Harry S. Wieand

BACKGROUND: Radiation therapy as an adjunct to surgery for rectal cancer has been shown to reduce local recurrence but has not improved survival. In a previous study, combined radiation and chemotherapy improved survival significantly as compared with surgery alone, but not as compared with adjuvant radiation, which many regard as standard therapy. We designed a combination regimen to optimize the contribution of chemotherapy, decrease recurrence, and improve survival as compared with adjuvant radiation alone. METHODS: Two hundred four patients with rectal carcinoma that was either deeply invasive or metastatic to regional lymph nodes were randomly assigned to postoperative radiation alone (4500 to 5040 cGy) or to radiation plus fluorouracil, which was both preceded and followed by a cycle of systemic therapy with fluorouracil plus semustine (methyl-CCNU). RESULTS: After a median follow-up of more than seven years, the combined therapy had reduced the recurrence of rectal cancer by 34 percent (P = 0.0016; 95 percent confidence interval, 12 to 50 percent). Initial local recurrence was reduced by 46 percent (P = 0.036; 95 percent confidence interval, 2 to 70 percent), and distant metastasis by 37 percent (P = 0.011; 95 percent confidence interval, 9 to 57 percent). In addition, combined therapy reduced the rate of cancer-related deaths by 36 percent (P = 0.0071; 95 percent confidence interval, 14 to 53 percent) and the overall death rate by 29 percent (P = 0.025; 95 percent confidence interval, 7 to 45 percent). Its acute toxic effects included nausea, vomiting, diarrhea, leukopenia, and thrombocytopenia. These effects were seldom severe. Severe, delayed treatment-related reactions, usually small-bowel obstruction requiring surgery, occurred in 6.7 percent of all patients receiving radiation, and the frequencies of these complications were comparable in both treatment groups. CONCLUSIONS: The combination of postoperative local therapy with radiation plus fluorouracil and systemic therapy with a fluorouracil-based regimen significantly and substantively improves the results of therapy for rectal carcinoma with a poor prognosis, as compared with postoperative radiation alone.

BACKGROUND: The combination of radiation therapy and chemotherapy with fluorouracil plus semustine after surgery has been established as an effective approach to decreasing the risk of tumor relapse and improving survival in patients with rectal cancer who are at high risk for relapse or death. We sought to determine whether the efficacy of chemotherapy could be improved by administering fluorouracil by protracted infusion throughout the duration of radiation therapy and whether the omission of semustine would reduce the toxicity and delayed complications of chemotherapy without decreasing its antitumor efficacy. METHODS: Six hundred sixty patients with TNM stage II or III rectal cancer received intermittent bolus injections or protracted venous infusions of fluorouracil during postoperative radiation to the pelvis. They also received systemic chemotherapy with semustine plus fluorouracil or with fluorouracil alone in a higher dose, administered before and after the pelvic irradiation. RESULTS: With a median follow-up of 46 months among surviving patients, patients who received a protracted infusion of fluorouracil had a significantly increased time to relapse (P = 0.01) and improved survival (P = 0.005). There was no evidence of a beneficial effect in the patients who received semustine plus fluorouracil. CONCLUSIONS: A protracted infusion of fluorouracil during pelvic irradiation improved the effect of combined-treatment postoperative adjuvant therapy in patients with high-risk rectal cancer. Semustine plus fluorouracil was not more effective than a higher dose of systemic fluorouracil given alone.

The purpose of this study was to evaluate the effectiveness of several new approaches designed to enhance the activity of fluorouracil (5-FU) in the management of advanced colorectal cancer. A total of 429 patients were randomized to one of the following regimens: single-agent 5-FU, given by standard 5-day, intensive-course intravenous bolus technique; 5-FU plus high-dose folinic acid (leucovorin) or 5-FU plus low-dose leucovorin; 5-FU plus high-dose methotrexate (MTX) with oral leucovorin rescue; 5-FU plus low-dose MTX; and 5-FU plus cisplatin (CDDP). The median survival for patients receiving 5-FU alone was 7.7 months. The high- and low-dose leucovorin plus 5-FU regimens had median survivals of 12.2 and 12.0 months, respectively, and offered a significant survival advantage over 5-FU alone with one-sided P values of .037 and .050, respectively (P = .051 for each treatment after correction for prognostic variables). The only other regimen possibly associated with improved survival was high-dose MTX plus 5-FU, with a median survival of 10.5 months (P = .21, P = .076 corrected). In addition, both high- and low-dose leucovorin plus 5-FU regimens were associated with significantly improved tumor response rates (P = .04 and .001) and significantly improved interval-to-tumor-progression rates (P = .015 and .007) when compared with 5-FU alone. Only the low-dose leucovorin plus 5-FU regimen was associated with significant (P less than .05) superiority in each of the following parameters of quality of life: performance status, weight gain, and symptomatic relief. The overall most therapeutically favorable regimen in this trial was 5-FU given with low-dose leucovorin; fortuitously, this regimen is associated with very low drug cost. Whereas this is the first study to demonstrate both improved palliation and survival for any regimen compared with 5-FU given by rapid intravenous (IV) injection for 5 consecutive days at a dose of 500 mg/m2/d in patients with advanced colorectal cancer, the magnitude of the gain is still relatively small. Our low-dose leucovorin plus 5-FU regimen is currently being studied in a national trial with the hope that this increased advanced disease activity may produce more substantive gains in the surgical adjuvant setting.

PURPOSE: A traditional end point for colon adjuvant clinical trials is overall survival (OS), with 5 years demonstrating adequate follow-up. A shorter-term end point providing convincing evidence to allow treatment comparisons could significantly speed the translation of advances into practice. METHODS: Individual patient data were pooled from 18 randomized phase III colon cancer adjuvant clinical trials. Trials included 43 arms, with a pooled sample size of 20,898 patients. The primary hypothesis was that disease-free survival (DFS), with 3 years of follow-up, is an appropriate primary end point to replace OS with 5 years of follow-up. RESULTS: The recurrence rates for years 1 through 5 were 12%, 14%, 8%, 5%, and 3%, respectively. Median time from recurrence to death was 12 months. Eighty percent of recurrences were in the first 3 years; 91% of patients with recurrence by 3 years died before 5 years. Correlation between 3-year DFS and 5-year OS was 0.89. Comparing control versus experimental arms within each trial, the correlation between hazard ratios for DFS and OS was 0.92. Within-trial log-rank testing using both DFS and OS provided the same conclusion in 23 (92%) of 25 cases. Formal measures of surrogacy were satisfied. CONCLUSION: In patients treated on phase III adjuvant colon clinical trials, DFS and OS are highly correlated, both within patients and across trials. These results suggest that DFS after 3 years of median follow-up is an appropriate end point for adjuvant colon cancer clinical trials of fluorouracil-based regimens, although marginally significant DFS improvements may not translate into significant OS benefits.

A total of 401 eligible patients with resected stages B and C colorectal carcinoma were randomly assigned to no-further therapy or to adjuvant treatment with either levamisole alone, 150 mg/d for 3 days every 2 weeks for 1 year, or levamisole plus fluorouracil (5-FU), 450 mg/m2/d intravenously (IV) for 5 days and beginning at 28 days, 450 mg/m2 weekly for 1 year. Levamisole plus 5-FU, and to a lesser extent levamisole alone, reduced cancer recurrence in comparison with no adjuvant therapy. These differences, after correction for imbalances in prognostic variables, were only suggestive for levamisole alone (P = .05) but quite significant for levamisole plus 5-FU (P = .003). Whereas both treatment regimens were associated with overall improvements in survival, these improvements reached borderline significance only for stage C patients treated with levamisole plus 5-FU (P = .03). Therapy was clinically tolerable with either regimen and severe toxicity was uncommon. These promising results have led to a large national intergroup confirmatory trial currently in progress.