Radiotherapy: long-term effects on gastrointestinal function. Curr Opin Support Palliat Care. 2008;2:40-44. [PMID: 18685393 DOI: 10.1097/spc.0b013e3282f4451f]

Resveratrol attenuates intestinal injury in irradiated rats via PI3K/Akt/mTOR signaling pathway

Radiation-induced enteritis is one of the greatest challenges in radiotherapy. The current study was designed to evaluate the ameliorative effect of resveratrol, which exhibits anti-inflammatory property, against radiation-induced intestinal injury in rats and to explore the underlying mechanism. Rats were exposed to a single dose of 5 Gy. Resveratrol (20 mg/kg/day) was orally administered to irradiated rats over 3 weeks. Results showed that resveratrol ameliorated the intestinal oxidative stress parameters; malondialdehyde (MDA) content, glutathione (GSH) level, and catalase (CAT) activity compared to irradiated group. Furthermore, resveratrol reduced the contents of inflammatory cytokines; tumor necrosis factor α (TNF-α), nuclear factor-kappa (NF-κB), and interleukin 1β (IL-1β) in intestine. Western blotting analysis revealed that resveratrol down-regulated the proteins expression of phosphoinositide 3-kinases (PI3K), protein kinase B (Akt) as well as the mammalian target of rapamycin (mTOR) in intestinal tissues of irradiated rats and thus reduced the inflammatory mediator production. These results were confirmed by histopathological investigation. In conclusion, resveratrol attenuated intestinal inflammation following irradiation via modulating PI3K/Akt/mTOR pathway and thereby could be a promising adjuvant in radiotherapy.

Bowel Radiation Injury: Complexity of the Pathophysiology and Promises of Cell and Tissue Engineering

Ionizing radiation is effective to treat malignant pelvic cancers, but the toxicity to surrounding healthy tissue remains a substantial limitation. Early and late side effects not only limit the escalation of the radiation dose to the tumor but may also be life-threatening in some patients. Numerous preclinical studies determined specific mechanisms induced after irradiation in different compartments of the intestine. This review outlines the complexity of the pathogenesis, highlighting the roles of the epithelial barrier in the vascular network, and the inflammatory microenvironment, which together lead to chronic fibrosis. Despite the large number of pharmacological molecules available, the studies presented in this review provide encouraging proof of concept regarding the use of mesenchymal stromal cell (MSC) therapy to treat radiation-induced intestinal damage. The therapeutic efficacy of MSCs has been demonstrated in animal models and in patients, but an enormous number of cells and multiple injections are needed due to their poor engraftment capacity. Moreover, it has been observed that although MSCs have pleiotropic effects, some intestinal compartments are less restored after a high dose of irradiation. Future research should seek to optimize the efficacy of the injected cells, particularly with regard to extending their life span in the irradiated tissue. Moreover, improving the host microenvironment, combining MSCs with other specific regenerative cells, or introducing new tissue engineering strategies could be tested as methods to treat the severe side effects of pelvic radiotherapy.

Effector function of CTLs is increased by irradiated colorectal tumor cells that modulate OX-40L and 4-1BBL and is reversed following dual blockade

Background

Sub-lethal doses of ionizing radiation (IR) can alter the phenotype of target tissue by modulating genes that influence effector T cell activity. Previous studies indicate that cancer cells respond to radiation by up-regulating surface expression of death receptors, cell adhesion molecules and tumor-associated antigens (TAA). However, there is limited information available regarding how T cells themselves are altered following these interactions with irradiated tumor cells.

Methods

Here, several human colorectal tumor cell lines were exposed to radiation (0–10 Gy) in vitro and changes in the expression of molecules costimulatory to effector T cells (4-1BBL, OX-40L, CD70, ICOSL) were examined by flow cytometry. T cell effector function was assessed to determine if changes in these proteins were directly related to the changes in T cell function.

Results

We found OX-40L and 4-1BBL to be the most consistently upregulated proteins on the surface of colorectal tumor cells post-IR while ICOSL and CD70 remained largely unaltered. Expression of these gene products correlated with enhanced killing of irradiated human colorectal tumor cells by TAA-specific T-cells. Importantly, blocking of both OX-40L and 4-1BBL reversed radiation-enhanced T-cell killing of human tumor targets as well as T-cell survival and activation.

Conclusions

Overall, results of this study suggest that, beyond simply rendering tumor cells more sensitive to immune attack, radiation can be used to specifically modulate expression of genes that directly stimulate effector T cell activity.

Assessment of long-term rectal function in patients who received pelvic radiotherapy: a pooled North Central Cancer Treatment Group trial analysis, N09C1

PURPOSE

Pelvic radiotherapy (PRT) is known to adversely affect bowel function (BF) and patient well-being. This study characterized long-term BF and evaluated quality of life (QOL) in patients receiving PRT.

METHODS

Data from 252 patients were compiled from two North Central Cancer Treatment Group prospective studies, which included assessment of BF and QOL by the BF questionnaire (BFQ) and Uniscale QOL at baseline and 12 and 24 months after completion of radiotherapy. BFQ scores (sum of symptoms), Uniscale results, adverse-event incidence, and baseline demographic data were compared via t test, χ (2), Fisher exact, Wilcoxon, and correlation methodologies.

RESULTS

The total BFQ score was higher than baseline at 12 and 24 months (P < 0.001). More patients had five or more symptoms at 12 months (13 %) and 24 months (10 %) than at baseline (2 %). Symptoms occurring in greater than 20 % of patients at 12 and 24 months were clustering, stool-gas confusion, and urgency. Factors associated with worse BF were female sex, rectal or gynecologic primary tumors, prior anterior resection of the rectum, and 5-fluorouracil chemotherapy. Patients experiencing grade 2 or higher acute toxicity had worse 24-month BF (P values, <.001-.02). Uniscale QOL was not significantly different from baseline at 12 or 24 months, despite worse BFQ scores.

CONCLUSIONS

PRT was associated with worse long-term BF. Worse BFQ score was not associated with poorer QOL. Further research to characterize the subset of patients at risk of significant decline in BF is warranted.

Dosimetric comparison of intensity modulated radiotherapy and three-dimensional conformal radiotherapy in patients with gynecologic malignancies: a systematic review and meta-analysis

BACKGROUND

To quantitatively evaluate the safety and related-toxicities of intensity modulated radiotherapy (IMRT) dose-volume histograms (DVHs), as compared to the conventional three-dimensional conformal radiotherapy (3D-CRT), in gynecologic malignancy patients by systematic review of the related publications and meta-analysis.

METHODS

Relevant articles were retrieved from the PubMed, Embase, and Cochrane Library databases up to August 2011. Two independent reviewers assessed the included studies and extracted data. Pooled average percent irradiated volumes of adjacent non-cancerous tissues were calculated and compared between IMRT and 3D-CRT for a range of common radiation doses (5-45 Gy).

RESULTS

In total, 13 articles comprised of 222 IMRT-treated and 233 3D-CRT-treated patients were included. For rectum receiving doses ≥30 Gy, the IMRT pooled average irradiated volumes were less than those from 3D-CRT by 26.40% (30 Gy, p = 0.004), 27.00% (35 Gy, p = 0.040), 37.30% (40 Gy, p = 0.006), and 39.50% (45 Gy, p = 0.002). Reduction in irradiated small bowel was also observed for IMRT-delivered 40 Gy and 45 Gy (by 17.80% (p = 0.043) and 17.30% (p = 0.012), respectively), as compared with 3D-CRT. However, there were no significant differences in the IMRT and 3D-CRT pooled average percent volumes of irradiated small bowel or rectum from lower doses, or in the bladder or bone marrow from any of the doses. IMRT-treated patients did not experience more severe acute or chronic toxicities than 3D-CRT-treated patients.

CONCLUSIONS

IMRT-delivered high radiation dose produced significantly less average percent volumes of irradiated rectum and small bowel than 3D-CRT, but did not differentially affect the average percent volumes in the bladder and bone marrow.

Practical approaches to effective management of intestinal radiation injury: Benefit of resectional surgery

AIM: To study the outcome of patients undergoing surgical resection of the bowel for sustained radiation-induced damage intractable to conservative management.

METHODS: During a 7-year period we operated on 17 cases (5 male, 12 female) admitted to our surgical department with intestinal radiation injury (IRI). They were originally treated for a pelvic malignancy by surgical resection followed by postoperative radiotherapy. During follow-up, they developed radiation enteritis requiring surgical treatment due to failure of conservative management.

RESULTS: IRI was located in the terminal ileum in 12 patients, in the rectum in 2 patients, in the descending colon in 2 patients, and in the cecum in one patient. All patients had resection of the affected region(s). There were no postoperative deaths, while 3 cases presented with postoperative complications (17.7%). All patients remained free of symptoms without evidence of recurrence of IRI for a median follow-up period of 42 mo (range, 6-96 mo).

CONCLUSION: We report a favorable outcome without IRI recurrence of 17 patients treated by resection of the diseased bowel segment.

Abdominal pain in special populations

Evaluation and management of acute abdominal pain in special populations can be challenging for the emergency physician. This article focuses on two specific populations: patients with altered immunologic function and postprocedural patients. Recognition of life-threatening abdominal diseases may be delayed in immunosuppressed patients because of the atypical presentations of these conditions. In postprocedural patients, evaluation of acute abdominal symptoms requires an understanding of the complications of procedures often performed by others. The unique characteristics of abdominal pain in these two populations and, more specifically, which diseases to consider and how to use appropriate testing to detect life-threatening conditions, are discussed.

Cancer emergencies: the acute abdomen

The most common complaints among patients with cancer who present to the emergency department are related to the gastrointestinal system, and 40% of these patients complain of abdominal pain. These presentations can stem from the underlying malignancy itself, treatment directed toward the disease, or the full range of pathologies present in a healthy population. Immunosuppression may blunt many of the findings one expects in a healthy population of patients, thus rendering the clinical exam less reliable in many patients with cancer. Moreover, the degree of immunosuppression shapes both the types of pathologies the clinician should consider and the rate at which the disease may progress. Understanding the limitations of physical examination, pathophysiology of disease, and the methods by which these diagnoses are established is of critical importance in this population. This article focuses specifically on patients with cancer who present with an acute abdomen, and it discusses how a concurrent malignancy can shape the differential diagnosis in these cases.

Recent advances in the management of radiation colitis

Radiation colitis, an insidious, progressive disease of increasing frequency, develops 6 mo to 5 years after regional radiotherapy for malignancy, owing to the deleterious effects of the latter on the colon and the small intestine. When dealing with radiation colitis and its complications, the most conservative modality should be employed because the areas of intestinal injury do not tend to heal. Acute radiation colitis is mostly self-limited, and usually, only supportive management is required. Chronic radiation colitis, a poorly predictable progressive disease, is considered as a precancerous lesion; radiation-associated malignancy has a tendency to be diagnosed at an advanced stage and to bear a dismal prognosis. Therefore, management of chronic radiation colitis remains a major challenge owing to the progressive evolution of the disease, including development of fibrosis, endarteritis, edema, fragility, perforation, partial obstruction, and cancer. Patients are commonly managed conservatively. Surgical intervention is difficult to perform because of the extension of fibrosis and alterations in the gut and mesentery, and should be reserved for intestinal obstruction, perforation, fistulas, and severe bleeding. Owing to the difficulty in managing the complications of acute and chronic radiation colitis, particular attention should be focused onto the prevention strategies. Uncovering the fibrosis mechanisms and the molecular events underlying radiation bowel disease could lead to the introduction of new therapeutic and/or preventive approaches. A variety of novel, mostly experimental, agents have been used mainly as a prophylaxis, and improvements have been made in radiotherapy delivery, including techniques to reduce the amount of exposed intestine in the radiation field, as a critical strategy for prevention.