Clinical Characteristics of and Treatment Pattern for EGFR-Amplified Colorectal Cancer

This study aimed to compare clinicopathologic features and clinical outcomes of metastatic colorectal cancer (mCRC) based on epidermal growth factor receptor (EGFR) amplification status.

Patients with mCRC who underwent next-generation sequencing using a targeted 244-gene panel from 2016 to 2021 were identified and screened for EGFR copy numbers. Cases with at least five copies were reviewed for tumor purity adjustment, and those with an adjusted copy number of ≥ 6 were defined as EGFR-amplified (EGFR amp+). Their clinical characteristics were compared with those without EGFR amplification (EGFR amp-).

Among 2,421 patients, 35 (1.4%) were EGFR amp+. Clinical characteristics did not significantly differ according to EGFR amplification status, but EGFR amp+ cases had fewer instances of peritoneal seeding (8.6% vs. 21.8%). Overall survival (OS) tended to be better in EGFR amp+ patients compared with EGFR amp- patients (median OS [mOS], 76 vs. 37 months; p=0.145). Among 572 patients who received anti-EGFR antibody-based chemotherapy (anti-EGFR CTx) during disease course, mOS tended to be better in 16 EGFR amp+ patients (79 months) compared with 556 EGFR amp- patients (39 months, p=0.048). Seven out of 35 EGFR amp+ patients were treated with front-line anti-EGFR CTx, and their progression-free survival did not differ from that of EGFR amp- patients treated with front-line anti-EGFR CTx (20 vs. 14 months, p=0.344).

This study may suggest a favorable predictive impact of EGFR amplification in patients treated with anti-EGFR CTx. However, the benefit of front-line anti-EGFR antibody treatment in this group was not notable.