Carbon ion therapy for metastatic cancer is used in Japan for patients whose cancer has spread to only a few spots in the lung, liver or lymph nodes (oligometastasis). A nationwide Japanese analysis of particle therapy (Journal of Radiation Research, 2023) covering 614 patients reported 3-year local control of 83.2% for lung, 73.2% for liver and 72.8% for lymph node metastases, with grade 3 or higher side effects at 4% or less. This article covers eligibility, the latest results, the treatment schedule and fees for overseas patients. To ask whether your case could be reviewed, use our consultation on eligibility and cost.
Why consider carbon ion therapy for oligometastases?
Not all metastatic cancer is the same. When spread is limited to one or a few sites, it is called oligometastasis. A growing body of research shows that treating these sites directly with surgery or radiation, alongside drug therapy, can keep the disease under control for a long time.
The challenge is when a metastasis sits in a hard-to-operate location, or when the patient has already had several operations. Carbon ions release most of their energy at a set depth and then stop (the Bragg peak), so normal tissue behind the tumor receives little dose. Their cell-killing effect is 2 to 3 times that of X-rays, which is why they are also used for adenocarcinomas and sarcomas that respond poorly to X-rays. Learn more in What Is Carbon Ion Therapy?
Recovery is also easier. There is no incision, each session takes 15 to 30 minutes, and most patients are treated as outpatients, which makes it easier to continue drug therapy afterward.
Which metastases are eligible?
QST Hospital (Chiba, Japan) lists three types of metastatic tumors as eligible for carbon ion therapy. The common condition is that there is no active cancer other than the metastases being treated.
| Site | QST Hospital criteria | Notes |
|---|---|---|
| Lung metastases | No spread outside the lungs; 3 or fewer lung metastases | 2-year survival of 71% reported |
| Liver metastases | Primary tumor treated; no spread to other organs; 3 or fewer liver lesions | 2-year survival of 65% in 34 colorectal cancer patients |
| Lymph node metastases | A few nodes within a limited region; no other active lesions | Most often lung, colorectal and uterine cancers |
Bone and adrenal metastases are not currently eligible at QST Hospital. When cancer has spread to several organs or there are many lesions, systemic therapy usually comes first. If the same area was irradiated before, see carbon ion re-irradiation after radiotherapy. General criteria are in eligibility for carbon ion therapy.
What did the Japanese nationwide analysis of 614 patients show?
Researchers of the Japanese Society for Radiation Oncology analyzed oligometastasis patients registered at particle therapy centers across Japan (Aibe et al., Journal of Radiation Research, 2023). There were 132 lung, 200 liver and 282 lymph node patients, 614 in total; 173 received carbon ions and 441 protons.
| Site | Patients | 3-year local control | 3-year overall survival | Grade ≥3 side effects |
|---|---|---|---|---|
| Lung | 132 | 83.2% | 68.1% | 0.8% |
| Liver | 200 | 73.2% | 38.5% | 3.5% |
| Lymph node | 282 | 72.8% | 50.2% | 3.2% |
Local control is the share of treated tumors that did not regrow in place. No grade 4 or higher side effects occurred. Local control did not differ significantly between carbon ions and protons at any site.
The researchers also compared results with published high-precision X-ray therapy (such as stereotactic radiotherapy). For lung metastases, the risk of local progression was 0.56 times and the risk of death 0.66 times; for liver metastases, the risk of local progression was 0.52 times. Lymph node results were similar to X-rays. Even for 38 liver metastases larger than 5 cm, 3-year local control was 84.5%, and the authors suggested particle therapy may be a new option for large liver metastases. Because this comparison used other studies' data, the right treatment for each patient is decided together with the physicians. See carbon ion vs proton therapy.
Results for lymph node recurrence, colorectal and ovarian metastases
Lymph node oligo-recurrence: 323 patients at 4 centers
The Japan Carbon-Ion Radiation Oncology Study Group (J-CROS) analyzed 323 patients treated for lymph node recurrence at four centers (Okonogi et al., International Journal of Clinical Oncology, 2019). Primary cancers were lung (30.7%), lower gastrointestinal (23.8%) and uterine (11.8%). Two-year local control was 85.4% and 2-year overall survival 62.9%; one patient (0.31%) had a grade 3 late effect. Results were especially good with 3 or fewer nodes, size under 3 cm, and at least 16 months from first treatment to recurrence. The most common dose was 48.0 Gy (RBE) in 12 fractions.
Colorectal cancer metastases to lung or liver: Gunma University
Gunma University Heavy Ion Medical Center reported 19 patients (23 tumors) with oligometastatic colorectal cancer in the lung or liver (Shiba et al., Anticancer Research, 2021). At a median follow-up of 19 months, 2-year overall survival was 100% and 2-year local control 67%, with no grade 2 or higher side effects. See also carbon ion therapy for recurrent rectal cancer.
Ovarian and fallopian tube cancer: Italy–Japan study
CNAO (Italy) and QST Hospital jointly analyzed 26 patients (36 lesions) with oligometastatic or recurrent ovarian and fallopian tube cancer (Barcellini, Murata et al., Clinical and Translational Radiation Oncology, 2024). At 12 months, 97% of lesions had shrunk and 47% had disappeared on imaging. Local control was 92% at 1 year and 83% at 2 years. There was one grade 3 late enterocolitis, and the 5 previously irradiated patients also completed treatment safely.
Schedule and cost
The Japanese Society for Radiation Oncology (JASTRO) 2022 particle therapy policy lists, for oligometastatic lymph nodes, 48.0–55.2 Gy (RBE) in 12 fractions or 57.6 Gy (RBE) in 16 fractions, 4 days a week, about 3 to 4 weeks. Lung and liver metastases are treated in 1 to 12 sessions depending on size and location. QST Hospital notes a 1 to 2 week gap after preparation; patients may return home but must be back the day before treatment starts.
| Item | Amount (QST Hospital) | Notes |
|---|---|---|
| Carbon ion therapy (self-pay) | 5.786 million yen (tax included) | Overseas patients without Japanese public insurance |
| Hospital stay, visits, tests | 33 yen per medical fee point (tax included) | Charged separately as used |
| Medical coordinator fee | Not included | Varies by registered coordinator or agency |
| Accommodation, flights, interpreting | Not included | Plan for a 3 to 6 week stay |
Fees are from QST Hospital's page for overseas patients, checked on 29 October 2026. Fees and procedures differ by center; compare in carbon ion therapy cost and Japanese institutions.
The number of sessions and cost depend on the number and size of metastases and prior treatment. Contact us or call +82-2-517-5117 with your current records and we will explain which hospitals could review your case and how to prepare.
Records to prepare before a consultation
For oligometastasis treatment, confirming that there is no hidden spread elsewhere matters most. These records speed up review by Japanese hospitals:
- Referral letter: primary diagnosis, stage, dates of surgery, chemotherapy and radiation
- PET-CT and chest/abdominal CT from the last month (original DICOM CD); MRI for liver metastases
- Pathology reports for the primary tumor and metastases (if biopsied)
- Records of any previous radiotherapy (site and dose)
- Blood tests including tumor marker trends (such as CEA), other illnesses and current medicines
See documents for carbon ion therapy for details.
Frequently asked questions
Can stage 4 cancer be treated with carbon ion therapy?
If the spread is limited to a few sites in the lung, liver or lymph nodes, it can be reviewed. QST Hospital sets limits such as 3 or fewer lung or liver metastases. When cancer has spread to several organs, systemic therapy comes first.
Can I have carbon ion therapy during chemotherapy?
Treatment is coordinated with the chemotherapy schedule. The JASTRO policy describes treating oligometastatic lymph nodes with carbon ions alone, so the timing of any break in chemotherapy is decided by your oncologist and the Japanese team.
How common are side effects?
In the nationwide analysis, grade 3 or higher side effects occurred in 0.8% (lung), 3.5% (liver) and 3.2% (lymph node), with none of grade 4 or higher. Skin redness and fatigue are the most common and usually settle after treatment. See side effects of carbon ion therapy.
Can bone metastases be treated?
QST Hospital does not currently include bone or adrenal metastases. Pain from bone metastases is often well managed with conventional radiotherapy.
How much does it cost for overseas patients?
QST Hospital lists 5.786 million yen (tax included) for carbon ion therapy for overseas patients without Japanese public insurance. Hospital stay and tests are charged separately at 33 yen per point.
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
- Aibe N, et al. Comprehensive analysis of Japanese nationwide cohort data of particle beam therapy for pulmonary, liver and lymph node oligometastases. J Radiat Res. 2023
- Okonogi N, et al. Carbon-ion radiotherapy for lymph node oligo-recurrence: a multi-institutional study by J-CROS. Int J Clin Oncol. 2019
- Shiba S, et al. Carbon-ion Radiotherapy for Oligometastatic Colorectal Cancer in the Liver or Lung. Anticancer Res. 2021
- Barcellini A, Murata K, et al. Carbon ion radiotherapy for oligo-metastatic, persistent, or recurrent ovarian/fallopian tube cancer. Clin Transl Radiat Oncol. 2024
- QST Hospital — Metastatic Tumor (indications)
- QST Hospital — For patients from abroad (fees)
- JASTRO particle therapy policy 2022 — oligometastatic lymph nodes
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.