Epidermal Growth Factor Receptor Inhibitor Treatment Timing does not Impact Survival in Stage 4 Colon Cancer Treatment: A Retrospective Study

EGFR Inhibitor Treatment Line Outcomes

Abstract

Introduction. Colon cancer impacts the lives of Kansans and those across the United State.^{(1, 2)} Epidermal growth factor receptor (EGFR) inhibitors, such as panitumumab and cetuximab, have gained popularity as first-line treatment for stage 4 colon cancer despite their toxicities.^(3-5) EGFR inhibitors are an efficacious first-line treatment for stage 4 colon cancer, but no study has investigated outcomes comparing EGFR inhibitors as first-line treatment to it used as second- or third-line treatment. This study investigates EGFR inhibitor therapy estimated survival when used as first-, second-, and third-line.

Methods. A retrospective review was done for patients with stage 4 colon cancer who underwent EGFR inhibitor treatment at a large academic center from November 2007 to August 2021. The patients were stratified into five groups by the line in which they received the EGFR inhibitor treatment. A log-rank test was used to analyze the groups, and the median survival for each group was determined.

Results. A total of 68 patients were reviewed; 18 received first-line, 23 received second-line, 18 received third-line, 6 received fourth-line, and 3 received sixth-line treatment with an EGFR inhibitor. Fourth- and sixth-line therapies were excluded due to the small patient size. There was no significant difference in estimated survival time between any of the lines. Median survival of the therapies was found.

Conclusions. There is no statistical difference in survival when EGFR inhibitors are used as first-, second-, or third-line for stage 4 colon cancer which should be considered when prescribing chemotherapy second- or third-line for this cancer.