Can carbon ion therapy for liver cancer be used for hepatocellular carcinoma (HCC) larger than 10 cm? In a Japanese study published in BMC Cancer in May 2026, Osaka Heavy Ion Therapy Center reported 33 patients with HCC of 10 cm or more: 1-year local control was 85.9% and 1-year overall survival was 74.8%. This was a retrospective review from a single center with a small number of patients and a short follow-up (median 15.1 months), so it is not yet evidence of an established standard. In Japan, carbon ion therapy for HCC of 4 cm or larger is covered by public insurance, but overseas patients pay out of pocket. To ask whether your images and test results may qualify, please use our consultation on eligibility and cost.
What is the latest study on liver cancer over 10 cm?
Large HCC is often hard to remove surgically, and giving high doses with conventional X-ray radiotherapy risks damaging the surrounding normal liver. Carbon ion therapy uses the Bragg peak — carbon ions release most of their energy at a set depth — to deliver a high dose to the tumor while sparing tissue beyond it. The principle is explained in What Is Carbon Ion Therapy?
Researchers from Osaka Heavy Ion Therapy Center and Osaka University reviewed patients with HCC of 10 cm or more treated at the center between December 2018 and December 2024. Of 34 eligible patients, 33 were analyzed (one had no follow-up). The paper was received in February 2026, accepted in April and published online on 25 May 2026.
| Item | Details |
|---|---|
| Institutions | Osaka Heavy Ion Therapy Center; Osaka University Graduate School of Medicine |
| Design | Single-center retrospective review |
| Patients | 33; median age 83 (54–94) |
| Tumor size | Median diameter 11.0 cm (10.0–18.0 cm) |
| Liver function | Child-Pugh A 27, B 6 |
| Dose | 60 Gy (RBE) in 4 fractions: 19; 67.2 Gy (RBE) in 12: 8; 60 Gy (RBE) in 12: 6 |
| Follow-up | Median 15.1 months (2.8–54.0) |
More than half of the patients were in their 80s or older. Most were considered inoperable, and each case was reviewed by the center's Cancer Board, so these were patients the team judged able to tolerate treatment — not every patient with a large tumor.
Results — local control and survival
| Measure | Result | Meaning |
|---|---|---|
| 1-year local control | 85.9% | Recurrence in the treated area: 3 of 33 (9.1%) |
| 1-year overall survival | 74.8% | Median survival 25.4 months |
| 1-year progression-free survival | 30.0% | New lesions elsewhere in the liver were the most common cause |
| Site of first recurrence | Liver outside the treated field 18 (54.5%), distant 4, lymph nodes 2 | Local treatment alone does not protect the whole liver |
The large tumor itself was largely controlled, but new lesions often appeared elsewhere in the liver. Because HCC tends to arise in several places on a background of chronic liver disease, regular monitoring and further treatment may still be needed after carbon ion therapy. The authors found a strong link between local control duration and survival, but noted it may be overestimated given the small sample.
Side effects and liver function
Side effects were graded with CTCAE version 5.0. Grade 3 or higher events occurred in 5 of 33 patients (15%); there were no grade 4 or higher events.
- Pleural effusion: 2 (6%)
- Hepatic failure, bile duct stenosis, biliary tract infection, heart failure: 1 each (3%); one patient had both effusion and heart failure
- Radiation-induced liver damage (Child-Pugh increase of 2 points or more): 5 (15%)
For comparison, QST Hospital's information for physicians reports that 6 months after carbon ion therapy for HCC, 22% of patients had a 1-point and 5% a 2-point Child-Pugh increase. The tumor sizes differ, so the numbers cannot be compared directly. See also Carbon ion therapy side effects.
How to read these results
The authors list several limitations: a single-center retrospective design with no direct comparison with surgery, TACE or drug therapy; possible selection bias because the Cancer Board chose patients; and short follow-up that may underestimate late toxicity. Two- and three-year results have not been reported. The study is best read as short-term evidence that carbon ion therapy can be considered for HCC of 10 cm or more; the authors call for larger prospective trials. General eligibility for liver cancer is summarized in Liver cancer carbon ion therapy — criteria.
Eligibility in Japan and cost
According to QST Hospital's physician information (as of 1 April 2022), HCC and intrahepatic cholangiocarcinoma of 4 cm or more are covered by insurance in Japan, while HCC under 4 cm and liver metastases are treated under Advanced Medical Care. For HCC, candidates generally have a Child-Pugh score of 9 or less and no widespread disease (about 3 or fewer lesions), with 1 to 12 fractions (up to 3 weeks).
Patients without Japanese public insurance pay out of pocket. Osaka Heavy Ion Therapy Center's cost page (checked October 2026) lists 3.14 million yen (excluding consumption tax) for self-pay care and 4.8 million yen (excluding tax) for overseas patients, not including travel, lodging or coordinator fees. See Carbon ion therapy cost in Japan, 7 carbon ion therapy hospitals in Japan and Japanese Institutions.
Eligibility for large liver cancer depends on tumor size and location, liver function and other lesions. Prepare recent CT/MRI images, blood tests and your treatment history, and contact us to prepare a review by a Japanese institution.
Checklist before consultation
- Contrast CT or MRI within the last 3 months (CD/DICOM) and reports
- Liver function tests (bilirubin, albumin, prothrombin time); ascites or encephalopathy
- Tumor markers (AFP, PIVKA-II) over time
- Previous treatments (surgery, TACE, RFA, drugs, radiotherapy)
- Underlying liver disease such as hepatitis B/C, and current medications
Frequently asked questions
Q. Can liver cancer larger than 10 cm be treated with carbon ion therapy?
Osaka Heavy Ion Therapy Center reported 33 patients with HCC of 10–18 cm. They were selected case by case, and liver function, other lesions and general condition may make a patient ineligible. The Japanese institution's physicians decide based on images and test results.
Q. How many sessions are needed?
In this study, 4 fractions (19 patients) or 12 fractions (14 patients) were used. QST Hospital describes 1 to 12 fractions (up to about 3 weeks), depending on tumor size and distance from the stomach, bowel and bile ducts.
Q. Does liver function get worse after treatment?
In 15% (5 patients), the Child-Pugh score rose by 2 points or more. There were no grade 4 or higher events, but follow-up was short.
Q. Can patients in their 80s be treated?
The median age was 83 and the oldest was 94. Age alone does not exclude a patient, but general condition and the ability to keep still during treatment are assessed; 97% of patients had a performance status of 0–1.
Q. How much does it cost for overseas patients?
Osaka Heavy Ion Therapy Center lists 4.8 million yen (excluding consumption tax) for overseas patients (checked October 2026). Examinations, hospital stay, lodging and interpreting are extra, and amounts differ by hospital.
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
- BMC Cancer (2026) Efficacy and safety of carbon-ion radiotherapy for large hepatocellular carcinoma (diameter ≥ 10 cm) — Osaka Heavy Ion Therapy Center
- QST Hospital — Carbon ion radiotherapy for liver cancer, information for physicians (Japanese source)
- Osaka Heavy Ion Therapy Center — Treatment costs (Japanese source)
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.