EGFR — What It Means for Cancer Treatment
EGFR is a protein on some cancer cells that tells them to grow. When EGFR has specific mutations, certain drugs can block that signal and shrink tumors. Knowing whether a tumor has an EGFR change often changes the whole treatment plan, especially for lung and colorectal cancers.
If you or someone you care for is facing a cancer diagnosis, EGFR testing is one of the tests doctors commonly order. It’s not optional for many lung cancers — it can be the reason you get a targeted pill instead of standard chemotherapy.
How EGFR testing guides treatment
Testing looks for mutations like exon 19 deletions and L858R. Those two predict a good response to first- and second-generation EGFR inhibitors. If a cancer develops the T790M resistance mutation, a third-generation drug can work when earlier drugs stop working.
Testing methods include tissue biopsy and liquid biopsy (blood test). Tissue biopsy is the safest bet for accuracy, but liquid biopsy is useful when getting tissue is hard or you want to track resistance over time. Labs use PCR or NGS panels; NGS gives broader information if you want to check for multiple gene changes at once.
Ask your doctor which test they’re ordering, how long results will take, and whether the lab will look for resistance mutations if the cancer progresses.
Common EGFR drugs and what to expect
Several EGFR-targeted drugs are widely used. Erlotinib and gefitinib were early options. Afatinib and dacomitinib are next, and osimertinib is a newer drug that works against many resistant tumors and reaches the brain better.
For colorectal cancer, EGFR-targeting antibodies like cetuximab and panitumumab can help — but only when specific RAS genes are normal. That’s why molecular testing matters across cancers, not just in lung cancer.
Side effects are common but manageable. Skin rash, dry skin, diarrhea, and mouth sores are typical with EGFR drugs. A rash often means the drug is working, but it can be uncomfortable. Your care team can prescribe creams, antibiotics, or dose changes to help.
Resistance happens. Tumors adapt through new mutations or bypass pathways. When that occurs, doctors may switch drugs, add other targeted agents, use chemotherapy, or consider clinical trials for newer combinations.
Practical tips: get a clear copy of your molecular report, save it for future treatment decisions, and consider a second opinion if tests are incomplete. If travel is needed for a specialist, bring both pathology slides and the molecular report or ensure the lab shares results electronically.
Knowing EGFR status gives you options. It turns a one-size-fits-all approach into a more personal plan. Ask direct questions, keep copies of results, and talk to your team about side effect management and clinical trial possibilities.
