Radiation therapy for colorectal cancer

Adjuvant versus neoadjuvant chemoradiotherapy in distal rectal cancer: Comparison of two decades in a single center

OBJECTIVE

Standard surgery alone was not able to decrease local recurrence (LR) rate below 20% in rectal cancer treatment. Thus, many centers administered neoadjuvant radiotherapy (preopRTx) with or without concomitant chemotherapy for the prevention of LR. In this study, the results of 164 consecutive patients with mid- and distal rectal cancer who received surgery and adjuvant chemoradiotherapy (Group A) or neoadjuvant chemoradiotherapy (Group NA) followed by surgery are presented.

MATERIAL AND METHODS

The staging system used in this study is that of the American Joint Committee on Cancer (AJCC), also known as the TNM system. Eligible patients were required to have radiologically assessed stage 1 (only T2N0M0) to stage 3C (T4bN1-2M0) tumor with pathologically confirmed R0 resection. The surgical method was total mesorectal excision (TME). Radiotherapy was applied with daily 180 cGy fractions for 28 consecutive days. Chemo-therapy comprised 5-fluorouracil (450 mg/m(2)/d) and leucovorin (20 mg/m(2)/d) bolus at days 1-5 and 29-33.

RESULTS

Nine patients (13%) in Group NA achieved pathologic complete response (pCR). In Group NA and Group A, locoregional recurrence (LRR) rates were 6.7% and 30.8%, (p<0.001), the mean LR-free survival was 190.0±7.3 months and 148.0±11.7 months (p=0.002) and the mean overall survival (OS) was 119.2±15.3 months and 103.0±9.4 months (p=0.23), respectively. A significant difference with regard to LR has been obtained with a statistical power of 0.92. Secondary outcome measures (DFS and OS) have not been met.

CONCLUSION

Neoadjuvant chemoradiotherapy with TME is an efficient treatment protocol, particularly for the treatment of magnetic resonance imaging-staged 2A to 3C patients with two or three distal rectal adenocarcinomas. Given that a considerable proportion of patients with cT2N0M0 would develop pCR, this method of treatment can be considered for further studies.

Potential regional differences for the tolerability profiles of fluoropyrimidines

PURPOSE

We conducted a retrospective analysis of safety data from randomized, single-agent fluoropyrimidine clinical trials (bolus fluorouracil/leucovorin [FU/LV] and capecitabine) to test the hypothesis that there are regional differences in fluoropyrimidine tolerability.

METHODS

Treatment-related safety data from three phase III clinical studies were analyzed by multivariate analysis: two comparing capecitabine with bolus FU/LV in metastatic colorectal cancer (MCRC) and one comparing capecitabine plus oxaliplatin (XELOX) with bolus FU/LV as adjuvant treatment for colon cancer. The United States (US) was compared with non-US countries (all three studies) and with the rest of the world and East Asia (adjuvant study).

RESULTS

In the MCRC studies (n = 1,189), more grade 3/4 adverse events (AEs; relative risk [RR], 1.77), dose reductions (RR, 1.72), and discontinuations (RR, 1.83) were reported in US versus non-US patients. Likewise, in the adjuvant colon cancer study (n = 1,864), more grade 3/4 AEs (RR, 1.47) and discontinuations (RR, 2.09) were reported in US versus non-US patients. After further dividing non-US patients into those in East Asia and the rest of the world, differential RRs for related grade 3/4 AEs, grade 4 AEs, and serious AEs were again observed, with East Asian patients having the lowest and US patients the highest RR.

CONCLUSION

Regional differences exist in the tolerability profiles of fluoropyrimidines. More treatment-related toxicity was reported in the US compared with the rest of the world for bolus FU/LV and capecitabine in first-line MCRC and adjuvant colon cancer. In the adjuvant setting, a range of fluoropyrimidine tolerability was observed, with East Asian patients having the lowest, and US patients the highest, RR.

Treatment of colon and rectal cancer

This article discusses multimodal treatment of noncomplicated colon and rectal cancer, considerations for specific types of colon cancer, considerations that may modify the extent and technique of surgery, the role of adjuvant chemotherapy for colon adenocarcinoma and rectal cancer, and surgical treatment of complicated colorectal cancer.

Low rectal cancer: impact of radiation and chemotherapy on surgical treatment

INTRODUCTION

The aim of this study was to evaluate the impact of combined radiotherapy and chemotherapy (leucovorin and 5-fluorouracil) on the treatment of potentially resectable low rectal cancer using the following end points: 1) toxicity of this combined modality regimen; 2) clinical and pathologic response rate and local control; 3) down-staging of the tumor and its influence on the number of sphincter-saving operations; 4) disease-free interval, patterns of relapse, and overall survival.

METHODS

From 1991 to 1996, 118 patients with potentially resectable cases of histologically proven adenocarcinoma and no distant metastases were enrolled into this protocol. All patients were evaluated by clinical and proctologic examination, abdominal computed tomography, transrectal ultrasound, and chest radiography. Therapy consisted of 5,040 cGy (6 weeks) and concurrent leucovorin (20/mg/m2/day) with bolus doses of 5-fluorouracil administered intravenously at 425 mg/m2/day for three consecutive days on the first and last three days of radiation therapy. After two months, all patients underwent repeat evaluation and biopsy of any suspected residual lesions or scar tissue.

RESULTS

Median follow-up was 36 months. Toxicity of chemotherapy regimen was minimum. Thirty-six patients (30.5 percent) were classified as being complete responders. In six of these patients, complete response was confirmed by the absence of tumor in the surgical specimens (3 abdominoperineal resections and 3 proctosigmoidectomies with coloanal anastomosis). In the remaining 30 patients, confirmation of a complete response was made by the absence of symptoms, negative findings on physical examination, and biopsy, transrectal ultrasound, and pelvic computed tomographic test results during follow-up. Eighty-two patients (69.4 percent) were considered incomplete responders. Residual lesions had already been identified during the first examination in 74 patients. In the other eight patients, residual tumor was only identified after 3 to 14 months. All patients underwent surgical treatment, except one patient who refused surgery. Eighty-seven patients underwent 90 surgical procedures: local excision, 9; coloanal anastomosis, 36; abdominoperineal resection, 4; Hartmann's procedure, 1. Isolated local recurrences occurred in five patients (4.3 percent) and combined local and distant failure in eight patients (6.7 percent). Ninety patients are alive and disease-free at a median follow-up of 36 months.

CONCLUSIONS

Combined up-front chemoradiotherapy was associated with tolerable and acceptable side effects. A significant number of patients had complete disappearance of their tumors (30.5 percent) within a median follow-up of 36 months. This regimen spared 26.2 percent of patients from surgical treatment and allowed sphincter-saving management in 38.1 percent of patients who may have required abdominoperineal resection. Preliminary results of this trial suggests a reduction in the number of local recurrences and reinforces the concept that infiltrative low rectal cancer may be initially treated by chemoradiotherapy.

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.

Progress toward hormonal therapy of gastrointestinal cancer

OBJECTIVE

The authors discuss ongoing research to determine the mechanisms by which peptide hormones regulate growth of gastrointestinal cancer and ways in which this information might be used to develop noncytotoxic therapy.

SUMMARY BACKGROUND

Approximately 100,000 people die of cancer of the gastrointestinal (GI) tract each year. Surgery is curative only when the tumor is localized. Chemotherapy and radiotherapy have limited efficacy for locally advanced or widespread disease. Various peptide hormones regulate the growth of these tumors. As for breast and prostate cancer, the growth regulatory effect of these hormones is being studied as a potential mechanism of hormonal therapy.

CONCLUSION

Gut peptide hormones regulate the growth of GI malignancies through all-specific receptors and signal transduction pathways. Interruption or modification of these growth regulatory mechanisms may lead to specific noncytotoxic therapy. In combination with surgical extirpation, such hormonally based treatment may be curative of advanced GI cancer.

Management of advanced rectal cancer

If possible, palliative resection should be undertaken for advanced rectal cancer as it provides good relief of local symptoms; there is, however, little evidence that it prolongs survival. If palliative excision is not possible, endoscopic transanal resection may be used for obstructing lesions at or below the peritoneal reflection. Laser therapy is an alternative in the frail. Both procedures allow quick and effective relief of symptoms. These methods and other options for treating advanced rectal cancer are described in this review.