Rate of conversion from unresectable to resectable metastatic colorectal cancer (mCRC) in real-world patients (RWP) treated with FOLFIXIRI ± bevacizumab: A population-based retrospective cohort study.

Abstract

21 Background: Recent evidence from randomized trials suggests that FOLFOXIRI (5FU, oxaliplatin, and irinotecan) ± bevacizumab is associated with higher response rates with a potential for conversion of unresectable to resectable disease in mCRC. Yet limited evidence is available about efficacy and safety of this regimen in RWP with mCRC. The current study aims to evaluate conversion rate and safety of FOLFOXIRI ± bevacizumab in RWP with unresectable mCRC. Methods: Each year about 175 patients are diagnosed with mCRC in Saskatchewan. Patients who were diagnosed with unresectable mCRC between Jan 2015 to Dec 2018 and received FOLFOXIRI ±bevacizumab were assessed. Kaplan Meier survival methods and log rank test were performed. Logistic regression analysis was performed to assess factors correlate with conversion. Results: 28 eligible patients with median age of 51 yrs (IQR:39-60) and M:F of 11:16 were identified. 42% patients had a comorbid illness, and 43% had WHO performance status of 0. 39% had rectal cancer, 46% had extrahepatic disease and 46% had bilobar liver metastases. 58% patients had a positive response to therapy, 60% had grade 3/4 toxicity & 32% required hospital admission. No treatment-related mortality was noted. 54% patients underwent metastasectomy (liver 73%, peritoneum and or ovaries 20%, lung 6%). 68% had primary tumor resection, 29% received rectal radiation, 21% had ablation and 18% had second surgery for recurrence. At 4 years 50% patients are alive. Median progression free survival of patients who underwent surgery is 18 (95%CI:11.3-24.7) vs. 11 months (4-18.1) without surgery (P = 0.28). Median overall survival of patients with surgery is 33 (17.5-48.5) vs. 16 months (8.3-23.7) without surgery (P = 0.03). Positive response to treatment is correlated with conversion (odd ratio 21.7, p = 0.002). Conclusions: In the real world setting younger patients with good performance status received FOLFIRINOX ± bevacizumab. Despite high rates of toxicity, more than half of patients were able to undergo surgery. A positive response to treatment significantly correlates with metastasectomy.