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Future Directions in Adjuvant Therapy for Stage III Colon Carcinoma Published on Physicians Practice (http://www.physicianspractice.com) Future Directions in Adjuvant Therapy for Stage III Colon Carcinoma Review Article [1] | March 02, 2001 By Henry C. Pitot, MD [2] and Richard M. Goldberg, MD [3] The current recommendation for adjuvant chemotherapy for patients with newly diagnosed stage III colon cancer involves 6 months of fluorouracil (5-FU) plus low- or high-dose leucovorin. In clinical trials performed throughout Introduction olorectal cancer is the second leading cause of cancer-related death in the United States. It is the most common cause of cancer-related death in nonsmokers.[1] The estimated number of new colon cancers diagnosed in 2000 was 93,800, and that of new rectal cancers was 36,400.[2] Most patients presenting with this disease can undergo complete gross resection with the possibility of negative microscopic margins. Any residual cancer is likely microscopic in nature. Adjuvant therapy generally refers to the administration of chemotherapy and/or radiation therapy following surgery of curative intent. The goal of postoperative chemotherapy is to eradicate the invisible micrometastases that are responsible for postoperative relapses. C Despite many clinical trials from the 1950s to the 1980s, there was no convincing evidence that effective adjuvant therapy existed for patients with resected colon cancer. A meta-analysis published in 1988 showed a nonsignificant survival benefit in patients who received adjuvant treatment with fluorouracil (5-FU) that ranged from a 2.3% to 5.7% difference in 5-year overall survival for treated patients over surgical controls.[3] A small study by the North Central Cancer Treatment Group (NCCTG) published in 1989 reported on the possible benefits of levamisole (Ergamisol) in combination with 5-FU for patients with surgically treated stage II and III colon cancer.[4] Subsequent trials were performed to confirm and build upon this experience. With the introduction of many new active agents for the treatment of advanced colorectal cancer, current and future adjuvant trials will be testing a variety of new regimens. This article will briefly review clinical trials of treatments for colorectal cancer that were reported in the past decade and then focus on ongoing and future studies. Past Trials of Adjuvant Therapy The first Intergroup trial to confirm the efficacy of 5-FU and levamisole set a new standard for treatment of patients with resected node-positive colon cancer (Table 1).[5] The trial enrolled patients over 3.5 years through October 1987. The benefits of 5-FU plus levamisole in stage III disease translated into an absolute reduction in risk of recurrence of 15% with a relative-risk reduction of 41% (P < .0001). The death rate was reduced by 33% (P = .0007). No benefit was noted for the group receiving levamisole alone. Final results after a median follow-up of 6.5 years showed no loss of protection from recurrence over time.[6] Based on the initial results, the National Cancer Institute (NCI) issued a clinical update in October 1989 that stated "the therapeutic option of postsurgical observation (‘no treatment’ control groups) is no longer justifiable for NCI-sponsored adjuvant studies for Dukes’ C patients." A subsequent National Institutes of Health (NIH) consensus conference in 1990 confirmed this recommendation but concluded that optimal adjuvant therapy "has not yet been devised" and encouraged continued efforts to discover more active regimens.[7] The next generation of trials all included 5-FU and levamisole administered for 12 months as the control arm. An NCCTG trial addressed the important issue of whether 6 or 12 months of adjuvant therapy were required for patients with resected colon carcinoma.[8] After a median follow-up of 5.1 years, results showed a significant duration-by-regimen interaction. Specifically, the standard 5-FU Page 1 of 7 Future Directions in Adjuvant Therapy for Stage III Colon Carcinoma Published on Physicians Practice (http://www.physicianspractice.com) plus levamisole was inferior to 5-FU/levamisole plus leucovorin when treatment was given for 6 months (P < .01). The authors concluded that 5-FU plus levamisole for 6 months should not be used in clinical practice. The three-drug regimen for 6 months was as effective as 12 months of standard 5-FU and levamisole. The largest study of adjuvant therapy for colon cancer that has been conducted in the United States is Intergroup-0089. Of 3,759 patients enrolled, 80% had stage III colon cancer. The trial initially had a surgery-alone control arm that was discontinued in 1989 and replaced by standard 5-FU plus levamisole for 12 months. At the same time, a three-drug regimen of 5-FU, levamisole, and leucovorin for 6 months was added. The other two original study arms prescribed 5-FU with leucovorin either in the high-dose weekly leucovorin regimen developed at Roswell Park Cancer Institute or the regimen of low-dose leucovorin daily for 5 days in a row each month developed at the Mayo Clinic. Mature results of Intergroup-0089 showed that 5-year disease-free and overall survival rates were not significantly different for the various treatment strategies and schedules, except for the comparison between 5-FU and levamisole vs 5-FU, leucovorin, and levamisole.[9] Toxicity data revealed important differences among the various treatments. Regimens containing 5-FU plus low-dose leucovorin (with or without levamisole) had significantly higher incidences of stomatitis than the 5-FU/levamisole or 5-FU/high-dose leucovorin regimens (Table 2).[10] Conversely, diarrhea was more common with 5-FU and high-dose leucovorin than with 5-FU plus levamisole or 5-FU plus low-dose leucovorin. In the National Surgical Adjuvant Breast and Bowel Project (NSABP) C-04 trial, more than 2,100 patients with stage II and III colon cancer were randomly assigned to receive one of three different 5-FU regimens (Table 1).[11] The results indicated that 5-FU and high-dose leucovorin given for 8 months conferred a small disease-free survival advantage (P = .04) and a prolongation in overall survival of borderline significance (P = .07) as compared with 5-FU and levamisole for 12 months. The addition of levamisole to the 5-FU and leucovorin regimen provided no additional benefit. Based on results from these studies, clinicians treating patients with stage III colon cancer who are not enrolled in a clinical trial may choose from a variety of regimens with apparently equivalent efficacy and overall treatment durations of 6 to 12 months. Because Intergroup-0089 has shown that either of the 5-FU plus leucovorin regimens given for approximately 6 months is equivalent to 5-FU and levamisole given for 12 months, there is little reason for clinicians to use 5-FU and levamisole outside of a clinical trial setting. Current and Future Trials of Adjuvant Therapy Researchers assessing current and future directions for adjuvant treatment of resected colon cancer are using two possible approaches: Some investigators seek to improve on the toxicity profile of current standard regimens by incorporating new orally administered fluorinated pyrimidine compounds into adjuvant therapy trials. Others will investigate new chemotherapy or immunotherapy agents that have demonstrated activity in colorectal carcinoma patients. UFT A series of new orally administered fluorinated pyrimidine compounds are of particular interest in colon cancer. UFT, which was developed in the 1970s, is a combination of uracil and tegafur in a 4:1 molar concentration. Tegafur is a 5-FU prodrug, and uracil competes with 5-FU as a substrate for dihydropyrimidine dehydrogenase, an enzyme responsible for the catabolism of 5-FU. In phase II studies of UFT administered orally with the biochemical modulator leucovorin (calcium folinate) to metastatic colon cancer patients, response rates ranged from 25% to 43%.[12,13] In a phase III trial of more than 800 patients with advanced disease, UFT and oral leucovorin had similar response rates and survival to a standard intravenous (IV) regimen.[14] Use of UFT was associated with a significant decrease in grade 4 stomatitis and hematologic toxicity. The toxicity profiles observed in these studies were considered acceptable for treatment in the adjuvant setting. Page 2 of 7 Future Directions in Adjuvant Therapy for Stage III Colon Carcinoma Published on Physicians Practice (http://www.physicianspractice.com) The NSABP C-06 study is comparing the relative efficacies of 5-FU and high-dose leucovorin to UFT plus oral leucovorin. In this phase III trial, patients with resected stage II and III colon carcinoma were stratified by number of positive lymph nodes before random assignment to one of the regimens. The accrual goal of more than 1,450 patients has been satisfied and the study is currently closed with analysis pending. Preliminary toxicity assessment involving more than 470 evaluable patients indicates that both regimens are well tolerated and have similar toxicity profiles (Table 3).[15] The toxicity profile is favorable in that the oral regimen is not associated with any significant increase in hematologic or nonhematologic toxicity. This study is important because an oral treatment with efficacy equal to that of IV approaches would be preferred by many patients and physicians in the adjuvant setting. Capecitabine Capecitabine (Xeloda) is a prodrug of 5-FU that is currently approved in the United States as third-line therapy for advanced breast cancer.[16] Capecitabine is converted to 5-FU in a series of four enzymatic activation steps. In the first activation step, capecitabine is converted to 5-deoxy-5-fluorocytidine by carboxylesterase in the liver while the final activation step occurs in tumor tissue and in normal cells by the enzyme thymidine phosphorylase. Capecitabine is thought to be selectively activated to 5-FU in tumor cells because of increased amounts of thymidine phosphorylase in tumor tissue relative to normal tissue. This preferential activation in the tumor cell may increase its therapeutic index, resulting in higher cytotoxicity in colon cancer cells than in normal tissue. Ongoing trials are assessing its efficacy in patients with advanced colon cancer.[17] Capecitabine would be an excellent agent to test as adjuvant treatment of patients with resected colorectal carcinoma. Raltitrexed (Tomudex) is a quinazoline analog that began clinical development in the early 1990s. The drug is a direct, specific inhibitor of thymidylate synthetase that undergoes intracellular polyglutamination.[18] This increases the drug’s potency and allows for every-3-week dosing. Raltitrexed has demonstrated less toxicity (stomatitis, diarrhea, and leukopenia) as compared with 5-FU and high-dose leucovorin in patients with advanced colorectal cancer.[19] Although response and median survival rates were comparable, time to progression was statistically shorter in the raltitrexed group. Despite these results, the Pan-European Trials in Adjuvant Colon Cancer (PTACC) planned to enroll more than 2,700 patients with resected node-positive colon cancer in a randomized trial comparing raltitrexed and 5-FU/low-dose leucovorin. The trial opened in February 1998 and accrued more than 360 patients in the first 6 months. Unfortunately, an early safety analysis demonstrated excessive toxicity in the raltitrexed arm, primarily related to cases of lethal toxicity in patients with compromised renal function, and accrual was suspended (personal communication, D. Cunningham, study chair, June 2000). Combination regimens that include raltitrexed may offer new avenues of research for future trials of adjuvant therapy.[20] Irinotecan Irinotecan (CPT-11, Camptosar) is a potent inhibitor of topoisomerase I with demonstrated single-agent activity in advanced colorectal cancer patients who have previously received 5-FU.[21] In two studies, the combination of irinotecan with 5-FU and leucovorin resulted in a statistically significant survival advantage over standard 5-FU and leucovorin regimens (Table 4).[22,23] Toxicity was manageable in one study, with slightly more grade 3 diarrhea and vomiting and less mucositis, grade 4 neutropenia, and neutropenic fevers in the irinotecan combination arm.[22] The Cancer and Leukemia Group B (CALGB) is leading an NCI-sponsored phase III trial of irinotecan, 5-FU, and leucovorin vs 5-FU and high-dose leucovorin in resected node-positive patients. The accrual goal is 1,260 patients over 3 years. Patients are stratified according to lymph node involvement (1-3 vs ≥ 4), histology, and preoperative serum carcinoembryonic antigen levels. The schedules both involve weekly chemotherapy administration of similar duration (30 vs 32 weeks, respectively). Two European trials will also evaluate irinotecan in combination with 5-FU in the adjuvant setting. A Page 3 of 7 Future Directions in Adjuvant Therapy for Stage III Colon Carcinoma Published on Physicians Practice (http://www.physicianspractice.com) multicenter trial, with a planned enrollment of 1,800 patients with stage II and III disease, will administer one of two 5-FU/leucovorin regimens commonly used in Europe (the infusional 5-FU de Gramont regimen[24] and the high-dose 5-FU German AIO [German Cancer Society] regimen).[24,25] Investigators may choose to use either of these 5-FU regimens, and patients will be randomly assigned to receive additional irinotecan or no further therapy. A smaller French study will evaluate irinotecan in high-risk stage III patients (more than four positive nodes or any positive nodes with obstruction and/or perforation). A total of 400 patients will be randomly assigned to the de Gramont regimen with or without irinotecan. The primary end point is event-free survival at 3 years; secondary objectives are overall survival, toxicity, and quality of life. Despite the use of three different standard regimens, nearly 3,500 patients will be included in these randomized studies evaluating the role of irinotecan in resected colon cancer. Oxaliplatin Oxaliplatin is a diaminocyclohexane (DACH) platinum derivative that has demonstrated activity in advanced colorectal carcinoma. Levi and colleagues first reported results combining oxaliplatin, 5-FU, and leucovorin in a chronomodulated fashion and observed a 55% response rate in 42 patients with metastatic colorectal carcinoma.[26] These impressive phase II results led to subsequent phase III trials in Europe comparing 5-FU plus leucovorin with or without oxaliplatin. In one trial, more than 200 patients received the combination regimen in a chronomodulated fashion (Table 5).[27] In the second, larger trial, 5-FU and leucovorin were administered by bolus and short continuous infusion (de Gramont schedule) for 2 days every 2 weeks with or without oxaliplatin.[28] In both of these trials, response rates and median progression-free survivals (the primary end points in each trial, respectively) were statistically significantly different in favor of the oxaliplatin arm. However, median overall survival was not significantly different. Several explanations for these findings have been proposed, including (1) use of oxaliplatin or irinotecan in secondary salvage chemotherapy regimens, (2) use of aggressive salvage surgery in select patients enrolled in these trials, and (3) use of too small a sample to detect a survival difference. The clinical data on oxaliplatin in advanced disease have led investigators to assess oxaliplatin in the adjuvant setting. The NSABP C-07 study was initiated to compare weekly 5-FU and high-dose leucovorin with and without oxaliplatin in stage II and III colon cancer. Each study arm will consist of three 8-week cycles of 5-FU and high-dose leucovorin with oxaliplatin (85 mg/m2) given on days 1, 15, and 19 of each cycle. The projected accrual is approximately 2,500 patients over 3 years. In Europe, approximately 1,500 of a planned accrual of 2,000 patients with stages II and III disease have been enrolled in a multicenter international study of oxaliplatin/5-FU and leucovorin as adjuvant therapy for colon cancer (MOSAIC). The trial is comparing the de Gramont regimen of 5-FU and leucovorin to the same schedule with the addition of oxaliplatin (FOLFOX-4). Results of this trial will be eagerly awaited by the oncology community in the coming years. Monoclonal Antibody 17-1A Use of adjuvant immunotherapy has been an intriguing concept that has been tested in many colon cancer trials. Interferon-alpha combined with 5-FU and leucovorin was tested in NSABP C-05; the regimen only increased toxicity without improving outcomes for patients treated with immunotherapy.[29] Riethmuller and colleagues reported 7-year results of a study of monoclonal antibody therapy in patients with resected Dukes’ C colorectal cancer.[30] Monoclonal antibody 17-1A recognizes a 34-kd glycoprotein on the cell membrane of epithelial cells. The trial included 189 patients, 70 of whom had rectal cancer. Patients were randomly assigned to an observation arm or to receive monoclonal antibody treatment. After 7 years of follow-up, overall mortality was reduced by 32% (P ≤ .01) and recurrence rate decreased by 23% (P < .04). The benefits observed in this small trial were of the same order of magnitude as in the initial 5-FU and levamisole study,[5] with the therapeutic effect maintained after long-term follow-up. Page 4 of 7 Future Directions in Adjuvant Therapy for Stage III Colon Carcinoma Published on Physicians Practice (http://www.physicianspractice.com) Based on these results, a large international study was initiated. As of early 1999, more than 2,700 patients were enrolled and the trial was closed to accrual. Patients were randomly assigned to one of three treatment arms: 5-FU and low-dose leucovorin (six cycles), monoclonal antibody 17-1A (five infusions), or the combination 5-FU/leucovorin and monoclonal antibody 17-1A. This trial and a study being performed in North America of monoclonal antibody 17-1A vs no treatment in stage II patients will help determine whether monoclonal antibody 17-1A is effective adjuvant therapy and whether chemotherapy alters or enhances the immune effects of monoclonal antibody 17-1A. Carcinoembryonic Antigen Vaccine Vaccines offer an innovative approach to cancer therapy. Foon and colleagues have demonstrated clinical and immune responses in patients receiving an anti-idiotype antibody (termed CeaVac) that is an internal image of carcinoembryonic antigen (CEA).[31] Patients with CEA-positive resected or incompletely resected stage II-IV disease were treated with subcutaneous injections of CeaVac. Of 32 patients, 14 received concurrent 5-FU-based chemotherapy. All patients generated high-titer IgG (immunoglobulin G) and T-cell proliferative immune responses against CEA. The use of 5-FU did not change the quantitative or qualitative effect of the immune response. Several of these patients fared "remarkably well" according to the authors, even though patients were allowed to enter the trial up to 1 year after surgical resection. In an ideal world, adjuvant therapy would begin immediately after surgery. Thus, a cooperative group in the United States is considering conducting a large-scale clinical trial of CeaVac as adjuvant therapy for resected colon cancer, in which patients would be randomly assigned to receive 5-FU and leucovorin with or without CeaVac. Results of this trial may address whether specific immunization against the tumor-associated antigen in humans will result in beneficial immunotherapeutic antitumor effects. Summary In summary, adjuvant therapy for colon cancer is now widely accepted as a standard of care for patients with node-positive disease. The most commonly used regimens involve approximately 6 months of 5-FU and low- or high-dose leucovorin. New chemotherapy agents and immunotherapy agents offer the potential for less toxicity and/or improved overall survival for patients with stage III disease. In the coming years, thousands of patients with resected colon cancer will be enrolled in randomized clinical trials evaluating these new agents. Many of these trials will incorporate a translational component, which will help focus future innovative clinical research. With the multitude of treatment opportunities available to patients with colon cancer, the oncology community can hopefully move beyond 5-FU and leucovorin during the next decade. References: 1. Garfinkel L, Mushinski M: U.S. Cancer incidence. Mortality and survival: 1973-1996. Stat Bull 80:23-32, 1999. 2. Cancer Facts and Figures 2000. Atlanta, American Cancer Society, 2000. 3. Buyse M, Zeleniuch-Jacquotte A, Chalmers TC: Adjuvant therapy of colorectal cancer. Why we still don’t know. JAMA 259:3571-3578, 1988. 4. Laurie JA, Moertel CG, Fleming TR, et al: Surgical adjuvant therapy of large-bowel carcinoma: An evaluation of levamisole and the combination of levamisole and fluorouracil. J Clin Oncol 7:1447-1456, 1989. 5. Moertel CG, Fleming TR, MacDonald JS, et al: Levamisole and fluorouracil for adjuvant therapy of resected colon carcinoma. New Engl J Med 322:352-358, 1990. 6. Moertel CG, Fleming TR, Macdonald JS, et al: Fluorouracil plus levamisole as effective adjuvant therapy after resection of stage III colon carcinoma: A final report. Ann Intern Med 122:321-326, Page 5 of 7 Future Directions in Adjuvant Therapy for Stage III Colon Carcinoma Published on Physicians Practice (http://www.physicianspractice.com) 1995. 7. NIH Consensus Conference: Adjuvant therapy for patients with colon and rectal cancer. JAMA 264:1444-1450, 1990. 8. O’Connell MJ, Laurie JA, Kahn M, et al: Prospectively randomized trial of postoperative adjuvant chemotherapy in patients with high-risk colon cancer. J Clin Oncol 16:295-300, 1998. 9. Haller DG, Catalano PJ, MacDonald JS, et al: Fluorouracil (FU), leucovorin (LV), and levamisole (LEV) adjuvant therapy for colon cancer: Five-year final report of INT-0089. Proc Am Soc Clin Oncol 17:256a, 1998. 10. MacDonald JS: Adjuvant therapy of colon cancer. CA Cancer J Clin 49:202-219, 1999. 11. Wolmark N, Rockette H, Mamounas E, et al: 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. J Clin Oncol 17:3553-3559, 1999. 12. Pazdur R, Lassere Y, Rhodes V, et al: Phase II trial of uracil and tegafur plus oral leucovorin: An effective oral regimen in the treatment of metastatic colorectal carcinoma. J Clin Oncol 12:2296-2300, 1994. 13. Saltz LB, Leichman CG, Young CW, et al: A fixed-ratio combination of uracil and ftorafur (UFT) with low-dose leucovorin. Cancer 75:782-785, 1995. 14. Pazdur R, Douillard JY, Skillings JR, et al: Multicenter phase III study of 5-fluorouracil (5-FU) or UFT in combination with leucovorin (LV) in patients with metastatic colorectal cancer. Proc Am Soc Clin Oncol 18:263a, 1999. 15. Smith R, Wickerham DL, Wieand HS, et al: UFT plus calcium folinate versus 5-FU plus calcium folinate in colon cancer. Oncology 13(suppl 3):44-47, 1999. 16. Blum JL, Buzdar AU, LoRusso PM, et al: A multicenter phase II trial of Xeloda (capecitabine) in paclitaxel-refractory metastatic breast cancer (MBC). Proc Am Soc Clin Oncol 17:125a, 1998. 17. Cox JV, Pazdur R, Thibault A, et al: A phase III trial of Xeloda (capecitabine) in previously untreated advanced/metastatic colorectal cancer. Proc Am Soc Clin Oncol 18:265a, 1999. 18. Rustum YM, Harstrick A, Shousong C, et al: Thymidylate synthase inhibitors in cancer therapy: Direct and indirect inhibitors. J Clin Oncol 15:389-400, 1997. 19. Coccini G, Cunningham D, Van Cutsem E, et al: Open, randomized, multicenter trial of raltitrexed versus fluorouracil plus high-dose leucovorin in patients with advanced colorectal cancer. J Clin Oncol 16:2943-2952, 1998. 20. Bertino J, Schwartz GK, Kemeny N, et al: Raltitrexed (‘Tomudex’) plus 5-fluorouracil (5-FU): Improved palliation as second line therapy in patients with metastatic colorectal cancer. Proc Am Soc Clin Oncol 18:247a, 1999. 21. Von Hoff DD, Rothenberg ML, Pitot HC, et al: Irinotecan (CPT-11) therapy for patients with previously treated metastatic colorectal cancer (CRC): Overall results of FDA-reviewed pivotal US clinical trials. Proc Am Soc Clin Oncol 16:228a, 1997. 22. Saltz LB, Cox JV, Blanke C, et al: Irinotecan plus fluorouracil and leucovorin for metastatic colorectal cancer. N Engl J Med 343:905-914, 2000. 23. Doulliard JY, Cunningham D, Roth AD, et al: Irinotecan combined with fluorouracil compared with fluorouracil alone as first-line treatment for metastatic colorectal cancer: A multicentre randomised Page 6 of 7 Future Directions in Adjuvant Therapy for Stage III Colon Carcinoma Published on Physicians Practice (http://www.physicianspractice.com) trial. Lancet 355:1041-1047, 2000. 24. de Gramont A, Bosset JF, Milan C, et al: Randomized trial comparing monthly low-dose leucovorin and fluorouracil bolus with bimonthly high-dose leucovorin and fluorouracil bolus plus continuous infusion for advanced colorectal cancer: A French Intergroup study. J Clin Oncol 15:808-815, 1997. 25. Ardalan B, Chua L, Tiang EM, et al: A phase II study of weekly 24-hour infusion with high-dose fluorouracil with leucovorin in colorectal cancer. J Clin Oncol 9:625-630, 1991. 26. Levi F, Misset LL, Brienza S, et al: A chronopharmacologic phase II clinical trial with 5-fluorouracil, folinic acid, and oxaliplatin using an ambulatory multichannel programmable pump: High antitumor effectiveness against metastatic colorectal cancer. Cancer 69:893-900, 1992. 27. Giacchetti S, Perpoint B, Zidani R, et al: Phase III multicenter randomized trial of oxaliplatin added to chronomodulated fluorouracil-leucovorin as first-line treatment of metastatic colorectal cancer. J Clin Oncol 18:136-147, 2000. 28. de Gramont A, Figer A, Seymour M, et al: Leucovorin and fluorouracil with or without oxaliplatin as first-line treatment in advanced colorectal cancer. J Clin Oncol 18:2938-2947, 2000. 29. Wolmark N, Bryant J, Hyams DM, et al: The relative efficacy of 5-FU plus leucovorin (FU-LV) and 5-FU-LV plus interferon-alpha-2a in patients with Dukes’ B and C carcinoma of the colon (first report of NSABP C-05). Proc Am Soc Clin Oncol 17:255a, 1998. 30. Riethmuller G, Holz E, Schlimok G, et al: Monoclonal antibody therapy for resected Dukes’ C colorectal cancer: Seven-year outcome of a multicenter randomized trial. J Clin Oncol 16:1788-1794, 1998. 31. Foon KA, John WJ, Chakraborty M, et al: Clinical and immune responses in resected colon cancer patients treated with anti-idiotype monoclonal antibody vaccine that mimics the carcinoembryonic antigen. J Clin Oncol 17:2889-2895, 1995. Source URL: http://www.physicianspractice.com/review-article/future-directions-adjuvant-therapy-stage-iii-colon-c arcinoma Links: [1] http://www.physicianspractice.com/review-article [2] http://www.physicianspractice.com/authors/henry-c-pitot-md [3] http://www.physicianspractice.com/authors/richard-m-goldberg-md Page 7 of 7