Carbon ion therapy for lung cancer is becoming a new option even for stage III patients who cannot undergo surgery or concurrent chemoradiotherapy. In a national registry study pooled by four Japanese heavy ion cancer treatment centers (QST Hospital, SAGA HIMAT, Gunma University and Osaka; J-CROS-LUNG, Japanese Journal of Radiology, 2026), 55 patients with locally advanced non-small cell lung cancer treated with carbon ions alone reached a 3-year overall survival of 49.1%, and no patient had grade 4 or higher toxicity. This article summarizes the results, eligibility, the 16-fraction / 4-week schedule and the published fee for overseas patients (QST Hospital: 5.786 million yen). If you would like to know whether your own results qualify, please use our lung cancer carbon ion therapy eligibility and cost consultation.
What did the latest lung cancer carbon ion study report?
The standard treatment for locally advanced non-small cell lung cancer (stage IIB–III disease that has reached lymph nodes or grown near nearby organs) is concurrent chemoradiotherapy followed by immunotherapy maintenance. In real practice, however, many patients cannot receive all of this because of older age, heart or lung conditions, or a large tumor. This study focused on exactly those patients.
Carbon ion therapy (heavy ion therapy) uses accelerated carbon ions that stop at a set depth in the body and release most of their energy there (the Bragg peak). Little dose exits beyond the tumor, so a high dose can be given to the tumor while sparing the lungs, esophagus, trachea and heart. The principle is explained on What Is Carbon Ion Therapy?.
All seven carbon ion facilities in Japan take part in the Japan Carbon-Ion Radiation Oncology Study Group (J-CROS), which has run a prospective nationwide registry for lung cancer since May 2016. The 2026 report covers 55 patients treated with carbon ions alone between May 2016 and June 2020 because they were not candidates for surgery or concurrent chemoradiotherapy. No chemotherapy or immunotherapy was given before or after, so these are the results of carbon ion therapy itself.
How did stage III lung cancer patients do with carbon ion cancer treatment?
The median age was 73 years (49–90) and the median tumor diameter was 5.1 cm. Stages were IIB in 26, IIIA in 17 and IIIB in 12 patients; 9 patients (16%) also had interstitial pneumonia, and 16 (29%) had been judged unsuitable even for conventional X-ray radiotherapy.
| Item | Result | Note |
|---|---|---|
| 2-year overall survival | 66.0% | From start of treatment |
| 3-year overall survival | 49.1% | Median survival 35.1 months |
| 2-year progression-free survival | 37.5% | Median 15.1 months |
| Grade 4 or higher toxicity | 0 patients | No severe events reported |
| Radiation pneumonitis | Grade 2: 3 (5.5%); grade 3: 2 (3.6%) | None of 9 patients with interstitial pneumonia had grade 2+ pneumonitis |
The authors concluded that carbon ion therapy showed favorable tumor control with acceptable toxicity in these patients and may be a promising treatment option. Their discussion also notes that older trials of X-ray radiotherapy alone reported 2-year survival of 10–20%. The eras and patient groups differ, so this is not a direct comparison, but the figures are encouraging for patients in the same situation.
Safety in patients with weak lungs stands out: none of the 9 patients with interstitial pneumonia developed grade 2 or higher pneumonitis, which the authors link to the small number of mostly front-to-back beams that limit low-dose spread in the lungs. Because survival was lower in this subgroup, regular follow-up of lung condition after treatment is important. Side-effect management is covered in our carbon ion therapy side effects article.
Who is eligible for lung cancer carbon ion therapy?
QST Hospital (Chiba) divides eligibility into early-stage and locally advanced lung cancer. It treated 700 early-stage patients (1994–2017) and 141 locally advanced patients (1995–2015), and publishes a 2-year survival of 52% for locally advanced disease.
| Category | Early-stage | Locally advanced |
|---|---|---|
| Stage | Tis, T1–T4 N0 primary lung cancer (excluding T4 due to organ invasion) | Tany N1–N3 M0, or T4 N0 M0 with invasion of nearby organs |
| Other conditions | No distant metastasis | No distant metastasis, pleural or pericardial effusion; nodes limited to the chest |
| Sessions | Usually one day; about 3 weeks if a critical organ is close | 16 fractions (about 4 weeks) |
| Japanese insurance | Covered since 2024 for curative treatment of early-stage NSCLC | Depends on the form of care at each institution |
Each center's multidisciplinary team decides based on imaging and pathology. Cases where invasion makes irradiation dangerous, or where cancer has already spread to distant organs, fall outside these criteria. Lung metastases from other cancers have separate criteria; see carbon ion therapy for oligometastases.
How many sessions and weeks at a heavy ion cancer treatment center?
In the registry, most patients received 64–72 Gy (RBE) in 16 fractions under the unified policy of the Japanese Society for Radiation Oncology (JASTRO): 72 Gy in 32 patients and 64 Gy in 18. With nodal disease, the regional nodes were treated first, then the field was narrowed to the tumor for a boost.
| Step | Content | Time (per institution guidance) |
|---|---|---|
| 1. Records review | Submit records through a coordinator; physician assessment | Varies by institution |
| 2. First visit in Japan | Consultation, extra imaging, consent | A few days to about 1 week |
| 3. Preparation | Immobilization device, planning CT reflecting breathing motion | About 1–2 weeks of waiting |
| 4. Carbon ion irradiation | 16 fractions for locally advanced disease | About 4 weeks |
| 5. Follow-up at home | Regular chest CT with your local hospital | Several years |
QST Hospital says preparation starts soon after approval, leaving about 1–2 weeks of free time, and patients must be back by the day before treatment begins. Planning about 6–8 weeks from first visit to the end of treatment gives some margin. Other centers' procedures are compared in 7 carbon ion therapy hospitals in Japan.
Carbon ion cancer treatment cost for overseas patients
Patients not enrolled in Japan's public health insurance are treated as self-pay patients regardless of stage. QST Hospital publishes the following (viewed 19 October 2026; no effective date is shown on the page).
| Item | Amount (QST Hospital) | Note |
|---|---|---|
| Carbon ion therapy | 5.786 million yen (tax included) | Self-pay |
| Hospital stay, outpatient visits, tests | 33 yen per medical fee point (tax included) | Depends on care received |
| Medical coordinator fee | Not included | Set by each coordinator |
Total cost also includes extra tests, medical interpreting and about 6–8 weeks of travel and accommodation. For a hospital-by-hospital comparison see carbon ion therapy cost in Japan.
Eligibility and schedule depend on stage, lung function and previous treatment. Send us your records and we will help you prepare a consultation with a Japanese institution — Contact · +82-2-517-5117
Document checklist before a consultation
QST Hospital asks overseas patients to make first contact by email through a registered medical coordinator or travel agency; the QST physician makes the final decision after reviewing the records.
- Pathology report: histology (adenocarcinoma, squamous cell, etc.) and genetic test results if available
- Imaging CDs with reports: chest CT, PET-CT, brain MRI
- Pulmonary function tests: presence of interstitial pneumonia or emphysema
- Referral letter: why surgery or chemoradiotherapy is not possible, and treatment history
- Medical conditions and medications: heart disease, diabetes, anticoagulants, previous chest radiotherapy
- English translations of the referral letter and pathology report
Japanese carbon ion centers are listed on Japanese Institutions.
Frequently asked questions
Can stage III lung cancer be treated with carbon ion therapy?
Yes. Without distant metastasis and with nodes limited to the chest, it is assessed under the locally advanced criteria. In the Japanese registry, 17 stage IIIA and 12 stage IIIB patients were treated with carbon ions alone.
What is the survival rate?
In 55 locally advanced patients unable to have surgery or chemoradiotherapy, 2-year survival was 66.0% and 3-year survival 49.1%. For stage I, QST Hospital publishes 5-year survival of 45–56%.
Is treatment possible with interstitial pneumonia?
Nine such patients were treated in the study and none had grade 2 or higher radiation pneumonitis. Pulmonary function results should be submitted for assessment.
How many sessions and how long?
Locally advanced lung cancer is usually 16 fractions over about 4 weeks. Early-stage disease is often treated in one day, or about 3 weeks when a critical organ is close.
How much does it cost?
For overseas patients, QST Hospital charges 5.786 million yen (tax included) for carbon ion therapy, plus 33 yen per fee point for hospital stay and tests. Coordinator fees and living costs are separate.
Related articles
Wondering if carbon ion therapy is possible for you, and what it costs?
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Free consultationCall +82-2-517-5117Sources
- Aoki S, et al. Jpn J Radiol 2026;44(4):730-737 — J-CROS-LUNG (carbon-ion RT for inoperable LA-NSCLC)
- PubMed Central — J-CROS-LUNG full text (PMC13038780)
- QST Hospital — Lung cancer (indications, English)
- QST Hospital — For patients from abroad (fees, procedure)
General information based on public sources; not a substitute for diagnosis or treatment. Eligibility is decided by the treating physicians. Written by the FTH editorial team.