The impact of the microbiota on radiation (RT)-induced toxicity and cancer response to radiotherapy is an emerging area of interest. In this review, we summarize the available preclinical and clinical evidence concerning microbiota modulation of RT toxicity and efficacy in the main gastrointestinal (GI) districts. A huge amount of data supports the clinical application of microbiota modulation, particularly through prebiotics and probiotics, to prevent or mitigate radiotherapy-induced toxicity in rectal cancer. Preclinical and clinical studies also support the observation of microbiota modulation to impact the toxicity and efficacy of treatment in esophageal cancer, hepatocellular carcinoma (HCC), and anal squamous cell carcinoma (ASCC). However, insufficient evidence remains to endorse microbiota modulation as a strategy to enhance tumor radiosensitivity in clinical practice. Well-designed studies focusing on prebiotics, probiotics, and fecal microbiota transplantation are needed across all GI sites to evaluate their potential to improve treatment efficacy, as suggested by promising preclinical findings. The impact of pre-treatment microbiota analyses should be addressed in prospective studies to verify the efficacy of patient-level tailored strategies. Additionally, the repurposing of radioprotective agents with innovative delivery systems, such as encapsulated amifostine, holds significant promise for mitigating small bowel toxicity, thereby enabling more effective RT treatment.

Objective: The therapeutic landscape for localized prostate cancer (PC) is evolving. Stereotactic radiotherapy (SRT) has been reported to be at least not inferior to standard radiotherapy, but the effect of androgen deprivation therapy (ADT) in this setting is still unknown and its use is left to clinical judgment. There is therefore the need to clarify the role of ADT in association with SRT, which is the aim of the present study. Methods: We present a study protocol for a randomized, multi-institutional, Phase III clinical trial, designed to study SRT in unfavorable intermediate and a subclass of high-risk localized PC. Patients (pts) will be randomized 1:1 to SRT + ADT or SRT alone. SRT will consists in 36.25 Gy in 5 fractions, ADT will be a single administration of Triptorelin 22.5 mg concurrent to SRT. Primary end point will be biochemical disease-free survival. Secondary end points will be disease-free survival, freedom from local recurrence, freedom from regional recurrence, freedom from distant metastasis and overall survival (OS); quality of life QoL and patient reported outcomes will be an exploratory end point and will be scored with EPIC-26, EORTC PR 25, IPSS, IIEF questionnaires in SRT + ADT and SRT alone arms. Moreover, clinician reported acute and late toxicity, assessed with CTCAE v. 5.0 scales will be safety end points. Results: Sample size is estimated of 310 pts. For acute toxicity and quality of life results are awaited after 6 months since last patient in, whereas, for efficacy end points and late toxicity mature results will be available 3–5 years after last patient in. Conclusion: Evidence is insufficient to guide decision making concerning ADT administration in the new scenario of prostate ultra-hypofractionation. Hence, the need to investigate the ADT role in SRT specific setting. Advances in knowledge: The stereotactic prostate radiotherapy with or without ADT trial (SPA Trial) has been designed to establish a new standard of care for SRT in localized unfavorable intermediate and a subclass of localized high risk PC.

Objectives: To evaluate and indirectly compare overall survival (OS) and safety of regorafenib, fruquintinib, and trifluridine/tipiracil (TAS-102) monotherapy in refractory metastatic colorectal cancer (mCRC) beyond the third line. Methods: A systematic review and meta-analysis of phase II/III randomized controlled trials was conducted according to PRISMA guidelines. PubMed/MEDLINE, Embase, and Cochrane CENTRAL were searched from inception. Eligible studies included patients with mCRC previously treated with standard chemotherapy and biologic agents, receiving regorafenib, fruquintinib, or TAS-102 as monotherapy in the fourth line or later. OS data were reconstructed from published Kaplan–Meier curves. Pooled median and mean OS were estimated using a random-effects model, and heterogeneity was assessed using the I² statistic. Safety outcomes were descriptively summarized. Results: Four RCTs were included. The pooled median OS was 7.83 months (95% CI: 6.98–8.80), and the pooled mean OS was 8.90 months (95% CI: 8.00–9.81), with no heterogeneity (I² = 0%). Survival gains versus placebo ranged from 1.4 to 2.6 months. Survival curves largely overlapped, with differences below one month. Safety was consistent with known profiles. Conclusions: These agents provide comparable efficacy with modest survival benefit in late-line mCRC, highlighting the need for improved strategies and better treatment sequencing.