The Relationship Between HER-2 Expression Levels and 18F-FDG PET/CT Parameters in Gastric Cancer

Combining immune checkpoint inhibitors with standard treatment regimens in advanced human epidermal growth factor receptor-2 positive gastric cancer patients

BACKGROUND

Gastric cancer is one of the most common malignant tumors worldwide, with its incidence and mortality rates ranking among the highest in gastrointestinal cancers. The overexpression or gene amplification of human epidermal growth factor receptor 2 (HER-2) occurs in approximately 15%-20% of gastric cancers and serves as a critical molecular target influencing prognosis and treatment outcomes. For patients with HER-2-positive gastric cancer, trastuzumab combined with platinum-based chemotherapy has been established as the standard first-line treatment. However, despite the demonstrated clinical benefits in prolonging survival, the overall efficacy remains limited. In recent years, with the successful application of immune checkpoint inhibitors (ICIs) in various malignant tumors, combining ICIs with existing standard treatment regimens has emerged as a promising approach to enhance the therapeutic efficacy of HER-2-positive gastric cancer. Nevertheless, the efficacy and prognostic factors of ICIs combined with trastuzumab and chemotherapy in HER-2-positive gastric cancer remain unclear.

AIM

To analyze the efficacy of ICIs combined with standard treatment regimens and the prognostic factors in patients with advanced HER-2-positive gastric cancer.

METHODS

Clinical data from 104 patients with advanced HER-2-positive gastric cancer who were treated at our hospital between March 2021 and May 2023 were retrospectively analyzed. Patients were divided into a control group (n = 54, treated with trastuzumab combined with platinum-based chemotherapy as the standard regimen) and an observation group (n = 50, treated with ICIs in addition to the standard regimen). The therapeutic efficacy, survival outcomes, and adverse reactions were compared between the two groups. Univariate and Cox multivariate analyses were performed to identify factors influencing patient prognosis.

RESULTS

With a median follow-up time of 14.6 months, there were no significant differences between the two groups in terms of objective response rate or disease control rate (P > 0.05). The median progression-free survival (mPFS) and mPFS for patients with immunohistochemistry 3 + in the observation group were significantly higher than those in the control group (P < 0.05). Among patients in the observation group, those with positive programmed death-ligand 1 (PD-L1) expression had a significantly higher mPFS than those with negative PD-L1 expression (P < 0.05). Regarding adverse events, significant differences were observed between the two groups in hypothyroidism and neutropenia (P < 0.05). Cox multivariate analysis showed that Eastern Cooperative Oncology Group (ECOG) performance status, peritoneal metastasis, positive programmed death-1 expression, and treatment regimen were independent factors influencing PFS (hazard ratio > 1, P < 0.05).

CONCLUSION

ICIs combined with standard treatment regimens for patients with advanced HER-2-positive gastric cancer demonstrate favorable clinical efficacy, significantly prolonging PFS with manageable safety. ECOG performance status, peritoneal metastasis, positive PD-L1 expression, and treatment regimen are independent factors influencing PFS, warranting increased clinical attention to patients exhibiting these factors.

The relationship between HER2 status acquired from pathological data and metabolic parameters from pre-treatment [18F]FDG PET/CT in gastric adenocarcinomas

OBJECTIVE

Overexpression of Human Epidermal Growth Factor Receptor 2 (HER2) is thought to be more aggressive in gastric cancer. This study aimed to evaluate the predictability of HER2 status and other prognostic pathologic parameters using [18F]FDG PET/CT and to investigate its impact on survival.

METHODS

Pretreatment metabolic parameters measured by [18F]FDG PET/CT as a prognostic factor were retrospectively evaluated in 117 HER2-analysed patients. The relationship between pathological data, tumor metabolic characteristics, and distant metastases was examined, and the effect on survival was investigated.

RESULTS

Among the 117 patients, 17.1% were HER2-positive (HER2+), and 82.9% were HER2-negative (HER2-). There was no significant association between PET/CT parameters in the HER2+ and HER2- patient groups. HER2+ patients had higher 1- and 3-year survival expectations than HER2- patients (80%-%37.9; %47.5-%20; respectively). There was no statistically significant difference in overall survival. In Cox-regression analysis, while the presence of vascular invasion, local invasion, and distant metastasis were poor prognostic factors, HER2 was not a prognostic factor. Vascular invasion and local invasion (T3/T4) were also associated with higher SUVmax values. Patients with distant metastases had significantly higher SUVmax, SUVmean, and TLG.

CONCLUSION

This study showed no association between HER2 expression and [18F]FDG PET/CT metabolic parameters. However, regardless of HER2 status, the results indicated distant metastasis, local invasion, and vascular invasion could be associated with primary tumor metabolism. PET/CT parameters predict tumor aggressiveness and disease prognosis better than HER2 status.