Clinicopathologic features, treatment, and prognosis of postirradiation osteosarcoma in patients with nasopharyngeal cancer.

OBJECTIVES

Postirradiation osteosarcoma (PIOS) arising after radiation of nasopharyngeal cancer (NPC) is rare and seldom reported. In this article, we report its clinicopathologic features, outcome, and prognostic factors.

STUDY

DESIGN

Retrospective cohort study.

METHODS

Fifteen patients with NPC were determined to have PIOS after reviewing 426 patients with osteogenic sarcomas. Their clinical records, image and pathologic slides, and follow-up data after treatment were collected to perform analysis.

RESULTS

The incidence rate of PIOS in NPC was approximately 0.037% (15/40,719), which occupied approximately 3.5% (15/426) among all kinds of osteogenic sarcomas. The latent time of PIOS after irradiation for NPC ranged from 4 to 27 years, with a mean of 13.3 years. The location where PIOS arose included 33.3% (5/15) from maxilla, 46.7% (7/15) from mandible, and 20% (3/15) from a mixture of nasal cavity and paranasal sinuses. Radiologically, soft tissue mass, bone destruction, and tumor new bone formation were the main characteristics. Pathologic subtypes included 53.3% (8/15) of fibroblastic osteosarcoma, 33.3% (5/15) of chondroblastic osteosarcoma, and 13.3% (2/15) of mixed type osteosarcoma. Of 15 patients with PIOS, 12 patients were treated with curative intent, and the remaining 3 patients with palliative intent. For 12 patients who had undertaken ablative surgery, 1 patient had residual tumor, and 6 patients had tumor recurrence. The survival time after treatment for all patients ranged from 7 to 41 months, with a mean of 18 months. Kaplan-Meier estimates of 1 year and 2 year survival rates were 60% and 24%, respectively. Statistical analysis showed that sex and tumor bone formation are significant prognostic factors.

CONCLUSIONS

PIOS in NPC is a highly malignant disease with poorer prognosis than in other sites. Surgery combined with pre- and postoperative chemotherapy might be an effective way to improve survival.