Author: Tokugawa in Tokyo content team (Buntou Co., Ltd.). Medical review: pending professional review.

Why Japanese Specialists Often Ask for Your Previous Radiotherapy Plan Before a Second Opinion

Published: 2026-10-14 · Sources checked: 2026-10-14 · Medical review: pending professional review.

Short answer: “I already had radiotherapy” is not enough information to understand where radiation was delivered, how the dose was distributed, or how much nearby normal tissue may have received. If recurrent head and neck cancer is being reassessed for another local treatment—especially possible reirradiation—the previous treatment plan can help specialists estimate overlap with the new tumor, review earlier organ-at-risk exposure, and understand how reliable a cumulative dose assessment can be.

This does not mean that having the old plan makes a patient eligible for reirradiation. It is one important part of a broader clinical review.

Why the total dose alone is not enough

Radiotherapy is not delivered uniformly across the entire head and neck. A treatment plan shapes the dose around the tumor while trying to limit exposure to surrounding structures. Two patients who both received a similar prescription dose can therefore have very different dose distributions.

Recent international reirradiation consensus work emphasizes the importance of cumulative dose evaluation, documentation, image registration, anatomical change and uncertainty. Depending on what historical data are available, a team may be able to perform a more detailed three-dimensional dose accumulation—or may need to use a simpler, less precise approach and clearly acknowledge the uncertainty.

What specialists may want to learn from the old plan

1. How much the recurrence overlaps the previously irradiated region

A recurrence inside a previously high-dose region is not the same situation as a recurrence near the edge of the earlier field. Current CT or MRI images alone cannot fully reconstruct the historical dose distribution.

2. Which organs at risk were previously exposed

In the head and neck, structures such as the spinal cord, brainstem, carotid arteries, mandible, salivary glands and swallowing-related tissues may be relevant. Reirradiation assessment is therefore not based on one “total dose” number. The team needs to understand prior and potential new exposure to different structures, together with the uncertainty of those estimates.

3. Whether the historical plan can be aligned with today’s anatomy

Anatomy can change after surgery, reconstruction, weight change, tumor progression and time. International guidance describes methods such as rigid or deformable image registration for dose mapping when appropriate, while also stressing quality control and uncertainty. Having the prior planning CT and radiotherapy dose files can make this reconstruction more informative.

4. What the statement “you cannot have radiotherapy again” was based on

A second opinion is not intended to prove the original team wrong. The goal is to break a broad statement into reviewable questions: Where was the prior radiation delivered? What normal tissues were exposed? Where is the recurrence now? How long has it been since treatment? What treatment-related injury is already present? What are the patient’s current goals and overall condition?

The second opinion may still conclude that reirradiation is not advisable. Confirming that conclusion with better information can itself be valuable.

Which previous radiotherapy records are most useful?

Requirements differ by hospital. If older records cannot be retrieved, do not recreate or guess the missing dose information. Instead, list what is available and what is missing so the receiving team can judge how much uncertainty remains.

Does the old radiotherapy plan decide whether reirradiation is possible?

No. The 2026 international expert consensus on recurrent head and neck cancer reirradiation addresses multiple domains, including patient selection, imaging, target definition, treatment planning, dose accumulation and toxicity management. Prior radiotherapy data are a key input, but not an eligibility certificate. Resectability, disease extent, distant metastases, previous toxicity, general condition and the patient’s treatment goals also matter.

Treatment status in Japan and the evidence used here

The sources are Japanese treatment-planning guidance and international expert consensus documents, not a new regulatory approval or a clinical trial demonstrating a treatment benefit. The head and neck consensus concerns recurrent or second primary squamous cell carcinoma and should not be generalized to every head and neck tumor. Availability and suitability of reirradiation at a particular Japanese institution require individual confirmation.

FAQ

I only have a radiotherapy summary, not DICOM-RT. Can I still request a second opinion?

Yes, you can start with the records you have. However, the level of detail possible in a cumulative dose assessment depends on the quality and completeness of the historical information.

My old hospital says the detailed plan is no longer available. What should I do?

Ask what can still be retrieved—for example a treatment summary, planning screenshots, dose records or old imaging. Do not reconstruct missing numbers yourself. The missing information should be stated explicitly.

If I previously received a high radiotherapy dose, does that automatically rule out further radiation?

No single prescription-dose number can answer that question on its own. The decision requires specialist assessment of prior dose distribution, current anatomy, disease location, treatment interval and other clinical factors.

If specialists review the old plan, will they always find another local treatment option?

No. A second opinion may identify a reason to investigate further, or it may confirm that the current recommendation is the safer course. It does not guarantee a new treatment.

Practical next step

Before requesting a Japan expert second opinion, separate your previous radiotherapy records into one folder: treatment summary, planning CT, DICOM-RT, dose information and treatment dates. Then review these alongside pathology, current imaging and a chronological treatment history. The final submission format should follow the receiving hospital’s requirements.

Japan Expert Second Opinion – record preparation guide

Risk notice

This article is for medical education and record preparation only. It does not determine eligibility for reirradiation, recommend a radiation dose, or provide an individual treatment plan. Reirradiation can involve serious toxicity risks, and cumulative dose estimates may contain substantial uncertainty. Individual decisions require review by an experienced radiation oncology and multidisciplinary team.

Primary sources

  1. Japanese Society for Radiation Oncology (JASTRO), recognized guidelines including the 2024 Radiotherapy Treatment Planning Guidelines (released 2024-11-22) and 2026 IMRT guidance (released 2026-06-26); Japanese clinical practice guidance: https://www.jastro.or.jp/medicalpersonnel/guideline/jastro/
  2. Biau J, et al. Reirradiation for recurrent head and neck squamous cell carcinoma: international expert consensus recommendations. Lancet Oncology. 2026 Jul; international expert consensus for recurrent or second primary head and neck squamous cell carcinoma, not an efficacy trial. PubMed: https://pubmed.ncbi.nlm.nih.gov/42372755/
  3. Paradis KC, et al. ReCOG consensus on standards for dose evaluation and reporting in patients with multiple courses of radiation therapy. Lancet Oncology. 2026 Feb; international expert consensus for multiple courses of radiation therapy, not an efficacy trial. PubMed: https://pubmed.ncbi.nlm.nih.gov/41643699/
  4. ESTRO Reirradiation Focus Group. Cumulative dose evaluation in clinical reirradiation—Consensus guidance on technical considerations. Radiotherapy and Oncology. 2026 Jan (online 2025-11-27); technical expert consensus, not an efficacy trial. PubMed: https://pubmed.ncbi.nlm.nih.gov/41318002/

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