Can chemotherapy be discontinued in unresectable metastatic colorectal cancer? The GERCOR OPTIMOX2 Study.

Purpose: This study compared chemotherapy discontinuation with maintenance therapy with leucovorin and fluorouracil after six cycles of folinic acid, fluorouracil, and oxaliplatin (FOLFOX) chemotherapy in the first-line treatment of metastatic colorectal cancer.

Patients And Methods: Two hundred two patients with untreated metastatic colorectal cancer were randomly assigned to receive six cycles of modified FOLFOX7 (mFOLFOX7) followed by simplified leucovorin plus bolus and infusional fluorouracil until progression (arm 1 or maintenance arm, n = 98) or six cycles of mFOLFOX7 before a complete stop of chemotherapy (arm 2 or chemotherapy-free interval [CFI] arm, n = 104). Reintroduction of mFOLFOX7 was scheduled after tumor progression in both arms. The primary study end point was duration of disease control (DDC).

Results: Median DDC was 13.1 months in patients assigned to the maintenance arm and 9.2 months in patients assigned to the CFI arm (P = .046). Median progression-free survival (PFS) and overall survival were 8.6 and 23.8 months, respectively, in the maintenance arm and 6.6 and 19.5 months, respectively, in the CFI arm. Median duration of maintenance therapy (arm 1) and CFIs (arm 2) were 4.8 months and 3.9 months, respectively. Overall response rates were 59.2% and 59.6% for the initial FOLFOX chemotherapy and 20.4% and 30.3% for FOLFOX reintroduction in arms 1 and 2, respectively.

Conclusion: The planned complete discontinuation of chemotherapy had a negative impact on DDC and PFS compared with the maintenance therapy strategy. These results suggest that chemotherapy discontinuation cannot be decided before therapy is initiated in patients with advanced colorectal cancer.