Adjuvant therapy of resectable rectal cancer

Effects of gamboge in an orthotopic mouse model of colon cancer

AIM: To study the antitumor and anti-metastatic effects of gamboge in an orthotopic mouse model developed with human colon cancer cell line HCT116.

METHODS: A colon cancer model was developed by surgical orthotopic implantation of green fluorescent protein (GFP)-expressing HCT 116 tumor in nude mice. Forty mice were equally randomized into four groups. Group 1 served as a negative control and received intragastric infusion of normal saline once daily. Group 2 received intraperitoneal injection of 5-fluorouracil at a dose of 25 mg/kg three times per week. Groups 3 and 4 received intragastric infusion of gamboge extract at a dose of 10 and 20 mg/kg, respectively, once daily. Each animal was checked for mortality and signs of morbidity every day. Primary tumor volume and metastasis for each animal were observed under a fluorescence imaging system twice a week, and body weights were measured as well. At the end of the experiment, all mice were sacrificed and open fluorescent images of tumors and metastases expressing GFP were acquired, and the tumor was removed from each mouse and weighed.

RESULTS: After initiation of different treatment regimens, the average tumor volume (mm³) was significantly smaller in the gamboge (20 mg/kg) group than the control group at each observation point (d4: 104.5 ± 35.5 vs 164.1 ± 66.1; d7: 102.6 ± 53.8 vs 286.2 ± 132.0; d11: 137.6 ± 70.5 vs 324.4 ± 115.8; d14: 207.2 ± 101.7 vs 434.2 ± 169.3; d21: 229.8 ± 99.8 vs 480.4 ± 165.5; P < 0.05 for all). At the end of the study, the average tumor weight was significantly smaller in the gamboge group (20 mg/kg) than in the control group (0.58 ± 0.26 vs 0.92 ± 0.26, P < 0.05). There were no statistical differences between the gamboge (20 mg/kg) group and 5-fluorouracil group, as well as between the gamboge (10 mg/kg) group and control group, in term of average tumor volume and weight (P > 0.05 for all). At the end of the experiment, open GFP imaging demonstrated that all groups presented metastasis of lymph nodes or the pancreas, although there were no significant differences between the four groups with regard to the metastasis rate (P > 0.05 for all). No significant morbidity or weight loss was found in all tumor-bearing mice.

CONCLUSION: Gamboge at a dose of 20 mg/kg was able to suppress HCT 116 tumor growth in an orthotopic mouse model of colon cancer safely and effectively, and may possess clinical therapeutic potential for colorectal cancer.

Chemoradiotherapy and adjuvant chemotherapy for rectal cancer

Local recurrence is an important factor in determining the outcome of patients after surgery for rectal cancer, and various attempts have been made to reduce the local recurrence rate. Randomized controlled trials have shown that radiotherapy combined with total mesorectal excision can reduce the local recurrence rate in rectal cancer patients who undergo curative surgery. Chemoradiotherapy is more effective in achieving local control than radiotherapy alone, and preoperative chemoradiotherapy is superior to postoperative chemoradiotherapy in terms of adverse events. Recent advances have led to the identification of potential therapeutic targets such as epidermal growth factor receptor, vascular endothelial growth factor, and endothelial receptors. These new agents have been used in combination with conventional chemoradiotherapy, and higher pathological complete response rates have been reported for such combinations in comparison with conventional regimens. With regard to lateral node dissection, a recent study showed that postoperative chemoradiotherapy was more effective in reducing the local recurrence rate than lateral node dissection. As for adjuvant chemotherapy, one randomized controlled trial showed that patients who received uracil and tegafur as adjuvant therapy had significantly prolonged relapse-free survival times and overall survival times. As well, one metaanalysis has shown the efficacy of oral uracil-tegafur as adjuvant chemotherapy for rectal cancer.

The role of radiation therapy for colorectal cancer

Radiation therapy (RT) has been used to treat cancers for more than a century. Recent randomized trials have helped clarify the treatment recommendations in the use of RT for colorectal cancers. This article reviews these trials to illustrate key concepts, places these trials in perspective, and provides direction for future research.

Angiogenesis in colorectal cancer: prognostic and therapeutic implications

Angiogenesis is important for tumor growth and metastasis. This account reviews the clinicopathological studies conducted in the field of angiogenesis in colorectal cancer, the methods of assessing vascular-related characteristics in tissue sections and provides a background for the usefulness of antiangiogenic policies along with chemotherapy and radiotherapy. Highly angiogenic colorectal tumors are associated with aggressive histopathological features and poor patients' survival. Similarly, factors stimulating angiogenesis, such as vascular endothelial growth factor (VEGF), thymidine phosphorylase (TP), and others, are commonly related to increased vascular density (VD) and, therefore, to an unfavorable clinical course. Anti-VEGF agents have improved prognosis in patients with metastatic colorectal cancer, when added to standard chemotherapy. It is expected that, in addition to adjuvant chemotherapy and radiotherapy, agents blocking the stimulatory effect of VEGF on endothelial cells would prove beneficial to the patient.

Lactate dehydrogenase 5 expression in operable colorectal cancer: strong association with survival and activated vascular endothelial growth factor pathway--a report of the Tumour Angiogenesis Research Group

PURPOSE

Lactate dehydrogenase 5 (LDH-5) regulates, under hypoxic conditions, the anaerobic transformation of pyruvate to lactate for energy acquisition. Several studies have shown that serum LDH may be an ominous prognostic marker in malignant tumors. The clinical significance of tissue LDH-5, however, remains largely unexplored.

PATIENTS AND METHODS

We investigated the immunohistochemical expression of LDH-5 in a series of 128 stage II/III colorectal adenocarcinomas treated with surgery alone. In addition, markers of tumor hypoxia (hypoxia-inducible factor 1 alpha [HIF1alpha]), angiogenesis (vascular endothelial growth factor [VEGF] and phosporylated kinase domain receptor [pKDR]/flk-1 receptor) and the tumor vascular density (CD31 positive standard vascular density [sVD] and pKDR positive activated vascular density [aVD]) were assessed.

RESULTS

The expression of LDH-5, together with that of HIF1alpha and pKDR, was both nuclear and cytoplasmic. Assessment, with minimal interobserver variability, was achieved using a previously described scoring system. LDH-5 was significantly associated with HIF1alpha (P = .01), aVD (P = .001) and, particularly, with pKDR expression in cancer cells (P = .0001). Tissue LDH-5 expression was linked with elevated serum LDH levels, but serum levels failed to reflect tissue expression in 71% of LDH-5 positive cases. In univariate analysis tissue LDH-5 was associated with poor survival (P = .0003, HR 15.1), whereas in multivariate analysis this isoenzyme was the strongest independent prognostic factor (P = .0009). VEGF, pKDR, aVD, sVD and vascular invasion were all significantly related to unfavorable prognosis.

CONCLUSION

The immunohistochemical assessment of tissue LDH-5 and pKDR provides important prognostic information in operable colorectal cancer. The strong association between LDH-5 and pKDR expression would justify their use as surrogate markers to screen patients for tyrosine kinase inhibitor therapy.

Inclusion of Vasculature-Related Variables in the Dukes Staging System of Colon Cancer

PURPOSE

The Dukes stage is used to stratify colorectal cancer patients into groups of different prognosis and need of adjuvant radiotherapy and chemotherapy. However, approximately 80% of patients with Dukes stage C colorectal cancer receive cytotoxic therapy without any expected benefit, for such patients would either not relapse without adjuvant therapy or they would inevitably do so because of tumor resistance to the available regimens. On the other hand, as 20% of Dukes stage B patients would relapse after surgery, adjuvant therapy could improve their survival. Improvement of the Dukes stage predictive accuracy is necessary to better assign patients for adjuvant therapies, especially nowadays when antiangiogenic agents are being incorporated in the clinical practice.

PATIENTS AND METHODS

In this study, we examined the prognostic role of Dukes staging system in parallel with three vasculature-related variables (vascular invasion, tumor angiogenic activity, and vascular survival ability) in a series of 130 stage B/C patients with colorectal cancer treated with surgery alone (without adjuvant radiotherapy or chemotherapy).

RESULTS

Inclusion of vasculature-related variables in the Dukes staging system significantly improved the prognostic categorization of patients, identifying subgroups of B-stage and C-stage patients with an up to 40% and 60% 5-year survival difference, respectively.

CONCLUSIONS

Preliminary results show that the prognostic value of Dukes staging system is significantly improved after taking into account vasculature-related variables, which may be useful in stratifying patients for adjuvant therapies, highlighting also subgroups that may benefit the most from antiangiogenic agents.

Assessment of the prognostic factors for a local recurrence of rectal cancer: the utility of preoperative MR imaging

Objective

To determine the utility of MR imaging in evaluating the prognostic factors for a local recurrence of rectal cancer following a curative resection.

Materials and Methods

The preoperative MR images obtained from 17 patients with a local recurrence and 54 patients without a local recurrence, who had undergone a curative resection, were independently evaluated by three radiologists. The following findings were analyzed: the direct invasion of the perirectal fat by the primary rectal carcinoma, involvement of the perirectal lymph nodes, perirectal spiculate nodules, perivascular encasement, and an enlargement of the pelvic wall lymph nodes. The clinical and surgical profiles were obtained from the patients??medical records. The association of a local recurrence with the MR findings and the clinicosurgical variables was statistically evaluated.

Results

Of the MR findings, the presence of perivascular encasement (p = 0.001) and perirectal spiculate nodules (p = 0.001) were found to be significant prognostic factors for a local recurrence. Of the clinicosurgical profiles, the presence of a microscopic vascular invasion (p = 0.005) and the involvement of the regional lymph nodes (p = 0.006) were associated with a local recurrence. Logistic regression analysis showed that the presence of perirectal spiculate nodules was an independent predictor of a local recurrence (odds ratio, 7.382; 95% confidence interval, 1.438, 37.889; p = 0.017).

Conclusion

The presence of perirectal spiculate nodules and perivascular encasement on the preoperative MR images are significant predictors of a local recurrence after curative surgery for a rectal carcinoma. This suggests that preoperative MR imaging can provide useful information to help in the planning of preoperative adjuvant therapy.

Oxaliplatin

Oxaliplatin is available in numerous countries for the treatment of metastatic colorectal cancer (in conjunction with fluoropyrimidine therapy). The activity of oxaliplatin in advanced disease has led to investigation of its potential in operable disease. The addition of oxaliplatin to adjuvant therapy with fluorouracil and folinic acid (FOLFOX4 regimen) is associated with a significantly greater disease-free survival at 3 years (78% vs 73%; p = 0.002), according to results of the MOSAIC (Multicenter International Study of Oxaliplatin/5FU/Leucovorin [folinic acid] in the Adjuvant Treatment of Colon Cancer) trial, a study in 2246 patients with stage II or III colon cancer. In addition, a 23% reduction in the risk of disease recurrence after surgery was seen with FOLFOX4 compared with fluorouracil/folinic acid in the MOSAIC trial. Results from several phase I/II studies suggest that the addition of oxaliplatin to preoperative radiochemotherapy may be of benefit in patients with locally advanced lower rectal cancer in terms of disease downstaging and sphincter preservation. Oxaliplatin was generally well tolerated in the MOSAIC trial and neuro- and myelotoxicity with FOLFOX4 were manageable.

Impact of Preoperative Staging and Chemoradiation Versus Postoperative Chemoradiation on Outcome in Patients With Rectal Cancer: A Decision Analysis

BACKGROUND

Although radical resection and postoperative chemoradiation have been the standard therapy for patients with rectal cancer, preoperative staging by local imaging and chemoradiation are widely used. We used a decision analysis to compare the two strategies for rectal cancer management.

METHODS

We developed a decision model to compare survival outcomes after postoperative chemoradiation versus preoperative staging and chemoradiation in patients aged 70 years with resectable rectal cancer. In the postoperative chemoradiation strategy, patients undergo radical resection and receive postoperative chemoradiation. In the preoperative staging and chemoradiation strategy, patients with locally advanced cancer receive preoperative chemoradiation and radical resection, whereas those with amenable localized tumors undergo local excision. The cohorts of patients were entered into a Markov model incorporating age-adjusted and disease-specific mortality. Outcomes were evaluated by modeling 5-year disease-specific survival for preoperative chemoradiation as less than, equal to, or greater than that of postoperative chemoradiation. Base-case probabilities were derived from published data; the Surveillance, Epidemiology, and End Results (SEER) Program database; and U.S. Life Tables. One-way and two-way sensitivity analyses were performed. The outcome measures were life expectancy and quality-adjusted life expectancy.

RESULTS

Life expectancy and quality-adjusted life expectancy were 9.72 and 8.72 years, respectively, in the postoperative chemoradiation strategy. In the preoperative staging and chemoradiation strategy, life expectancy was 9.36, 9.72, and 10.09 years and quality-adjusted life expectancy was 8.71, 9.04, and 9.37 years when 5-year disease-specific survival was less than, equal to, or greater than that of postoperative chemoradiation, respectively. The decision model was sensitive to differences in the long-term toxicity of pre- and postoperative chemoradiation. When the 5-year disease-specific survival for patients after pre- or postoperative chemoradiation was equal, the decision model was sensitive to surgical mortality and to the probability of residual lymph node disease after local excision.

CONCLUSION

If efficacy and toxicity after preoperative chemoradiation are equal to or better than that after postoperative chemoradiation in patients with locally advanced rectal cancer, then preoperative staging to select patients appropriate for preoperative chemoradiation is beneficial.