Clinical trial to assess the relative efficacy of fluorouracil and leucovorin, fluorouracil and levamisole, and fluorouracil, leucovorin, and levamisole in patients with Dukes' B and C carcinoma of the colon: results from National Surgical Adjuvant Breast and Bowel Project C-04

Adjuvant therapy in colon cancer: current status and future directions

The role of adjuvant chemotherapy in patients with stage III colon cancer is now well established and 5-FU/LV should be the reference regimen to which new drugs are tested against in the adjuvant setting. In stage II colon cancer, because the risk of recurrence is lower, any absolute benefit of chemotherapy is likely to be less than in stage III disease. The studies performed so far have been generally underpowered to detect what might be a clinically significant effect on survival. Molecular profiling of tumours may identify individuals more likely to benefit from adjuvant therapy and tailor individual treatment in the future. After potential curative treatment for localised colon cancer, about two out of five patients will experience disease recurrence, but the most effective strategies for follow-up remain to be established. New drugs such as irinotecan, oxaliplatin and oral fluoropyrimidines may offer improved efficacy or patients' convenience in the adjuvant setting and their impact on survival will be evaluated in the recently closed large randomised studies. This review summarises the current status of adjuvant therapy in colon cancer and describes the future directions for research.

Adjuvant chemotherapy for colorectal cancer

Colorectal cancer is the second leading cause of cancer death in Western countries. If surgery remains the only cure, recurrence rates for colon cancer range from 30% to 60% for stage III tumors. Adjuvant chemotherapy is the standard treatment for stage III colon tumors and consists of monthly administration of bolus 5-fluorouracil and leucovorin for 5 consecutive days a month over a 6-month period (Mayo regimen). Adjuvant chemotherapy for stage II colon cancer remains controversial, and its administration is not routinely recommended except in certain high-risk and selected patients. Immunotherapy, new drug-based therapies or combinations, and cyclooxygenase-2 inhibitors are being tested in the adjuvant setting. Total mesorectum excision is now the gold standard surgical technique for rectal cancer resection, and this procedure has dramatically decreased local recurrence. Nevertheless, adjuvant chemoradiotherapy is commonly indicated in the United States. In Europe, neoadjuvant radiotherapy is recommended for stage II and III resectable rectal cancers; the role of chemotherapy remains mostly investigational.

Chemotherapy for colorectal cancer

With effective chemotherapy as adjuvant treatment, the survival benefit is clearly achieved for certain (stage III) colorectal cancer patients, though there still exist many unsettled issues including the controversies in the treatment of stage II disease. Advances in the development of a new generation of cytotoxic agents in the past several years have allowed us to move forward from the "fluorouracil-only era" in the treatment of advanced/metastatic colorectal cancer. It is still not very clear how best to minimize toxicity without compromising efficacy of the combination therapy with newer agents, or how to maximize the benefit of chemotherapy (concurrent versus sequential). There are many current ongoing clinical trials designed to address these issues. With better understanding of the signal transduction and molecular biology characteristics of colorectal cancer, and the development of biologic and molecular target agents, the outcomes of patients with colorectal cancer will be improved further. Future clinical trials should be focused on optimizing and individualizing therapy for patients based on their molecular profiles to achieve maximal clinical benefit.

Adjuvant treatment of colorectal cancer (current expert opinion derived from the Third International Conference: Perspectives in Colorectal Cancer, Dublin, 2001)

This article summarises the progress that has been made in the adjuvant treatment of colorectal cancer over the last decade. In view of the consequent improvements in recurrence rates and in overall survival, the development of effective adjuvant treatments for colorectal cancer is considered as one of the most important to be made in clinical oncology over the last decade. Treatment recommendations based on evidence-based data and on expert opinions are summarised in this manuscript. However, a consensus cannot be reached on all aspects of treatment because of data that is currently emerging that will influence clinical practice and because of the many ongoing clinical trials. Those involved in the treatment of colorectal cancer should therefore be encouraged to continue to provide optimal patient care and to participate in well designed clinical trials in order to increase the evidence upon which they can base their clinical judgements and in order to make further progress.

Recent and ongoing clinical trials for treating colorectal cancer

Colorectal cancer is one of the most common cancers worldwide. Through well-designed clinical trials, advances have been made in the treatment of localised and advanced colorectal cancer. It has been established that 6 months of 5-fluorouracil-based chemotherapy will improve overall survival in patients with stage III colon cancer. The role of adjuvant chemotherapy in stage II colon cancer remains an unresolved issue. Recent studies have demonstrated an improved survival with the addition of irinotecan to 5-fluorouracil and leucovorin for the treatment of advanced colorectal cancer. Immunotherapy, molecular targeted therapy and liver-directed therapy, in addition to new chemotherapy combinations, are all being evaluated for the treatment of localised and advanced colorectal cancer. Ongoing and proposed studies are incorporating the identification of genetic and molecular abnormalities, which may provide prognostic information as well as direct treatment decisions.

Efficacy and toxicity of adjuvant chemotherapy in elderly patients with colon carcinoma: a 10-year experience of the Geisinger Medical Center

BACKGROUND

Although the benefit from adjuvant chemotherapy has been established clearly in patients with Stage III colon carcinoma, the degree to which elderly patients with colon carcinoma can tolerate such therapy generally has remained unknown.

METHODS

The authors reviewed all patients in their Tumor Registry with Stage II and Stage III adenocarcinoma of the colon who underwent potentially curative resection for their disease at the Geisinger Medical Center between January 1990 and September 2000. One hundred twenty patients underwent complete resection of their colon carcinoma and received 5-fluorouracil-based (5-FU) adjuvant chemotherapy.

RESULTS

The 5-year disease free survival rate for patients age > or =65 years (Group A) was 70% compared with 56% for patients age < 65 years (Group B) (P = 0.085). The 5-year overall survival rate for patients in Group B was 77% compared with 62% for the patients in Group A (P = 0.143). In a Cox regression model, age was not a predictor of disease free survival (P = 0.633) or overall survival (P = 0.900) when it was analyzed as a continuous variable. Only 19 patients were age > 75 years, and the disease free and overall survival rates for this group were similar but were underpowered compared with the rates for the patients ages between 65-75 years. When gender and disease stage were included in the model, age remained a nonsignificant variable (P = 0.400 for disease free survival; P = 0.615 for overall survival). Nine of 56 patients in Group A (16%) experienced Grade 3-4 toxicity compared with 14 of 64 patients in Group B (22%) (P = 0.420). The lack of a correlation between toxicity and age was maintained after controlling for disease stage and patient gender (P = 0.343). There were no correlations between preoperative carcinoembryonic antigen level, tumor grade, or lymph node involvement and patient age (P = 0.258, P = 0.256, and P = 0.519, respectively).

CONCLUSIONS

Elderly patients with Stage II and Stage III colon carcinoma benefit from 5-FU-based adjuvant therapy without a significant increase in toxicity compared with their younger counterparts. Adjuvant chemotherapy should be presented to elderly patients with high-risk, resected colon carcinoma. The data regarding age cannot be generalized to patients age > 75 years.

Adjuvant chemotherapy for colon cancer

Colorectal cancer is one of the most frequent cancers in the world, especially in occidental countries. The primary curative therapy is surgical resection of the tumour. Within the last 15 years, appropriately powered prospective randomized trials have demonstrated that adjuvant post-operative chemotherapy should be the standard treatment for stage III cancers (node-positive disease). 5-Fluorouracil(5FU)/levamisole was used in the early 1990s but has now been replaced by 5FU/leucovorin. The recommended duration of treatment is 6 months. Combining levamisole with 5FU/leucovorin does not improve efficacy. In patients with stage II colon cancer it is still unclear whether adjuvant chemotherapy is effective. In an attempt to define groups of stage II cases that may benefit from adjuvant chemotherapy, considerable efforts have been made to determine molecular genetic factors (tumour-ploidy and mutations or alterations in oncogenes and tumour-suppressor genes). Regional therapy (particularly portal vein infusion) is one of the other therapeutic strategies still considered to be investigational. Current clinical trials are evaluating the role of non-fluorinated pyrimidine agents in an adjuvant setting.

Construct validity of medicare chemotherapy claims: the case of 5FU

BACKGROUND

The elderly are under represented in clinical trials of cancer therapy and the elderly who are enrolled may be unrepresentative.

OBJECTIVE

To assess whether Medicare claims data might be used to understand the benefits and tolerance of chemotherapy in the general elderly population, the construct validity of Medicare 5FU claims for elderly colon cancer patients within the SEER-Medicare data set was determined.

METHODS

In this validation study of Medicare chemotherapy claims from the linked the SEER-Medicare data set, the patterns of 5FU chemotherapy claims were evaluated for an incident cohort of elderly colon cancer patients (n = 15,039) during the 13 months following their diagnosis. Patterns of Medicare National Claims History (NCH) 5FU claims were evaluated with respect to prespecified patient-level disease and demographic factors from the data set.

RESULTS

Twenty-two percent of patients had at least one detectable 5FU claim during the observation period. Among those patients, the median dose of 5FU was 1000 mg, the median interval between 5FU claims was 7 days, and the median number of claims during this period was 24. Multivariate regression revealed expected associations between demographic and disease factors and the likelihood of having a Medicare NCH 5FU claim. With increasing cancer stage, patients' likelihood of having a 5FU claim increased. Younger patients, married patients, white patients, patients with low comorbidity, and patients living in urban and less impoverished regions were each more likely to have 5FU claims.

CONCLUSION

Because their pattern is consistent with the standard of medical care and with previously described associations with disease and demographic factors, it was concluded that Medicare NCH claims for 5FU administration in the SEER-Medicare data set exhibit construct validity. Criterion validation studies with an external gold standard should be pursued to determine the sensitivity and specificity of chemotherapy codes in the Medicare NCH files.

Age, sex, and racial differences in the use of standard adjuvant therapy for colorectal cancer

PURPOSE

Dissemination of efficacious adjuvant therapies for resectable colorectal cancer has not been comprehensively described. Trends, patterns, and outcomes of adjuvant therapy for colorectal cancer, focusing on age, sex, and racial/ethnic differences, are reported.

MATERIALS AND METHODS

Population-based random samples of patients diagnosed with colorectal cancer diagnosed in nine geographic areas were collected annually between 1987 and 1991 and in 1995 (n = 4,706). Data were obtained from medical record reviews. Multiple logistic regression was used to assess the use of standard adjuvant chemotherapy for colon and rectal cancers. The Cox proportional hazards model was used to assess 9-year mortality.

RESULTS

From 1987 until 1995, the use of adjuvant therapy increased in all age groups. There was an increase starting in 1989 for colon and in 1988 for rectal cancer. Use of standard therapy was 78% for those younger than 55 years and 24% for those older than 80 years. White patients received standard therapy more frequently than African-Americans (odds ratio, 1.75; 95% confidence interval [CI], 1.09 to 2.83). All-cause and cancer-specific mortality exceeding 9 years were lower in those who received standard therapy (all-cause risk ratio [RR], 0.73; 95% CI, 0.61 to 0.88; cancer-specific RR, 0.87; 95% CI, 0.70 to 1.09).

CONCLUSION

Standard adjuvant therapies for colorectal cancer disseminated into community practices during the 1990s. However, evidence exists of differential use of therapies by older patients and by African-Americans. The use of standard therapies in the general population is associated with lower mortality. Improved dissemination of standard adjuvant therapies to all segments of the population could help reduce mortality.

Adjuvant therapy of colon cancer: a review

Colon cancer is a common cause of cancer-related mortality. Complete surgical resection of the primary tumor and/or select metastatic lesions can be curative in many patients. The risk of recurrence after resection can be predicted by pathologic staging. Large prospective randomized trials over the past 2 decades have clearly shown an increased overall survival for patients with resected stage III colon cancer who are treated with adjuvant 5-fluorouracil-based chemotherapy. The benefit of adjuvant chemotherapy for patients with stage II disease remains controversial. There is indirect evidence to support adjuvant chemotherapy after resection of metastatic disease. Locoregional approaches such as radiation, hepatic arterial infusion, or portal vein chemotherapy remain investigational. Adjuvant immunotherapy with monoclonal antibodies is emerging as a therapeutic option that might complement chemotherapy. Future challenges include improving adjuvant chemotherapy with the addition and/or substitution of new agents, resolving which subset of patients with stage II and resected stage IV colon cancer might benefit from therapy, validating the benefit of immunotherapy, and investigating locoregional therapies compared with systemic therapy.

Chemotherapy in colorectal cancer: new options and new challenges

Colorectal cancer is the second most common cause of cancer-related mortality in Europe and North America. Studies conducted in the last two decades have established the role of adjuvant therapy in stage III colon cancer. However, there is currently no international consensus with the role of adjuvant treatment in stage II disease. The introduction of irinotecan, oxaliplatin, oral fluoropyrimidines and raltitrexed has broadened the treatment options available for patients with advanced colorectal cancer. The integration of these drugs with the new molecular targeted therapies such as epidermal growth factor receptor, cyclooxygenase, angiogenesis and matrix metalloproteinase inhibition will form the basis of clinical research in the next few years and may, in the future, impact on the survival of patients with colorectal cancer. This review will focus on the place of chemotherapy in colorectal cancer, but not its role in combination with radiotherapy in rectal cancer.

Randomized clinical trials in colon cancer

Prospective randomized trials involving the surgical and chemotherapeutic treatment of resectable colon cancer are reviewed. Emphasis is placed on those trials that have impacted the current management of primary colon cancer.

Thymidylate synthase expression in stage II and III colon cancer: a retrospective review

This study is a retrospective analysis of thymidylate synthase (TS) levels in patients with stage II (T3 or T4) and III colon cancer. Two groups of patients were identified: one undergoing surgery alone (98 patients) and the second receiving adjuvant 5-fluorouracil chemotherapy (112 patients). TS analyses were carried out using the 106 monoclonal antibody and a published grading system dividing staining into high and low intensity. The distribution of patients with low versus high TS levels was similar in the two groups. There was no association between TS staining intensity and grade, stage or location of primary. Seventy-nine patients have relapsed: 46 (48%) in the surgery only group, 33 (30%) in the adjuvant therapy group (median follow-up: 51 and 61 months). Similar proportions relapsed when analyzed according to TS: in the surgery only group, 41% of patients with low TS, 48% with high TS; in the adjuvant group, 31% with low TS, 30% with high TS. In the surgery only group, a trend toward improved disease-free survival (DFS) was seen in the low TS group (84 versus 63% at 2 years, p = 0.08). No difference was seen in overall survival. There were no differences in DFS or overall survival in patients receiving adjuvant therapy according to TS intensity. The trend for worse outcome in patients with high TS is consistent with previous reports. The lack of difference in outcome for patients with low and high TS receiving chemotherapy suggests that high TS levels may predict greater benefit from adjuvant treatment.

Adjuvant 5FU plus levamisole in colonic or rectal cancer: improved survival in stage II and III

Based on the first favourable results of adjuvant therapy of 5FU plus levamisole in Dukes C colonic cancer in 1990, we conducted a prospective trial. 1029 patients were randomised to receive one year 5FU plus levamisole or no further treatment following curative surgery for stage II or III colon (n = 730) or rectal cancer (n = 299). 45% were in stage II and 55% in stage III. With a median follow-up of 4 years and 9 months a significant reduction in odds of death (25%, SD 9%, P = 0.007) was observed for those with adjuvant treatment (65% at 5 year) compared to the observation group (55%). Improved relative survival was present in stage III (56% vs 44%), and in stage II patients (78% vs 70%). In rectal cancer a non-significant difference in disease-free or overall survival was observed. Distant metastases developed in 76%, while local recurrence alone occurred in 14%. An early start of adjuvant treatment (< 4 weeks) did not affect results. Compliance to 5FU plus levamisole was 69%. Severe toxicity did not occur. In conclusion, one year 5FU plus levamisole was of benefit in stage II and III colonic cancer; in rectal cancer a significant positive effect could not be demonstrated.

Clinical experience with edrecolomab: a monoclonal antibody therapy for colorectal carcinoma

Edrecolomab (monoclonal antibody 17-1A) is a murine monoclonal antibody that recognizes the human tumor-associated antigen Ep-CAM (otherwise known as 17-1A). It is being developed for the adjuvant treatment of colorectal cancer. In a study of 189 patients with resected stage III colorectal cancer, treatment with edrecolomab resulted in a 32% increase in overall survival compared with no treatment (P<0.01) and decreased the tumor recurrence rate by 23% (P<0.04). In terms of safety, edrecolomab was well tolerated. Based on these study results, edrecolomab is currently under investigation in large multicenter phase III studies both as monotherapy and in combination with 5-fluorouracil-based chemotherapy versus chemotherapy alone for the treatment of stage III colon cancer. Although these studies are still ongoing, an interim analysis of safety data indicated that the combination of edrecolomab with chemotherapy is well tolerated. In addition, edrecolomab monotherapy demonstrated a favorable safety profile compared with chemotherapy. Edrecolomab is also currently being tested in large multicenter adjuvant phase III studies in stage II/III rectal cancer and stage II colon cancer. Edrecolomab represents a novel therapeutic approach and has the potential to become a treatment of choice as monotherapy in stage II colon cancer and in combination with chemotherapy in stage II/III rectal and stage III colon cancer.

Mortality associated with irinotecan plus bolus fluorouracil/leucovorin: summary findings of an independent panel

PURPOSE

To review and assign attribution for the causes of early deaths on two National Cancer Institute-sponsored cooperative group studies involving irinotecan and bolus fluorouracil (5-FU) and leucovorin (IFL).

PATIENTS AND METHODS

The inpatient, outpatient, and research records of patients treated on Cancer and Leukemia Group B protocol C89803 and on North Center Cancer Treatment Group protocol N9741 were reviewed by a panel of five medical oncologists not directly involved with either study. Each death was categorized as treatment-induced, treatment-exacerbated, or treatment-unrelated.

RESULTS

The records of 44 patients who experienced early deaths on C89803 (21 patients) or N9741 (23 patients) were reviewed. Patients treated with irinotecan plus bolus 5-FU/leucovorin had a three-fold higher rate of treatment-induced or treatment-exacerbated death than patients treated on the other arm(s) of the respective studies. For C89803, these rates were 2.5% (16 of 635) for IFL versus 0.8% (five of 628) for bolus weekly 5-FU and leucovorin. For N9741, these rates were 3.5% (10 of 289) for IFL, 1.1% (three of 277) for oxaliplatin plus bolus and infusional 5-FU and leucovorin, and 1.1% (three of 275) for oxaliplatin plus irinotecan. Multiple gastrointestinal toxicities that often occurred together were characterized into a gastrointestinal syndrome. Sudden, unexpected thromboembolic events were characterized as a vascular syndrome. The majority of deaths in both studies were attributable to one or both of these syndromes.

CONCLUSION

Close clinical monitoring, early recognition of toxicities and toxicity syndromes, aggressive therapeutic intervention, and withholding therapy in the presence of unresolved drug-related toxicities is recommended for patients receiving IFL or other intensive chemotherapy regimens.

Monthly 5-days 5-fluorouracil and low-dose leucovorin for adjuvant chemotherapy in colon cancer

We investigated the dose-related effect of the 5-fluorouracil (5-FU)/leucovorin regimen on survival in 139 colon cancer patients with Dukes' B2 and C2 stage disease. Chemotherapy consisted of 400 mg/m(2) of 5-FU and 20 mg/m(2) of leucovorin injected daily for 5 days in every 4 weeks for a maximum of 12 cycles. The total dose of 5-FU administered per body surface area had a significant effect on the 5-year disease-free survival and 5-year overall survival in stage B2 and C2 colon cancer patients (P=0.0018, P=0.0011). Analysis with reference to the median DSDI demonstrated that there was a significant difference in 5-year survival in Dukes' C2 (P=0.0016), but survival was not affected by the dose intensity. Multivariate analysis demonstrated that only the total dose of 5-FU administered per surface area affected the 5-year disease-free survival and 5-year overall survival (P=0.0016, P=0.0007, respectively). It can be concluded that the total dose of 5-FU administered is important in planned dosage schedule of adjuvant chemotherapy in colon cancer.

High-Dose Fluorouracil and Leucovorin: Weekly Continuous Infusions for Metastatic Colorectal Cancer

The increasing complexity of cancer chemotherapy makes it mandatory that pharmacists be familiar with these highly toxic agents. This column reviews various issues related to the preparation, dispensing, and administration of cancer chemotherapy, both commercially available and investigational.

Adjuvant chemotherapy for colon cancer

Colon cancer remains the third most common cancer, and cause of cancer-related death in the United States. Greater public awareness and acceptance of screening programs have contributed significantly to increasingly earlier detection of colon cancer and decreased mortality. Advances made in the understanding of this disease, both in terms of its clinical behavior and molecular pathogenesis, have translated into major improvements in its therapy. Several large randomized trials during the last two decades have helped the oncology community forge a successful multi-modality treatment strategy against colon cancer. These studies have defined the role of adjuvant therapy for colon cancer after curative surgery. Despite all the advances, a large number of patients continue to succumb to this disease, and the search for better therapies is still necessary. In this article, we discuss the evolution and the current state of adjuvant chemotherapy in colon cancer and briefly review new developments.

Weekly Fluorouracil and Leucovorin as Adjuvant Therapy for Early Stage Colon Cancer or Primary Therapy for Advanced Colorectal Cancer

The increasing complexity of cancer chemotherapy makes it mandatory that pharmacists be familiar with these highly toxic agents. This column reviews various issues related to the preparation, dispensing, and administration of cancer chemotherapy, both commercially available and investigational.

A Critical Appraisal of Treatment for T3N0 Colon Cancer

The purpose of this study was to evaluate the impact of adjuvant chemotherapy on survival after surgery for T3N0 colon cancer. All patients with node-negative (N0) colon cancer with tumor invasion beyond the muscularis propria (T3) treated with colectomy between 1982 and 1995 at a single institution were included. Patients were divided into two groups depending on postcolectomy treatment with or without adjuvant chemotherapy. Groups were evaluated to determine perioperative and pathologic variables that could potentially influence outcome and surveillance data to determine disease-free and overall survival. In 253 patients with T3N0 colon cancer 226 remained under observation and 27 were treated with adjuvant chemotherapy. The groups were similar ( P = not significant) when compared for tumor location, size, differentiation, number of nodes harvested, and transfusion requirements. Four of the 27 patients who received chemotherapy developed a recurrence (14.8%), whereas 22 of the 226 observation patients developed a recurrence (9.7%). Disease-free survival for the chemotherapy group at 5 years was 84 per cent and for the observation group 87 per cent. Statistical analysis (Mantel-Cox) showed no significant difference between the groups on the basis of survival ( P = 0.3743). We conclude that resection alone is a highly effective treatment for T3N0 colon cancer leaving limited opportunity for adjuvant chemotherapy to significantly impact survival. Adjuvant chemotherapy for T3N0 colon cancer patients should be limited to patients enrolled in clinical trials designed to identify subgroups of T3N0 colon cancer patients at a survival disadvantage or less toxic adjuvant chemotherapies.

National Surgical Adjuvant Breast and Bowel Project trials in colon cancer

During the last decade, the National Surgical Adjuvant Breast and Bowel Project (NSABP) has completed six adjuvant chemotherapy trials comparing different adjuvant therapy regimens or adjuvant therapy versus surgery alone. A seventh trial is ongoing. These trials have contributed to defining the role of adjuvant therapy in colon cancer. Patients eligible for inclusion in NSABP trials had been diagnosed as having stage II or III colon cancer with no evidence of gross residual or metastatic disease. The follow-up strategies were similar in the reported trials with follow-up every 3 months for the first 2 years, then every 6 months for the next 3 to 5 years, and annually thereafter. The NSABP C-01 protocol was a three-arm trial comparing an adjuvant semustine/vincristine/5-fluorouracil (5-FU) regimen (MOF) to a Bacille Calmette-Guerin treatment, and to surgery alone. The C-02 protocol investigated whether portal vein infusion of 5-FU improved survival outcome compared with surgery alone. Protocol C-03 compared a semustine/vincristine/5-FU regimen to a 5-FU plus leucovorin (LV) (5-FU/LV) regimen. The NSABP C-04 protocol was a three-arm trial comparing 5-FU/LV, 5-FU plus levamisole, and 5-FU/LV plus levamisole. The NSABP C-05 trial compared 5-FU/LV to 5-FU/LV plus alpha-interferon. Results of NSABP C-01, C-02, C-03, C-04, and C-05 trials are summarized in this report. Patient accrual has completed in the NSABP C-06 trial comparing 5-FU/LV with oral tegafur and plus uracil leucovorin. The NSABP is currently conducting another trial (C-07) comparing 5-FU/LV with 5-FU/LV plus oxaliplatin. The role of adjuvant chemotherapy in stage II colon cancer is also discussed in this report. A recent pooled analysis of studies C-01, C-02, C-03, and C-04 has indicated that the relative treatment benefit in stage II disease is at least equal to the benefit in stage III colon cancers, and concluded that adjuvant chemotherapy also should be considered as the standard of care for stage II colon cancer patients.

Should Dukes' B patients receive adjuvant therapy? A statistical perspective

The benefit of adjuvant therapy, such as 5-fluorouracil (5-FU) combined with leucovorin, is a matter of debate for patients with Dukes' B colon cancer. Several approaches have been taken to address this issue. Initially, studies were conducted to assess treatment benefits in both Dukes' B and Dukes' C patients. These studies identified an overall benefit of adjuvant treatment and enrolled enough Dukes' C patients to determine a treatment benefit for adjuvant 5-FU/leucovorin in this subpopulation. However, the individual studies were insufficiently powered to detect a treatment benefit in Dukes' B patients. An analysis of four separate studies (National Surgical Adjuvant Breast and Bowel project) compared the benefit of adjuvant treatment in Dukes' B patients with that in Dukes' C patients and showed similar relative reductions in mortality and disease-free survival in Dukes' B and in Dukes' C patients. The Liver Infusion Meta-Analysis Group also reported similar relative benefits from a portal vein infusion of 5-FU-based chemotherapy in Dukes' B and Dukes' C patients. The International Multicenter Pooled Analysis of Colon Cancer Trials B2 study, which combined data from patients with Dukes' B colon cancer in five separate trials, failed to show a statistically significant benefit of adjuvant 5-FU/leucovorin compared with surgery alone. We review the advantages and limitations of different approaches to detect treatment benefits in patients with Dukes' B colon cancer, and we argue that there is a need for a meta-analysis of all adjuvant trials to reliably address this question.

A United Kingdom coordinating committee on cancer research study of adjuvant chemotherapy for colorectal cancer: preliminary results

Standard adjuvant chemotherapy for colorectal cancer consists of 5-fluorouracil with leucovorin or levamisole. The large, multicenter, randomized, double-blind QUASAR (Quick and Simple and Reliable) trial investigated whether treatment with a higher dose of leucovorin or the addition of levamisole to 5-fluorouracil and leucovorin improved survival. In the QUASAR study, 4,927 patients with colorectal cancer with no evidence of residual disease following resection, were randomized to receive fluorouracil (370 mg/m2) with high-dose (175 mg) or low-dose (25 mg) leucovorin and either levamisole (50 mg) or placebo. The fluorouracil and leucovorin regimen was given either monthly (as six 5-day courses with 4 weeks between the start of each course) or weekly (as 30 once-weekly doses). Levamisole or placebo was given three times daily for 3 days, repeated every 2 weeks for 12 courses. The primary endpoint was death from any cause. Survival was similar with both high- and low-dose leucovorin (70.1% v 71.0% at 3 years; P = .43) as well as recurrence rates (36.0% v 35.8%; P = .94), and with levamisole compared with placebo (69.4% v 71.5%; P = .06) as well as recurrence rates (37.0% v 34.9%; P = .16). Monthly and weekly treatments were equally effective (although this was a nonrandomized comparison), while weekly treatment was associated with significantly fewer toxic effects (neutropenia, mucositis, and diarrhea). High-dose leucovorin was not associated with a survival or recurrence benefit when compared with low-dose leucovorin. The ongoing QUASAR-1 trial aims to establish whether adjuvant chemotherapy has any worthwhile survival benefit in colorectal cancer patients with an uncertain indication following surgical resection.

Randomized adjuvant study comparing two schemes of 5-fluorouracil and leucovorin in stage B2 and C colon adenocarcinoma: study design and preliminary safety results. Groupe d'Etude et de Recherche Clinique en Oncologie Radiotherapies

The aim of this randomized open-label study was to compare a bimonthly with a monthly regimen of 5-fluorouracil (5-FU) and leucovorin for the adjuvant treatment of colon and high-rectum adenocarcinoma. The bimonthly regimen was administered for 2 consecutive days every 14 days as d,L-leucovorin 200 mg/m2 or L-leucovorin 100 mg/m2 as a 2-hour infusion followed by 5-FU bolus of 400 mg/m2 and a 600 mg/m2 5-FU 22-hour continuous infusion (LVSFU2). In the monthly regimen, d,L-leucovorin 200 mg/m2 or L-leucovorin 100 mg/m2 15-minute infusion followed by a 400 mg/m2 15 minute 5-FU bolus was administered for 5 consecutive days every 28 days (FUFOL). Nine hundred five patients with recently resected stage B2 or C colon or high-rectum adenocarcinoma (inferior pole of the tumor subperitoneal) were recruited into the study. Patients were randomized in a 2 x 2 factorial design to receive either LV5FU2 or FUFOL for 24 or 36 weeks. Characteristics of the patients in the two different treatment groups were similar at baseline. Compliance was good. Mean 5-FU dose intensities were 930 mg/ m2/wk and 463 mg/m2/wk for LVSFU2 and FUFOL, respectively. The incidence of maximal grade III-IV toxicities for LVSFU2 and FUFOL was neutropenia 6% and 16% (P < .001), diarrhea 4% and 10% (P < .001), and mucositis 2% and 7% (P < .001), respectively. Maximum grade III-IV toxicities in the LV5FU2 treatment group were significantly lower than in the FUFOL group (10% v 26%; P < .001). Although patients in the LV5FU2 group received twice the dose of 5-FU compared with those in the FUFOL group, LV5FU2 was shown to be less toxic. Efficacy data will be available in 2001.

Adjuvant treatment of colorectal cancer at the turn of the century: European and US perspectives

BACKGROUND

Despite early scepticism, several studies of systemic adjuvant 5-fluorouracil (5-FU)-based chemotherapy demonstrated significant benefits in high-risk colon cancer. As many clinical investigations have since been conducted in this setting, a comprehensive literature review was undertaken to clarify the role of adjuvant therapy in the treatment of colorectal cancer.

DESIGN

Current and future adjuvant treatment approaches in colorectal cancer were reviewed, and differences in the present-day North American and European practices were highlighted.

RESULTS AND CONCLUSIONS

5-FU plus leucovorin for six months is generally considered the 'standard' adjuvant treatment in Dukes' stage C (stage II) colon cancer. Large-scale international trials of other strategies are required to provide further advances in treatment outcome. Following the lead of the USA Intergroup trials, a recently initiated cooperative effort, the Pan-European Trials in Adjuvant Colon Cancer (PETACC), may serve as a European model for such investigations. In T3 and/or lymph-node positive rectal cancer, postoperative (chemo)radiotherapy in the USA is considered the adjuvant treatment of choice. However, most European investigators have advocated for preoperative intensive short-course irradiation instead. Randomized trials in this area are ongoing. In the near future, new drugs for the treatment of colorectal cancer may lead to tailored therapies.

Immunomodulation therapy in colorectal carcinoma

There has been much progress in the understanding of the relationship between the immune system and colorectal cancer. This has led to the use of immunomodulatory therapy in the adjuvant and palliative treatment of the condition. Although attempts at the use of non-specific immunomodulation with agents such as levamisole, cimetidine, alpha interferon and Bacillus Calmette-Guerin (BCG) have not produced significant clinical benefits when tested in randomized trials in both the adjuvant setting and for metastatic disease, promising results are being obtained with more specific therapy. Edrecolomab [corrected], a murine monoclonal antibody targeting the 17-1A antigen on malignant colorectal cells has produced a reduction in relapse and mortality rates when used as adjuvant treatment following surgery for Dukes' C colon cancer. Active specific therapy with autologous tumour vaccine administered with BCG has produced similar benefits in Dukes' B cancer. Both 3H1 anti-idiotypic antibody against carcinoembryonic antigen and 105AD7 antibody to gp72 glycoprotein have demonstrated in-vitro and in-vivo immune activation against tumour. Non-randomized studies postulate prolongation of survival using these antibodies in advanced disease. These agents are all currently being tested in randomized studies powered to detect meaningful survival differences and clinical benefit. Immune therapy offers the potential of low toxicity therapy in colorectal cancer and may have a role as an adjunct to conventional chemotherapy.

Comparison of fluorouracil with additional levamisole, higher-dose folinic acid, or both, as adjuvant chemotherapy for colorectal cancer: a randomised trial. QUASAR Collaborative Group

BACKGROUND

Standard adjuvant chemotherapy for colorectal cancer consists of fluorouracil with folinic acid or levamisole. The large QUASAR randomised trial aimed to investigate (in a two x two design) whether use of a higher dose of folinic acid or addition of levamisole to fluorouracil and folinic acid improved survival.

METHODS

Patients with colorectal cancer, without evident residual disease, were randomly assigned fluorouracil (370 mg/m2) with high-dose (175 mg) or low-dose (25 mg) L-folinic acid and either active or placebo levamisole. The fluorouracil and folinic acid could be given either as six 5-day courses with 4 weeks between the start of the courses or as 30 once-weekly doses. Levamisole (50 mg) or placebo was given three times daily for 3 days repeated every 2 weeks for 12 courses. The primary endpoint was mortality from any cause. Analyses were by intention to treat.

FINDINGS

Between 1994 and 1997, 4,927 patients were enrolled. 1,776 had recurrences and 1,576 died. Survival was similar with high-dose and low-dose folinic acid (70.1% vs 71.0% at 3 years; p=0-43), as were 3-year recurrence rates (36.0% vs 35.8%; p=0.94). Survival was worse with levamisole than with placebo (69.4% vs 71.5% at 3 years; p=0.06), and there were more recurrences with the active drug (37.0% vs 34.9% at 3 years; p=0.16).

INTERPRETATION

The inclusion of levamisole in chemotherapy regimens for colorectal cancer does not delay recurrence or improve survival. Higher-dose folinic acid produced no extra benefit in these regimens over that from low-dose folinic acid. Trials of chemotherapy versus no chemotherapy will show whether these four treatments are equally effective or equally ineffective.

Biostatistics in the new millennium: a consulting statistician's perspective

This article attempts to predict the future for biostatistics and biostatisticians in the twenty-first century. Life will certainly be more complex and there will be growth in population, large corporations, and globalization generally. However, there will continue to be problems relating to biology, medicine, health and the environment, so biostatisticians can surely play an important role, if they are willing to adapt to changing circumstances. Personal views are expressed concerning those areas of most recent development that seem likely to be continued in the coming years: applications (clinical trials, epidemiology, vital statistics), philosophies, models, advances in computing, and the profession of biostatistics.