As of January 1, 2001, all cases reported to SEER are required to have an ICD-O-3 histology and behavior code. Cases diagnosed prior to this date used the ICD-O-2 coding scheme. When 1973-2000 SEER cases are converted from ICD-O-2 to ICD-O-3, some diseases yield an ICD-O-3 behavior of 1 (borderline). Also, when 2001+ SEER cases are converted from ICD-O-3 to ICD-O-2, some diseases yield an ICD-O-2 behavior of 1 (borderline). So after the conversion, cases that were previously unreportable/borderline are now reportable/malignant, and some that were reportable/malignant are no longer reportable. However, this conversion is only done for analysis convenience and does not affect which tumors are included in the SEER database. Specifically because, reportability to SEER continues to be behavior codes of 2 (in situ) and 3 (malignant) for the ICD-O coding scheme used at the time of diagnosis. To conveniently analyze data without including diseases that changed reportability, SEER has defined the term "malignant" to mean the case had a behavior code of 3 (malignant) in both ICD-O-2 and ICD-O-3.

1973-2004 SEER Research Data (November 2006 submission) and Later Releases

In these data releases, the "Behavior recode for analysis" variable available in SEER*Stat has the following formats:

0=Benign
1=Borderline malignancy
2=In situ
3=Malignant
4=Only malignant in ICD-O-3
5=No longer reportable in ICD-O-3*
6=Only Malignant 2010+

* Starting with the November 2020 Submission, these cases are no longer available in the SEER data.

This variable is no longer used in SEER analyses and published statistics. Visit the SEER Data Change History for more information.

How to create "Behavior recode for analysis"

The steps below were followed to recode behavior in the SEER databases.*

  1. SEER starts with the data submitted by the registries. These are the raw fields from the original NAACCR record with no adjustment.  If your data only has ICD-O-2 histology codes for data before 2001, please use the ICD Conversion Program to convert these codes to ICD-O-3.
  2. The behavior code for all the urinary bladder cases is set to a value of 3 (malignant).
  3. The recode is created based on  primary site, ICD-O-3 histology, and ICD-O-3 behavior:
    • 2004+ brain cases (C700-C701, C709-729, C751-C753) with ICD-O-3 behavior of 0 (benign) are coded as 0 (benign) in the new variable.
    • 2004+ brain cases (C700-C701, C709-729, C751-C753) with ICD-O-3 behavior of 1 (borderline) are coded as 1 (borderline malignancy) in the new variable.
    • Cases with ICD-O-3 behavior code of 2 (in situ) are coded as 2 (in situ) in the new variable.
    • Cases diagnosed  2001+ with an ICD-O-3 behavior code of 3 (malignant) and one of the following ICD-O-3 histology codes are coded as 4 (only malignant in ICD-O-3) in the new variable.
      9393, 9538, 9950, 9960-9962, 9980, 9982-9987, 9989
    • Lung cases (C340-C349) diagnosed  2001+ with an ICD-O-3 behavior code of 3 and ICD-O-3 histology code of 9133 are coded as 4 (only malignant in ICD-O-3) in the new variable.
    • Non-brain cases (C000-C699, C730-C750, C754-C809) with an ICD-O-3 behavior code of 1 (borderline) are coded as 5 (no longer reportable in ICD-O-3) in the new variable.
    • All cases not covered above, with an ICD-O-3 behavior code of 3 (malignant) are coded to 3 (malignant) in the new variable.  These are the only cases included in most analysis.
    • Cases diagnosed 2010+ with an ICD-O-3 behavior code of 3 (malignant) and one of the following ICD-O-3 histology codes are coded as 6 (Only Malignant 2010+).

      9724, 9751, 9759, 9831, 9975, 9991, 9992

*Prior to the November 2020 data release, any case with an ICD-O-3 behavior of 1 and ICD-O-3 histology of 9421-9422 would have the behavior set to 3.