Data Last Updated: Dec. 17, 2025

Percent Necrosis Post Neoadjuvant

Description

Percent Necrosis Post Neoadjuvant is a prognostic factor for bone sarcomas. For osteosarcoma and Ewing’s sarcoma/PNET, response to neoadjuvant chemotherapy is a prognostic factor. Patients with more than 90% tumor necrosis have a more favorable prognosis than those with less response. The CAP protocol for bone tumor resection provides the pathologist with specific instructions for determining the percentage of tumor necrosis. A separate method (system of Picci) may describe response to treatment in grades: grade I (macroscopic viable tumor), grade II (microscopic viable tumor), or grade III (no viable tumor). Do not code the Picci grade system in this data item.

Rationale

Percent Necrosis Post Neoadjuvant is a Registry Data Collection Variable for AJCC. It was previously collected as Bone, CS SSF #3.

Additional Info

**Source documents:** pathology report **Other names include** Histologic treatment response, therapy response, chemotherapy effect **For further information**, refer to the **Bone** cancer protocol published by the College of American Pathologists for the AJCC Staging System *Bone*.

Notes

**Note:** **Physician Statement** * Physician statement of microscopically confirmed Percent Necrosis Post Neoadjuvant Chemotherapy can be used to code this data item if no other documentation is available.

Coding Guidelines

**1)** Record the highest percentage value of the tumor necrosis post neo-adjuvant therapy as stated by the pathologist or in the pathology report. * Code the value of the tumor necrosis to the nearest tenth of a percent **2)** **Codes 001.0-100.0**. Record the percentage value of tumor necrosis post neo-adjuvant chemotherapy as stated by the pathologist in the pathology report **3)** **Code XXX.9** when * Surgical resection of the primary site is the initial therapy; therefore, no neoadjuvant therapy was performed * Surgical resection of the primary site after neoadjuvant therapy is performed and there is no mention of percent necrosis
Code Description
0.0 Tumor necrosis not identified/not present
0.1-100.0 0.1 - 100.0 percent tumor necrosis
(Percentage of tumor necrosis to nearest tenth of a percent)
XXX.2 Tumor necrosis present, percent not stated
XXX.8 Not applicable: Information not collected for this case
If this item is required by your standard setter, use of code XXX.8 will result in an edit error.
XXX.9 Not documented in medical record
No histologic examined of primary site
No neoadjuvant therapy
No surgical resection of primary site is performed