Therapeutic intervention based on gene sequencing analysis of microbial 16S ribosomal RNA of the intrauterine microbiome improves pregnancy outcomes in IVF patients: a prospective cohort study.

PURPOSE: A Lactobacillus-dominated microbiota in the endometrium was reported to be associated with favorable reproductive outcomes. We investigated in this study whether 16S ribosomal RNA (rRNA) gene sequencing analysis of the uterine microbiome improves pregnancy outcomes. METHODS: This prospective cohort study recruited a total of 195 women with recurrent implantation failure (RIF) between March 2019 and April 2021 in our fertility center. Analysis of the endometrial microbiota by 16S rRNA gene sequencing was suggested for all patients who had three or more failed embryo transfers (ETs). One hundred and thirty-one patients underwent microbial 16S rRNA gene sequencing (study group) before additional transfers, while 64 patients proceeded to ET without that analysis (control group). The primary outcome was to compare the cumulative clinical pregnancy rate of two additional ETs. MAIN RESULTS: An endometrial microbiota considered abnormal was detected in 30 patients (22.9%). All but one of these 30 patients received antibiotics according to the bacterial genus detected in their sample, followed by treatment with probiotics. As a result, the cumulative clinical pregnancy rate (study group: 64.5% vs. control group: 33.3%, p = 0.005) and the ongoing pregnancy rate (study group: 48.9% vs. control group: 32.8%, p = 0.028) were significantly increased in the study group compared to the control group. CONCLUSION: Personalized treatment recommendations based on the microbial 16S rRNA gene sequencing of the uterine microbiota can improve IVF outcomes of patients with RIF. TRIAL REGISTRATION: The University Hospital Medical Information Network (UMIN) Clinical Trial Registry: UMIN000036050 (date of registration: March 1, 2019).

Nationwide survey of intrauterine blood transfusion for fetal anemia in Japan.

AIM: The present study investigated the current situation regarding intrauterine blood transfusion (IUT) for fetal anemia in Japan. METHODS: We conducted a nationwide, multicenter, retrospective cohort questionnaire survey for cases that underwent IUT from 2011 to 2015. The questionnaire required perioperative information, indications, details of the procedure, procedure-related complications, and neonatal morbidity. RESULTS: A total of 100 IUT procedures were performed in 66 cases at 19 institutions during the study period. The most frequent indication of IUT was complicated monochorionic diamniotic (MCDA) twins in 28 (42.4%) cases, followed by 16 (24.2%) cases of red-cell alloimmunization, and 10 (15.2%) cases of parvovirus B19 infection. IUT was performed through the umbilical cord in the vast of majority cases (92%). Bleeding from the IUT site was the most common adverse event (40%). Two cases (2%) underwent emergency cesarean section after the procedure. There were no cases of rupture of membrane or intrauterine infection after IUT. The neonatal survival rate was 77.3% in the 66 total cases and 64% in the hydrops cases. The neonatal survival rates in MCDA twins, red-cell alloimmunization, and parvovirus B19 infection were 75%, 93.8%, and 70%, respectively. CONCLUSIONS: IUT was performed for mainly three indications in Japan: MCDA twins, red-cell alloimmunization, and parvovirus B19 infection. The incidences of severe adverse events seemed very low. The outcomes after IUT were favorable with variations in survival rates according to indications. However, further studies with long-term follow-up will be required to assess the effectiveness of IUT, especially for complicated MCDA twins.

Evaluation of the clinical performance of noninvasive prenatal testing at a Japanese laboratory.

AIM: We aimed to evaluate the sensitivity, specificity, positive predictive value (PPV), and negative predictive value (NPV) of noninvasive prenatal testing (NIPT) in high-risk pregnant women. METHODS: Pregnant women who underwent GeneTech NIPT, the most commonly used NIPT in Japan, between January 2015 and March 2019, at Japan NIPT Consortium medical sites were recruited for this study. The exclusion criteria were as follows: pregnant women with missing survey items, multiple pregnancy/vanishing twins, chromosomal abnormalities in the fetus other than the NIPT target disease, and nonreportable NIPT results. Sensitivity and specificity were calculated from the obtained data, and maternal age-specific PPV and NPV were estimated. RESULTS: Of the 45 504 cases, 44 263 cases fulfilling the study criteria were included. The mean maternal age and gestational weeks at the time of procedure were 38.5 years and 13.1 weeks, respectively. Sensitivities were 99.78% (95% confidence interval [95% CI]: 98.78-99.96), 99.12% (95% CI: 96.83-99.76), and 100% (95% CI: 88.30-100) for trisomies 21, 18, and 13, respectively. Specificities were more than 99.9% for trisomies 21, 18, and 13, respectively. Maternal age-specific PPVs were more than 93%, 77%, and 43% at the age of 35 years for trisomies 21, 18, and 13, respectively. CONCLUSION: The GeneTech NIPT data showed high sensitivity and specificity in the detection of fetal trisomies 21, 18, and 13 in high-risk pregnant women, and maternal age-specific PPVs were obtained. These results could provide more accurate and improved information regarding NIPT for genetic counseling in Japan.

Clonal analysis revealed functional heterogeneity in cancer stem-like cell phenotypes in uterine endometrioid adenocarcinoma.

Uterine endometrial carcinoma is one of the common cancers in females. Cancer stem-like cells (CSCs)/cancer-initiating cells (CICs) are a small subpopulation of cancer cells that are tumorigenic and are resistant to treatments, thus they are focused as treatment targets. However, the heterogeneity of CSCs/CICs is still elusive, and we therefore analyzed CSCs/CICs at the clonal level. We previously established sphere-cultured CSCs/CICs from primary human uterine endometrial carcinoma, and we isolated several clones from CSCs/CICs in this study. Interestingly, we established two types of clones based on the growth pattern. The clones were termed sphere clones (S clones) and leukemia-like clones (LL clones). Functional analysis revealed that S clones are resistant to chemotherapy, whereas LL clones are sensitive to chemotherapy. On the other hand, S clones are less tumorigenic, while LL clones are highly tumorigenic. Transcriptome analysis using serial analysis of gene expression sequencing (SAGE-Seq) revealed distinctive gene expression profiles in S clone cells and LL clone cells. The results indicate that CSCs/CICs are composed of functionally heterogenic subpopulations including highly tumorigenic clones and treatment-resistant clones and that the characteristics of CSCs/CICs might be determined by the characteristics of different clones that compose CSCs/CICs.

Obstetrical prognosis of patients who underwent vaginal radical trachelectomy during pregnancy.

AIM: Radical trachelectomy (RT) with pelvic lymphadenectomy has become an option for young patients with early invasive uterine cervical cancer who decide to maintain their fertility. However, this operative method entails a high risk for the following pregnancy due to its radicality. Therefore, RT for pregnant patients can be a challenge both for gynecologic oncologists and obstetricians. METHODS: We have performed vaginal RT for five pregnant patients with uterine cervical cancer stage 1B1 according to the method of Dargent et al. The operations were performed between 16 and 26 weeks of pregnancy, and the patients were followed up carefully according to the follow-up methods we reported previously. RESULTS: Vaginal RT was performed for five patients without any troubles. Four of the patients continued their pregnancies until almost 34 weeks or longer under our previously published follow-up schedule. The pregnancy of one patient was terminated at 26 weeks due to recurrence of the cancer. CONCLUSION: Expansion of vaginal RT for pregnant patients with uterine cervical cancer could be a practical option for pregnant patients with early invasive uterine cervical cancer.

Transabdominal cerclage (TAC) for patients with ultra-short uterine cervix after uterine cervix surgery and its impact on pregnancy.

AIM: Patients with an ultra-short uterine cervix as a result of large conization, repeated conization or radical trachelectomy (RT), are at high risk of preterm premature rupture of the membrane, which leads to preterm birth. We have commenced performing transabdominal cerclage (TAC) of the uterine cervix for these patients. In this study, we examined the safety of TAC and its impact on pregnancy. METHODS: We have performed TAC in 11 patients before pregnancy: in six after large cervical operations, such as repeated conization; and in five for difficulties with cervical cerclage after RT. After laparotomy, a Teflon thread was placed in the avascular space between the uterine vessels and the uterine muscle, and tied. The clinical course of the patients after TAC and their pregnancy course were retrospectively reviewed. RESULTS: TAC was performed safely without any complications. The mean operative duration was 53 ± 10 min, and the mean blood loss during the operation was 49 ± 64 mL. Seven women conceived within 2 years after TAC. Their pregnancy courses were favorable. Five of the women underwent scheduled cesarean sections, while two pregnancies are ongoing. CONCLUSIONS: Although there are risks of various complications as a result of the use of non-absorbable thread and the need for two extra laparotomies, TAC can be a safe and useful option for patients who show cervical incompetence after large uterine cervical operations, such as RT or large conization.

Placental endoplasmic reticulum stress negatively regulates transcription of placental growth factor via ATF4 and ATF6ß: implications for the pathophysiology of human pregnancy complications.

Low maternal circulating concentrations of placental growth factor (PlGF) are one of the hallmarks of human pregnancy complications, including fetal growth restriction (FGR) and early-onset pre-eclampsia (PE). Currently, PlGF is used clinically with other biomarkers to screen for high-risk cases, although the mechanisms underlying its regulation are largely unknown. Placental endoplasmic reticulum (ER) stress has recently been found to be elevated in cases of FGR, and to an even greater extent in early-onset PE complicated with FGR. ER stress activates the unfolded protein response (UPR); attenuation of protein translation and a reduction in cell growth and proliferation play crucial roles in the pathophysiology of these complications of pregnancy. In this study, we further identified that ER stress regulates release of PlGF. We first observed that down-regulation of PlGF protein was associated with nuclear localization of ATF4, ATF6α and ATF6ß in the syncytiotrophoblast of placentae from PE patients. Transcript analysis showed a decrease of PlGF mRNA, and an increase from genes encoding those UPR transcription factors in placentae from cases of early-onset PE, but not of late-onset (>34 weeks) PE, compared to term controls. Further investigations indicated a strong correlation between ATF4 and PlGF mRNA levels only (r = - 0.73, p < 0.05). These results could be recapitulated in trophoblast-like cells exposed to chemical inducers of ER stress or hypoxia-reoxygenation. The stability of PlGF transcripts was unchanged. The use of small interfering RNA specific for transcription factors in the UPR pathways revealed that ATF4 and ATF6ß, but not ATF6α, modulate PlGF transcription. To conclude, ATF4 and ATF6ß act synergistically in the negative regulation of PlGF mRNA expression, resulting in reduced PlGF secretion by the trophoblast in response to stress. Therefore, these results further support the targeting of placental ER stress as a potential new therapeutic intervention for these pregnancy complications.

Possibility of less radical treatment for patients with early invasive uterine cervical cancer.

AIM: Radical trachelectomy (RT) with lymphadenectomy has become a standard treatment modality for patients with early invasive uterine cervical cancer who hope to preserve fertility. However, pregnancy after RT has high risks of preterm birth. The possibility of more conservative RT and the application of RT for patients with higher clinical stages were studied. METHODS: The medical charts and specimens of 42 patients who underwent RT and 64 patients who underwent radical hysterectomy were retrospectively studied. Tumor size, distance between the margin of the cancer and the internal orifice of the uterus (os), parametrial invasion, lymph node metastasis and prognoses were investigated. RESULTS: The average distances between the inner margin of the cancer and the internal os were 37 mm, 29 mm, 18.7 mm and 14 mm for patients with stage 1 A2, 1B1 (≤ 2 cm), 1B1 (> 2 cm) and 1B2, respectively. When amputation was performed 10 mm below the internal os, all 10 patients with 1 A2, 57 with 1B1 (≤ 2 cm), 19 with 1B1 (> 2 cm), and one with 1B2 had a cancer-free margin > 10 mm. Patients with stage 1 A2 had a cancer-free margin > 10 mm even if we amputated the cervix 20 mm below the internal os. Parametrial invasion was detected in two patients with stage 1B1. CONCLUSIONS: A simple trachelectomy 20 mm below the internal os with pelvic lymphadenectomy might be possible for stage 1 A2 patients. The present method is best for stage 1B1 patients (≤ 2 cm). RT for stage 1B1 (>2 cm) or higher stages should be contraindicated.

Difficulty in the management of pregnancy after vaginal radical trachelectomy.

BACKGROUND: We have performed 26 vaginal radical trachelectomies (RTs) for patients with early invasive uterine cervical cancer since 2003 and, to date, have experienced 8 deliveries. The procedure has a high risk for preterm labor and the subsequent occurrence of preterm premature rupture of membranes (pPROM). We report the present situation and the limits of follow-up of pregnancy after vaginal RT. METHODS: Our operative procedure is based on that of Dargent et al. We usually amputate the cervix approximately 10 mm below the isthmus. To remove the parametrium, we cut at the level of type II hysterectomy. Pregnancy courses after vaginal RT were studied in 8 patients with respect to symptoms, cervical length, and several infectious signs. RESULTS: We recommended that patients enter hospital early in their second trimester, and prophylactic daily vaginal disinfection with povidone-iodine and an ulinastatin vaginal suppository were administered. Careful checking for vaginal infectious signs, as well as cervical length and abdominal tension of patients was also performed. Four patients followed up with this modality were able to continue their pregnancies until late in the third trimester. However, this follow-up modality was not effective for patients who showed cervical incompetence due to slack cervical cerclage. They suffered from pPROM at 26 and 19 weeks of gestation. CONCLUSION: We need a new approach for the management of pregnant patients after vaginal RT with cervical incompetence due to slack cervical cerclage to prevent cervical infection.

Novel oligomannose liposome-DNA complex DNA vaccination efficiently evokes anti-HPV E6 and E7 CTL responses.

The aim of this study was to establish an efficient human papilloma virus (HPV) type 16-targeting cancer immunotherapy. Persistent high-risk HPV infection causes cervical intra-epithelial neoplasia (CIN) and subsequent cervical carcinoma. HPV type16 (HPV16) is one of the common carcinogenic types and is found in about 50% of invasive cervical carcinomas. HPV16-derived viral proteins E6 and E7 are expressed in cancerous cells through the progression of the disease and have a role in carcinogenesis but are not expressed in normal cells. Thus, these proteins are regarded as ideal antigens for cervical carcinoma immunotherapy. In this study, we generated a novel HPV 16 E6 and E7 gene plasmid containing oligomannose liposomes (OML-HPV). We compared the cytotoxic T lymphocyte (CTL) induction efficiency of OML-HPV and that of standard liposome-HPV16 E6 and E7 DNA complex. HPV16 E6-specific CTLs could be generated from HPV 16-positive cervical carcinoma patient's peripheral blood mononuclear cells (PBMCs) by stimulating OML-HPV, but could not by stimulating standard liposome-HPV 16 E6, E7 DNA complex. Furthermore, we screened HLA-A24-restricted HPV16 E6- and E7-derived peptides, and found that one E6-derived peptide (E6 66-74) showed the highest immunogenicity with ELISPOT assay from 100% of HPV16-positive patients (4 out of 4). On the other hand, other E6- or E7-derived peptides, including E6 49-57, E6 82-90, E6 87-95, E6 98-106 and E7 83-93, showed less frequent reactivity. These results indicate that OML-HPV is a more effective approach than DNA vaccination using standard liposomes, and that a novel HLA-A24-restricted peptide, E6 66-74, might be a suitable target of cervical cancer immunotherapy.

Effectiveness of Cross Double McDonald Cerclage for Intractable Bleeding from a Cervical Varix in Pregnant Women.

Cervical varix during pregnancy is a rare condition, and standard management for bleeding from a varix has not been established. We performed cross double cervical cerclage and effectively stopped bleeding. A 41-year-old female had a twin pregnancy. The development of a cervical varix was observed during pregnancy and bleeding from ruptured varix started at 20 weeks of gestation. We performed surgical hemostasis by cervical cerclage. In the first cerclage, we could not stop the bleeding from the varix. For further restriction of blood supply to the cervical varix, we performed a second cerclage in a crossed position on a deeper side of the vagina than the first cerclage. Then the bleeding completely stopped and there was no bleeding until delivery. The "cross double McDonald cerclage" performed in our patient may be a useful modified cerclage method for stopping intractable bleeding from the cervix during pregnancy.

New treatment strategy for endometriosis using progestin-primed ovarian stimulation with dienogest: A prospective cohort study, comparison of dienogest versus dydrogesterone.

Dienogest (DNG) is an oral progestin effective for the treatment of symptomatic endometriosis, such as reduction of endometrial lesion and control of pain intensity. Progestin-primed ovarian stimulation (PPOS) is a new controlled ovarian hyperstimulation (COH) regimen, and several reports have shown that dydrogesterone (DYG) is an appropriate progestin for PPOS. The purpose of this study was to evaluate the efficacy of DNG in patients undergoing PPOS during COH in comparison with DYG. This was a prospective, cohort, parallel-group, non-inferiority trial of 150 women with endometriosis undergoing assisted reproductive technology between February 2018 and May 2020 at the single fertility center. The assignment to each protocol was based on the optimal treatment for each patient. Patients taking DNG 2 mg continuously were assigned in the DNG group(n = 73). The other patients were allocated in DYG group(n = 77). All viable embryos were cryopreserved for subsequent transfer. The main outcome measures were the mature oocyte and fertilization rates. During this study, no premature LH surge was detected. A smaller number of oocytes were retrieved in the DNG group than in the DYG group (6.18 ± 3.60 vs. 9.85 ± 5.77); however, the rate of mature oocytes was significantly higher in the DNG group than in the DYG group (89.1 % vs. 78.9 %). The fertilization rate was comparable between two groups. Therefore, patients taking DNG for PPOS can continue endometriosis treatment and obtain good-quality embryos during COH. Further prospective randomized-controlled trial should be performed to confirm of this novel strategy of DNG.

Changes of uterine blood flow after vaginal radical trachelectomy (VRT) in patients with early-stage uterine invasive cervical cancer.

BACKGROUND: Vaginal radical trachectomy (RT) ligates and cuts several arteries supplying the uterus. Changes of blood supply to the uterus in two patients who experienced pregnancy and delivery were studied by using 3-D CT scanning. Effects of changes of blood supply to the uterus on the pregnancy courses were also examined. METHODS: Vascular distribution in the uterus was studied in two patients who received vaginal RT after delivery. Effects of changes of vascular distribution after vaginal RT were studied with respect to pregnancy courses and cervical functions. RESULTS: New arterial vascularization from the ascending branches of uterine arteries or other arteries occurred, and these new vessels seemed to supply blood to the remaining cervix. Differences of fetal growth and histopathological changes in the placenta between the two patients could not be detected. CONCLUSION: Ligation and cutting of several supplying arteries by RT induces new arterial vascularization and it does not seem to affect fetal growth and placental function.

Successful uterus-preserving surgery for treatment of chemotherapy-resistant placenta increta.

Treatment of placenta increta often entails abdominal total hysterectomy. We present a case of placenta increta in which 3-dimensional computed tomography shows very high blood flow to the placenta, even after chemotherapy with methotrexate. Nonetheless, we were able to remove the region of the uterus that had been invaded by chorionic villi. Massive bleeding during the operation was prevented by ligation of the hypogastric artery and local injection of vasopressin. The combination of chemotherapy and partial resection of the uterus is quite a unique treatment for placenta increta patients. This approach enabled preservation of the uterus and the patient's fertility. We suggest this procedure could be one of the treatments for patients who have placenta increta and wish to retain their fertility.

Successful administration of recombinant human antithrombin in a pregnant Japanese woman with hereditary antithrombin deficiency.

OBJECTIVE: Hereditary antithrombin (AT) deficiency increases the risk of venous thromboembolism (VTE) in pregnant woman. We report the first case of administration of recombinant human antithrombin (rhAT) to a pregnant Japanese woman with AT deficiency. CASE REPORT: A 30-year-old woman, gravida 2 para 0, was referred to our hospital because of AT deficiency. Unfractionated heparin was administered from 13 weeks of gestation and rhAT was administered from labor onset. A cesarean section was performed and the patient and her baby were healthy, with no sequelae. CONCLUSION: We concluded that rhAT was effective for preventing VTE during delivery, with no potential infection risks.

Androgen potentiates the expression of FSH receptor and supports preantral follicle development in mice.

Hyperandrogenism is one of the cardinal symptoms in polycystic ovary syndrome and plays a key role in the pathogenesis of polycystic ovary syndrome. However, the precise effects and mechanisms of excess androgen during follicular development are still unclear. Here we investigated the effects of androgen on mouse follicle development in vitro. Androgen did not affect the growth of follicles smaller than 160-180 µm in the presence of follicle-stimulating hormone (FSH). However, in the presence of low FSH, androgen supported the growth of follicles larger than 160-180 µm, a size at which growing follicles acquire FSH-dependency. Androgen did not change the mRNA expression of various growth-promoting factors but did increase mRNA expression of the FSH receptor. We suggest that androgen has a positive impact on follicle development by augmentation of the actions of FSH. Therefore, FSH-responsive but FSH-independent follicles grow in the presence of a certain level of FSH or androgen, and androgen compensates for FSH deficiency in FSH-dependent follicles.

Matrix metalloproteinase-10 regulates stemness of ovarian cancer stem-like cells by activation of canonical Wnt signaling and can be a target of chemotherapy-resistant ovarian cancer.

Epithelial ovarian cancer (EOC) is one of the most lethal cancers in females. Cancer stem-like cells (CSCs)/cancer-initiating cells (CICs) have been reported to be origin of primary and recurrent cancers and to be resistant to several treatments. In this study, we identified matrix metalloproteinase-10 (MMP10) is expressed in CSCs/CICs of EOC. An immunohistochemical study revealed that a high expression level of MMP10 is a marker for poor prognosis and platinum resistance in multivariate analysis. MMP10 gene overexpression experiments and MMP10 gene knockdown experiments using siRNAs revealed that MMP10 has a role in the maintenance of CSCs/CICs in EOC and resistance to platinum reagent. Furthermore, MMP10 activate canonical Wnt signaling by inhibiting noncanonical Wnt signaling ligand Wnt5a. Therefore, MMP10 is a novel marker for CSCs/CICs in EOC and that targeting MMP10 is a novel promising approach for chemotherapy-resistant CSCs/CICs in EOC.

Brother of the regulator of the imprinted site (BORIS) variant subfamily 6 is involved in cervical cancer stemness and can be a target of immunotherapy.

Cervical cancer is a major cause of cancer death in females worldwide. Cervical cancer stem-like cells (CSCs)/cancer-initiating cells (CICs) are resistant to conventional radiotherapy and chemotherapy, and CSCs/CICs are thought to be responsible for recurrence. Eradication of CSCs/CICs is thus essential to cure cervical cancer. In this study, we isolated cervical CSCs/CICs by sphere culture, and we identified a cancer testis (CT) antigen, CTCFL/BORIS, that is expressed in cervical CSCs/CICs. BORIS has 23 mRNA isoform variants classified by 6 subfamilies (sfs), and they encode 17 different BORIS peptides. BORIS sf1 and sf4 are expressed in both CSCs/CICs and non-CSCs/CICs, whereas BORIS sf6 is expressed only in CSCs/CICs. Overexpression of BORIS sf6 in cervical cancer cells increased sphere formation and tumor-initiating ability compared with those in control cells, whereas overexpression of BORIS sf1 and BORIS sf4 resulted in only slight increases. Thus, BORIS sf6 is a cervical CSC/CIC-specific subfamily and has a role in the maintenance of cervical CSCs/CICs. BORIS sf6 contains a specific c-terminal domain (C34), and we identified a human leukocyte antigen (HLA)-A2-restricted antigenic peptide, BORIS C34_24(9) encoded by BORIS sf6. A BORIS C34_24(9)-specific cytotoxic T cell (CTL) clone showed cytotoxicity for BORIS sf6-overexpressing cervical cancer cells. Furthermore, the CTL clone significantly suppressed sphere formation of CaSki cells. Taken together, the results indicate that the CT antigen BORIS sf6 is specifically expressed in cervical CSCs/CICs, that BORIS sf6 has a role in the maintenance of CSCs/CICs, and that BORIS C34_24(9) peptide is a promising candidate for cervical CSC/CIC-targeting immunotherapy.

Prognostic impact of human leukocyte antigen class I expression and association of platinum resistance with immunologic profiles in epithelial ovarian cancer.

Epithelial ovarian cancer (EOC) is one of the most deadly carcinomas in females. Immune systems can recognize EOCs; however, a defect of human leukocyte antigen (HLA) class I expression is known to be a major mechanism for escape from immune systems, resulting in poor prognosis. The purpose of this study is to identify novel correlations between immunologic responses and other clinical factors. We investigated the expression of immunologic components in 122 cases of EOCs for which surgical operations were performed between 2001 and 2011. We immunohistochemically stained EOC specimens using an anti-pan HLA class I monoclonal antibody (EMR8-5) and anti-CD3, -CD4, and -CD8 antibodies, and we analyzed correlations between immunologic parameters and clinical factors. In multivariate analysis that used the Cox proportional hazards model, independent prognostic factors for overall survival in advanced EOCs included low expression level of HLA class I [risk ratio (RR), 1.97; 95% confidence interval (CI), 1.01-3.83; P = 0.046] and loss of intraepithelial cytotoxic T lymphocyte (CTL) infiltration (RR, 2.11; 95% CI, 1.06-4.20; P = 0.033). Interestingly, almost all platinum-resistant cases showed a significantly low rate of intraepithelial CTL infiltration in the χ(2) test (positive vs. negative: 9.0% vs. 97.7%; P < 0.001). Results from a logistic regression model revealed that low CTL infiltration rate was an independent factor of platinum resistance in multivariate analysis (OR, 3.77; 95% CI, 1.08-13.12; P = 0.037). Platinum-resistant EOCs show poor immunologic responses. The immune escape system of EOCs may be one of the mechanisms of platinum resistance.