Background: The objectives of the current study were: 1) to verify whether the addition of modulating low doses of interferon-2b (IFN) to 5-fluorouracil (5-FU) and levofolinic acid (1-FA) could improve clinical results in patients with advanced colorectal carcinoma; and 2) to evaluate the role of tumor burden and liver involvement as prognostic factors.
Methods: A total of 204 untreated patients were randomized to receive 1-FA at 100 mg/m2 and 5-FU at 375 mg/m2 for 5 consecutive days with or without IFN every 3 weeks. IFN was given subcutaneously at 3 MU/day for 7 days starting 2 days before chemotherapy administration. Patients were stratified according to the presence or absence of hepatic disease (H+ or H-) and to total tumor burden defined as "low" or "high" using an area of 10 cm2 as the cutoff value. Thus, four patient categories were obtained: Group 1: H+ > or = 10 cm2; Group 2: H+ < 10 cm2; Group 3: H- > or = 10 cm2; and Group 4: H- < 10 cm2.
Results: No differences were observed in the objective response rate (23% for the combination of 1-FA and 5-FU vs. 24% for the 1-FA, 5-FU, and IFN regimen), median duration of response (11 months vs. 10 months), time to progression (5 months in both arms), and median survival (11 months vs. 12 months). A statistically significant improvement in response rate was observed in patients with limited liver involvement versus those with massive involvement independent of the chemotherapy arm (44% vs. 22%; P = 0.02). Overall survival also was improved in patients with limited liver disease (P = 0.0001) and in those without liver involvement (P = 0.004). Multivariate analysis confirmed these data and identified response and female gender as positive prognostic factors. Toxic side effects (mainly diarrhea, mucositis, and fever) were statistically more frequent in the IFN arm.
Conclusions: The addition of low modulating doses of IFN to the regimen of 5-FU and I-FA failed to increase the response rate and survival of patients with advanced colorectal adenocarcinoma and significantly worsened toxicity. High tumor burden and the presence of liver involvement were confirmed prospectively as poor prognostic factors and should be taken in account in designing future Phase II or comparative trials.