Phase III Study of Adjuvant Chemotherapy and Radiation Therapy Compared With Chemotherapy Alone in the Surgical Adjuvant Treatment of Colon Cancer: Results of Intergroup Protocol 0130

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.

Endpoints in Adjuvant Treatment Trials: A Systematic Review of the Literature in Colon Cancer and Proposed Definitions for Future Trials

Disease-free survival is increasingly being used as the primary endpoint of most trials testing adjuvant treatments in cancer. Other frequently used endpoints include overall survival, recurrence-free survival, and time to recurrence. These endpoints are often defined differently in different trials in the same type of cancer, leading to a lack of comparability among trials. In this Commentary, we used adjuvant studies in colon cancer as a model to address this issue. In a systematic review of the literature, we identified 52 studies of adjuvant treatment in colon cancer published in 1997-2006 that used eight other endpoints in addition to overall survival. Both the definition of these endpoints and the starting point for measuring time to the events that constituted these endpoints varied widely. A panel of experts on clinical research on colorectal cancer then reached consensus on the definition of each endpoint. Disease-free survival--defined as the time from randomization to any event, irrespective of cause--was considered to be the most informative endpoint for assessing the effect of treatment and therefore the most relevant to clinical practice. The proposed guidelines may add to the quality and cross-comparability of future studies of adjuvant treatments for cancer.

Colorectal cancer

Cancers of the colon and rectum will affect 1 in 17 North Americans during their lifetime. The progress witnessed in the treatment of these cancers in recent years has been remarkable. Improvements have been realized in surgical technique, radiation therapy, and systemic therapies, particularly with the addition of oxaliplatin and irinotecan to the previously limited armamentarium of fluorouracil alone. Targeted therapies directed at the vascular endothelial growth factor pathway and the epidermal growth factor pathway are now key players in the treatment of colorectal cancer. With current-day therapies, more than 75% of patients with localized disease are recurrence free at 3 years, and up to 50% of patients with advanced unresectable disease are alive at 2 years. This review focuses on the evidence supporting the current role of chemotherapy and radiation therapy in the adjuvant management of colorectal cancers and the strategy of combining chemotherapy and biological therapy in the treatment of metastatic disease.

Colorectal cancer

Cancers of the colon and rectum will affect 1 in 17 North Americans during their lifetime. The progress witnessed in the treatment of these cancers in recent years has been remarkable. Improvements have been realized in surgical technique, radiation therapy, and systemic therapies, particularly with the addition of oxaliplatin and irinotecan to the previously limited armamentarium of fluorouracil alone. Targeted therapies directed at the vascular endothelial growth factor pathway and the epidermal growth factor pathway are now key players in the treatment of colorectal cancer. With current-day therapies, more than 75% of patients with localized disease are recurrence free at 3 years, and up to 50% of patients with advanced unresectable disease are alive at 2 years. This review focuses on the evidence supporting the current role of chemotherapy and radiation therapy in the adjuvant management of colorectal cancers and the strategy of combining chemotherapy and biological therapy in the treatment of metastatic disease.

Radiation therapy for gastrointestinal cancer

This article has reviewed the current role of radiation in the treatment of gastrointestinal malignancies and discussed the data supporting its use. Radiation treatment in this setting continues to evolve with the increasing implementation of more conformal delivery techniques. Further scientific investigation is needed to establish the optimal role of radiation and to better define its integration with novel systemic and biologic modalities.

Effects of 5-fluorouracil adjuvant treatment of colon cancer

Since the late 1980s and early 1990s, 5-fluorouracil-based chemotherapy has been the standard adjuvant treatment for Stage III colon cancer. After the initial introduction of 5-fluorouracil in standard treatment protocols, several changes have been made based on results of randomized studies on various treatment regimens, including new cytotoxic agents. In Stage II patients, the role of adjuvant chemotherapy is debatable. However, there might be a role for adjuvant treatment in certain high-risk patients. Following a search of the Medline database, the results of randomized studies on 5-fluorouracil-based adjuvant therapy are reviewed, and future therapeutic options are discussed.

Radiation therapy and combined modality treatment of gastrointestinal carcinomas

BACKGROUND

Ionizing radiation (IR) is a potent agent in enhancing tumor control of locally advanced cancer and has been shown to improve disease-free and overall survival in several entities. However, the role of radiotherapy (RT) in the treatment of gastrointestinal tumors remains controversial because of the marked radiation sensitivity of neighboring organs frequently compromising application of high doses of ionizing radiation.

METHODS

The Medline and the Cochrane Library from 1980 until 2005 were searched using subject heading (MeSH) terms including "esophageal neoplasm", "gastric neoplasm", "pancreatic neoplasm" and "rectal neoplasm", in combination with the subheadings "radiotherapy", "chemotherapy". The term, "randomized controlled trial", was used to identify randomized trials. The proceedings of the annual meeting of the American Society for Therapeutic Radiology and Oncology from 1999 to 2004 and the annual meeting of the American Society of Clinical Oncology from 1999 until 2005 were searched. Ongoing trials were identified through the Physician Data Query database (www.cancer.gov/search/clinical_trials).

RESULTS

RT in combination with surgery enhances tumor control of locally advanced cancer disease and has been shown to improve disease-free and overall survival in rectal cancer. In esophageal adenocarcinoma, survival was prolonged with pre-operative chemo-radiation in a meta-analysis. In gastric cancer, post-operative chemo-radiation can be considered after limited lymphadenectomy. Evidence for improving survival remains to be shown for pancreatic cancer and hepatobiliary carcinoma. In colon cancer, post-operative chemotherapy has proven to prolong survival. The impact of RT seems to be most prominent in the pre-operative setting in patients treated with curative intent.

CONCLUSIONS

Pre-operative RT or pre-operative chemo-radiation may be considered in individual cases, but should not be used routinely for gastro-intestinal carcinoma, except for rectal carcinoma. In many studies, pre-operative radiotherapy/chemo-radiation yielded promising results and merits validation in large controlled trials.

Adjuvant therapy in colon cancer--what, when and how?

Bolus fluorouracil and leucovorin has been accepted as the standard adjuvant therapy in stage III colon cancer for many years. New drugs such as irinotecan, oxaliplatin and oral fluoropyrimidines have all completed phase III randomised evaluation in colon cancer. Several of these studies have been reported in the last 24 months. Oxaliplatin-based chemotherapy is now emerging as the new standard of care in adjuvant treatment of stage III colon cancer. The advent of monoclonal antibodies such as cetuximab and bevacizumab has further broadened the treatment horizon for colorectal cancer and they are the focus of the on-going randomised studies in adjuvant therapy of colon cancer. In stage II colon cancer, adjuvant treatment remains controversial and is not routinely recommended in all medically fit patients by the current American Society of Clinical Oncology guidelines, except several subsets including poorly differentiated histology, T4 lesions, bowel perforation presentation and inadequately sampled lymph nodes (<13). This review focuses on the relative merits of these agents, their safety, duration of treatment, timing of commencing treatment after surgery and the role of adjuvant therapy in stage II colon cancer, thereby assisting clinicians in deciding the optimal adjuvant treatment for patients in routine clinical practice.

Advances in Treatment of Colorectal Cancer

The purpose of this review is to provide the practicing surgeon with an outline of several significant developments in colorectal cancer treatment that have affected the care of patients. This review is not intended to report on every important publication of the past few years nor is it intended to be encyclopedic. The author simply hopes to provide a useful reference for surgeons in their daily practice.

Adjuvant chemotherapy in curative resected colon carcinoma: 5-fluorouracil/leucovorin versus high-dose 5-fluorouracil 24-h infusion/leucovorin versus high-dose 5-fluorouracil 24-h infusion

BACKGROUND

Adjuvant postoperative treatment with 5-fluorouracil (5-FU) and leucovorin in curatively resected stage III colon cancer significantly reduces the risk of cancer recurrence and improves survival. The impact of continuous 5-FU with and without leucovorin on survival and tumor recurrence was analyzed in this study compared with the effects of bolus 5-FU/leucovorin.

PATIENTS AND METHODS

Patients with a curatively resected UICC stage III colon cancer were stratified according to T, N and G category and randomly assigned to receive one of the three adjuvant treatment schemes: 5-FU 450 mg/m2 and leucovorin 100 mg/m2 x 5 days every 4 weeks; six cycles, arm A; 24-h infusion of high-dose 5-FU/leucovorin 2,600 mg/m2 and 500 mg/m2, two cycles of six applications, arm B; 24-h infusion of high-dose 5-FU 2,600 mg/m2, two cycles of six applications, arm C.

RESULTS

One hundred and forty-five patients enrolled into this study were eligible. To date, 28 patients have died; 9 on arm A, 11 on arm B, and 8 on arm C (P was nonsignificant). After a median follow-up time of 45 months, there was no statistical difference in survival and tumor recurrence between the three treatment arms. Adjuvant treatment in all arms was generally well tolerated; only a minority of patients experienced grade 3 and 4 toxicities.

CONCLUSION

There is no statistical difference in efficacy and toxicity in patients receiving either high-dose 5-FU with or without leucovorin or the standard 5-FU bolus regime after a curative resection of a stage III colon cancer.

Colorectal cancer

Every year, more than 945000 people develop colorectal cancer worldwide, and around 492000 patients die. This form of cancer develops sporadically, in the setting of hereditary cancer syndromes, or on the basis of inflammatory bowel diseases. Screening and prevention programmes are available for all these causes and should be more widely publicised. The adenoma-carcinoma sequence is the basis for development of colorectal cancer, and the underlying molecular changes have largely been identified. Prognosis depends on factors related to the patient, treatment, and tumour, and the expertise of the treatment team is one of the major determinants of outcome. New information on the molecular basis of this cancer have led to the development of targeted therapeutic options, which are being tested in clinical trials. Further clinical progress will largely depend on the broader implementation of multidisciplinary treatment strategies following the principles of evidence-based medicine.