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SEER 13 Delay Model

Starting with the April 2009 release of the Cancer Statistics ReviewExternal Web Site Policy we estimated delay adjusted rates for SEER 13 registries. SEER 13 consists of SEER 9 registries, covering diagnosis years 1975 through the present, plus 4 newer registries (Los Angeles, San Jose-Monterey, Rural Georgia, Alaska Native Tumor Registry) covering diagnosis years 1992 through the present. These four registries will be referred to here as SEER 13-9.

Delay-adjusted rates for SEER 13 were obtained through a 2 step process. First, the delay adjustment factors are derived separately for SEER 9 and SEER13-9. Delay adjusted age specific case counts are computed for SEER 9 and SEER 13-9 using their respective delay adjustement factors and then summed to get the delay-adjusted case counts for SEER 13. These adjusted case counts are then paired with the appropriate denominator to obtain age-specific rates, and are age-adjusted in the usual manner. The formula to compute the age-adjusted combined SEER 13 rates is:

Formula for delay adjusted rate for the ith age group Formula for the age adjusted rate using delay adjusted rate for the ith age group

i is for age, j is for stratum defined by multiple variables included in the delay model.

Future developments will include an application program to allow the computation of SEER 13 combined delay adjusted rates based on this formula.

Consecutive data submissions were not available for the Alaska Native Tumor Registry for the entire period of interest. Modeling SEER 13-9, therefore, was conducted using only Los Angeles, San Jose-Monterey and Rural Georgia though the final delay-adjustment factors were applied across the four registries.

In creating the SEER 13-9 model, we first followed the same process of model selection and delay adjustment factor estimation as is used in SEER 9. We then modified the SEER 13-9 factors to share the same delay adjustment factors as SEER 9 under the assumption that the data have the same delay distribution prior to 1992. The modified delay adjusted factors are then the final estimated factors for SEER 13-9. As with SEER 9, we also assume that in SEER 13-9 there is no delay after 30 year of reporting.

Example (Based on November 2008 submission)

The example in the graph below shows white female breast cancer delay adjustment factors for SEER 9, SEER 13-9, and modified SEER 13-9 for diagnosis years 1981 through 2006. In the November 2008 submission, the maximum delay time for the registries in SEER13-9 was only 16 years. We assumed that the delay adjustment factors for SEER 13-9 are the same as those for SEER 9 factors when delay time is greater than 16 years.

Delay Adjustment Factors by SEER Region - White Female Breast Cancer

The black line represents the fit to the SEER 9 registries and assumes there is no delay after 27 years. When analyzing the November 2008 submission, the 27 year maximum delay was set based on the available data submissions (1983-2008) in our archive and also because updates to case information beyond 27 years is deemed minimal. The blue line represents the fit to SEER 13-9 registries and has a maximum 16 year delay which corresponds to the first NCI data submission for these registries in 1994.

The SEER 9 line shows that at 16 years there is a delay adjustment of 1.002 (0.02% further adjustment from 16 to 27 years). Finally, the red line corresponds to the modified delay adjustment factors for SEER 13-9, assuming that 0.02% also remains to be reported by SEER 13-9 after 16 years. The combined SEER 13 delay adjusted rates for 2006 are obtained by utilizing the delay adjustment factors for both SEER 9 (1.021) and SEER 13-9 (1.018).