Circulating tumor cell count as a biomarker of a specific gastric cancer subgroup characterized by bone metastasis and/or disseminated intravascular coagulation - an early indicator of chemotherapeutic response.

The incidence of gastric cancer coupled with multiple bone metastases, and/or disseminated intravascular coagulation (DIC), is characterized by the clinical presentation of rapid progression and a poor prognosis, and differs from typical gastric cancers. Circulating tumor cells (CTCs) are negligible in typical advanced gastric cancers, however, a considerable number of CTCs in the bloodstream may be detected in the subgroup demonstrating multiple bone metastases and/or DIC. The present study analyzed two cases, with the first case regarding a 51-year-old male who exhibited a CTC count of 275 cells/7.5 ml following an initial, ineffective, chemotherapy cycle. The patient underwent a second chemotherapy course that was effective, and the cell count was observed to reduced to 2 cells/7.5 ml. A decreased CTC count was first confirmed on day 16 following treatment. During the chemoresistant phase, the CTC count was observed to increase again. The second case presented by the current study describes a 59-year-old female who exhibited a CTC count of 235 cells/7.5 ml prior to chemotherapy. This subsequently decreased to 7 cells/7.5 ml following an effective course of chemotherapy. Notably, the CTC count increased alongside disease progression in this case. Within the rare subgroup of gastric cancer patients with multiple bone metastases and/or DIC, CTC count may serve as an early biomarker allowing the evaluation of therapeutic efficacy. However, due to the aggressive nature of this type of cancer, imaging analysis is not recommended as it may typically take several months to complete.