5-Fluorouracil (5FU) with or without folinic acid (LV) in human colorectal cancer? Multivariate meta-analysis of the literature

Reversal of Resistance to Doxifluridine and Fluorouracil in Metastatic Colorectal Cancer: The Role of High-Dose Folinic Acid

The benefits from medical treatment in colorectal cancer are limited. Fluorouracil remains the only recognized drug, and how to treat unresponsive patients is still debated. To evaluate the role of folinic acid (FA) in circumvence resistance in colorectal cancer, 28 patients pretreated with fluoropyrimidine were candidated to receive one of the following schedules: fluorouracil (600 mg/m2) associated with FA (500 mg/m2) weekly for 6 weeks (Regimen A: 21 cases), or fluorouracil (370 mg/m2) plus FA (200 mg/m2) dally for 5 days every 4 weeks (Regimen B: 7 cases). Fourteen patients were pretreated with doxifluridlne, a new fluoropyrimldine derivative with a peculiar mechanism of action, and the remaining 14 patients with fluorouracil. All but 2 patients were unresponsive to first-line treatments. When the treatment began, the median age of the patients was 60 years (range, 30-68). The performance status (ECOG) was 0/1 in 25 of them, and the primary tumor was in the colon and rectum in 19 and 9 patients, respectively. Sites of disease were liver (64 %), lung (35 %), local recurrence (10 %) and peritoneum (10 %). A median of 3 cycles (range, 1-7) was delivered, and no objective response was observed in the group of patients pretreated with doxlfluridine or in the group pretreated with fluorouracil. In 5 cases a significant decrease in baseline CEA values was observed. Therapy was well tolerated, and no grade 4 toxicity was encountered. Severe toxicity was limited and included diarrhea (7 patients), stomatitis (1 patient) and nausea/vomiting (1 patient). High-dose FA has no role in reversing resistance to fluoropyrimidine, and other mechanisms of refractoriness are surely involved. FA should be associated with fluoropyrimidine as first-line therapy together with other biochemical modulators. Further rescue therapies need to be developed.

What can we learn from a meta-analysis of trials testing the modulation of 5-FU by leucovorin? Advanced Colorectal Meta-analysis Project

BACKGROUND AND DESIGN

We previously reported a meta-analysis of all randomized clinical trials comparing 5-FU to 5-FU plus intravenous d.l. leucovorin (LV) in patients with advanced colorectal cancer.

RESULTS

The meta-analysis confirmed the advantage of 5-FU/LV over 5-FU alone in terms of response rate: overall, the response rate was 11% with 5-FU alone vs 23% with 5-FU/LV (p < 10(-7)). At the same time, it was showed that tumor regression can not be considered a surrogate end point for survival in patients with advanced colorectal cancer: no significant survival advantage was observed for patients allocated to 5-FU/LV. The present paper focuses on the interest of meta-analysis to study the role of the biomodulation of 5-FU by LV. This approach is compared with the analysis of individual clinical trials in terms of power, bias and credibility. It is argued that for the meta-analysis to be reliable, individual patient data from all available studies must be used, rather than summary data extracted from published papers.

CONCLUSION

It is concluded that meta-analysis is very useful as a tool to explore and summarize available data on a given clinical problem, though its purpose is not to recommend any treatment modality. This meta-analysis has confirmed both the benefit of biomodulation of 5-FU by LV, and the limitations of the current modalities to impact significantly on overall patient survival. Further laboratory and clinical research is warranted on the biomodulation of 5-FU by LV.