Nomogram for Chondrosarcoma
軟骨肉腫のノモグラム

According to the WHO 2020 classification, chondrosarcoma is a group of heterogeneous tumors that share the common characteristic of producing hyaline cartilage matrix by neoplastic cells. Most are conventional chondrosarcomas (approximately 80%), and are histologically classified as grades I to III. Dedifferentiated chondrosarcoma is a highly malignant variant in which a low-grade chondroid tumor coexists with a high-grade spindle-cell sarcoma. The most common age of onset is in the 50s, and the most common sites are the pelvis and proximal femur.

Chondrosarcoma is radioresistant, and currently there is no effective chemotherapy. Therefore, surgery is the mainstay of treatment. Grade I chondrosarcoma [also called atypical cartilaginous tumor (ACT) in the case of the limbs] tends to be highly invasive locally, but the possibility of metastasis is limited. Grade I chondrosarcoma of the limbs can be treated with intralesional curettage, which provides better functional outcomes and fewer complications than en bloc resection without compromising oncological outcome. On the other hand, high-grade tumors (grades II and III, dedifferentiated) and all chondrosarcomas of the pelvis or axial skeleton must be surgically resected with wide margins.

Local recurrence, regardless of tumor grade, negatively impacts survival and patient outcomes in chondrosarcoma. These effects are more pronounced in high-grade tumors. Long-term survival is possible even after local recurrence in grade I chondrosarcoma. Local recurrence can be reduced by paying attention to the appropriateness of the surgical margin. For local recurrence of chondrosarcoma, aggressive treatment with wide resection should be pursued if there is no evidence of metastasis after re-staging.

Risk factors for local recurrence after surgery for chondrosarcoma include age, histological type, tumor site (upper extremities, lower extremities, trunk), tumor size, compartment, and surgical margin. To integrate these factors and predict local recurrence risk as a specific numerical value, we decided to create a nomogram.

Using this nomogram, the interval between postoperative X-ray examinations can be shortened, or MRI or CT scans can be added. In patients who have undergone reconstruction with a mega-prostheses and are predicted to be at high risk of local recurrence, PET/CT can be added. Early detection of local recurrence using the above methods may improve the possibility of limb-sparing surgery instead of amputation. In grade I chondrosarcoma (ACT) of the limbs, the risk of local recurrence can be predicted numerically for each surgical margin before surgery, and the surgical margin can be selected considering limb function and the risk of surgical complications.

This nomogram has been developed by Masunaga T, Tsukamoto S, Kurakami H, Honoki K, Fujii H, Kido A, and Kawamura K from Nara Medical University, Nara, Japan, and Kawai A from National Cancer Center Hospital, Tokyo, Japan, and Nakata E, Aso A, Donati DM and Errani C from IRCCS Istituto Ortopedico Rizzoli, Bologna, Italy.

The nomogram is intended solely to provide reference information based on statistics. When making actual treatment decisions, we recommend consulting with your attending physician. Our institutes shall not be liable for any disadvantages arising from the use of this nomogram. Use of this nomogram and the results of calculations are at your own risk. We encourage the user to rely on the published papers for details.