Osteosarcoma, though rare, remains the most common malignant bone tumor in children and adolescents, typically arising in the long bones of the arms or legs during growth spurts. Despite advances in cancer care, survival rates have remained largely unchanged for over four decades, particularly for patients whose cancer spreads beyond the original site.
Now, researchers at Cleveland Clinic Children’s and collaborating institutions have identified a previously unrecognized genetic risk factor for this aggressive disease. In a study published in the Journal of Clinical Oncology, the team pinpointed SMARCAL1, a gene involved in maintaining genome stability, as a potential driver of inherited osteosarcoma susceptibility.
“These findings not only deepen our biological understanding of osteosarcoma, but allows for earlier detection, and the potential for developing targeted treatments for this rare but aggressive cancer,” said Richa Sharma, MD, pediatric hematologist-oncologist and senior author of the study.
DNA repair and cancer risk
The team analyzed genomic data from nearly 6,000 children with cancer and compared them to 14,000 adults without cancer, focusing on 189 genes involved in various DNA repair pathways—the cellular systems that correct damage caused by replication errors, radiation, or environmental exposure.
Defects in these pathways are a known source of cancer risk: mutations in genes like TP53 (Li-Fraumeni syndrome) or RB1 (retinoblastoma) have long been linked to pediatric malignancies. However, most osteosarcoma cases have lacked clear genetic explanations.
This large-scale analysis revealed that 2.6% of children with osteosarcoma carried inherited mutations in SMARCAL1, a gene that helps resolve DNA replication stress and prevent harmful chromosomal rearrangements.
When SMARCAL1 function is impaired, cells accumulate DNA damage faster than they can repair it—potentially triggering the uncontrolled growth characteristic of cancer.
SMARCAL1: From rare disease to cancer link
SMARCAL1 has previously been associated with a rare genetic disorder called Schimke immuno-osseous dysplasia (SIOD), which affects bone growth and immune function. The new findings suggest that milder inherited variants of the same gene, though not causing SIOD, may still disrupt DNA stability enough to increase cancer risk.
While osteosarcoma remains uncommon—affecting fewer than 1,000 people annually in the U.S.—genetic insights like this one could help identify children at risk before symptoms appear.
Screening for germline mutations in SMARCAL1 and other DNA repair genes could one day become part of personalized cancer risk assessments, particularly in families with multiple cancer cases or unusual tumor patterns.
Moreover, this discovery may inform the development of precision therapies that exploit DNA repair weaknesses. In other cancers, such as BRCA-mutant breast cancer, drugs called PARP inhibitors selectively target tumor cells with defective repair machinery while sparing healthy tissue—a similar strategy might one day apply to osteosarcoma.
A step toward closing a decades-long gap
Despite progress in chemotherapy and surgery, outcomes for metastatic or relapsed osteosarcoma remain poor, with only about 20% of children surviving when the cancer spreads. The discovery of a genetic contributor to osteosarcoma risk represents a crucial step toward changing that trajectory.
“With little progress in osteosarcoma treatment over the past 40 years, this discovery could pave the way for significant advancements in care for patients with this condition.” Sharma concluded in a press statement.
