ROS1

ROS1 is a gene that makes a protein called a receptor tyrosine kinase, which helps control how cells grow and divide. In some cancers, most often a small subset of non-small cell lung cancers, the ROS1 gene becomes abnormally fused to another gene, producing a faulty protein that drives tumor growth. When this fusion is present, specific targeted drugs can often shrink the cancer effectively.

Origin

ROS1 was identified in the 1980s as a human gene related to v-ros, a cancer-causing gene first found in an avian (chicken) sarcoma virus called UR2. The name reflects this viral ancestry. Its role as a therapeutic target in lung cancer was established after ROS1 gene fusions were described in non-small cell lung cancer around 2007.

Significance in Asbestos Context

If you have been diagnosed with lung cancer after asbestos exposure, your tumor may be sent for molecular testing that looks for ROS1 fusions along with EGFR, ALK, KRAS, and other markers. A positive ROS1 result does not change the fact that asbestos contributed to your cancer. Asbestos can cause lung cancer regardless of the tumor's molecular profile, but it opens the door to targeted oral drugs such as crizotinib, entrectinib, or repotrectinib, which often work better and are easier to tolerate than standard chemotherapy. ROS1 status is documented in pathology reports that become part of both your medical record and any legal claim, where it helps establish your diagnosis, treatment course, and prognosis.

Example Sentence

"After her mesothelioma was ruled out and she was diagnosed with asbestos-related lung adenocarcinoma, her oncologist ordered molecular testing that revealed a ROS1 fusion, making her eligible for targeted therapy."

Related Terms

Gene Fusion, Tyrosine Kinase Inhibitor, Non-Small Cell Lung Cancer, Targeted Therapy, Molecular Testing, EGFR

Notes

• If you are diagnosed with non-small cell lung cancer, ask your oncologist whether comprehensive molecular or biomarker testing, including ROS1, has been performed on your tumor tissue.
• Request copies of all pathology and molecular testing reports; these documents matter both for treatment decisions and for documenting your diagnosis in a legal claim.
• ROS1 fusions are uncommon (roughly 1–2% of non-small cell lung cancers) and are found more often in non-smokers or light smokers with adenocarcinoma, a profile that frequently fits asbestos-exposed patients.
• A ROS1-positive result does not weaken an asbestos causation claim; asbestos remains a recognized cause of lung cancer across molecular subtypes, and your legal team can address this with a qualified medical expert.