FAST-Forward Boost: A randomised clinical trial testing a 1-week course of curative simultaneous integrated boost radiotherapy against a standard 3-week schedule in patients with early breast cancer

Research question: Can people with breast cancer receiving radiotherapy (RT) with a tumour bed boost be treated as effectively and safely in 1-week instead of 3-weeks to reduce treatment burden for patients and NHS?

Background: In the UK 37,000 people/year with breast cancer receive curative RT. In 2020 the NIHR FAST-Forward Trial changed international practice, enabling those needing RT to the breast/chest wall alone to be treated in 1-week rather than 3-weeks. 1-week RT benefits people and reduces impact of RT on their work/carer responsibilities. It also frees NHS resources and reduces carbon emissions.?

10,000 people/year however still require RT which lasts >1-week. These are primarily younger people and those with higher grade disease who require an additional RT “boost” dose to the site of the original cancer. This boost has typically been given sequentially over 5-8 days extending RT duration to up to 4.5 weeks.?

In 2023, the IMPORT HIGH trial showed that using intensity-modulated RT to deliver boost RT concurrently with 3-week whole breast radiotherapy (known as a simultaneous integrated boost (SIB)) is as effective in preventing local recurrence but with similar or fewer patient-reported side-effects than sequential boost. The next step is to integrate appropriately dosed SIB within a 1-week RT schedule and test whether this is as effective in preventing local cancer recurrence and as gentle on normal tissues as the 3-week SIB, whilst characterising the extent to which it reduces burden for patients, the NHS and the environment.?

The final group in whom 1-week RT has not been tested is those requiring radiotherapy to nodes behind the breastbone (the internal mammary chain (IMC)) who have been excluded from 1-week RT trials to date as evidence to support IMC RT only recently emerged. 15% patients requiring boost also need IMC RT and the proposed trial can provide the necessary lung-related safety data to support 1-week IMC RT.?

Aims & objectives: FAST-Forward Boost aims to compare 1-week SIB RT with 3-week SIB RT in people with breast cancer requiring breast RT with a boost. The main objective, co-developed with patient partners, is to identify a 1-week SIB schedule that is at least as safe and effective as the current SOC 3-week SIB schedule.? A secondary objective is to show the safety of 1-week IMC RT.?

Methods: 4828 people with breast cancer from at least 40 UK centres requiring RT to the breast +/- nodes with a boost will be invited to join a clinical trial to receive either 3-week SIB RT (standard of care) or 1-week SIB RT at one of 2 doses. Treatment will be allocated randomly, 1:1:1 allocation ratio. Using digitally enabled validated measures we will collect data directly from participants about changes in breast appearance/comfort (asking clinicians about these aspects too), fatigue, impact on quality-of-life and activities of daily living.

The primary outcome is risk of cancer recurrence in the breast (up to 5-years). Financial and carbon impact for patients and NHS will be assessed.?

Anticipated impact & dissemination: FAST-Forward Boost can change practice across the NHS and globally. Results will be reported via international meetings, high-impact publications & translated into standard of care via NICE guidance & Royal College of Radiologists consensus.