Coding CS Tumor Size
Important
These modules are archived and should only be referenced for historical purposes.
This field records the largest dimension, or the diameter of the primary tumor, and is always recorded in millimeters. To convert centimeters to millimeters, multiply the dimension by 10.
The table below shows the allowable values for the 3-digit Tumor Size field in Collaborative Staging, using colon as an example.
| Code | Description |
|---|---|
| 000 | Indicates no mass or no tumor found. |
| 001-998 | Exact size in millimeters. |
| 989 | 989 millimeters or larger. |
| 990 | Microscopic focus or foci only; no size of focus is given. |
| 991 | Described as less than 1 cm. |
| 992 | Described as less than 2 cm. |
| 993 | Described as less than 3 cm. |
| 994 | Described as less than 4 cm. |
| 995 | Described as less than 5 cm. |
| Code | Description |
|---|---|
| 998 | Familial polyposis (M8220/8221) |
| 999 | Unknown; size not stated; not stated in patient record. |
Click here to see the General Rules for Coding Tumor Size.
Suggested Citation
SEER Training Modules: Coding CS Tumor Size. U.S. National Institutes of Health, National Cancer Institute. Cited 26 December 2025. Available from: https://training.seer.cancer.gov.