What Is a "Second Opinion" in Oncology? (2026 Update)

A second opinion is the process of having a diagnosis or treatment plan you've already received reviewed again by a different medical team. At the diagnosis stage, asking "Can you help me get another doctor's opinion?" is itself one of the recommended questions.

Key Takeaways

• A second opinion is a process in which a different medical team re-examines whether a treatment plan is appropriate, based on staging, tissue type, and biomarker results.
• The U.S. National Cancer Institute (NCI) lists 'Can you help me get another doctor's opinion?' as one of its recommended questions during the diagnosis stage.
• Staging is determined by combining imaging, biopsy, and blood tests, with the TNM system (tumor size T, lymph nodes N, metastasis M) being the most widely used.
• When seeking a second opinion from abroad, you need the pathology report, original imaging (CT/MRI DICOM files), tissue slides or blocks, and a treatment summary that includes medication history.
• Remote review (pre-arrival review) is completed within 5 business days from the date all records are received, and the KRW 1,000,000 (about US$730) fee is deducted from treatment costs if you proceed with treatment.

When Is a Second Opinion Needed?

• Biomarker testing isn't necessary for every patient, but it's commonly recommended for metastatic or recurrent cancers, and is routinely performed for certain cancers such as non-small cell lung cancer, breast cancer, and colorectal cancer.
• Targeted therapies only work for patients with specific genetic or protein abnormalities—such as EGFR mutations, ALK rearrangements, or HER2 abnormalities—so treatment direction can change entirely depending on test results. In such cases, confirmation from another medical team can be helpful.
• If anything about your test results or treatment plan is unclear, asking again before treatment begins is a natural right, and this is the starting point for seeking a second opinion.

What Records Are Needed for a Second Opinion? — Preparation Steps

1. Step 1 — Pathology report: Prepare the complete tissue type, differentiation grade, and immunohistochemistry (IHC) results.
2. Step 2 — Imaging data: Obtain CT, MRI, and other scans from multiple time points, in original DICOM format if possible. Also include the radiology reports.
3. Step 3 — Tissue slides or paraffin blocks: Bringing these allows for re-examination and additional testing.
4. Step 4 — Medication history: Compile the names, dosages, start/stop dates, and responses for all chemotherapy and targeted therapy drugs used so far.
5. Step 5 — Treatment summary: Create a summary including the diagnosis date, cancer type, surgery date, and radiation site and dose.
6. Once these records are compiled and sent for remote review, a written opinion is provided within 5 business days from the date all records are received. If any records are missing, a coordinator will contact you first, and that waiting period is not counted within the 5 business days.

FAQ — Will Treatment Change After Getting a Second Opinion?

It may change, or it may confirm the same conclusion. Staging is determined at the time of diagnosis, and even if the disease progresses afterward, the original stage does not change—progression is noted as an addition. A second opinion re-examines this staging and biomarker results to assess whether the treatment direction is appropriate, and regardless of the conclusion, the final decision is made jointly by the patient and the treating medical team.

FAQ — Can I Use Test Results Obtained in Another Country As-Is?

If the local results are recent and sufficiently comprehensive, they can be used as reference material. However, biomarkers such as HER2 can yield different results depending on the testing method and interpretation criteria, and since they determine drug selection, re-confirmation using tissue slides or paraffin blocks is recommended in ambiguous cases.

Sources and Notes

• This article was prepared based on the U.S. National Cancer Institute (NCI) guidance on diagnosis, staging, and questions to ask, National Cancer Information Center materials, and remote review operating standards.
• This content is intended for general medical information purposes only, and diagnostic and treatment methods and outcomes may vary depending on individual circumstances. Accurate diagnosis and treatment must be determined through consultation with your medical team.