Improving the morbidity of anorectal injury from pelvic radiotherapy

Synergistic effects of tetrandrine combined with ionizing radiation on a murine colorectal carcinoma‑bearing mouse model

Tetrandrine (TET), a traditional Chinese clinical agent, has been used for the treatment of many diseases, including cancers. The purpose of the present study was to investigate the combined effects of TET and ionizing radiation (IR) on murine CT26 colorectal adenocarcinoma cells in vitro and in vivo. A CT26 cell line transfected with dual HSV-1 thymidine kinase and firefly luciferase (luc) reporter genes was used. The half-maximal inhibitory concentration (IC₅₀) of TET in CT26/tk-luc cells was ~10 µM. An additive effect was observed after combination of both agents based on a colony formation assay. Apoptosis and cleaved caspase-3 levels were increased significantly in cells after combination treatment, as shown by flow cytometric analysis, DNA fragmentation and western blotting. However, tumor growth inhibition and therapeutic efficacy of TET combined with IR in vivo were identified to be synergistic, as monitored by tumor growth delay time, measured with a digital caliper. A significant inhibition of tumor growth was identified in the combination group compared with the radiation only group. Furthermore, non-invasive bioluminescent imaging (BLI) and gamma scintigraphy were also used to evaluate therapeutic efficacy. Both modalities revealed that the best tumor growth control was under combination treatment among all groups. The present study demonstrated that TET is not only beneficial for chemotherapy, but also has potential as a radiosensitizer for the treatment of cancer.

Impact of pelvic radiotherapy on gut microbiota of gynecological cancer patients revealed by massive pyrosequencing

Although pelvic irradiation is effective for the treatment of various cancer types, many patients who receive radiotherapy experience serious complications. Gut microbial dysbiosis was hypothesized to be related to the occurrence of radiation-induced complications in cancer patients. Given the lack of clinical or experimental data on the impact of radiation on gut microbiota, a prospective observational study of gut microbiota was performed in gynecological cancer patients receiving pelvic radiotherapy. In the current study, the overall composition and alteration of gut microbiota in cancer patients receiving radiation were investigated by 454 pyrosequencing. Gut microbial composition showed significant differences (P < 0.001) between cancer patients and healthy individuals. The numbers of species-level taxa were severely reduced after radiotherapy (P < 0.045), and the abundance of each community largely changed. In particular, the phyla Firmicutes and Fusobacterium were significantly decreased by 10% and increased by 3% after radiation therapy, respectively. In addition, overall gut microbial composition was gradually remolded after the full treatment course of pelvic radiotherapy. In this set of cancer patients, dysbiosis of the gut microbiota was linked to health status, and the gut microbiota was influenced by pelvic radiotherapy. Although further studies are needed to elucidate the relationship between dysbiosis and complications induced by pelvic radiotherapy, the current study may offer insights into the treatment of cancer patients suffering from complications after radiation therapy.

The gut microbiota predispose to the pathophysiology of acute postradiotherapy diarrhea

INTRODUCTION

Severe diarrhea may complicate pelvic radiotherapy and force interruption of treatment. As there is no current clinical or experimental information on the role of the gut microbiota in this pathogenesis, we conducted a pilot observational study on the fecal microbiota in patients receiving pelvic radiotherapy.

METHODS

The study involved 10 patients who underwent 5 wk of radiotherapy for abdominal tumors and 5 controls. Four fecal samples were collected from each individual: before, during, at the end, and 2 wk after treatment. Following the amplification of the bacterial 16S rRNA gene from the samples, DNA fingerprinting and cloning-sequencing techniques were used to determine their microbial profile and composition, respectively.

RESULTS

Six patients suffered acute postradiotherapy diarrhea and 4 did not. In patients without diarrhea, as well as in healthy volunteers, microbial diversity was stable over a period of 7 wk. However, patients exhibiting diarrhea showed a progressive modification in their microbial diversity. A radical drop in similarity index was observed at the end (P= 0.026) and still 2 wk after radiotherapy (P= 0.014). Interestingly, cluster analysis of the microbial profile in the first sample (S1) (collected before radiotherapy) displayed a dendogram where patients that presented diarrhea clustered separately from those that did not develop diarrhea after radiotherapy. Moreover, sequence analysis of dominant bacteria in the S1 sample confirmed differences between the diarrhea and nondiarrhea groups.

DISCUSSION

In this set of patients, susceptibility or protection against diarrhea after radiotherapy could be linked to different initial microbial colonization.

[Nonsurgical treatment of chronic radiation-induced hemorrhagic proctitis]

The incidence of radiation-induced chronic hemorrhagic proctitis is less than 10 to 20%. The onset of this proctitis is delayed relative to the radiation therapy and generally develops from 6 to 24 months later. There are numerous predisposing factors, the most important of which is the radiation therapy dose: risk increases exponentially above 40-45 Gy. Its pathophysiology involves progressive obliterating endarteritis and transmural interstitial fibrosis, which induce chronic ischemia that is irreversible and progressive during the years after radiation therapy. Its diagnosis depends most often on the combination of clinical history and typical endoscopic appearance (congestive mucosa and/or telangiectases). Topical administrative of sucralfate or corticosteroids as well as argon plasma coagulation, with formalin treatment if necessary, provides relief for most patients.

Effect of neoadjuvant chemoradiation on postoperative fecal continence and anal sphincter function in rectal cancer patients

BACKGROUND AND AIMS

Neoadjuvant chemoradiation (nCRT) followed by curative surgery has gained acceptance as the therapy of choice in locally advanced rectal cancer. This prospective study evaluates the effect of nCRT on postoperative anorectal function and continence.

PATIENTS AND METHODS

Group A consisted of 12 patients (59.8 +/- 11.9 years, male:female = 8:4) who received nCRT (5-FU, CPT-11. 45 + 5.4 Gy boost) before surgery and Group B of 27 patients (61.9 +/- 10.6 years, male:female = 16:11) who were treated by surgery alone. All patients received a questionnaire to evaluate stool continence and anorectal function before as well as after surgery. Anorectal function was further analyzed by perfusion manometry pre- and postoperatively.

RESULTS

Preoperatively, none of the patients had signs or symptoms of fecal incontinence, and preoperative measurements showed values within normal limits. Postoperatively, fecal continence was impaired in both groups, but no significant difference was found between patients with or without nCRT. Anorectal manometry revealed an impairment of anorectal function after low anterior resection regardless of the treatment regime.

CONCLUSION

nCRT does not impair anorectal function and fecal continence. The deterioration of continence and anal sphincter function after sphincter preserving surgery is solely caused by the surgical procedure.