HER2 overexpression or amplification may be a potentially predictive factor for anti-HER2 response and anti-EGFR resistance in colorectal cancer (CRC). However, the prevalence of HER2 positivity in CRC patients and its correlation with clinicopathologic features are not clear.
HER2 and MMR protein expression were tested by immunohistochemistry (IHC) in formalin-fixed, paraffin-embedded samples from 4,913 consecutive CRC patients treated with surgical resection during 2011-2014 in our institution. Dual color silver-enhanced in situ hybridization (DISH) was performed in all IHC 3+/2+ cases. The scoring criteria of HER2 status in gastric cancer was used. RAS/BRAF mutation status was assessed by Sanger DNA sequencing.
HER2 positivity was found in 160/4,913 (3.3%) cases, including 68 cases (42.5%) with IHC 3+ and 92 cases (57.5%) with IHC 2+/DISH+. HER2 positivity was more common in younger patients (
To our knowledge, this is the largest study of HER2 status in Asian patients with CRC. HER2 positivity occurred in a small number of patients with CRC, related to unfavorable prognostic factors, more common in younger patients and rare in MMR deficiency cases. Compared with previous results in western population, the RAS/BRAF mutation rate of HER2 positive Chinese CRC patients seems much higher. The further study regarding molecular information of these HER2 positive CRC patients is ongoing.
Clinical trial identification
Legal entity responsible for the study
Fudan University Shanghai Cancer Center
All authors have declared no conflicts of interest.