Precision Medicine in Colorectal Cancer—Choosing the Right Drug for the Right Patient

Interview with Kuo-Cheng Huang, MD, Medical Oncologist

For decades oncologists hit cancer with the same handful of drugs, hoping they would work for most patients and accepting that some would receive little benefit. Imagine lining up one hundred people and giving each exactly the same pill—you waited to see who responded and who did not. Genomics has shown why that scatter-shot approach falls short: every tumor carries its own DNA blueprint and reacts differently to treatment. Precision medicine takes those differences seriously, matching therapy to the genetic quirks of each patient’s cancer so benefit rises and side-effects shrink.

Why Genomics Matters Even More in Colorectal Cancer

Colorectal cancer remains one of Taiwan’s most common malignancies. Once it reaches stage IV or spreads to distant organs, standard chemotherapy often stalls. Genetic testing opens a new set of doors. Dr. Huang routinely orders five key assays before deciding on a drug plan:

• RAS mutation panel – The basic screen. If RAS is wild type, anti-EGFR antibodies can work; if mutated, anti-VEGF therapy is the better choice.

• BRAF mutation – A positive result adds the option of a BRAF inhibitor.

• MSI-H (high microsatellite instability) – Tumors with this signature respond well to immune-checkpoint inhibitors.

• HER2 overexpression – Fewer than 5 percent of colorectal cancers show it, but when they do, anti-HER2 agents enter the lineup.

• NTRK fusion – Extremely rare, yet when present it unlocks NTRK inhibitors.

Think of these tests as a GPS that guides the oncologist to the most powerful, least toxic weapon for each tumor.

Immunotherapy: Powerful—but Only for the Right Subset

Many patients ask, “Is immunotherapy the miracle everyone says it is?” Checkpoint inhibitors revolutionized melanoma and lung cancer, but in colorectal cancer their impact is limited to MSI-H disease. Without that mutation the success rate plummets, and Dr. Huang advises against using the drugs. Most people tolerate immunotherapy well, yet a few develop unusual autoimmune flares—skin blisters, persistent diarrhea, rising liver enzymes, or a stubborn cough. Any lingering symptom deserves a quick clinic visit to decide whether to pause or continue treatment.

Personalized Oncology Is No Longer Science Fiction

The advancement of precision medicine is more than a technological triumph; it is a blessing for patients. Oncologists no longer treat “colon cancer” as if every case were identical. They map each tumor’s genome, then craft a tailored combat plan—more effective, less punishing, and infinitely more hopeful.