First-in-human trial tests ultra-fast “FLASH” proton radiotherapy for painful bone metastases

Early HumanInvestigationalNot addressed

FAST-02, a single-arm, FDA investigational-device-exemption (IDE)-approved feasibility trial, is testing proton FLASH radiotherapy — an experimental technique that delivers a full course of radiation in under 1 second, more than 100 times faster than conventional radiotherapy — to treat painful bone metastases in the thorax (excluding the spine), in patients with 1 to 3 such metastases regardless of their cancer’s primary origin. In preclinical (laboratory and animal) studies, delivering radiation at this ultra-high dose rate has shown the potential to reduce damage to healthy surrounding tissue while maintaining effective tumor control — the hypothesis this human feasibility trial is testing. The trial protocol was published in the journal Radiation Oncology (DOI 10.1186/s13014-024-02419-4). As of this record, FAST-01 and FAST-02 are the only in-human proton FLASH trials conducted worldwide; this remains an experimental technique, not yet a standard or widely available radiotherapy option, and this record makes no claim of proven superiority over conventional radiotherapy — that would require larger, comparative, longer-follow-up trials.

What This Means

FAST-02 is a single-arm feasibility trial testing proton FLASH radiotherapy -- an experimental technique that delivers a full course of radiation in under 1 second, more than 100 times faster than conventional radiotherapy -- for painful bone metastases in the thorax, in 10 patients under an FDA investigational device exemption. As of this record, FAST-01 and FAST-02 are the only in-human proton FLASH trials conducted worldwide.

What This Doesn't Mean

This is an early feasibility trial in a very small number of patients, not a treatment available outside this and one predecessor trial, and not yet compared head-to-head against conventional radiotherapy in a randomized trial. This record makes no claim that FLASH radiotherapy is proven superior to conventional radiotherapy -- the preclinical (lab/animal) rationale for reduced healthy-tissue damage is the hypothesis this human trial is testing, not yet a confirmed human result.

Why It Matters

An entirely novel radiation-delivery technique, if it holds up in larger trials, could meaningfully reduce treatment time and potentially reduce side effects for patients receiving palliative radiotherapy -- real, genuine progress in radiation oncology worth tracking early, in a topic area (radiation advances) that had no real content on this site before this record.

Promise & Proof

Proof — strength of the evidence 2 / 5

Base score from evidence stage: Early Human.

Promise — potential significance if later evidence holds up 3 / 5

Baseline — a validly-evidenced story starts here; every further point below is an explicit, checkable reason.
The record includes substantive editorial reasoning about why this discovery matters.
An early-stage finding (preclinical or early human) that already shows at least one concrete signal of significance above.

These two ratings are automatically computed from this story's own structured evidence fields and are shown separately on purpose — they are never combined into one score. They describe this record, not a medical recommendation: they do not establish medical certainty, do not substitute for reading the cited sources, and are recalculated whenever the underlying evidence changes.

Population / Applicability

Studied in: Adults with 1 to 3 painful bone metastases in the thorax (excluding the spine), regardless of the primary cancer's site of origin, enrolled in the single-arm, FDA investigational-device-exemption-approved FAST-02 feasibility trial. (Adults)

Not an available or standard treatment outside this and one predecessor feasibility trial (FAST-01) -- experimental technology requiring specialized proton-therapy equipment. This record has not independently reviewed the trial's full safety/toxicity data, which should be added before publication.

Full evidence details

Study design: Non-randomized trial
Sample size: 10

Funding & Conflicts

Reported academic/institutional and device-manufacturer involvement (proton-therapy equipment vendors) -- not independently confirmed against a primary corporate/grant-disclosure document.

Regulatory status by jurisdiction

Unspecified jurisdiction

Status: Investigational
Last verified: 2026-08-13

This record has no structured cancer-type scope on file yet — editorial review recommended before treating it as applicable to a specific cancer type.

Guideline positions

Guideline

Position: Not addressed
Last verified: 2026-08-13

Primary evidence supporting this story

FLASH radiotherapy for the treatment of symptomatic bone metastases in the thorax (FAST-02): protocol for a prospective study of a novel radiotherapy approach (Radiation Oncology) (opens in a new tab) (Peer-reviewed paper) [Peer-reviewed] 10.1186/s13014-024-02419-4 Load-bearing source DOI 10.1186/s13014-024-02419-4
FLASH radiotherapy for the treatment of symptomatic bone metastases in the thorax (FAST-02): protocol for a prospective study of a novel radiotherapy approach (Radiation Oncology). DOI 10.1186/s13014-024-02419-4.

Why Should I Trust This?

1 source at Tier 2 — Peer-reviewed primary research, trial registries, regulatory documents, official conference abstracts
Last reviewed: 2026-08-13

This panel summarizes real, checkable facts about this record's own sources and review status — it is not a trust score, and reading it is not a substitute for reading the cited sources yourself.

Discovery Timeline

Every recorded change to this record's content or publication status, in order.

2026-08-13 Status change — Status changed from "Legacy / Unverified" to "In editorial review".
2026-08-13 Status change — Status changed from "In editorial review" to "Verified".

Last reviewed 2026-08-13