Abstract 4620: Somatic mutation profile of gastric cancer cases from the Hispanic population

e16067 Background: The clinical and mutational profile of Hispanic patients with metastatic colon cancer is not well documented. In this retrospective study, we aim to describe the clinical and mutational profile of Hispanic patients with metastatic colon cancer in central California. Methods: We retrospectively evaluated the clinical and mutational profile of colon cancer at a single institution in Fresno, California from 2010-2019. We selected 136 patients out of which 70 patients self-identified as Hispanic and 66 self-identified as non-Hispanic. We studied clinical parameters and next-generation sequencing via Foundation one testing for these patients. Results: Among Hispanics, there were 43(61%) males and 27(38%) females. The median age at diagnosis was similar in both groups at 57. Right sided colon cancer accounted for 52% of Hispanic patients versus 40% in non-Hispanics. Fifty two percent of Hispanic patients presented with metastatic disease versus 45% in non-Hispanics. The frequency of commonly mutated genes in colon cancer in Hispanics versus non-Hispanics are as follows. KRAS (35.7% vs 37%), NRAS (11% vs 4%) BRAF (8% vs 7%), Her2/neu 0% in both groups. The frequency of other mutations such as TP53, APC, ATM, PTEN, CDKN2A, Myc amplification were also noted to be similar in both groups. PIK3CA mutation was seen in 18.6% of Hispanic patients versus 34% in non-Hispanic population which was statistically significant with a p value = 0.032. Microsatellite instability (MSI) was seen at 3.3% in Hispanics versus 10.6% in non-Hispanics. Tumor mutational burden was similar in both groups. Conclusions: The frequency of actionable mutations was similar in both Hispanic and non-Hispanic patients. Hispanics were noted to have lower PIK3CA and microsatellite instability. Metastatic disease and right sided colon cancer were seen at higher frequency in Hispanic population. Our results were similar to another population-based study which analyzed KRAS mutation with colon cancer patients in Puerto Rico[1]. Larger population based studies would be needed to further assess the differences in this patient population. Ruiz-Candelaria, Y., C. Miranda-Diaz, and R.F. Hunter-Mellado, K-RAS mutation profile in Puerto Rican patients with colorectal cancer: trends from April 2009 to January 2011. Int J Biol Markers, 2013. 28(4): p. e393-7.

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Prevalence of HER2/neu overexpression/amplification in a Hispanic population with gastric adenocarcinoma.

Journal of Clinical Oncology ◽

10.1200/jco.2011.29.4_suppl.25 ◽

2011 ◽

Vol 29 (4_suppl) ◽

pp. 25-25

Author(s):

M. Rodarte Shade ◽

J. Flores Gutierrez ◽

L. Garcia Labastida ◽

L. Villela ◽

A. Barbosa Quintana ◽

...

Keyword(s):

Gastric Cancer ◽

Cancer Patients ◽

Gastric Adenocarcinoma ◽

The Body ◽

Hispanic Population ◽

Hispanic Patients ◽

Cancer Tumor ◽

Study Population ◽

Gastric Cancer Patients ◽

Degree Of Differentiation

25 Background: In Europe, Asia, and North America, studies have identified that approximately 20% of patients with gastric adenocarcinoma exhibit overexpression of HER2/neu. This group of patients has been shown to benefit from combination therapy with the anti-HER2/neu monoclonal antibody trastuzumab. These findings have not been studied in Hispanics who may possess a distinct gastric cancer genotype. The aim of this study is to determine the rate of HER2/neu positivity in a completely Hispanic population with gastric adenocarcinoma and to analyze the clinical factors associated with HER2/neu. Methods: We conducted a retrospective study in three different hospitals in Monterrey, Mexico. The study population consisted of Hispanic patients with gastric adenocarcinoma who have had a gastric resection and for whom there were adequate amounts of tissue available in paraffin blocks. Tissue was tested for HER2/neu using both Immunohistochemistry (IHC) and the fluorescent in situ hybridization (FISH) techniques. Results: From 2000 to 2010, we initially evaluated 27 gastric cancer tumor samples. Sex distribution was 15 males and 12 females with a mean age of 57±15 (SD) years. Anatomic distribution of tumor was 4% in the cardias, 40% in the body and 56% in the antrum. Lauren's histological type distribution was 52% diffuse and 48% intestinal. Fifty-three percent of the tumors were high grade and nodal positivity was present in 69%. Overexpression of Her-2/neu (IHC ++ and +++) was found in five (17.4%) of the samples, being moderate (++) in two (7.4%) and strong (+++) in three (11%) tumor samples. FISH amplification for the HER2/neu gene was found in two (7.4%) tumors and was only seen in samples with a strong (+++) IHC result. There was no association identified between HER2/neu status with age, gender, degree of differentiation, T stage, or nodal status. Conclusions: In a homogeneous Hispanic population, 17.4% of gastric cancer patients were found to overexpress HER2/neu by IHC. FISH did not identify any additional HER2/neu positive tumors. It is important to consider IHC testing for HER2/neu in Hispanic gastric cancer patients as they could benefit from a chemotherapy regimen containing trastuzumab. No significant financial relationships to disclose.

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