Background: Current cancer treatments by immune checkpoint blockades are limited due to severe adverse events caused by alteration of the immune system required for homeostasis of normal tissues. Common cancer chemotherapy alters the quality of patients' lives. Platinum-based treatment can lead to severe neurotoxicity with chronic debilitation. Additionally, survival of patients with epithelial ovarian cancers (EOCs) has remained poor despite extensive cytoreductive surgery, high dose chemotherapy, checkpoint blockades and immunotherapies effective in some other types of cancer. The pathobiology of EOC cancer stem cells (CSCs) is not well understood. Observations demonstrate that EOCs exhibit in vivo two distinct CSC types -perivascular diploid CSCs dividing asymmetrically with the help of the host suicidal CD8+ T cells, and haploid CSCs at the cancer abdominal surface originating from meiosis I cytokinesis of bulk surface cancer cells. The perivascular CSCs contribute to the cancer cell bulk and, via left ovary venous blood, can cause EOC liver metastases. Haploid CSCs released from the bulk cancer surface cause the common pelvic and abdominal EOC spread. Former elimination of the host antibodies blocking T cell effectors by intermittent doses of cyclophosphamide exhibiting significant immunomodulatory anticancer effects, facilitation of the immune system reactivity against alloantigens of cancer cells by blood transfusions, and augmentation of anticancer immunity by bacterial toxins, resulted during the subsequent treatment-free period into rejection of inoperable EOCs without any adverse events during the treatnment. To help prevent cancer relapses, patients treated for advanced primary epithelial cancers should be considered as candidates for continuously stimulating immune anticancer activity by treatments such as daily metformin and weekly lentinan consumptions.