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

Purpose: To compare clinicopathologic features and clinical outcomes of metastatic colorectal cancer (mCRC) based on EGFR amplification status.

Materials and methods: 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 5 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-).

Results: 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 76 vs. 37 months, p=0.15). 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).

Conclusion: 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.