SEER Sequence Num

Field Length: 2

The SEER sequence number represents the order of all primary reportable tumors diagnosed during a patient's lifetime. It counts the occurrence of independent, malignant primaries that are required to be reported to the SEER Program.

The sequence number 00 indicates that this patient has one primary cancer. The sequence 01 indicates that the case is the first of multiple primaries.

Sequence numbers in the range of 60-88 have a special meaning to SEER. They are reserved for conditions that are collected by the registry but are not required to be reported to SEER. These include all basal and squamous cell carcinomas of the skin diagnosed and reported before 2003 (C44._ with M8000-M8110) as well as all pre-invasive carcinomas of the cervix diagnosed in 1996 and 1997.

As of January 1, 2004, benign and borderline intracranial tumors became reportable to SEER as well as KCR. These are sequenced in the 60-88 series.

Codes (conditions reportable to SEER):

 Series 1: In-Situ/malignant as Federally Required based on Diagnosis Year      

Series 2: Non-malignant Tumor as Federally Required based on Diagnosis Year (or state or regional defined)

Note: Conversion Guidance
Do not change the sequence numbers for neoplasms whose histology codes were associated with behavior
codes that changed from in situ/malignant to benign/borderline or vice versa during the conversion from
ICD-O-2 to ICD-O-3 or the conversion from ICD-O-3 to ICD-O-3.2.

In situ/Malignant Coding Instructions

1. Count all previous and current in situ/malignant reportable primaries which occur(red) over the
lifetime of the patient, regardless of where he/she lived at diagnosis

a. A ‘reportable’ primary refers to the site/histology/behavior of the tumor and the years
when reporting was required. Review of the reportability requirements in effect during
the diagnosis year will be needed.

2. Code 00 when there is only one primary in the patient’s lifetime

3. Sequence in situ/malignant primaries chronologically as 01 (first of one or more), 02 (second
primary), 03 (third primary), and assign the appropriate sequence number to all primaries in the
database when there are multiple primaries

Example 1: The patient has a history of breast cancer in 1999. She has colon cancer in 2010.
Assign sequence number 02 to the colon cancer and change the sequence number on the breast
cancer from 00 to 01.

Example 2: In 1987, patient was diagnosed and treated for childhood leukemia in another state.
After becoming a resident of a SEER region, the patient develops bladder cancer. The SEER
registry assigns a sequence number of 02 to the bladder cancer. Document the first diagnosis in
a text field.

a. Change the sequence number of the first primary from 00 to 01 when one patient has a
primary with sequence 00 and then develops another reportable /2 or /3 primary

b. Exception: There are certain cancers that were only reportable for some years. The
following are some examples (not a complete list)

• • • Borderline tumors of the ovary were reported for 1992-2000
      • Sequence 00-59
    • Refractory anemia is reported only for 2001+
      
    • Myelodysplastic syndromes are reported only for 2001+
      
    • Newly reportable hematopoietic neoplasms as of 01/01/2010
      

4. Assign the lower sequence number to the primary with the worse prognosis when two
primaries are diagnosed simultaneously

a. Base the prognosis decision on the primary site, histology, and extent of disease for each
of the primaries

b. If there is no difference in prognosis, the sequence numbers may be assigned in any order

Non-Malignant Coding Instructions

1. Include all non-malignant primary intracranial /CNS tumors diagnosed in 2004, and forward
regardless of where the patient lived at diagnosis

2. Assign sequence number 60 when there are no prior or subsequent non-malignant intracranial/
CNS tumors

a. The sequence number is 60 when a patient has only one reportable non-malignant tumor.
If a tumor has a sequence of 60 and there is another reportable non-malignant tumor,
change the sequence number of the first primary from 60 to 61.

3. Assign sequence numbers in chronological order according to the order in which they
occur(red). Reportable benign and borderline intracranial/CNS tumors are restricted to primary
site codes C700-C729, C751-C753 with behavior codes of /0 or /1.

4. Sequence multiple non-malignant tumors chronologically as 61 (first of two or more), 62
(second), etc.

5. Sequence a non-malignant intracranial/CNS tumor and a malignant intracranial/CNS tumor (/2
or /3) independently when one patient has both. The non-malignant tumor has a sequence
number of 60 and the malignant (/2 or /3) tumor has a sequence number of 00.

6. Sequence tumors other than those required by SEER in the 60-87 range when a registry chooses
to collect non-reportable tumors. These non-reportable tumors are often referred to as
“Reportable by agreement.”

Example: Cervix in situ was diagnosed in 2003 and lung cancer was diagnosed in 2023. The
cervix in situ, if collected by the registry, would be a sequence number 60 and the lung would
be assigned a sequence number of 00.

Note: Sequence all cervix in situ cases in the 60-87 range regardless of diagnosis year. Submission of in situ
cervical cancer is no longer required as of 2018 NCI SEER data submission.

*This field will automatically be calculated by the computer based on the CPDMS sequence number for this case and the number and types of primaries stored for this patient.