ESTRO recommendations for the use, planning and delivery of reirradiation in locally recurrent rectal cancer - Endorsed by ASTRO.

BACKGROUND AND PURPOSE: Reirradiation for locally recurrent rectal cancer (LRRC) has historically been restricted by concerns regarding significant adverse effects, particularly with reirradiation doses (in EQD2Gy) ≥ 30 Gy. Advances in radiation technology now enable safer delivery, renewing interest in (chemo)reirradiation as part of multimodal management. Given the scarcity of prospective data and the considerable variability in radiotherapy approaches, there is a clear need for recommendations to enhance treatment homogeneity and quality.

METHODS

A writing committee was established by the Lower Gastrointestinal Cancer Sub-Committee of the European Society for Radiotherapy and Oncology (ESTRO) Guidelines Committee. We performed a systematic literature review following PRISMA guidelines; aiming to answer 14 key questions regarding the indications, planning and delivery of reirradiation in LRRC. Recommendations were based on available evidence or expert consensus and graded using the American Society for Radiation Oncology (ASTRO) grading system.

RESULTS

Careful patient selection, consideration of treatment intent, treatment planning taking into account prior rectal cancer treatment, organ dose guidance and patient goals are essential to optimize outcomes and minimize adverse effects. The key questions guided a summary of appropriate literature and a series of recommendations to support the implementation of reirradiation in LRRC into routine clinical care. Almost all levels of evidence were low with recommendations mostly based on low quality of evidence or expert opinion, underscoring the urgent need for prospective studies and registry data.

CONCLUSIONS

(Chemo)reirradiation in LRRC can be applied in the context of neoadjuvant treatment, definitive treatment and palliation, to increase radical resection rate, enhance local control and improve symptom control. Optimal patient selection, along with advanced imaging and precision techniques, is essential to maximize the therapeutic benefit while minimizing harm. In the absence of high-level evidence, these recommendations represent expert consensus and provide practical guidance to ensure the safe and consistent delivery of (chemo)reirradiation in routine clinical practice.