Kei Kawana

Intrauterine manipulator use during laparoscopic hysterectomy for endometrial cancer: association for pathological factors and oncologic outcomes

To examine the association between intrauterine manipulator use and pathological factors and oncologic outcomes in patients with endometrial cancer who had laparoscopic hysterectomy in Japan. This was a nationwide retrospective cohort study of the tumor registry of the Japan Society of Obstetrics and Gynecology. Study population was 3846 patients who had laparoscopic hysterectomy for endometrial cancer from January 2015 to December 2017. An automated 1-to-1 propensity score matching with preoperative and intraoperative demographics was performed to assess postoperative pathological factors associated with the intrauterine manipulator. Survival outcomes were assessed by accounting for possible pathological mediators related to intrauterine manipulator use. Most patients had preoperative stage I disease (96.5%) and grade 1-2 endometrioid tumors (81.9%). During the study period, 1607 (41.8%) patients had intrauterine manipulator use and 2239 (58.2%) patients did not. In the matched cohort, the incidences of lymphovascular space invasion in the hysterectomy specimen were 17.8% in the intrauterine manipulator group and 13.3% in the non-manipulator group. Intrauterine manipulator use was associated with a 35% increased odds of lymphovascular space invasion (adjusted odds ratio 1.35, 95% confidence interval (CI) 1.08 to 1.69). The incidences of malignant cells identified in the pelvic peritoneal cytologic sample at hysterectomy were 10.8% for the intrauterine manipulator group and 6.4% for the non-manipulator group. Intrauterine manipulator use was associated with a 77% increased odds of malignant peritoneal cytology (adjusted odds ratio 1.77, 95% Cl 1.29 to 2.31). The 5 year overall survival rates were 94.2% for the intrauterine manipulator group and 96.6% for the non-manipulator group (hazard ratio (HR) 1.64, 95% Cl 1.12 to 2.39). Possible pathological mediators accounted HR was 1.36 (95%Cl 0.93 to 2.00). This nationwide analysis of predominantly early stage, low-grade endometrial cancer in Japan suggested that intrauterine manipulator use during laparoscopic hysterectomy for endometrial cancer may be associated with an increased risk of lymphovascular space invasion and malignant peritoneal cytology. Possible mediator effects of intrauterine manipulator use on survival warrant further investigation, especially with a prospective setting.

Impact of COVID-19 on gynecological cancer incidence: a large cohort study in Japan

The influence of the coronavirus disease 2019 (COVID-19) pandemic on the number of newly diagnosed gynecological cancers has not been extensively investigated in Japan. This study determined the impact of COVID-19 on the incidence of gynecological cancer. Using the Japanese Society of Obstetricians and Gynecologic Oncology registry database, the distribution of the number of patients based on clinical staging or tumor-node-metastasis classifications before and during the COVID-19 pandemic was analyzed to compare the trends. The clinical staging classification of cervical cancer in Japan was based on the International Federation of Gynecology and Obstetrics (FIGO) 2008 from 2018 to 2020 and on the FIGO 2018 from 2021. Since FIGO-2018 classified N1 cases as stage IIIC, we focused on T classification without referencing the clinical staging (FIGO staging) of patients with cervical cancer in 2021. The number of patients with endometrial cancer and malignant ovarian tumors of all clinical stages increased uniformly yearly, while that of those with stage III cervical cancer rapidly increased in 2021 owing to the adoption of the revised classification. On comparing cases of cervical cancer in 2020 and 2021, we found that T1 cases decreased and T2 and T3 cases increased in 2021 compared to those in 2020 (p = 0.006). Cervical intraepithelial neoplasia/adenocarcinoma in situ incidence decreased in 2020 compared to that in 2019 but increased again in 2021. The number of patients with cervical cancer decreased in most prefectures in 2020. The incidence of locally advanced cervical cancer increased during the COVID-19 pandemic.

Quality of care measurement for patients with ovarian cancer in Japan

Abstract Aim Quality of care is important to reduce disease progression, and improve both survival and quality of life. The Japan Society of Gynecologic Oncology has published treatment guidelines to promote standardized high‐quality care for ovarian cancer in Japan. We developed quality indicators based on the guideline recommendations and used them on large datasets of health service use to examine the quality of ovarian cancer care. Methods A panel of experts developed the indicators using a modified Delphi method. Adherence to each indicator was evaluated using data from a hospital‐based cancer registry of patients diagnosed in 2018. All patients receiving first‐line treatment at participating facilities were included. The adherence rates were returned to participating hospitals, and reasons for nonadherence were collected. A total of 580 hospitals participated, and the study examined the care received by 6611 patients with ovarian cancer and 1879 with borderline tumors using 11 measurable quality indicators. Results The adherence rate ranged from 22.6% for “Estrogen replacement within 6 months of operation” to 93.5% for “Bleomycin, etoposide, and cisplatin for germ cell tumor more than Stage II.” Of 580 hospitals, 184 submitted the reasons for nonadherence. Conclusions The quality of ovarian cancer care should be continuously assessed to encourage the use of best practices. These indicators may be a useful tool for this purpose.

Prognostic impact of peritoneal cytology on treating endometrial cancer using data from the Japan Society of Obstetrics and Gynecology cancer registry

The prognostic value and clinical usage of peritoneal cytology in endometrial cancer are uncertain. This study aimed to determine whether positive cytology is associated with the prognosis for endometrial cancer. A Japanese nationwide retrospective registry study was conducted between 2012 and 2019. Clinicopathological data were analyzed for patients who were registered in the Japan Society of Obstetrics and Gynecology (JSOG) gynecological tumor registry and underwent initial treatment for endometrial cancer. In total, 83,027 patients who met the inclusion criteria were identified. Data on peritoneal cytology status and overall survival (OS) were available for 74,984 and 36,995 patients, respectively. Positive peritoneal cytology was found in 11,536 (15.4%) patients. A higher proportion of patients who had positive peritoneal cytology were related to advanced stages, high-grade histology, deep myometrial invasion, lymph node (LN) metastasis, and poor risk of recurrence. After controlling for age, stage, myometrial invasion, LN metastasis, distant metastasis, and risk of recurrence, positive peritoneal cytology was associated with poor prognosis (p<0.001). Multivariate Cox regression analysis revealed that clinicopathological factors (i.e., age, International Federation of Gynecology and Obstetrics stage, histological type, myometrial invasion, LN metastasis, distant metastasis, and peritoneal cytology), including positive peritoneal cytology, were also significant prognostic factors for OS. Positive peritoneal cytology was a prognostic factor for endometrial cancer for the JSOG gynecological tumor registry.

Detailed report on the clinicopathological factors of patients with endometrial cancer in Japan: a JSOG gynecologic tumor registry-based study

In this study, we collected data over 8 years (2012-2019) from the Japan Society of Obstetrics and Gynecology (JSOG) tumor registry to determine the status of endometrial cancer in Japan, and analyzed detailed clinicopathological factors. The JSOG maintains a tumor registry that gathers information on endometrial cancer treated at the JSOG-registered institutions. Data from the patients whose endometrial cancer treatment was initiated from 2012 to 2019 were analyzed retrospectively. A total of 82,969 patients with endometrial cancer underwent treatment from 2012 to 2019. Chemotherapy alone or in combination with hormonal therapy is more common among endometrial cancer patients under 40 years compared with those over 40 years. The number of patients with endometrial cancer, treated with laparoscopic or robot-assisted surgery was observed to have increased yearly. Small cell carcinomas and undifferentiated carcinomas were more likely to be diagnosed at an advanced stage. Lymphadenectomy was most commonly performed for stage IIIC2 disease, whereas positive peritoneal washing cytology was most common for stage IVB and serous carcinoma. Multi-year summary reports provided detailed clinicopathological information regarding endometrial cancer that could not be obtained in a single year. These reports were useful in understanding treatment strategies and trends over time based on age, histology, and stage.

Trend and characteristics of minimally invasive surgery for patients with endometrial cancer in Japan

Owing to the potential benefits of minimally invasive hysterectomy for endometrial cancer, the practice pattern has recently shifted in Japan. This study examined the trends in minimally invasive surgery (MIS) in patients with endometrial cancer in Japan. This retrospective observational study examined the Japan Society of Obstetrics and Gynecology Tumor Registry database between 2015-2019. This study examined the time-specific proportion change and predictors of MIS use in initial endometrial cancer treatment in Japan, and compared it with the use of abdominal surgery. Additionally, the association between hospital surgical treatment volume and MIS use was examined. A total of 14,059 patients (26.5%) underwent minimally invasive hysterectomy, and 39,070 patients (73.5%) underwent abdominal hysterectomy in the study period. Patients who underwent MIS were more likely to be treated at high-volume centers, younger, central, or western Japan residents, registered in recent years, and had a tumor with stage I disease, type 1 histology, and less myometrial invasion (all adjusted p<0.05). The proportion of MIS treatments increased from 19.1% in 2015 to 34.3% in 2019 (p<0.001). On multivariable analysis, treatment at high-volume centers was a contributing factor for MIS (adjusted odds ratio=3.85; 95% confidence interval=3.44-4.30). MIS at high-volume centers increased significantly from 24.8% to 41.0% (p<0.001) during the study period, whereas MIS at low-volume centers remained at median 8.8%. MIS has increased significantly in recent years, accounting for nearly 34% of surgical management of endometrial cancer in Japan. High-volume treatment centers take the lead in performing MIS.

Low CD86 expression is a predictive biomarker for clinical response to the therapeutic human papillomavirus vaccine IGMKK16E7: results of a post hoc analysis

Abstract Background Although therapeutic human papillomavirus vaccines could offer a noninvasive treatment for patients with cervical intraepithelial neoplasia, none has been clinically implemented. Oral administration of the therapeutic human papillomavirus vaccine IGMKK16E7 results in the histological regression of human papillomavirus 16–positive cervical intraepithelial neoplasia 2/3 to normal (complete response). We investigated biomarkers that could predict complete response after oral administration of IGMKK16E7. Methods Forty-two patients administered high-dose oral IGMKK16E7 in a phase I/II trial were included. Cervix-exfoliated cells were collected before vaccine administration. Gene expression of CD4, CD8, FOXP3, programmed cell death 1 protein, CTLA4, CD103, CD28, CD80, CD86, and programmed cell death 1 ligand 1 in the cells was measured by quantitative reverse transcriptase–polymerase chain reaction. Receiver operating characteristic curve analysis and Mann-Whitney tests were used to explore potential biomarkers. Pearson correlation coefficient analysis was used to correlate gene expression profiles with clinical outcome. Results The only predictive biomarker of vaccine response for which receiver operating characteristic curve analysis showed significant diagnostic performance with histological complete response was CD86 (area under the curve = 0.71, 95% confidence interval = 0.53 to 0.88, P = .020). Patients with complete response had significantly lower CD86 expression (CD86-low) than patients with no complete response (P = .035). The complete response rates for CD86-low and CD86-high patients were 50% and 19%, respectively, and CD86-low patients had a significantly higher complete response rate (P = .047). Compared with all patients, the CD86-low group had a 1.5-fold increase in the complete response rate. Gene expression of CD86 and CTLA4 showed the strongest positive correlation with clinical outcomes in the incomplete response group (P &amp;lt; .001). Conclusion Low expression of CD86 in exfoliated cervical cells can be used as a pretreatment biomarker to predict histological complete response after IGMKK16E7 administration.

Carcinogenesis and epidemiology of cervical cancer: The hallmark of human papillomavirus‐associated cancer

AbstractCervical cancer affects women worldwide and is the most common human papillomavirus (HPV)‐associated cancer. Carcinogenesis caused by HPV results in specific cancer behavior because of the underlying viral infection. The mechanism and timing of the transformation from viral infection to cancer cells have been elucidated in detail. Treatments for this cancer are based on its characteristics and are being implemented. Moreover, HPV infection is widespread worldwide and is transmitted through sexual activity. Although the HPV vaccination is the most effective strategy of preventing cervical cancer, it is not feasible to vaccinate the entire human population especially in low‐ and middle‐income countries. In order to consider the next step for HPV vaccination, we need to understand the characteristics of HPV carcinogenesis and cervical cancer. Additionally, treatment aimed at preservation of reproductive function in patients with cervical cancer is often required, as the cervix is a reproductive organ and because the disease is more prevalent in the adolescent and young adult generation. Thus, there are still many challenges in the diagnosis, treatment, and prevention of cervical cancer.

Allelic loss of HLA class I facilitates evasion from immune surveillance in cervical intraepithelial neoplasia

Loss of heterozygosity (LOH) has been reported to occur in HLA regions in cervical intraepithelial neoplasia (CIN) and cervical cancer. However, the details of how this is related to the progression of CIN have been unclear. In this study, we examined the human papillomavirus (HPV) antigen‐presenting capacity of people with CIN and the significance of LOH of HLA class I in the progression of CIN. It was shown that differences in antigen‐presenting capacity among each case depended on HLA types, not HPV genotypes. Focusing on the HLA type, there was a positive correlation between antigen‐presenting capacity against HPV and the frequency of allelic loss. Furthermore, the lost HLA‐B alleles had a higher HPV antigen‐presenting capacity than intact alleles. In addition, frequency of LOH of HLA class I was significantly higher in advanced CIN (CIN2–3) than in cervicitis or early‐stage CIN (CIN1): around half of CIN2–3 had LOH of any HLA class I. Moreover, the antigen‐presenting capacity against E5, which is the HPV proteins that facilitate viral escape from this immune surveillance by suppressing HLA class I expression, had the most significant impact on the LOH in HLA‐B. This study suggests that HPV evades immune surveillance mechanisms when host cells lose the capacity for antigen presentation by HLA class I molecules, resulting in long‐term infection and progression to advanced lesions.

Reconstructed uterine length is critical for the prevention of cervical stenosis following abdominal trachelectomy in cervical cancer patients

AbstractAimAlthough the procedure of abdominal trachelectomy has been remarkably improved, preventing subsequent cervical stenosis remains challenging. In this study, we analyzed the clinicopathological risk factors for cervical stenosis to explore the appropriate surgical procedures for the prevention of cervical stenosis following trachelectomy.MethodsThirty‐two patients who underwent abdominal extended and radical trachelectomy were assessed retrospectively (median follow‐up period = 33 months). To evaluate the risk factors, the clinicopathological factors were analyzed by univariate and multivariate analyses. The reconstructed uterine length (UtL), that is, the length between the vaginal end of the neo‐cervix and the uterine fundus, was measured by transvaginal ultrasound after surgery. The cut‐off value for the UtL was assessed by a receiver operating characteristic (ROC) curve analysis.ResultsCervical stenosis of any grade was observed in 12 patients (grade 1 = 9, grade 3b = 3). Among the various clinicopathological factors, the UtL and cervical length (CL) were significantly related to cervical stenosis following trachelectomy. The multivariate analysis revealed that the UtL, but not CL, is an independent risk factor for stenosis. The ROC curve analysis revealed that stenosis was significantly more likely to occur in patients with a UtL shorter than 53 mm (area under the ROC curve = 0.902). UtL in the patients who became pregnant was longer than that in the patients who did not. No evidence of recurrent cancer was observed during the follow‐up period.ConclusionOur proposed method may provide a functional reconstructed uterus with preserving fertility by remaining UtL more than 53 mm.

Impact of COVID‐19 on cervical cancer screening in Japan: A survey of population‐based screening in urban Japan by the Japan Society of Gynecologic Oncology

AbstractAimTo assess the impact of COVID‐19 on cervical cancer screening.MethodThe Japanese Society of Gynecologic Oncology launched COVID‐19 Task Force surveyed the municipalities in urban areas of Japan. Questionnaires were sent to 20 ordinance‐designated cities and 23 wards of Tokyo metropolitan area in Japan via telephone and mail in January 2021. An additional survey was conducted in March and April 2021, counted the monthly checkups in 2020 and, as a control data, the number of monthly checkups in 2019. “The State of Emergency” between April 7 and May 25, 2020, included 13 prefectures. The data collected in this research involved the number of screenings only. The chi‐square test was performed for statistical analysis.ResultsThe number of cancer screenings from March to August, with May being the month with the lowest number of screenings, was less than 50% of that in the previous year. In particular, the drop in the number of cancer screenings in the “Prefectures operating under special safety precautions” was remarkable and significantly lower than that in other Prefectures. However, after August, the number recovered to the usual level, despite the second wave of the pandemic occurring nationwide. The initial “the State of Emergency” caused a significant decrease in the number of people receiving population‐based screenings, but the recovery has been remarkable, and the total number is expected to be the same as in previous years.ConclusionThe initial “the State of Emergency” caused a significant decrease in the number of people receiving population‐based screenings.

Phase I and II randomized clinical trial of an oral therapeutic vaccine targeting human papillomavirus for treatment of cervical intraepithelial neoplasia 2 and 3

Abstract Background Although many human papillomavirus (HPV)–targeted therapeutic vaccines have been examined for efficacy in clinical trials, none have been translated into clinical use. These previous agents were mostly administered by intramuscular or subcutaneous injection to induce systemic immunity. We investigated the safety and therapeutic efficacy of an HPV-16 E7-expressing lacticaseibacillus-based oral vaccine. Methods In a double-blind, placebo-controlled, randomized trial, a total of 165 patients with HPV-16–positive high-grade cervical intraepithelial neoplasia 2 and 3 were assigned to orally administered placebo or low, intermediate, or high doses of IGMKK16E7 (lacticaseibacillus paracasei expressing cell surface, full-length HPV-16 E7). In the 4 groups, IGMKK16E7 or placebo was administered orally at weeks 1, 2, 4, and 8 postenrollment. The primary outcomes included histopathological regression and IGMKK16E7 safety. Results In per-protocol analyses, histopathological regression to normal (complete response) occurred in 13 (31.7%) of 41 high-dose recipients and in 5 (12.5%) of 40 placebo recipients (rate difference = 19.2, 95% confidence interval [CI] = 0.5 to 37.8). In patients positive for HPV-16 only, the clinical response rate was 40.0% (12 of 30) in high-dose recipients and 11.5% (3 of 26) in recipients of placebo (rate difference = 28.5, 95% CI = 4.3 to 50.0). There was no difference in adverse events that occurred in the high-dose and placebo groups (P = .83). The number of HPV-16 E7–specific interferon-γ producing cells within peripheral blood increased with level of response (stable disease, partial, and complete responses; P = .004). The regression to normal (complete response) rates among recipients with high levels of immune response were increased in a dose-dependent manner. Conclusion This trial demonstrates safety of IGMKK16E7 and its efficacy against HPV-16–positive cervical intraepithelial neoplasia 2 and 3. IGMKK16E7 is the first oral immunotherapeutic vaccine to show antineoplastic effects. Trial registration jRCT2031190034.

The 2020 Japan Society of Gynecologic Oncology guidelines for the treatment of ovarian cancer, fallopian tube cancer, and primary peritoneal cancer

The fifth edition of the Japan Society of Gynecologic Oncology guidelines for the treatment of ovarian cancer, fallopian tube cancer, and primary peritoneal cancer was published in 2020. The guidelines contain 6 chapters-namely, (1) overview of the guidelines; (2) epithelial ovarian cancer, fallopian tube cancer, and primary peritoneal cancer; (3) recurrent epithelial ovarian cancer, fallopian tube cancer, and primary peritoneal cancer; (4) borderline epithelial tumors of the ovary; (5) malignant germ cell tumors of the ovary; and (6) malignant sex cord-stromal tumors. Furthermore, the guidelines comprise 5 algorithms-namely, (1) initial treatment for ovarian cancer, fallopian tube cancer, and primary peritoneal cancer; (2) treatment for recurrent ovarian cancer, fallopian tube cancer, and primary peritoneal cancer; (3) initial treatment for borderline epithelial ovarian tumor; (4) treatment for malignant germ cell tumor; and (5) treatment for sex cord-stromal tumor. Major changes in the new edition include the following: (1) revision of the title to "guidelines for the treatment of ovarian cancer, fallopian tube cancer, and primary peritoneal cancer"; (2) involvement of patients and general (male/female) participants in addition to physicians, pharmacists, and nurses; (3) clinical questions (CQs) in the PICO format; (4) change in the expression of grades of recommendation and level of evidence in accordance with the GRADE system; (5) introduction of the idea of a body of evidence; (6) categorization of references according to research design; (7) performance of systematic reviews and meta-analysis for three CQs; and (8) voting for each CQ/recommendation and description of the consensus.

Cationic nanogel–based nasal therapeutic HPV vaccine prevents the development of cervical cancer

Therapeutic vaccines against cervical cancer caused by human papillomavirus (HPV) are still an unmet medical need, despite a prophylactic HPV vaccine being available, and the now-licensed systemic vaccines may have a limited effect on the reproductive tract. To specifically inhibit cervical cancer development, the concept of mucosal immunity based on the reproductive-respiratory axis was adopted to develop a nasal HPV therapeutic vaccine. We used a cationic nanogel for the nasal vaccine delivery system and targeted HPV16 E7, an oncoprotein in HPV-driven cervical cancer to demonstrate the feasibility of a nasal therapeutic vaccine. The vaccine was combined with cyclic di–adenosine monophosphate as a cell-mediated immunity-inducing adjuvant. Intranasal immunization with the nanogel vaccine induced E7-specific CD4 + and CD8 + T cells in mouse cervicovaginal tissue. An antitumor effect due to the infiltration of vaccine-induced E7-specific T cells was also observed in an orthotopic tumor model in mice. Furthermore, intranasal immunization of nonhuman primates with the nanogel vaccine using a spray device that is also applicable to humans induced E7-specific T cells in the reproductive tissues. Our findings demonstrated that this nasal therapeutic vaccine effectively controlled cervical cancer and will contribute to preclinical evidence for clinical testing in the near future.

Subsequent primary cancer incidence in cervical cancer survivors: insights from a comprehensive cohort study utilizing combined Japanese population-based cancer registries

This study aimed to evaluate the incidence of subsequent primary cancer (SPC) among cervical cancer survivors in Japan. Data from the cancer registries of Osaka, Kanagawa, and Miyagi prefectures were combined. The cohort included individuals diagnosed with invasive and in situ cervical cancer between 1980 and 2010, with the SPC incidence evaluated until 2015. The incidence and standardized incidence ratio (SIR) for different SPC sites were calculated. In addition, the association between SPC and radiotherapy was examined via competitive regression analysis. A total of 49,824 cervical cancer survivors were followed for up to 35 years, during which 4,507 (9.0%) of these survivors experienced SPC. Aside from the initial cancer, SPC was the most common cause of death among cervical cancer survivors. The most frequent SPC sites were the colorectal, breast, lung, and stomach, consistent with the frequency in the general population. A significant increase in the SIRs for bladder, lung, and colorectal cancers was observed (2.52, 1.63, and 1.44, respectively). Individuals who underwent radiotherapy had a higher risk of developing bladder cancer than those who did not, with a subdistribution hazard ratio of 2.28. The SIR for lung cancer significantly increased, particularly for the smoking-associated types, indicating the influence of smoking habits among survivors. Increased risk of specific SPCs was seen in both invasive and in situ cancer survivors. Cervical cancer survivors should be informed about the risks of SPCs and educated on the prevention methods. Our study provides valuable insights into specific actions SPC prevention.

Feasibility, accuracy and acceptability of self-sampled human papillomavirus testing using careHPV in Cambodia: a cross-sectional study

Self-sampled human papillomavirus (HPV) testing is a potential option for cervical cancer screening, but research is scarce in Cambodia. We evaluated the feasibility, accuracy, and acceptability of self-sampled HPV testing using careHPV. A cross-sectional study including women aged 20-49 years attending 2 national hospitals in the capital city was conducted. Women underwent both self-sampling and clinician-sampling of specimens, and were then asked to complete an acceptability questionnaire. The paired samples were analyzed for high-risk HPV by careHPV and genotyped by polymerase chain reaction (PCR). A total of 375 women were eligible for inclusion. Based on PCR, 78.9% were negative for HPV in both self and clinician-samples, 9.9% had a complete HPV type match, and 6.1% had all HPV types in clinician-samples also detected in self-samples. In 5.1%, one or more HPV types identified in the clinician-samples were missed in self-samples. When using careHPV, the overall agreement between the 2 sampling methods was 95.7% (95% confidence interval [CI]=95.8-95.6) with good concordance (κ=0.66, 95% CI=0.56-0.76). Nearly 90% of the women preferred clinician-sampling over self-sampling, citing greater comfort, ease, and speed. Self-sampled HPV testing using careHPV could be an option for cervical cancer screening in Cambodia; however, it requires periodic quality control of handling procedures. In addition, women's health education regarding the accuracy of self-sampled HPV testing and the importance of follow-up in cases of positive results is needed.

Serum Free Fatty Acid Changes Caused by High Expression of Stearoyl-CoA Desaturase 1 in Tumor Tissues Are Early Diagnostic Markers for Ovarian Cancer

Ovarian cancer has a poor prognosis and is difficult to detect in early stages. Therefore, developing new diagnostic markers for early-stage ovarian cancer is critical. Here, we developed a diagnostic marker for early-stage ovarian cancer on the basis of fatty acid metabolism characteristics of cancer cells. The expression of various fatty acid metabolizing enzymes such as stearoyl-CoA desaturase 1 (SCD1) was altered in early-stage ovarian cancer tissue compared with that in normal ovarian tissue. Changes in the expression of fatty acid metabolizing enzymes, particularly SCD1, in cancer tissues were found to alter concentrations of multiple free fatty acids (FFA) in serum. We were the first to show that fatty acid metabolic characteristics in tissues are related to the FFA composition of serum. Surprisingly, patients with stage I/II ovarian cancer also showed significant changes in serum levels of eight FFAs, which can be early diagnostic markers. Finally, using statistical analysis, an optimal early diagnostic model combining oleic and arachidic acid levels, fatty acids associated with SCD1, was established and confirmed to have higher diagnostic power than CA125, regardless of histology. Thus, our newly developed diagnostic model using serum FFAs may be a powerful tool for the noninvasive early detection of ovarian cancer. Significance: Measurement of serum FFA levels by changes in the expression of fatty acid metabolizing enzymes in tumor tissue would allow early detection of ovarian cancer. In particular, the SCD1-associated FFAs, oleic and arachidic acid, would be powerful new screening tools for early-stage ovarian cancer.