Although advances in chemotherapy have improved the prognosis of gastric cancer patients, many patients still suffer from adverse events. Therefore, it is necessary to establish personalized treatment by identifying patients at high risk for side effects. Although paclitaxel-based therapy is the standard second-line treatment, peripheral neuropathy is a troublesome adverse event. The purpose of this study is to establish a liquid biopsy assay to predict paclitaxel-induced peripheral neuropathy in gastric cancer patients.

Paclitaxel-based therapy is the standard second-line treatment for gastric cancer patients, but approximately 30-40% of patients develop peripheral neuropathy that interferes with daily life, and about 10% develop severe grade 3 peripheral neuropathy. Particularly severe side effects can cause patients to lose strength, forcing them to discontinue treatment, and thus losing the opportunity to receive other treatments that were originally expected to have a therapeutic effect. This study aims to predict peripheral neuropathy in the side effects of second-line treatment (paclitaxel plus ramucirumab) in patients with gastric cancer using liquid biopsies (small RNA). If patients at high risk for side effects can be predicted prior to treatment, high-risk patients can be offered drug reductions or other chemotherapy options. The aim of this study is to predict peripheral neuropathy of paclitaxel in second-line chemotherapy for gastric cancer by liquid biopsy.

Inclusion Criteria:

1. unresectable or recurrent Gastric cancer (GC) histologically confirmed to be primary adenocarcinoma of the stomach.
2. age over 20 years.
3. Eastern Cooperative Oncology Group performance status score of 0-2.
4. written informed consent following full study information is provided to the patient.
5. progression or intolerance for first-line chemotherapy comprising fluorinated pyrimidine and platinum anticancer drugs (cisplatin or oxaliplatin) for advanced GC.
6. presence of evaluable lesions as confirmed using a computed tomography (CT) or magnetic resonance imaging.

Exclusion Criteria:

1. Patients with a life expectancy of shorter than 3 months
2. Patients with severe complications (angina pectoris, myocardial infarction, or arrhythmia) or uncontrollable diabetes mellitus, blood hypertension, or bleeding tendency.
3. Patients with a history of serious allergic reactions or serious drug allergy.
4. Patients with a clinically relevant mental disorder that prohibits response to questionnaires.
5. Patients for whom the attending physician considered that enrollment in the study is inappropriate.

Patients need second-line chemotherapy with unresectable or recurrent Gastric cancer.