Proton therapy for lung cancer has been an approved treatment covered by Japan's public health insurance since June 2024 for stage I to IIA lung cancer that is difficult to cure with surgery. In a nationwide Japanese study of 669 patients with stage I non-small cell lung cancer, 3-year overall survival was 79.5%, the 3-year local progression-free rate was 89.8%, and grade 3 or higher radiation pneumonitis occurred in under 2%. This guide covers eligibility, schedules of 2 to 8 weeks, published hospital fees, and how it differs from carbon ion therapy. To find out whether proton or carbon ion therapy suits your case, ask us about eligibility and cost for lung cancer particle therapy.
How does proton therapy for lung cancer work?
Proton beams are accelerated hydrogen nuclei. Ordinary X-rays pass through the body and leave energy in healthy tissue in front of and behind the tumor. Protons release most of their energy at a set depth and then stop (the Bragg peak). This greatly lowers the dose to healthy lung, heart and spinal cord behind the tumor.
The lung is sensitive to radiation, so preserving remaining lung function matters as much as tumor control. Particle therapy that spares the surrounding lung has become a valuable option, especially for older patients or those with chronic obstructive pulmonary disease (COPD) for whom surgery is a burden. Carbon ion therapy uses the same principle with heavier particles. See What is carbon ion therapy? for illustrations.
Results from a 669-patient nationwide study in Japan
Japanese proton therapy centers pooled patients with histologically or clinically diagnosed stage I non-small cell lung cancer in the first nationwide analysis, published in the International Journal of Radiation Oncology, Biology, Physics (IJROBP), volume 106, 2020. It included 669 patients with 682 tumors: 470 stage IA and 199 stage IB.
| Measure | All | Stage IA | Stage IB |
|---|---|---|---|
| 3-year overall survival | 79.5% | 82.8% | 70.8% |
| 3-year local progression-free rate | 89.8% | 93.5% | 79.4% |
| Grade 3 radiation pneumonitis | 1.0% (grade 4: 0%) | ||
| Grade 3+ dermatitis | 0.4% | ||
The local progression-free rate is the share of patients whose treated tumor did not grow back. More than nine in ten stage IA patients had good control at the treated site over 3 years. The authors concluded that proton therapy yielded good survival with a low rate of side effects. Grade 2 pneumonitis (9.8%) was the most common; cough or breathlessness is usually managed with steroid medicine, and regular CT scans help detect it early. See side effects of particle therapy.
In its June 2024 newsletter, the Hyogo Ion Beam Medical Center presented pooled data: 3-year overall survival was 78.7% with particle therapy and 60.4% with stereotactic body radiotherapy (SBRT). Patient backgrounds differ, so direct comparison has limits, but the data show particle therapy is a strong option for early lung cancer that is hard to operate on.
Who is eligible? Criteria by hospital
Japanese insurance covers "stage I to IIA lung cancer that is difficult to cure with surgery." The Hyogo Ion Beam Medical Center explains that patients who decline surgery are also eligible. Tumors near the mediastinum or hilum, and patients with interstitial pneumonia or COPD, are cited as cases where particle therapy is especially suitable.
| Hospital | Lung cancer criteria (published) | Treatment length |
|---|---|---|
| University of Tsukuba Hospital Proton Beam Therapy Center (overseas patients) | Stage I, good respiratory function, no interstitial pneumonia, expected prognosis of 1 year or more | 2–7 weeks |
| Fukui Prefectural Hospital Proton Therapy Center | Inoperable stage I–IIA (insurance), locally advanced NSCLC, up to 3 lung metastases | 10 sessions in 2 weeks, or 20–37 sessions in 4–8 weeks |
| Hyogo Ion Beam Medical Center | Inoperable stage I–IIA (insurance), including patients who decline surgery; locally advanced lung cancer under Advanced Medical Care | Decided at consultation |
For the same stage I cancer, hospitals judge interstitial pneumonia differently: Tsukuba excludes it for overseas patients, while Hyogo describes particle therapy as advantageous for such patients. Which hospital you approach first can change the answer. Locally advanced lung cancer is treated under Japan's Advanced Medical Care system. For stage III, see carbon ion therapy for stage III lung cancer.
Treatment length and stay in Japan
According to the Fukui Prefectural Hospital brochure (June 2024), lung cancer proton therapy is given once a day on weekdays. Each session takes about 20 to 30 minutes, with no pain or heat during irradiation. Peripheral tumors may be treated in 10 sessions over 2 weeks; central or larger tumors take 20 or more sessions over 4 to 8 weeks.
| Step | What happens | Note |
|---|---|---|
| Eligibility check | Hospital replies based on the referral checklist and records | Via guarantor or referring doctor |
| First visit | Explanation of plan and side effects | Bring referral, test data, images |
| Preparation | Custom immobilization device, planning CT/MRI | Rehearsal the day before |
| Proton irradiation | Monday to Friday, once a day | 2 to 8 weeks |
| After returning home | Regular follow-up with your doctor | CT checks of the lungs |
Plan your stay with extra time for the first visit and preparation on top of the irradiation period. See treatment length and stay schedule.
How much does proton therapy for lung cancer cost?
Under Japanese insurance, the fee is set in medical fee points. According to Fukui Prefecture's FY2024 fee revision summary, proton therapy for early lung cancer is 187,500 points per course, plus a suitability assessment add-on of 40,000 points and a medical management add-on of 10,000 points. At 10 yen per point, the total is 2,375,000 yen. People enrolled in Japanese public insurance pay only their co-payment share.
| Item | Amount | Source and date |
|---|---|---|
| Insurance fee for irradiation (early lung cancer) | 187,500 points (1,875,000 yen) | Fukui Prefecture fee revision summary, March 2024 |
| Add-ons (assessment, management) | 50,000 points (500,000 yen) | Same document |
| Advanced Medical Care diseases (up to 20 sessions) | 2,600,000 yen | Fukui Prefectural Hospital, for treatment starting July 1, 2026 |
| Advanced Medical Care (21–25 / 26+ sessions) | 2,700,000 / 2,800,000 yen | Same notice |
Overseas patients without Japanese public insurance are treated as self-pay, and each hospital sets its own price. The table is a guide to scale; the actual estimate comes after the hospital reviews your records. Consultations, tests, admission, stay and interpreting are extra. Compare with carbon ion therapy costs in carbon ion therapy cost by hospital in Japan.
To learn the total cost of proton or carbon ion therapy for lung cancer and which hospitals can accept you, contact us or call +82-2-517-5117.
How does it differ from carbon ion therapy?
Both are particle therapies that spare surrounding lung using the Bragg peak. The difference lies in particle mass and biological effect. A carbon ion is about 12 times heavier than a proton and damages cancer DNA more strongly, which allows fewer sessions. QST Hospital in Japan treats early lung cancer with a single session.
| Item | Proton therapy | Carbon ion therapy |
|---|---|---|
| Japanese insurance for early lung cancer | Since June 2024 | Since June 2024 |
| Typical number of sessions | 10 (2 weeks) to 37 | Short schedules such as 1 to 4 |
| Centers in Japan | Widely distributed nationwide | 7 |
| Good fit | Peripheral or central early lung cancer, locally advanced lung cancer | Early lung cancer needing a short stay, radioresistant tumors |
If a short stay matters, carbon ion therapy may help; if location or appointment timing matters, proton centers widen the options. See carbon ion vs proton therapy, carbon ion therapy for stage I lung cancer, and Japanese medical institutions.
Application steps and documents
The University of Tsukuba Hospital does not accept overseas inquiries by email; patients apply only through a guarantor registered with Japan's Ministry of Foreign Affairs (medical coordinator or travel agency). At Fukui Prefectural Hospital, the referring doctor sends a checklist and the center replies on eligibility. Either way the hospital reviews records first, so complete documents save time.
- Referral letter: stage (T, N, M), why surgery is difficult, previous treatment
- Pathology report: histology (adenocarcinoma, squamous cell, etc.), or the reason a biopsy was not possible
- Imaging CD (DICOM): recent chest CT, PET-CT, brain MRI if needed
- Pulmonary function test and whether you have interstitial pneumonia or COPD
- Medication list and records of other conditions such as heart disease or diabetes
See the document checklist for particle therapy and our lung cancer page.
FAQ
How effective is proton therapy for lung cancer?
In a nationwide Japanese study of 669 stage I NSCLC patients, 3-year overall survival was 79.5% (82.8% for stage IA) and the 3-year local progression-free rate was 89.8% (93.5% for stage IA).
How long does proton therapy for lung cancer take?
From 10 sessions over 2 weeks to 37 sessions over 8 weeks, depending on tumor location and size. The stay in Japan is longer because of the first visit and preparation.
Can I receive it if I have interstitial pneumonia?
It depends on the hospital. Tsukuba excludes interstitial pneumonia for overseas patients, while Hyogo describes it as a case where particle therapy is especially suitable. Send pulmonary function tests and CT for review.
Which is better, proton or carbon ion therapy?
Both are covered by Japanese insurance for early lung cancer. Carbon ion therapy needs fewer sessions and a shorter stay; proton therapy has more centers. The choice depends on tumor location and lung condition.
What does it cost for overseas patients?
Overseas patients pay each hospital's self-pay price. The Japanese insurance total is 2,375,000 yen (FY2024 points), and Fukui Prefectural Hospital lists 2,600,000 yen for Advanced Medical Care (from July 2026, up to 20 sessions). Tests and stay are extra.
Related articles
Wondering if carbon ion therapy is possible for you, and what it costs?
We help you prepare consultations with Japanese institutions and provide medical interpreting.
Free consultationCall +82-2-517-5117Sources
- Proton Beam Therapy for Stage I NSCLC: First Nationwide Retrospective Study in Japan (IJROBP 2020;106(1):82-89)
- Hyogo Ion Beam Medical Center newsletter No.20, June 2024 — early lung cancer insurance coverage (Japanese)
- University of Tsukuba Hospital Proton Beam Therapy Center — Conditions for Acceptance
- Fukui Prefectural Hospital Proton Therapy Center brochure, June 2024 (Japanese)
- Fukui Prefectural Hospital — proton therapy fee revision from July 1, 2026 (Japanese)
- Fukui Prefecture — FY2024 medical fee revision summary for particle therapy (Japanese)
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.