Radiation therapy for advanced colorectal cancer

ZEB2-AS1 Accelerates Epithelial/Mesenchymal Transition Through miR-1205/CRKL Pathway in Colorectal Cancer

Background: Accumulating reports have demonstrated that long-noncoding RNAs (lncRNAs) play critical roles in the pathological progression of colorectal cancer (CRC). However, the role of lncRNA zinc finger E-box binding homeobox 2 antisense RNA 1 (ZEB2-AS1) in CRC remains largely unknown. Methods: The authors detected the ZEB2-AS1 expression in CRC tissue sample and CRC cell lines. The effects of ZEB2-AS1 on CRC were identified through in vitro assays (i.e., transwell assay, wound-healing assay, immunofluorescence assay, and Western blot) in a ZEB2-AS1 knockdown system. The molecular mechanism of ZEB2-AS1 was explored via bioinformatic tools, quantitative real-time polymerase chain reaction (qRT-PCR), dual-luciferase reporter assay, RNA immunoprecipitation assay, and so on. Moreover, a series of gain-of-function experiments were performed to identify the effect of ZEB2-AS1 and miR-1205 on epithelial-to-mesenchymal transition (EMT) in CRC cells. Results: This analysis clarified that ZEB2-AS1 was upregulated in both CRC tissue sample and cells lines; meanwhile, the high expression of ZEB2-AS1 was correlated with poor overall survival rate. ZEB2-AS1 knockdown significantly suppresses the EMT in CRC cells. Furthermore, the authors identified that the expression of ZEB2-AS1 was negatively correlated with expression of miR-1205, and CRKL could be a direct target of miR-1205. Through the gain-of-function experiments, they found that ZEB2-AS1 accelerates EMT in CRC cells via modulating the expression of miR-1205 and CRKL. Conclusion: Taken together, this study revealed that ZEB2-AS1 accelerates EMT in CRC through the miR-1205/CRKL pathway, suggesting that ZEB2-AS1 may potentially serve as a target of CRC.

In search of a dose-response relationship with radiotherapy in the management of recurrent rectal carcinoma in the pelvis: a systematic review

PURPOSE

A systematic review of the literature was undertaken to address the question: "What is the most effective dose fractionation schedule for the relief of symptoms in patients with pelvic recurrence from rectal or colorectal carcinoma?"

METHODS AND MATERIALS

Cancerlit/Medline-computerized databases were searched between the years 1966-1996. Studies that explored the response to radiotherapy in patients with pelvic recurrence from rectal/rectosigmoid carcinoma were included. Factors that may contribute to differences in results were postulated in advance and the variations encountered between articles were presented. Articles with data applicable to recurrent disease only were included in the primary analysis. The effect of including articles that reported outcomes of recurrences with unresectable primaries and residual disease was presented as a sensitivity analysis.

RESULTS

Only retrospective series (level V evidence) were available. The many sources of potential bias inherent in retrospective analyses make the data suitable for hypothesis generation only. Comparison of response was made between "lower" vs. "higher" doses, using 45-50 Gy as the dividing dose, base on the primary analysis. There were no significant differences observable in terms of initial response and the proportion maintaining a response at 6 months, within the range of doses employed. When data from articles that reported outcomes of recurrent disease with primary untreated cancers and postoperative residual disease were included, there was a suggestion for a more favorable response with higher doses. This requires cautious interpretation within the methodological limitations of the data.

CONCLUSION

The optimal dose fractionation schedule for the palliation of pelvic recurrence from rectal carcinoma remains undefined. Well-designed randomized studies, with study arms that are sufficiently diverse biologically to allow the detection of a dose-response relationship if one existed, equipped with suitable symptom control end points, are necessary to provide a clinically relevant answer.

Intraoperative radiotherapy for primary and recurrent rectal cancer

A total of 40 primary and 20 recurrent adenocarcinomas of the rectum were treated. Intraoperative radiation therapy was combined with pre- or postoperative irradiation and 5-FU and leucovorin treatment. An abdomino-perineal excision was performed in 32 and an anterior resection in 26 cases. A Hartmann's procedure was performed in two patients. Forty-two tumours were completely resected. Residual disease was microscopically detectable in 10 cases. In eight patients, tumour residual was evident macroscopically. Postoperatively, wound infection was observed in six and anastomotic dehiscence in four cases. After a follow-up of 20 months, 46 patients revealed no evidence of disease. Local recurrences and distant metastases were detected in two patients each. Ten patients died of their disease.

A randomized feasibility study evaluating the effect of radiotherapy alone or combined with 5-fluorouracil in the treatment of locally recurrent or inoperable colorectal carcinoma

The effect of radiotherapy alone or given simultaneously with 5-FU in the treatment of locally recurrent or inoperable colorectal carcinoma was investigated in a randomized feasibility trial. Twenty-nine patients were randomized to radiotherapy alone (50 Gy/5 weeks + 10-20 Gy boost), and 30 patients to the same radiotherapy with weekly 5-FU (600 mg/m2) given before treatment every Monday during the first 5 weeks. The two groups were comparable with regard to age, sex, previous treatment, symptoms, tumour size and performance status. Treatment compliance to radiotherapy was the same in both groups with 87% receiving at least 50 Gy. Drug treatment was completed in 18/30 patients. Overall the treatment resulted in a significant palliative effect in 73% of evaluable patients with a median duration of 26 months, and objective response in 32% (8 CR, 11 PR), with a median duration of 18 months. The 3-year actuarial survival rate was 9% (median 12 months). Only patients who achieved CR became long-time survivors (63% 3-year actuarial survival). Similarly, performance status had a strong association with survival. Multivariate analysis showed complete response and high performance status to be the only parameters having prognostic influence on survival. Addition of 5-FU did neither influence the objective or symptomatic response, nor the development of distant metastases. However, addition of the drug resulted in an apparent increase in the frequency of severe acute radiation complications (33% vs. 13% after irradiation alone).