Diagnosis by biopsy is difficult in the ovary, since it is located deep in the abdomen. As a result, ovarian
cancer is mostly found insidiously during exploratory laparotomy. Consequently, early diagnosis of ovarian
cancer is often difficult. The likelihood of peritoneal dissemination increases with the progress of ovarian
cancer. With further progression, ovarian cancer metastasizes to the omentum, retroperitoneal lymph nodes,
large intestine, small intestine, diaphragm, spleen, and other organs. Ovarian cancer has been considered a
tumor that has a favourable response to chemotherapy, but more effective treatments are still being explored.
Tumors use their own immune escape mechanism to evade host immunity. The immune checkpoint (IC)
mechanism, one of the immune escape mechanisms, is established by programmed cell death-1 (PD-1)/PDligand-1 (PD-L1) communication. It has been shown that inhibiting PD-1/PD-L1 communication in various
malignancies produces antitumor effects. However, the antitumor effect of ICI monotherapy on ovarian
cancer is limited in actual clinical practice. In this review, we describe a novel cancer immunotherapeutic
agent that targets myeloid-derived suppressor cells (MDSCs).
Myeloid-derived suppressor cells in ovarian cancer: friend or foe?