Carbon ion therapy duration ranges from a single day (1 session) to about 5 weeks (20 sessions), depending on the cancer. Most Japanese carbon ion cancer treatment centers irradiate four days a week, so the course is much shorter than the 6–7 weeks typical of conventional X-ray radiotherapy. For overseas patients, however, the total stay in Japan also includes the first consultation, immobilization device, and treatment planning (about 1–2 weeks). This guide brings together the session counts, daily treatment time, outpatient/inpatient arrangements and sample stay schedules published by Japanese carbon ion centers. To find out how many sessions and weeks your case may need, please request a duration and eligibility consultation and send your diagnostic records.
How many carbon ion therapy sessions and weeks by cancer type?
Carbon ion therapy uses the fact that carbon ions release most of their energy at a set depth in the body (the Bragg peak). Because a large dose can be delivered to the tumor at once, the number of sessions can be reduced, which is why the course is short. The principle is explained in What is carbon ion therapy?
The table combines figures published on the websites of QST Hospital (Chiba), Gunma University Heavy Ion Medical Center, Osaka Heavy Ion Therapy Center, Yamagata University East Japan Heavy Ion Center and SAGA HIMAT. Even for the same cancer, physicians set the number of sessions according to tumor size, distance from the bowel and stage.
| Cancer | Sessions | Duration | Notes |
|---|---|---|---|
| Early lung cancer (stage I, peripheral) | 1 or 4 | 1 day–1 week | Yamagata also offers single-session treatment |
| Locally advanced lung cancer (stage II–III) | 16 | About 4 weeks | When surgery/chemotherapy is difficult |
| Hepatocellular carcinoma | 2–4 | 2 days–1 week | 12 sessions (3 weeks) if close to the bowel |
| Prostate cancer | 12 | 3 weeks | Hormone therapy first, depending on risk group |
| Pancreatic cancer | 12 | About 3 weeks | Often combined with chemotherapy |
| Kidney / esophageal cancer | 12 | 3 weeks | Esophageal: stage I (T1b) |
| Head and neck cancer | 16 | About 4 weeks | Some (e.g., lacrimal gland) 12 |
| Bone and soft tissue sarcoma / skull base tumors | 16 (some 12) | About 4 weeks | Includes chordoma and chondrosarcoma |
| Pelvic recurrence of rectal cancer after surgery | 16 | About 4 weeks | No bowel invasion |
| Cervical cancer (adenocarcinoma, etc.) | 16–20 | 4–5 weeks | Gunma adds 3 brachytherapy sessions, within 6 weeks overall |
| Oligometastases (lung, liver, lymph node) | 4, 12 or 16 | 1–4 weeks | Per site |
In short: liver and early lung cancer take about a week; prostate, pancreas and kidney 3 weeks; head and neck, sarcoma, rectal recurrence and locally advanced lung cancer 4 weeks; and cervical cancer about 5 weeks. See also prostate cancer carbon ion therapy and osteosarcoma carbon ion therapy.
How many days a week, and how long each day?
Japanese centers generally treat four times a week. Yamagata University East Japan Heavy Ion Center treats Tuesday to Friday and uses Mondays for equipment maintenance. Osaka Heavy Ion Therapy Center also bases its schedule on four sessions a week. So 16 sessions take about 4 weeks and 12 sessions about 3 weeks.
Each day is shorter than many expect. According to the Osaka center, the beam itself runs 5–20 minutes and the total time in the treatment room is 15–120 minutes. Gunma University says beam delivery usually takes a few minutes or less, with 30–60 minutes in the room. Lung, liver, bone/soft tissue and some pancreatic treatments take longer because they are synchronized with breathing. QST Hospital notes that patients feel no pain or heat during irradiation.
- Positioning in a custom mold or mask each day: 5–20 minutes
- Beam delivery: under 1 minute to 10 minutes or more, depending on the site
- The rest of the day is free, and many patients commute from nearby accommodation
How much longer is the stay in Japan than the treatment itself?
For overseas patients, what matters is the total time in Japan, not just the irradiation period. QST Hospital's guidance for overseas patients and its treatment flow describe these steps:
- Pre-assessment (before travel): diagnostic, imaging and pathology records are sent via a medical coordinator, and the QST physician in charge makes the final eligibility decision.
- First visit and consent: consultation in Japan, with extra imaging if needed.
- Preparation: immobilization device (20 minutes–1 hour) and planning CT (30 minutes–1 hour). It takes about 10 days from planning CT to the first session.
- Free time: about 1–2 weeks after preparation. QST says patients may go home and return by the day before treatment starts.
- Irradiation: the number of sessions in the table, as outpatient or inpatient.
Sample total stays calculated from this (actual schedules must be confirmed with the hospital):
| Example | First visit & prep | Free time | Treatment | Approx. total |
|---|---|---|---|---|
| Liver cancer, 4 sessions | About 1 week | 1–2 weeks | 1 week | About 3–4 weeks |
| Prostate cancer, 12 sessions | About 1 week | 1–2 weeks | 3 weeks | About 5–6 weeks |
| Bone/soft tissue sarcoma, 16 sessions | About 1 week | 1–2 weeks | 4 weeks | About 6–7 weeks |
| Cervical cancer, 20 sessions | About 1 week | 1–2 weeks | 5 weeks | About 7–8 weeks |
Going home once during the free time can shorten the stay. Intermediate/high-risk prostate cancer patients may receive hormone therapy for several months beforehand (Gunma gives about 6 months as an example); discussing in advance whether this can be done by your home physician helps you plan the stay in Japan separately. Hospital contacts and how each accepts international patients are summarized in 7 carbon ion therapy hospitals in Japan and Japanese institutions.
Before booking flights and accommodation, check "how many sessions for my stage" and "whether I can go home during the free time" to keep costs down. Use our consultation form or call +82-2-517-5117 to request a review of your records.
Outpatient or inpatient?
Most carbon ion centers say outpatient treatment is the norm. According to Gunma University, prostate cancer is treated as an outpatient in principle, and rectal recurrence, bone/soft tissue tumors, lung and liver cancer may be outpatient depending on condition, while head and neck, pancreatic and uterine cancers combined with chemotherapy are generally inpatient. The Osaka center treats outpatients as a rule, but some patients are admitted to the referring or a nearby hospital.
| Category | Mainly outpatient | Mainly inpatient |
|---|---|---|
| Typical cancers | Prostate, early lung, liver (case by case), bone/soft tissue | Head and neck, pancreatic and cervical cancer with chemotherapy |
| For overseas patients | Accommodation near the hospital, interpreter schedule | Admission procedures; inpatient fees (by medical fee points) extra |
Whether you are admitted directly affects living costs, so confirm it at the consultation stage.
How does duration relate to carbon ion therapy cost?
The carbon ion technical fee is a fixed amount regardless of the number of sessions. QST Hospital lists the fee for overseas patients without Japanese public insurance as 5.786 million yen (tax included); hospitalization, follow-up and tests are charged separately at 33 yen per medical fee point (tax included) (QST Hospital overseas patient page, checked 22 October 2026). Medical coordinator fees are not included. So the fee is the same for 4 or 16 sessions; what grows with a longer course is accommodation, living costs, interpreting and inpatient fees. Hospital-by-hospital fees are compared in carbon ion therapy cost in Japan.
Note that QST Hospital does not accept overseas patients with breast or esophageal cancer, so other centers should be considered for these two.
Records that speed up scheduling
- Referral letter and diagnosis in English
- Recent CT, MRI, PET images on CD (DICOM) with reports
- Biopsy pathology report (for prostate cancer: Gleason score and PSA history)
- Records of previous surgery, chemotherapy and radiotherapy
- Preferred travel dates and accompanying family details
Frequently asked questions
How many carbon ion therapy sessions are needed?
Based on Japanese centers' published data, 1–20 sessions: liver 2–4, early lung 1–4, prostate and pancreas 12, head and neck, sarcoma and rectal recurrence 16, cervical cancer 16–20.
Is treatment given on weekends?
Most centers treat four weekdays a week. Yamagata treats Tuesday–Friday with Monday maintenance. Weekends are free for rest or light daily activities.
How many weeks do I need to stay in Japan?
Add about 1 week for the first visit and preparation and 1–2 weeks of free time to the treatment period. For example, about 5–6 weeks for prostate cancer (12 sessions) and 3–4 weeks for liver cancer (4 sessions). Ask the hospital whether you can go home during the free time.
Can I go home right after treatment?
Outpatients can usually leave after the last session; inpatients are discharged the day after treatment ends or several weeks later (QST Hospital). Follow-up often alternates between the Japanese hospital and your home physician; the Osaka center describes follow-up every 1–6 months.
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
- QST Hospital — Guide for patients from abroad (treatment period, fees)
- QST Hospital — Process of carbon ion radiotherapy
- Gunma University Heavy Ion Medical Center — Indicated diseases (Japanese)
- Gunma University Heavy Ion Medical Center — FAQ (Japanese)
- Osaka Heavy Ion Therapy Center — Treatable cancers (Japanese)
- Osaka Heavy Ion Therapy Center — FAQ (Japanese)
- Yamagata University East Japan Heavy Ion Center — Sessions and duration (Japanese)
- SAGA HIMAT — About carbon ion 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.