Objective:To evaluate the safety and efficacy of the probiotic Bifidobacterium longum subsp. longum BL21 (BL21) in preventing radiation-induced diarrhea (RID) in cervical cancer patients during radiotherapy (RT) and to investigate the intestinal microbiota in the patients. Methods:This study was a prospective, single-arm, phase Ⅱ clinical trial, involving cervical cancer patients treated with radical and adjuvant RT. From the first day of RT, participants took one pack of BL21 powder (containing 20 billion colony-forming unit(CFU) of Bifidobacterium longum subsp. longum BL21) orally every day until the end of RT. The occurrence of adverse events and RID during RT were assessed as per Common Terminology Criteria for Adverse Events ( CTCAE) v5.0. In this way, the safety and efficacy of BL21 in preventing RID were evaluated. Additionally, the intestinal microbiota in fecal samples collected from the patients before and after RT were analyzed using 16S rRNA sequencing. Results:A total of 35 cervical cancer patients were enrolled in this study, with 29 cases incorporated for the final analysis. No serious adverse event related to the administration of BL21 was observed. The patients exhibited slight RID, with the majority (22/29) developing no or grade 1 RID during RT. The microbiota in the fecal samples showed decreased alpha diversity after RT, as indicated by the Chao1 ( P = 0.002) and Shannon ( P = 0.005) indices. Furthermore, these samples exhibited a notably higher abundance of genus Clostridium (LDA score = 3.98). The fecal samples from patients with grade 1 RID or no RID post-RT exhibited higher alpha diversity than those from patients with grade 2 RID or above post-RT (Chao1: P = 0.07, Shannon: P = 0.28), as well as a high abundance of genera Gemmiger (LDA score = 4.48) and Dorea (LDA score = 3.83). Conclusions:The administration of BL21 to cervical cancer patients during RT is simple, convenient, safe, and effective in preventing RID, thus warranting further investigation.

Objective:To evaluate the safety and efficacy of the probiotic Bifidobacterium longum subsp. longum BL21 (BL21) in preventing radiation-induced diarrhea (RID) in cervical cancer patients during radiotherapy (RT) and to investigate the intestinal microbiota in the patients. Methods:This study was a prospective, single-arm, phase Ⅱ clinical trial, involving cervical cancer patients treated with radical and adjuvant RT. From the first day of RT, participants took one pack of BL21 powder (containing 20 billion colony-forming unit(CFU) of Bifidobacterium longum subsp. longum BL21) orally every day until the end of RT. The occurrence of adverse events and RID during RT were assessed as per Common Terminology Criteria for Adverse Events ( CTCAE) v5.0. In this way, the safety and efficacy of BL21 in preventing RID were evaluated. Additionally, the intestinal microbiota in fecal samples collected from the patients before and after RT were analyzed using 16S rRNA sequencing. Results:A total of 35 cervical cancer patients were enrolled in this study, with 29 cases incorporated for the final analysis. No serious adverse event related to the administration of BL21 was observed. The patients exhibited slight RID, with the majority (22/29) developing no or grade 1 RID during RT. The microbiota in the fecal samples showed decreased alpha diversity after RT, as indicated by the Chao1 ( P = 0.002) and Shannon ( P = 0.005) indices. Furthermore, these samples exhibited a notably higher abundance of genus Clostridium (LDA score = 3.98). The fecal samples from patients with grade 1 RID or no RID post-RT exhibited higher alpha diversity than those from patients with grade 2 RID or above post-RT (Chao1: P = 0.07, Shannon: P = 0.28), as well as a high abundance of genera Gemmiger (LDA score = 4.48) and Dorea (LDA score = 3.83). Conclusions:The administration of BL21 to cervical cancer patients during RT is simple, convenient, safe, and effective in preventing RID, thus warranting further investigation.