**1. Introduction**

Gastric cancer is the fourth most common cancer worldwide [1]. The stage of gastric cancer at diagnosis determines treatment options and has a strong influence on the length of the patient's survival.

Early diagnosis of earlier stages of the disease with adequate treatment/R0 resection of stomach + D2 lymphadenectomy + suitable perioperative chemotherapy/bring a better outlook [3] (**Figure 1**).

**Figure 1.** Percentage of cases and 5-year relative survival by stage at diagnosis: gastric cancer. The earlier gastric cancer is diagnosed, the better chance a patient has of surviving 5 years after diagnosis. For gastric cancer, 26.0 and 29.0% of cases are diagnosed at the local and distant stage, respectively. Of note, the stage of disease is unknown at diagnosis in more than onethird of cases. The 5-year survival for localized gastric cancer is 65.4%, compared with 4.5% for distant stomach cancer [2].

Remote metastases as a sign of systemic disease reduce the overall patient survival. The most common site for gastric cancer metastasis is the liver [4].

For the sake of comparison, at present, the liver resection is currently accepted as a treatment for liver metastases of colorectal cancer with referred 5-year survival in 40–56% of patients [5]. Thanks to advances in surgical techniques and perioperative chemotherapy, the indication range keeps expanding.

Compared with colorectal cancer, the gastric cancer represents a more aggressive cancer disease with heterogenic nature [6].

Other metastatic lesions associated with gastric cancer such as peritoneal carcinomatosis or extensive involvement of the regional lymph nodes significantly deteriorates the patient's outcome, contraindicating the surgical treatment.

GCLM is considered a systemic disease with adverse outcome and systemic chemotherapy is indicated as the first line of treatment [7].

Thanks to the effort on the part of some of the surgeons to reverse the adverse outcome in resectable GCLM, who performed resection or RFA surgery on the liver, we were able to collect interesting outcomes—5-year survival of 0–45% of patients [8, 9].

These studies are greatly handicapped by the low number of patients, mostly from a single center [8].

However, over 90% of mortality in cancer patients is described to the subsequent spread of cancer cells to distant tissues [10]. In patients, the threat of tumor can return after chemotherapy and radiation remains terrifying and painfully real.

This phenomenon is described as tumor or cell dormancy. The experimental models have revealed that cancer patients may have hundreds to thousands of disseminated cancer cells in circulation but only a small portion of these cells progresses to form clinically overt metastases [11].

Metastasis is a multistep process. The metastatic cancer cells acquire epithelial-mesenchymal transition (EMT)-like phenotype allowing them to disseminate from the primary tumor into circulation; the early step of metastasis (intravasate, survival, arrest, and extravasation) is a very complicated and complex process [12].

However, only a small subset of these cells (~2%) can initiate growth as micrometastases, and an even smaller fraction of these cells (~0.02%) is able to persist and forms macrometastases [12].

The sub-population of cancer cells has stem-like properties and is capable of initiating tumor, invasive growth, and spread to distant organs [13]. These cancer stem cells (CSCs) have the ability to self-renew, to produce more cancer cells, as well as undergo differentiation to give rise to phenotypically diverse nontumorigenic cancer cells.
