The radiation-induced changes in rectal mucosa: Hyperfractionated vs. hypofractionated preoperative radiation for rectal cancer

Potential role of gut microbiota and its metabolites in radiation-induced intestinal damage

Radiation-induced intestinal damage (RIID) is a serious disease with limited effective treatment. Nuclear explosion, nuclear release, nuclear application and especially radiation therapy are all highly likely to cause radioactive intestinal damage. The intestinal microecology is an organic whole with a symbiotic relationship formed by the interaction between a relatively stable microbial community living in the intestinal tract and the host. Imbalance and disorders of intestinal microecology are related to the occurrence and development of multiple systemic diseases, especially intestinal diseases. Increasing evidence indicates that the gut microbiota and its metabolites play an important role in the pathogenesis and prevention of RIID. Radiation leads to gut microbiota imbalance, including a decrease in the number of beneficial bacteria and an increase in the number of harmful bacteria that cause RIID. In this review, we describe the pathological mechanisms of RIID, the changes in intestinal microbiota, the metabolites induced by radiation, and their mechanism in RIID. Finally, the mechanisms of various methods for regulating the microbiota in the treatment of RIID are summarized.

Clinical selection strategy for and evaluation of intra-operative brachytherapy in patients with locally advanced and recurrent rectal cancer

BACKGROUND AND PURPOSE

A radical resection of locally advanced rectal cancer (LARC) or recurrent rectal cancer (RRC) can be challenging. In case of increased risk of an R1 resection, intra-operative brachytherapy (IOBT) can be applied. We evaluated the clinical selection strategy for IOBT.

MATERIALS AND METHODS

Between February 2007 and May 2018, 132 LARC/RRC patients who were scheduled for surgery with IOBT standby, were evaluated. By intra-operative inspection of the resection margin and MR imaging, it was determined whether a resection was presumed to be radical. Frozen sections were taken on indication. In case of a suspected R1 resection, IOBT (1 × 10 Gy) was applied. Histopathologic evaluation, treatment and toxicity data were collected from medical records.

RESULTS

Tumour was resected in 122 patients. IOBT was given in 42 patients of whom 54.8% (n = 23) had a histopathologically proven R1 resection. Of the 76 IOBT-omitted R0 resected patients, 17.1% (n = 13) had a histopathologically proven R1 resection. In 4 IOBT-omitted patients, a clinical R1/2 resection was seen. In total, correct clinical judgement occurred in 72.6% (n = 88) of patients. In LARC, 58.3% (n = 14) of patients were overtreated (R0, with IOBT) and 10.9% (n = 5) were undertreated (R1, without IOBT). In RRC, 26.5% (n = 9) of patients were undertreated.

CONCLUSION

In total, correct clinical judgement occurred in 72.6% (n = 88). However, in 26.5% (n = 9) RRC patients, IOBT was unjustifiedly omitted. IOBT is accompanied by comparable and acceptable toxicity. Therefore, we recommend IOBT to all RRC patients at risk of an R1 resection as their salvage treatment.

Radiation-induced injury on surgical margins: a clue to anastomotic leakage after rectal-cancer resection with neoadjuvant chemoradiotherapy?

Background

Few studies on anastomotic condition after rectal-cancer resection and its effect on anastomotic leakage (AL) are available up to now. This study aimed to investigate potential radiation-induced injury left on surgical margins of anterior resection after neoadjuvant chemoradiotherapy (nCRT) and its association with AL.

Methods

We retrospectively identified 161 consecutive patients who underwent anterior resection with nCRT, neoadjuvant chemotherapy without radiation (nCT) or no neoadjuvant therapy between 2014 and 2015. Tissue samples of resection margins were assessed using a specific histopathological score and microvessel density in submucosa. Propensity score matching was used to balance the baseline characteristics. Association between AL and histopathological features was analysed.

Results

AL occurred in 13 of 54 patients undergoing nCRT, 5 of 48 patients undergoing nCT and 7 of 59 patients without neoadjuvant therapy. Comparisons after matching showed median (range) histopathological scores as follows: 3 (0–8) vs 0 (0–3) vs 0 (0–2) for the proximal margin (P < 0.001); 4 (2–9) vs 0 (0–4) vs 0 (0–3) for the distal margin (P < 0.001). Correspondingly, mean (SD) microvessel densities were as follows: 21.7 (7.9) vs 27.2 (8.6) vs 27.3 (9.4) for the proximal margin (P = 0.003); 18.1 (9.3) vs 25.2 (12.9) vs 24.9 (7.4) for the distal margin (P < 0.001). Among patients undergoing nCRT, AL was associated with increased histopathological score (P = 0.003) and decreased microvessel density (P = 0.004) on the proximal margin.

Conclusions

Surgical margins of rectal-cancer resection are exposed to certain radiation-induced injury after nCRT. AL is associated with aggravated radiation damage on the proximal margin.

Role of Angiogenesis in Chronic Radiation Proctitis: New Evidence Favoring Inhibition of Angiogenesis Ex Vivo

BACKGROUND

Chronic radiation proctitis (CRP), a common complication after radiotherapy for pelvic malignancies, compromises patient quality of life. Vascular damage and aberrant angiogenesis in the mucosal layer are essential histological features, but changes to the submucosal layer are unclear. Thus, we evaluated the histological characteristics and distribution changes of key angiogenic factors in full-layered human CRP samples.

METHODS

Thirty paraffin-embedded CRP and twenty-nine non-CRP tissues were used to evaluate histopathological changes. Immunohistochemistry with anti-CD34 antibody was performed to calculate microvascular density (MVD). Frozen tissues from eight CRP patients and five non-CRP controls were collected and analyzed by antibody array, which contained sixty human angiogenesis-related factors. Quality controls with positive and negative controls were performed during antibody array analysis. Two differentially expressed factors were confirmed by ELISA.

RESULTS

CRP lesions showed vasculopathy, fibrosis, mucosal ulceration, edema, and inflammatory cell infiltration. Human angiogenesis antibody array and ELISA confirmed the increased angiostatin in CRP lesions. Immunohistochemical staining showed dispersed distribution of angiostatin throughout the mucosal and submucosal layers in CRP lesions, while angiostatin accumulated within the vessel lumens in non-CRP tissues. MVD significantly decreased in the submucosal layer of CRP, suggesting a potential association with increased angiostatin.

CONCLUSIONS

Angiostatin increased and had a distinct distribution in CRP lesions. Compensatory telangiectasia in the mucosa, vessel stenosis, and reduced MVD might attenuate blood flow in the submucosa and contribute to CRP progression. Restoration of vascular functionality by promoting angiogenesis in the submucosal layer may help alleviate CRP in clinical practice.

Mobility of molecules and ions solubilized in protein gels: diffusion in the thick fraction of hen egg white

The thick fraction of hen egg white is a protein hydrogel with an immeasurably high viscosity composed of ∼90% water that can serve as a model system for mammalian mucous membrane. Measurements of the rate constants of diffusion-controlled reactions occurring within the gel (and corresponding activation energies) and electric conductivity revealed that the thick fraction of egg white can be envisioned as a 3D network comprising hydrated protein molecules (held by intermolecular S-S bridges) surrounded by water pools and channels (of nonuniform diameters) that have a microviscosity that is very similar to that of bulk water. This was corroborated by differential scanning calorimetry measurements that revealed that 16% of water is bound to proteins. The melting kinetics of ice crystallites (produced from the freezable water) indicates nonhomogeneous water pool size.

Mitomycin-C/5-fluorouracil/leucovorin and hyperfractionated radiation therapy for rectal carcinoma: a phase II study with long-term follow-up

PURPOSE

Preoperative chemotherapy followed by surgery and adjuvant chemotherapy is a standard treatment for most patients with rectal cancer. We aimed to determine efficacy and tolerability of preoperative mitomycin, fluorouracil (5-FU), and leucovorin (LV) concurrent with hyperfractionated radiation therapy (RT) followed by surgery and adjuvant chemotherapy.

PATIENTS AND METHODS

Patients with clinical stage II/III disease were treated with mitomycin 10 mg/m(2) on day 1, continuous venous infusion 5-FU 600 mg/m(2) per day for 96 hours, and oral LV 25 mg every 6 hours on days 1-5. All patients received concurrent RT in fractions of 150 cGy twice daily beginning on day 1. Unfixed tumors received 3000 cGy, whereas fixed tumors received a dose of 4500 cGy. Patients then underwent resection and postoperative adjuvant chemotherapy with oral LV and continuous venous infusion 5-FU 600 mg/m(2) per day on days 1-5 on a 28-day cycle for 6 cycles. Primary endpoints were to determine the rate of pathologic response and downstaging, long-term locoregional control, progression-free survival, and overall survival.

RESULTS

Between the years 1993 and 2000, 83 patients were enrolled. Eighteen patients (31%) were downstaged. Six patients (7%) had pathologic complete response. Median follow-up was 62 months with a 5-year overall survival of 71%. Local control rate was 96%. Treatment was well tolerated with stomatitis, diarrhea, and radiation proctitis being the most common toxicities.

CONCLUSION

This regimen is effective in the treatment of rectal carcinoma. The favorable toxicity profile of mitomycin and hyperfractionated RT allows these strategies to be utilized with the newer chemotherapies for this disease.