FOLFOX and FOLFIRI Use in Stage IV Colon Cancer: Analysis of SEER-Medicare Data

Abstract

Background: Shortly after the year 2000, randomized trials demonstrated that patients with metastatic colon cancer treated with infusional 5-fluorouracil (5-FU)/leucovorin with either oxaliplatin (FOLFOX) or irinotecan (FOLFIRI) had a comparable progression-free survival benefit, superior to patients who received 5-FU/leucovorin alone. Factors associated with the initial receipt of the FOLFOX or FOLFIRI regimen are unknown. Our goal was to investigate the patterns and predictors of use for first-line FOLFOX and FOLFIRI.

Patients and methods: We used the Surveillance, Epidemiology, and End Results (SEER)-Medicare linked data set to identify patients with newly diagnosed stage IV colon cancer between the years 2005 and 2013 who received either first-line FOLFOX or FOLFIRI. We used logistic regression to assess demographic and clinical predictors for FOLFOX versus FOLFIRI. Survival was compared by Kaplan-Meier models.

Results: Overall, 3000 patients (79.3%) received FOLFOX and 785 (20.7%) FOLFIRI. FOLFOX was associated with later year of diagnosis (odds ratio [OR] = 0.66, 95% confidence interval [CI], 0.54 to 0.82 for 2011-2013 vs. 2005-2007), being female (OR = 0.82; 95% CI 0.69 to 0.98), and living in the southern region of the United States. FOLFIRI was associated with having a higher comorbidity index (OR = 1.33; 95% CI, 1.07 to 1.67 for >1 comorbidity score vs. 0). There was no survival difference observed between the two treatments.

Conclusion: The majority of SEER-Medicare patients received FOLFOX and not FOLFIRI as a first-line treatment for stage IV colon cancer. Several demographic and clinical factors were associated with the use of each specific regimen. No survival difference was detected for the 2 groups.

Keywords: Chemotherapy; First-line therapy; Health outcomes; Metastatic cancer; Survival.

Figure 1.

Kaplan-Meier curves of overall survival in SEER-Medicare patients with Stage IV colon cancer treated with FOLFOX (dashed lines) or FOLFIRI (solid lines) from 2005–2013 stratified by treatment group

Figure 2.

Kaplan-Meier curves of SEER-Medicare patients with Stage IV colon cancer comparing overall survival between patients treated with FOLFOX (dashed lines) or FOLFIRI (solid lines) from 2005–2013 stratified by tumor location a) for right sided tumors b) for left sided tumors

Figure 3.

Kaplan-Meier curves of SEER-Medicare patients with Stage IV colon cancer comparing overall survival between patients treated with FOLFOX (dashed lines) or FOLFIRI (solid lines) from 2005–2013 stratified by comorbidity a) for a Charlson comorbidity score of 0 b) for a Charlson comorbidity score of 1 c) for a Charlson comorbidity score 2