KRAS G12C

KRAS G12C is a specific mutation in the KRAS gene in which the building block glycine is swapped for cysteine at position 12 of the KRAS protein. This change keeps the protein stuck in an "on" position, driving uncontrolled cell growth. It is found in roughly 12–13% of non-small cell lung cancers (especially adenocarcinoma) and is one of the few KRAS mutations that can now be targeted with specific drugs.

Origin

KRAS stands for Kirsten Rat Sarcoma viral oncogene homolog, named after the virus studied by Werner Kirsten in the 1960s. The "G12C" notation follows standard mutation nomenclature: the 12th amino acid (Glycine, G) is replaced by Cysteine (C). For decades KRAS was considered "undruggable" until the cysteine residue in G12C provided a chemical handle for the first targeted inhibitors, approved beginning in 2021.

Significance in Asbestos Context

For patients with lung cancer and an asbestos exposure history, knowing whether the tumor carries KRAS G12C can directly change treatment. Two FDA-approved drugs, sotorasib (Lumakras) and adagrasib (Krazati), specifically target this mutation and are options after initial chemotherapy or immunotherapy. KRAS G12C is most commonly seen in smokers, so a patient with combined asbestos and tobacco exposure may be more likely to carry it; the mutation itself does not prove or disprove asbestos causation, because asbestos can contribute to lung cancer regardless of the tumor's specific mutation profile (see the Helsinki Criteria). For your case, the pathology report identifying KRAS G12C documents the molecular nature of your cancer but does not undermine an asbestos-causation claim.

Example Sentence

After her biopsy, the oncologist ordered molecular testing and found a KRAS G12C mutation, making her eligible for sotorasib as a second-line therapy.

Related Terms

Non-Small Cell Lung Cancer, Adenocarcinoma, Targeted Therapy, Molecular Profiling, Oncogene, Helsinki Criteria

Notes

• Ask your oncologist whether your tumor has had comprehensive molecular (biomarker) testing. KRAS G12C testing is standard for non-small cell lung cancer and should be done before starting second-line treatment.
• Request a copy of the molecular pathology report and keep it with your medical records; it documents the tumor type and may be referenced by both your treatment team and your legal team.
• If KRAS G12C is found, ask specifically about sotorasib (Lumakras), adagrasib (Krazati), and any active clinical trials, and whether prior immunotherapy affects the timing of these drugs.
• The presence of a KRAS mutation does not exclude asbestos as a cause of your lung cancer; preserve your occupational and exposure history regardless of the molecular findings.