SEER*Stat Statistical Methods for Incidence and Mortality

SEER*Stat is statistical software for the analysis of SEER and other cancer-related databases. Methods associated with the reporting of basic cancer incidence and mortality statistics are added directly to SEER*Stat.

• Age-Adjusted Rates - An age-adjusted incidence or mortality rate is a weighted average of the age-specific incidence or mortality rates, where the weights are the proportions of persons in the corresponding age groups of a standard million population.
• Gamma Confidence Intervals for Age-Adjusted Rates: This method provides confidence intervals with good statistical properties even when the cancer is rare, the population is small, or the population of interest is very different from the standard.
  Reference: Fay MP, Feuer EJ. Confidence intervals for directly standardized rates: A method based on the Gamma distribution. Statistics in Medicine 1997;16:791-801.
• Trends in Rates - Trends over time based on frequencies (percent change, annual percent change)
• Risk-adjusted Incidence Rates - The usual SEER incidence rates which are reported count multiple instances of primaries of the same cancer in the numerator, and use the total population as the denominator. However, in many situations, interest focuses instead on first instances of a particular cancer type and the population who has never had the cancer as the denominator. This type of incidence rate is sometimes called "Risk-Adjusted Incidence" since it represents the risk estimate that would be used in a population model for the transition rate from the healthy population to the population with cancer. First instances of a particular cancer can be derived directly from SEER data (under certain assumptions), while the size of the cancer-free population must be derived indirectly by subtracting out the population with prevalent cancers. These rates are sometimes lower than the standard rates (e.g. prostate cancer with high prevalence and almost no instances of multiple cancers), sometimes higher than the standard rates (e.g. melanoma with low prevalence and many instances of multiple cancers), and sometimes very close to the standard rates (e.g. breast cancer with relatively high prevalence and relatively high instances of multiple cancers). For more information on this topic, see: Merrill RM, Feuer EJ. Risk-adjusted cancer-incidence rates (United States).Cancer Causes Control. 1996 Sep;7(5):544-52.
• Multiple Primary - Standardized Incidence Ratios (MP-SIR): These ratios can be used to compare incidence of cancer in a defined cohort of persons previously diagnosed with cancer to the incidence of cancer in the general population.
• Incidence-based Mortality - The incidence-based mortality rate allows a partitioning of mortality by variables associated with the cancer onset.