WSCR-DO Technical Notes: Table of Contents

General Information

Query Option Details

WSCR Online Query Options and Data Results Headings

Cancer Site (Query Options and Results)

Data Type (Query Options and Results)

Incidence

Mortality

Stage at Diagnosis (Query Options and Results)

Rate (Query Options and Results)

Age-Adjusted Rate

Age-Specific Rate

Age Group

Gender (Query Options and Results)

Time period or Year (Query Options and Results)

Geography (Query Options and Results)

Output (Query Option)

Show Chart

Data Labels

Error Bars

Zero Minimum

Output (Results)

Annual Observations (Results)

Annual Population (Results)

Average Annual Population (Results)

Average Annual Observations (Results)

Rate/100,000 (Results)

95% CI (Results)

Data Results Notes

NR: "Not reported"

References

Appendix

Direct method of age adjustment

Confidence Intervals

References

General Information

The data available in the Washington State Cancer Registry (WSCR) online database change as new incidence data are added. WSCR regularly receives information on people newly diagnosed with cancer and new information about previously diagnosed cancer cases. Thus, the current online data may differ from earlier printed reports. WSCR online provides data on cancer of all types combined and the 24 most frequently diagnosed cancers. Information is also provided on "Hodgkin lymphoma" and "Larynx" because previous years of the WSCR Annual Report included them among the 24 most frequently diagnosed cancers. See the Background and Cancer Case Reporting sections in About WSCR for the information on the WSCR data collection system.

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Query Option Details

The following notes provide information for WSCR Online query options and results. Query options vary depending on the user’s initial selections. Selecting common types of cancer with relatively large numbers of cases each results in more query options than selecting rare types of cancer with few cases each year. Even when query options are available, WSCR Online suppresses output when there are less than ten cases for the query options selected.

When numbers are small, some parameter values may be aggregated (for example, you may not be able to obtain single years, but only three-year periods). Similarly, you may not be able to query multiple parameters simultaneously (for example, if you want data by county, you may not be able to select individual age groups). If you can see that there is a parameter available, such as geography, but no options appear for that parameter, try aggregating other parameters. For example, change age to all-ages-combined, and then check to see if the other parameters are available. For some measures with small numbers, you may be able to stratify only one or two parameters at a time. For some measures where the numbers are very small, few options for sub-group analysis are possible; if you need to conduct sub-group analysis, contact assessment staff in your local health agency, who have access to the restricted data.

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WSCR Online Query Options and Data Results Headings

Cancer Site (Query Options and Results)

New cases of cancer (incidence) are coded to International Classification of Disease for Oncology Third Edition (ICD-O-3) codes. The WSCR Online query results produces the definition box for each selected cancer site with the ICD-O-3 primary site and histology codes. The cancer sites definitions (http://seer.cancer.gov/siterecode/icdo3_dwhoheme/index.html) are consistent with those used by the National Cancer Institute’s SEER program.

The underlying cause of death is coded to an International Classification of Diseases, 9th Revision (ICD-9) code for years prior to 1999 and 10th Revision (ICD-10) for 1999 and after. The WSCR Online query results produces the definition box for the selected cancer sites based on the selection of death year with the ICD-9 or ICD-10 codes. The cancer sites definitions (http://seer.cancer.gov/codrecode/1969+_d04162012/index.html) are consistent with those used by the National Cancer Institute’s SEER program. For some cancer sites (such as, colorectal, endometrial, leukemia, lung and bronchus, myeloma and thyroid), the SEER coding differs from the National Center for Health Statistics coding. Therefore, before comparing information from different reports, one must be sure that the definitions are consistent.

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Data Type (Query Options and Results)

Incidence

Incidence refers to new cases of cancer diagnosed in a calendar year (annual) or during a 3- or 5-year time span divided by 3 or 5 (average annual). Incidence data are from the Washington State Cancer Registry. For information on incidence rates, see age adjusted rate.

Mortality

Mortality refers deaths from cancer in a calendar year (annual) or during a 3-or 5-year time span divided by 3 or 5 (average annual). The cancer was not necessarily diagnosed in the same year (annual) or time period (average annual). Mortality data reflect the underlying cause of death as recorded on the death certificate. Mortality data are from the Washington State Center for Health Statistics. For information on mortality rates, see age adjusted rate.

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Stage at Diagnosis (Query Options and Results)

Stage at diagnosis refers to how far a cancer has spread from its site of origin at the time of diagnosis. The stages, in order of increasing spread, are in situ, local, regional and distant.

In Situ	A tumor that fulfills all microscopic criteria for malignancy, but does not invade or penetrate surrounding tissue.
Localized	A tumor that is invasive but remains restricted to the organ of origin.
Regional	A tumor that has spread by direct extension to immediately adjacent organs or tissues and/or metastasized (spread through the blood stream) to regional lymph nodes, but appears to have spread no further.
Distant	A tumor that has spread by direct extension beyond the immediately adjacent organs or tissues, and/or metastasized to distant lymph nodes or other distant tissues.
Unstaged	Insufficient information available to determine the stage of disease at diagnosis.

 

Cancers staged as local, regional, distant, or unstaged are referred to as invasive. For most cancers, diagnosis at an early stage (in situ or local) results in improved survival.

WSCR uses the national Surveillance Epidemiology and End Results (SEER) guidelines to code stage at diagnosis. WSCR online allows users to obtain data by stage at diagnosis (in situ, invasive, or in situ and invasive combined) for all cancer sites combined, female breast cancer and melanoma of the skin. For the remaining types of cancer, WSCR online provides data on all diagnoses reported to WSCR irrespective of stage.

Stage at diagnosis option is not available for other types of cancers because

• The total numbers of cases are small, such as anal cancer.
• Very few cancers have in situ diagnoses, such as prostate and liver cancers.
• Diagnosis of in situ is not compatible with the type of cancer, such as leukemia and lymphoma.
• WSCR does not collect data on cancer in situ. This applies only to cancer of the uterine cervix.

 

For information on stage at diagnosis for specific cancers see WSCR Reports.

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Rate (Query Options and Results)

Age-Adjusted Rate

Age-adjusted rate allows for comparisons between two or more populations that differ in their age composition. This is particularly important for age-related diseases like cancer. To develop age-adjusted rates, the age-specific rates of each population being compared are computed. These age-specific rates are weighted by multiplying them by the proportion their corresponding age-group represented in a “standard population.” The sum of each population’s weighted age-specific rates equals that population’s age-adjusted rate. The age-specific rates used to compute annual age-adjusted rates equal the number of new cases or deaths in given age group and year divided by the population in that age group. The age-specific rates used to compute average annual age-adjusted rates, equal the number of new cases or deaths for the 3- or 5-year period divided by the number of person-years over the 3- or 5-year period, respectively.

WSCR online age-adjusts using 19 age groups as shown below from the United States 2000 standard population.

US Standard Population Proportions

 

The formulas for computing the age adjusted rates can be found in Appendix A.

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Age-Specific Rate

Annual and average annual age-specific rates are the rates per 100,000 population for combinations of 5-year age groups. For annual rates, the age-specific rate is the number of new cases or deaths in given age group and year divided by the population in that age group. For average annual rates, the age-specific rate is the number of new cases or deaths for the 3- or 5-year period divided by the number of person-years over the 3- or 5-year period, respectively.

Age Group

The age group (combinations of 5 years) of the population used for calculating the age-specific rate.

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Gender (Query Options and Results)

Male, Female, All

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Time period or Year (Query Options and Results)

The time period or year of diagnosis or death used for calculating the rate and count. Options vary depending on the average annual number of cases diagnosed over the last 10 years. The following table shows available options.

Average Annual Number of New Cancer Cases or Deaths	WSCR Online Options
< 400	5 years combined
400 – 799	3 years combined 5 years combined
≥ 800	Single year 3 years combined 5 years combined

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Geography (Query Options and Results)

Geography includes Washington State, each of the 39 Washington Counties, and 6 multicounty regions shown below.

The following table show options available based on the average annual number of new cases or death diagnosed over the last 10 years.

 

Average Annual Number of New Cancer Cases or Deaths	WSCR Online Options
< 200	State Multi-County Region
≥ 200	State Multi-County Region County

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Output (Query Option)

Show Chart

When this box is checked, the horizontal bar chart is shown with rates.

Data Labels

When this box is checked, the chart includes rates above the corresponding bars.

Error Bars

When this box is checked, the chart includes bars showing the extent of variation attributable to chance. See “Confidence Intervals” below.

Zero Minimum

When this box is checked, the chart x-axis begins at zero. This box is automatically selected as default.

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Output (Results)

Annual Observations (Results)

Number of cancer cases or deaths of the specified cancer type for the population group and year selected.

Annual Population (Results)

Number of people estimated to live in the specified geographic area for the population group and year selected.

Average Annual Population (Results)

Number of people estimated to live in the specified geographic area for the population group and years selected divided by 3 or 5 for the 3- or 5-year ranges, respectively.

Average Annual Observations (Results)

Number of cancer cases or deaths of the specified cancer type for the population group and years selected divided by 3 or 5 for the 3- or 5-year ranges, respectively.

Rate/100,000 (Results)

Either the age-adjusted rate or the age-specific rate chosen by the user.

95% CI (Results)

95% confidence interval (CI) around the rate. While the incidence and death statistics in this report are not subject to sampling error, they may be affected by random variation. The confidence interval is used to describe the range of that variation.

When the confidence interval for the area of interest does not overlap with the confidence interval for the comparison area, the two areas are statistically significantly different, i.e., the difference between the two rates is more than that expected by random variation or chance. However, if we are making many comparisons, we may still find statistically significant differences just by chance. In fact, with a 95% confidence interval, we expect that 5% of the comparisons will be statistically significant by chance. Thus, with 39 counties and 26 cancer sites, we might see as many as 50 instances where the rate for a county is statistically significantly different from the state rate just by chance.

Confidence intervals for the age-adjusted rates are calculated with a method based on the gamma distribution (Fay and Feuer, 1997). This method produces valid confidence intervals even when the number of cases is very small. When the number of cases is large the confidence intervals produced with the gamma method are equivalent to those produced with the more traditional methods, as described by Chiang (1961) and Brillinger (1986). The formulas for computing the confidence intervals can be found in Appendix A.

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Data Results Notes

NR: "Not reported"

Statistic is not reported or calculated when the number of observations is less than or equal to nine (9) for rates and stage at diagnosis.

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Appendix A

Direct method of age adjustment

Multiply the age-specific rates in the target populatiMultiply the age-specific rates in the target population by the age distribution of the standard population.

	=		=

Where m is the number of age groups, d_i  is the number of events in age group i, P_i  is the population in age group i and s_i is the proportion of the standard population in age group i. This is a weighted sum of Poisson random variables, with the weights being ( s_i / P_i ).

Confidence Intervals

Confidence intervals for the age-adjusted rates were calculated with a method based on the gamma distribution (Fay and Feuer, 1997). This method produces valid confidence intervals even when the number of cases is very small. When the number of cases is large the confidence intervals produced with the gamma method are equivalent to those produced with the more traditional methods, as described by Chiang (1961) and Brillinger (1986). The formulas for computing the confidence intervals are given below. Although the derivation of this method is based on the gamma distribution, the relationship between the gamma and Chi-squared distributions allows the formulas to be expressed in terms of quantiles of the Chi-squared distribution, which can be more convenient for computation.

Lower Limit =
Upper Limit =

where y is the age-adjusted rate, v is the variance as calculated as shown below, w_M is the maximum of the weights s_iP_i ,  1-α is the confidence level desired (e.g., for 95% confidence intervals, = 0.05), and ( x² )_x^-1 is the inverse of the x²distribution with x degrees of freedom.

	=

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References

Brillinger, D. R. The natural variability of vital rates and associated statistics [with discussion]. Biometrics 42:693-734, 1986.

Chiang, C. L. Standard error of the age-adjusted death rate. Vital Statistics, Special Reports 47:271-285, USDHEW, 1961.

Fay, M.P. and Feuer, E.J. Confidence intervals for directly rates: a method based on the gamma distribution. Stat Med16:791-801, 1997.

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