Study findings point to an independent association between HER2-positivity and poor rates of disease-free survival (DFS) among patients with stage II colon cancer and no high-risk factors, according to data being presented at the virtual 2021 American Society of Clinical Oncology (ASCO) Annual Meeting.

“We examined the frequency, tumor characteristics, and prognostic impact of HER2 protein expression in stage II and III colon cancer after curative resection,” explained lead investigator Zehua Wu, MD, Sixth Affiliated Hospital of Sun Yat-sen University, Guangzhou, China, and colleagues.

Between April 2013 and May 2020, the researchers evaluated paraffin-embedded tumors from 2088 consecutive patients with primary stage II and III colon for HER2 expression using immunohistochemistry.

“HER2 determination of immunohistochemistry scores (0/1+/2+/3+) was according to HERACLES diagnostic criteria,” Dr Wu et al said.

Among the patients in the study, 53.8% had stage II disease whereas 46.3% had stage III. According to the findings, 48 (2.3%) tumors had HER2 scored positive (3+), and this expression correlated with younger age (P <.001), well/moderate differentiation (P = .026), proficient mismatch repair (pMMR; P = .045), and KRAS wild-type (P <.001).

Of note, HER2 scored positive (3+) was not found to be significantly associated with DFS tumors that scored HER2 negative (0/1+) in patients with stage III (multivariable hazard ratio [HR], 0.86; 95% CI, 0.38-1.94; P = .717) or stage II (multivariable HR, 1.68; 95% CI, 0.74-3.84; P = .218) disease.

“In a separate analysis involving stage II patients without any high-risk factor (n = 741), those with HER2 scored positive (3+) tumors (n = 16) showed significantly reduced DFS (multivariable HR, 2.91; 95% CI, 1.04-8.81; P = 0.041) compared with patients with HER2 scored negative (0/1+) tumors, independent of sex, age and MMR status,” the researchers reported.

“HER2 scored positive (3+) was independently associated with poor DFS in stage II colon cancer patients without high-risk factors. HER2 expression determination may help to judge the prognosis of those patients and guide adjuvant chemotherapy,” they concluded.—Hina Porcelli

Wu Z, Hu H, Deng Y. Association of HER2 expression with pathologic features and prognosis in stage II and III colon cancer. Presented at: the 2021 ASCO Annual Meeting; June 4-8, 2021; virtual. Abstract 3524.