HER2 EXPRESSION AS A PROGNOSTIC FACTOR IN METASTATIC GASTRIC CANCER

ABSTRACT

Background

- Human epidermal growth factor receptor 2 (EGFR2/HER2/ErbB2) is a transmembrane receptor that stimulates cell proliferation when activated. The correlation of HER2 expression with prognosis has been studied in many cancer types. However, its relationship with survival of patients with metastatic gastric cancer remains unknown. Moreover, there is a lack of information on this issue in a Brazilian population.

Objective

- To assess the proportion of patients whose tumor cells express HER2 and correlate this with clinical characteristics as well as treatment outcomes.

Methods

- This was a retrospective study. We included adult patients with metastatic gastric cancer treated at an University Hospital between 2011 and 2015. Patients did not receive anti-HER2 therapy. Receptor expression was evaluated by immunohistochemistry. Survival risk factors were assessed individually with univariate Cox regression, and a P value <0.05 was considered statistically significant.

Results

- Forty-nine patients were included in this study. However, only 32 had samples assessed for HER2 expression. Five (16%) patients were positive. Among HER2-negative patients, the average age was 54 years, 44% received a treatment protocol with three drugs, 70% had a performance status score 0-1, and 41% had well or moderately differentiated histology. Among HER2-positive patients, the average age was 58 years, 40% received three drugs, 100% had a performance status score 0-1, and 67% had well or moderately differentiated histology. Response rate was evaluated in 28 cases, and there was no difference between the groups (HER2-negative 52% vs. HER2-positive 40%; P=0.62). Survival outcomes were numerically worse among HER2-positive patients. Median progression-free survival was 8.3 months for HER2-positive patients and 10.6 months for HER2-negative patients (HR 1.61, 95% CI: 0.59-4.38); median overall survival was 14.8 months and 16.9 months for HER2-positive and HER2-negative patients, respectively (HR 1.52, 95% CI: 0.50-4.66).

Conclusion

- HER2 overexpression in metastatic gastric cancer patients may be a predictor of poor prognosis and further validation is warranted.

HEADINGS -
Stomach neoplasms; Receptor ErbB2; Drug therapy; Molecular targeted therapy.