The Latest Breast Cancer Treatment: What's Different in 2026?

"The latest treatment" for breast cancer isn't a single new drug—it's a precision treatment pathway that combines surgical sequencing and medication based on subtype test results such as hormone receptor status and HER2. The current standard is to combine neoadjuvant chemotherapy, targeted therapy, immunotherapy, and hormone therapy differently depending on the subtype.

Key Takeaways

• Breast cancer subtypes are determined by four tests—ER, PR, HER2, and Ki-67—and this subtype determines the sequence of treatment and which drugs are used.
• Korea's 5-year relative survival rate for breast cancer is 94.7% (National Cancer Registration Statistics, 2019–2023), while the US SEER 5-year relative survival rate for female breast cancer is 91.9% (2016–2022). Both figures are national-level statistics and are not predictions for any individual patient's outcome.
• For HER2-positive or triple-negative breast cancer, it has become standard to give chemotherapy (combined with targeted therapy for HER2-positive cases) before surgery rather than operating first.
• For stage 4 (metastatic) breast cancer, treatment is combined by subtype: hormone therapy plus CDK4/6 inhibitors; anti-HER2 targeted therapy plus antibody-drug conjugates; or chemotherapy plus immunotherapy or antibody-drug conjugates.
• Sentinel lymph node biopsy reduces unnecessary lymph node removal, and immediate reconstruction at the same time as total mastectomy is possible in many cases.

Why Does 'Subtype' Determine Treatment?

• Breast cancer is viewed not as a single disease but as several diseases with different courses and treatments depending on subtype. At the biopsy stage, ER, PR, HER2, and Ki-67 are checked together, and this serves as the starting point for the treatment plan.
• If hormone receptors are positive, hormone therapy continues long-term; if HER2 is positive, anti-HER2 targeted therapy is used both around the time of surgery and at the metastatic stage. Triple-negative (all three negative) breast cancer centers on chemotherapy, with immunotherapy or antibody-drug conjugates added if conditions are met.
• So even at the same stage, an individual's own subtype matters more for their personal course than the overall survival rate figure for the stage as a whole.

What Is the Recently Established Standard of 'Neoadjuvant Chemotherapy'?

• For HER2-positive or triple-negative breast cancer, it is now standard to give chemotherapy first (combined with targeted therapy if HER2-positive) rather than surgery, in order to shrink the tumor and directly confirm whether the drug is actually working.
• This increases the likelihood of breast-conserving surgery and allows the follow-up treatment plan to be determined based on how much tumor remains after surgery, improving treatment precision.
• The process proceeds as follows: Step 1: biopsy and subtype testing. Step 2: staging workup with imaging (breast MRI, axillary ultrasound, and CT, bone scan, or PET-CT as needed). Step 3: neoadjuvant chemotherapy (or targeted therapy). Step 4: surgery (breast-conserving or total mastectomy, with reconstruction if needed). Step 5: postoperative adjuvant treatment (combination of chemotherapy, targeted therapy, hormone therapy, and radiation). Step 6: regular follow-up observation.

What Treatment Combinations Are Used for Metastatic (Stage 4) Breast Cancer?

• For stage 4, the goal shifts from cure to controlling the tumor for as long and as comfortably as possible. If hormone receptors are positive, treatment often starts with hormone therapy combined with a CDK4/6 inhibitor.
• If HER2 is positive, anti-HER2 targeted therapy is combined with an antibody-drug conjugate; if triple-negative, chemotherapy is combined with immunotherapy or an antibody-drug conjugate. If there is bone metastasis, bone-protecting medication is added.
• Targeted therapies work by aiming at specific molecules that are abundant or mutated in cancer cells, resulting in relatively less impact on normal cells. When resistance develops, it is common practice to re-test and move on to the next drug.

Do Newer Treatments Have Fewer Side Effects?

• It's more accurate to say they're 'different' rather than 'fewer.' Targeted therapies tend to cause relatively less hair loss and severe nausea, but diarrhea and liver function problems are the most common side effects, and depending on the drug, rash, high blood pressure, and nail changes can also occur.
• Anti-HER2 targeted therapy has been reported to cause cardiac toxicity, so regular heart function monitoring is needed. Immunotherapy can cause immune-related inflammation in the thyroid, lungs, intestines, liver, skin, and other organs, so attention to new symptoms is needed both during and after treatment.
• Hormone therapy causes menopause-like symptoms (hot flashes, joint stiffness, vaginal dryness) and decreased bone density, so bone density tests are managed alongside treatment over several years.

FAQ — Can Reconstruction Be Done on the Same Day as Surgery?

Immediate reconstruction at the same time as total mastectomy is possible in many cases. Whether an implant or autologous tissue is more suitable is determined by body type, radiation therapy plans, and recovery-time preferences, and in some cases the timing of reconstruction is adjusted if radiation therapy is planned.

FAQ — Can HER2 Test Results from My Home Country Be Used As-Is?

In most cases, they can be used as reference material. However, since HER2 results can vary depending on the testing method and interpretation criteria, and it is a key indicator that determines drug selection, re-confirmation using the paraffin block is sometimes recommended when the score is borderline.

Sources and Notes

• This article was written based on general explanations from National Cancer Registration Statistics 2019–2023 (National Cancer Center Korea), SEER 2016–2022, the National Cancer Information Center, and NCCN patient guidelines.
• This content is provided for general medical information purposes only, and diagnosis, treatment methods, and outcomes may vary depending on individual condition. Accurate diagnosis and treatment should always be determined through consultation with medical professionals.