Laterality

Field Length:  1

Enter the one digit code which describes this primary with regard to involvement of one or both sides of paired organs (see list below).

Coding Instructions

1.  Use code 0 (not a paired organ) when:

a.  The primary site is not a paired site

b.  Primary site is unknown primary site (C80.9)

c.  Laterality is unknown for a death certificate only (DCO) case and the primary site is NOT one of the primary site codes listed in the table below: (Sites for Which Laterality Codes Must Be Recorded)

2.  Code laterality using codes 1-9 for all of the sites listed in the table: (Sites for Which Laterality Codes Must Be Recorded) 

a.  Laterality may be coded for sites other than those required, for example, Thyroid

3.  Code the side where the primary tumor originated.

a.   Assign code 3 if the laterality is not known but the tumor is confined to a single side of the paired organ.

Example: Pathology report: Patient has a 2cm carcinoma in the upper pole of the kidney. Code laterality as 3 because there is documentation that the disease exists in only one kidney, but it is unknown if the disease originated in the right or left kidney.

4.  Code 4 is seldom used EXCEPT for the following:

a. Both ovaries involved simultaneously with a single histology, or epithelial histologies (8000-8799)

b. Diffuse bilateral lung nodules

c. Bilateral retinoblastomas

d. Bilateral Wilms tumors 

e. Both breasts when inflammatory carcinoma is bilateral at diagnosis

f. Bilateral involvement at time of diagnosis and lateral origin unknown for a site listed in the table Sites for Which Laterality Must Be Recorded

Example: Both arms are involved with Kaposi sarcoma and no other sites are involved. It is not known on which arm the Kaposi sarcoma originated. Assign Laterality code 4.

Skin of upper limb and shoulder is listed as a paired organ in the table Sites for Which Laterality Must Be Recorded.

5.  Assign code 5 when the tumor originates in the midline of a site listed in 5.a

a. C700, C710-C714, C722-C725, C443, C444, C445

i. Do not assign code 5 to sites not listed in 5.a

Example 1: Patient has an excision of a melanoma located just above the umbilicus (C445, laterality code 5).

Example 2: Patient has a midline meningioma of the cerebral meninges (C700, laterality code 5).

6.  Assign code 9 when:

a. The neoplasm originated in a paired site and

i. Laterality is unknown, AND

ii. There is no statement that only one side of the paired organ is involved

Example 1: Admitting history says patient was diagnosed with lung cancer based on positive sputum cytology. Patient is treated for painful bony metastases. There is no information about laterality in the diagnosis of this lung cancer.

Example 2: Widely metastatic ovarian carcinoma surgically debulked. Ovaries could not be identified in the specimen.

b. Laterality is unknown for a death certificate only (DCO) case with primary site code listed in the table below (Sites for Which Laterality Codes Must Be Recorded)

7.  Document the laterality in a text field

Sites for Which Laterality Codes Must Be Recorded

Starting with cases diagnosed January 1, 2004 and later, laterality is coded for select invasive, benign, and borderline primary intracranial and CNS tumors.

A laterality code other than 0 must be assigned for the sites listed in the table below. There is an effective date for assigning laterality for some of the sites. If the site is not listed on the table, code 0 may be assigned for laterality.

Laterality may be coded for sites other than those required below. For example: Code 2 may be assigned for a tumor originating in the left lobe of thyroid.

Note: Laterality will be automatically coded to 0 in SEER*DMS for sites not listed in the table below.