# Osteosarcoma Arising as a Secondary Malignancy following Treatment for Hematologic Cancer: A Report of 33 Affected Patients from the Cooperative Osteosarcoma Study Group (COSS)

## TL;DR

This study examines 33 patients who developed osteosarcoma after being treated for hematologic cancer, finding that radiation therapy is a major risk factor and that some patients can survive with proper treatment.

## Contribution

The study identifies radiation therapy as a key risk factor for secondary osteosarcoma and provides survival data for patients with this rare condition.

## Key findings

- Radiation therapy for hematologic cancer is a major risk factor for later osteosarcoma.
- Osteosarcoma typically develops about a decade after hematologic cancer treatment.
- Selected patients can achieve long-term survival with appropriate treatment.

## Abstract

Osteosarcoma may arise as a secondary malignant neoplasm following a previous hematologic malignancy. We set out to identify potential risk factors, treatments given, and outcomes. Thirty-three eligible patients were identified in the database of our Cooperative Osteosarcoma Study Group. On average, the osteosarcomas developed close to a decade after the hematologic cancer, when patients were mostly still pediatric. Radiotherapy administered to battle the hematologic cancer seemed to be a major risk factor, and genetic tumor predispositions were identified in a subset of patients. Modern interdisciplinary osteosarcoma treatment, with adaptations for previous therapies, seemed feasible. The prognosis of the affected patients was inferior to patients without preceding cancers, but was far from being universally fatal. Additional malignancies complicated the course in a subset of patients. These results will help us to interpret the findings and to guide treatment in future patients.

Purpose: Osteosarcoma may arise as a secondary cancer following leukemias or lymphomas. We intended to increase the knowledge about such rare events. Patients and methods: We searched the Cooperative Osteosarcoma Study Group’s database for individuals who developed their osteosarcoma following a previous hematological malignancy. The presentation and treatment of both malignancies was investigated, and additional neoplasms were noted. Outcomes after osteosarcoma were analyzed and potential prognostic factors were searched for. Results: A total of 33 eligible patients were identified (male: 23, female: 10; median age: 12.9 years at diagnosis of hematological cancer; 20 lymphomas, 13 leukemias). A cancer predisposition syndrome was evident in one patient only. The hematological cancers had been treated by radiotherapy in 28 (1 unknown) and chemotherapy in 26 cases, including bone-marrow transplantation in 9. The secondary bone sarcomas (high-grade central 27, periosteal 2, extra-osseous 2, undifferentiated pleomorphic sarcoma of bone 2) arose after a median lag-time of 9.4 years, when patients were a median of 19.1 years old. Tumors were considered radiation-related in 26 cases (1 unknown). Osteosarcoma-sites were in the extremities (19), trunk (12), or head and neck (2). Metastases at diagnosis affected eight patients. Information on osteosarcoma therapy was available for 31 cases. All of these received chemotherapy. Local therapy involved surgery in 27 patients, with a good response reported for 9/18 eligible patients. Local radiotherapy was given to three patients. The median follow-up was 3.9 (0.3–12.0) years after bone tumor diagnosis. During this period, 21 patients had developed events as defined, and 15 had died, resulting in 5-year event-free and overall survival rates of 40% (standard error: 9%) and 56% (10%), respectively. There were multiple instances of additional neoplasms. Several factors were found to be of prognostic value (p < 0.05) for event-free (osteosarcoma site in the extremities) or overall (achievement of a surgical osteosarcoma-remission, receiving chemotherapy for the hematologic malignancy) survival. Conclusions: We were able to prove radiation therapy for hematological malignancies to be the predominant risk factor for later osteosarcomas. A resulting overrepresentation of axial and a tendency towards additional neoplasms affects prognosis. Still, selected patients may become long-term survivors with appropriate therapies, which is an argument against therapeutic negligence.