Targeted Therapy for Cancer: A Patient Guide

Overview

Targeted therapy is a type of precision cancer treatment designed to attack specific genes, proteins, or other molecules that help cancer cells grow, divide, and spread. Unlike traditional chemotherapy, which kills all fast-growing cells in the body (including healthy ones), targeted therapy is designed to focus only on cancer cells, which often leads to fewer and less severe side effects for many patients. It is used to treat many types of cancer, including breast, lung, colorectal, skin, and blood cancers, and is often combined with other treatments like surgery, chemotherapy, or immunotherapy.

Signs & Symptoms

Side effects of targeted therapy vary widely depending on the specific drug you receive and your individual health. Common mild to moderate side effects include:

• Fatigue or mild weakness
• Skin rashes, dryness, or changes in nail color
• Diarrhea or nausea
• Mouth sores
• Joint or muscle pain

Causes & Risk Factors

Targeted therapy is only recommended if your cancer has specific genetic or molecular changes that the drug is designed to target. Factors that may increase your risk of experiencing more severe side effects include pre-existing heart, liver, or kidney conditions, taking other medications that interact with the targeted therapy, and a history of severe allergic reactions to medications. Your care team will review your full medical history and run tests to confirm you are a good candidate for treatment before you start.

Diagnosis

Before starting targeted therapy, your doctor will order molecular or genomic testing on a sample of your tumor (from a biopsy or previous surgery) to look for specific biomarkers (such as genetic mutations or proteins) that the targeted drug is designed to attack. Common tests include next-generation sequencing (NGS, a test that looks for many genetic changes at once), fluorescence in situ hybridization (FISH, a test that looks for specific genetic changes in cancer cells), and immunohistochemistry (IHC, a test that checks for specific proteins in cancer cells). These tests confirm that your cancer is likely to respond to the targeted therapy, so you do not receive treatment that will not work for your specific cancer type.

Treatment & Management

Targeted therapy is usually taken as an oral pill or capsule you swallow at home, though some types are given through an intravenous (IV) infusion at a clinic or hospital. Your treatment schedule will depend on your cancer type, the specific drug you are prescribed, and how your body responds to treatment. Many people take targeted therapy daily for several months or years, as long as the treatment is working and side effects are manageable. Your care team will monitor you closely during treatment with regular check-ins, blood tests, and imaging scans (like CT or MRI) to check if the cancer is shrinking or staying stable, and to watch for side effects. If side effects become severe, your doctor may lower your dose, pause treatment temporarily, or switch you to a different targeted therapy.

Living With It

Many people are able to live relatively normal lives while taking targeted therapy, as side effects are often less severe than chemotherapy. However, there are steps you can take to manage side effects and maintain your quality of life during treatment:

• Keep a symptom journal to track side effects, their severity, and what makes them better or worse. Share this log with your care team at every appointment.
• Use gentle, fragrance-free skincare products if you have a rash, and avoid sun exposure, which can worsen skin side effects.
• Eat small, frequent bland meals if you have nausea or digestive issues, and stay hydrated with water or electrolyte drinks.
• Stay active with light exercise like walking or stretching if you feel up to it, as this can reduce fatigue and improve your mood.
• Connect with a cancer support group or mental health professional if you are feeling anxious or overwhelmed about your treatment.