have been age-adjusted using the 2000 U.S. standard. Studies have shown that cancer rates age-adjusted to the new 2000 standard still have the same time trend slopes as rates adjusted to the old 1970 standard. However, rates age-adjusted to the 2000 standard will appear to be about 15-20% higher than rates age-adjusted to the old 1970 standard, which illustrates why rates adjusted by different standards should not be compared.

Standard Errors of Rates

Age-adjusted rates are presented here with standard errors, which are a measure of the reliability or precision of calculated rates. Rates based on larger populations have smaller standard errors while rates based on smaller populations have larger standard errors.

Confidence Intervals

The age-adjusted incidence rates calculated on this site, due to the expected standard errors of rates, estimate the true incidence rates. Setting a confidence interval (CI) around a calculated rate allows users to evaluate the estimate. For this site, a 95% confidence interval is presented which means that the true rate has a 95% probability of being within the upper and lower bound of the confidence interval. The bounds of the CI are calculated as plus or minus 1.96 times the standard error of the rate.

An approximate statistical test to compare two rates statistically is to determine whether their confidence intervals overlap. If the confidence intervals do not overlap, the difference in rates is statistically significant. Otherwise, the rates are within expected statistical variation.

Another better (because it incorporates the combined variability of the two rates) approximate test to compare two rates statistically can be calculated using the following formula:

S.E. is the standard error of the rate. If the absolute value of Z is greater than 1.96, the two rates are significantly different at a p-value of 0.05. This test can be inaccurate for rates based on fewer than 10 cases, and it should not used for rates based on fewer than six cases.

Cancer Site Choices

Selections available for cancer sites and groups are determined by coding available from the National Cancer Institute’s Surveillance, Epidemiology, and End Results Program (SEER) Site Recodes (http://seer.cancer.gov/siterecode/icdo3_d01272003) based on the International Classification of Diseases for Oncology, 3rd Edition (ICD-O-3).

Many quality control edits are built into the data reporting and compilation system of the Cancer Registry and COHID. Also, the Cancer Registry is certified for quality and completeness by the North American Association of Cancer Registries. However, as with all large, complex data sets, completeness and accuracy of reporting may vary by individual data item. As such, the cancer data available here are subject to change over time as new data are reported and existing data are corrected and/or updated.

Confidentiality

Colorado Revised Statutes 2005, Section 25-1.5-101 (1) (q) establishes the Colorado Central Cancer Registry ( http://www.cdphe.state.co.us/pp/cccr/index.html) within the Colorado Department of Public Health and Environment (CDPHE) to “collect, compile, and tabulate general statistical information with regard to cancer cases” from many medical sources. The Department “may disclose general, non-individual identifying information, numerical and statistical data developed therefrom or related thereto.” As per the CDPHE regulation referring to the Registry and passed by the Colorado Board of Health ( http://www.cdphe.state.co.us/regulations/preventionservices/100903.pdf), all reports of cancer cases received by the Department, in connection with the Registry, shall be and remain strictly privileged and confidential as “medical records and reports” within the purview and intent of Section 25-1-122 (4), Colorado Revised Statutes 1989. Per this statute ( http://www.cdphe.state.co.us/pp/cccr/laws.html), “release may be made of medical and epidemiological information in a manner such that no individual person can be identified.” In addition, the CDPHE has instituted a Policy on Release of Disease Surveillance Data, which refers to this statute and prescribes data release limitations based on population size, time period, etc. This policy has been followed in presenting Cancer Registry statistics for the COHID website.

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