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Inhibition of chaperone-mediated autophagy may be a novel approach to increase platinum susceptibility in ovarian cancer cell lines
Abstracts / Gynecologic Oncology 133 (2014) 2–207
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196 — Poster Session A Gene expression profiles of high-grade serous ovarian cancers in patients with normal CA-125 levels at the time of recurrence V. Broach, F. Dao, D.A. Levine. Memorial Sloan Kettering Cancer Center, New York, NY, USA.
197 — Poster Session A Association of in vitro chemotherapy drug resistance assays in ovarian cancer patients with BRCA1/2 mutations J. Lee, A.W. Menzin, V.S. John, J.L. Lovecchio, J.S. Whyte. Hofstra — North Shore Long Island Jewish School of Medicine, Manhasset, NY, USA.
Objectives: CA-125 is a useful tool for monitoring response to therapy and recurrence in patients with high-grade serous ovarian cancer (HGSOC). However, 15% to 20% of patients have normal levels of CA-125 at the time of recurrence, limiting the prognostic ability of CA-125 in this population. We aimed to determine differences in gene expression profiles of tumors from patients with and without elevated CA-125 levels at the time of recurrence. Methods: Patients with stage IIIC or IV HGSOC who underwent primary surgical cytoreduction and initial platinum-based chemotherapy were identified from The Cancer Genome Atlas (TCGA). All patients had platinum-sensitive, radiographic-confirmed recurrent disease. Patients were stratified into two groups: those with elevated CA-125 (N35 U/mL) and those with normal CA-125 (≤35 U/mL) at time of recurrence. Gene expression profiling was performed using 1 Agilent and 2 Affymetrix expression microarray platforms. Expression data were combined across microarrays using factor analysis for genes present on all array platforms. Gene expression levels for 11,864 genes were analyzed. Mean gene expression was compared using student t-test and significance was defined as P b 0.001. Results: Data were available for 21 patients with normal CA-125 (≤35 U/mL) and 32 patients with elevated CA-125 (N35 U/mL) at the time of recurrence. There were no statistical differences in mean age (56 years, STD 11 years) or median time to recurrence (13 months, range 6–50 months) between the two study groups. Of the 11,864 genes analyzed, 14 showed a statistically significant difference in expression between the two groups (figure); six genes had increased expression and eight genes had decreased expression in patients with normal CA-125 levels at recurrence. The gene functions were consistent with known CA-125/MUC16 biology, including regulation of transcription and DNA binding, which would affect growth, mobility, and invasion. Conclusions: Gene expression profiles vary between advancedstage, platinum-sensitive HGSOC patients who recur with and without elevated CA-125 levels. These findings may indicate inherent differences in tumor biology. Further evaluation of the functional significance of this variable gene expression may lead to better stratification and monitoring approaches based on primary tumor genomics.
Objectives: To evaluate performance of an in vitro chemotherapy drug response assay in BRCA1/2-deficient patients with primary ovarian cancer (OVCA). Methods: Retrospective review of newly diagnosed OVCA patients undergoing primary staging/debulking surgery with performance of commercially available in vitro chemosensitivity assays (CSTA). All patients were offered genetic counseling and testing. Progressionfree survival (PFS) and overall survival (OS) were analyzed. Comparative analysis was performed using Fisher's exact test. PFSs were analyzed using Kaplan–Meier curves. Results: A total of 140 patients met inclusion criteria and had adequate follow-up information. Deleterious mutations in BRCA1 and BRCA2 were found in 8.6% (12/140) and 6.4% (9/140) of patients, respectively, with 25.7% (25/140) patients negative for BRCA mutation. The remaining 59.3% (83/140) declined testing. All patients underwent primary chemotherapy with a platinum agent and a taxane. The mean age at diagnosis was 55 and 61 years in BRCA1/2 mutated and negative/not tested patients (neg/NT). The majority of patients were diagnosed with stage III/IV disease: 71.4% (15/21) BRCA and 80.7% (96/119) neg/NT patients. BRCA1/2 patients had a trend toward improved PFS when compared to PFS in neg/NT (19 vs 26) (P =0.08). There were no statistically significant differences in CTSA between BRCA1/2 and neg/NT patients: carboplatin (73.7% response vs 61.6% response, P = 0.43), cisplatin (64.3% vs 49.3% P = 0.39), carboplatin with paclitaxel (80% vs 80%, P = 1.00), carboplatin with docetaxel (83.3% vs 85.3%, P = 1.00), carboplatin with gemcitabine (77.3% vs 76.7%, P = 1.00), doxorubicin (20.0% vs 33.7%, P = 0.37), gemcitabine (35.0% vs 32.3%, P = 0.80), paclitaxel (57.9 vs 56.4%, P = 1.00), and docetaxel (37.5% vs 34.4%, P = 0.78). Conclusions: In this review of primary OVCA patients tested with CTSA, no significant difference in chemosensitivities based on BRCA mutation status was observed. Although BRCA mutation has been linked to increased platinum sensitivity, this was not demonstrated based on the drug assay. An in vivo mechanism not evaluated by in vitro assay may account for clinically observed increased platinum sensitivity. doi:10.1016/j.ygyno.2014.03.217
Figure: 198 — Poster Session A Inhibition of chaperone-mediated autophagy may be a novel approach to increase platinum susceptibility in ovarian cancer cell lines L.A. Spoozak1, C. Park1, M.R. Ewart1, G.L. Goldberg2, A.M. Cuervo1. 1 Albert Einstein College of Medicine, Bronx, NY, USA, 2Albert Einstein College of Medicine/Montefiore Medical Center, Bronx, NY, USA.
doi:10.1016/j.ygyno.2014.03.216
Objectives: Chaperone-mediated autophagy (CMA) assures lysosomal degradation of specific damaged cytosolic proteins. Our group has previously shown that CMA is upregulated in different types of cancer cells and is required for lung and melanoma tumor growth. We hypothesized that upregulation of CMA may underlie chemotherapy resistance in serous ovarian cancer by removing cellular damage generated by the treatment. Methods: CMA and macroautophagy (MA) activity were assessed in ovarian cancer cell lines with different sensitivities to cisplatin and in formalin-fixed tumor specimens using biochemical and image-based procedures. Markers of both pathways were measured by immunoblot,
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Abstracts / Gynecologic Oncology 133 (2014) 2–207
immunofluorescence, and immunohistochemistry (IHC). MA activity was assessed by LC3B flux assay and CMA activity using a photoactivatable fluorescent reporter. CMA was inhibited using RNA interference against LAMP-2A, the CMA lysosomal receptor. Changes in protein expression between knockdown cells and control were assessed. Cell proliferation and cell viability were measured using standard assays to analyze changes in susceptibility to chemotherapy. Results: Tumor IHC revealed significantly increased expression of LAMP-2A for all ovarian cancer stages, while LC3 was decreased in all stages compared to control. MA activity was comparable in control and platinum-sensitive cell lines, but it was reduced in the platinumresistant cell line. CMA markers and activity were increased in the ovarian cancer cells compared to control but most notably in the platinum-resistant cell line. Blockage of CMA by LAMP-2A knockdown decreased proliferation rates of both cancer cell lines and partially restored cisplatin sensitivity in the platinum-resistant cell line. We are currently investigating the molecular changes induced by the blockage of CMA in the platinum-resistant cells that contributed to their increased sensitivity. Conclusions: Inhibition of chaperone-mediated autophagy may be a novel approach to increase chemotherapy susceptibility of platinumresistant ovarian cancers. doi:10.1016/j.ygyno.2014.03.218
199 — Poster Session A The management of peritoneal surface malignancies: Single-center initial experience M.A.F. Seoud, F. Jamali, A. Shamesseddine, M.J. Khalifeh. American University of Beirut Medical Center, Beirut, Lebanon. Objectives: Peritoneal carcinomatosis (PC) has been traditionally considered a terminal disease, with median survivals reported in the literature of 6 to 12 months. Cytoreductive surgery (CRS) and hyperthermic intraperitoneal chemotherapy (HIPEC) have gradually gained acceptance as the standard of care in the management of selected cases of PC. Excellent results have been achieved in well-selected patients, but there is a very steep learning curve when starting a new program. Methods: A program for the multidisciplinary treatment of peritoneal surface malignancies of gastrointestinal or gynecologic origin was initiated in January 2010 at the American University of Beirut Medical Center. Patients enrolled in the program were treated using multimodality therapy with combinations of systemic therapy, cytoreductive surgery (CRS), and HIPEC. We present the results of our initial experience using a retrospective review of a prospectively collected database. Results: Twenty-three patients were treated with CRS and HIPEC. There were 10 male and 13 female patients. The most common indication (35%) was PC of colorectal origin, followed closely by pseudomyxoma (30%), ovarian malignancies (22%), gastric cancer (8%), and mesothelioma (4%). The mean duration of surgery was 480 min. Mean Peritoneal Cancer Index was 26. Twenty-one (91%) patients had a complete cytoreduction. Major morbidity and mortality rates were 35% and 4.3%, respectively. Mean hospital stay was 16 days. At a mean follow-up of 18 months, median survival has not been reached. Conclusions: We report the successful establishment of an active peritoneal surface malignancy multidisciplinary treatment program with excellent early results that are comparable to those published by reputable centers in the literature. Careful patient selection, a multidisciplinary approach, and proper surgical training and technique are essential for the success of such a program. doi:10.1016/j.ygyno.2014.03.219
200 — Poster Session A The mTOR inhibitor RAD001 exhibited more efficacy against ovarian cancer ascites after pharmacologic inhibition of Mirk kinase X. Deng1, J. Hu1, M.J. Cunningham2, E.A. Friedman1. 1Upstate Medical University, Syracuse, NY, USA, 2GYN Oncology of CNY, PC, East Syracuse, NY, USA. Objectives: The PI3K/PTEN/Akt/mTOR pathway is one of the most frequently deregulated signaling pathways in ovarian cancer and is often responsible for the chemoresistance characterizing recurrent ovarian cancers. Several inhibitors of this pathway have shown limited clinical responses due to upregulation of other survival pathways in complex feedback loops. Because pharmacologic inhibition of mTOR causes Akt or PI3K upregulated expression of Mirk/dyrk1B kinase, we determined whether pharmacologic inhibition of Mirk kinase would enhance the toxicity of mTOR inhibitors toward ovarian cancer ascites taken from patients. Mirk is expressed in most ovarian cancers, and depletion or pharmacologic inhibition of Mirk forces ovarian cancer cells to enter the cycle with elevated reactive oxygen species (ROS) levels, leading to cell death. Methods: Ascites were maintained as nonadherent multicellular aggregates or spheroids by culture in serum-free spheroid media in ultralow-attachment dishes. Specimens were obtained from eight patients with newly diagnosed epithelial ovarian cancer. Results: A Mirk/dyrk1B kinase inhibitor increased the sensitivity of three ovarian cancer cell lines to the mTOR inhibitor RAD001 (everolimus). Spheroids from these lines, like ascites spheroids, were largely quiescent, mostly in G0/G1, and enriched in Mirk/dyrk1B kinase and the quiescence proteins p130/Rb2 and the CDK inhibitor p27. Inhibition of Mirk/dyrk1B kinase led to a decrease in spheroid quiescence markers, an increase in ROS levels, and up to a sevenfold decrease in spheroid volume and viable cell numbers. Significantly, treatment of eight of eight patient-derived ovarian cancer ascites with a Mirk/dyrk1B kinase inhibitor together with the mTOR inhibitor RAD001 led first to an induction of apoptosis markers, then to a disruption of spheroid structure, and finally to loss in viable tumor cells. The Mirk inhibitor, at the concentration that killed patient-derived ovarian cancer ascites cells in vitro, had no detectable toxicity in mice, but reduced the size of xenografts up to threefold. Conclusions: The mTOR inhibitor RAD001 was more effective against ovarian cancer ascites when Mirk/dyrk1B kinase was inhibited. doi:10.1016/j.ygyno.2014.03.220
201 - Poster Session A The usefulness of ovarian cancer risk scoring in the discrimination of an isolated pelvic mass L.R. Eiriksson1, H.C. Millar2, G.K. Lennox2, C.J.M. Reade2, F. Leung2,3, E.P. Diamandis2,3,4, V. Kulasingam2,4, K.J. Murphy5, S.E. Ferguson5, M.Q. Bernardini5. 1Juravinski Hospital and Cancer Centre, Hamilton Health Sciences, Hamilton, ON, Canada, 2University of Toronto, Toronto, ON, Canada, 3Mount Sinai Hospital, Toronto, ON, Canada, 4University Health Network, Toronto, ON, Canada, 5Princess Margaret Hospital, Toronto, ON, Canada. Objectives: Treatment by a gynecologic oncologist improves survival for women with ovarian cancer. When patients present with a pelvic mass, risk-scoring systems are commonly applied to predict the likelihood of benign vs malignant disease based on menopausal status, tumor markers, and ultrasound findings. The objective of this study was to determine the usefulness of the Risk of Malignancy Index (RMI) to guide appropriate referral in patients with an isolated pelvic mass using a prospective population-based cohort. Methods: All patients presenting to our institution from February 2011 through November 2012 with known ovarian cancer, BRCA
81
196 — Poster Session A Gene expression profiles of high-grade serous ovarian cancers in patients with normal CA-125 levels at the time of recurrence V. Broach, F. Dao, D.A. Levine. Memorial Sloan Kettering Cancer Center, New York, NY, USA.
197 — Poster Session A Association of in vitro chemotherapy drug resistance assays in ovarian cancer patients with BRCA1/2 mutations J. Lee, A.W. Menzin, V.S. John, J.L. Lovecchio, J.S. Whyte. Hofstra — North Shore Long Island Jewish School of Medicine, Manhasset, NY, USA.
Objectives: CA-125 is a useful tool for monitoring response to therapy and recurrence in patients with high-grade serous ovarian cancer (HGSOC). However, 15% to 20% of patients have normal levels of CA-125 at the time of recurrence, limiting the prognostic ability of CA-125 in this population. We aimed to determine differences in gene expression profiles of tumors from patients with and without elevated CA-125 levels at the time of recurrence. Methods: Patients with stage IIIC or IV HGSOC who underwent primary surgical cytoreduction and initial platinum-based chemotherapy were identified from The Cancer Genome Atlas (TCGA). All patients had platinum-sensitive, radiographic-confirmed recurrent disease. Patients were stratified into two groups: those with elevated CA-125 (N35 U/mL) and those with normal CA-125 (≤35 U/mL) at time of recurrence. Gene expression profiling was performed using 1 Agilent and 2 Affymetrix expression microarray platforms. Expression data were combined across microarrays using factor analysis for genes present on all array platforms. Gene expression levels for 11,864 genes were analyzed. Mean gene expression was compared using student t-test and significance was defined as P b 0.001. Results: Data were available for 21 patients with normal CA-125 (≤35 U/mL) and 32 patients with elevated CA-125 (N35 U/mL) at the time of recurrence. There were no statistical differences in mean age (56 years, STD 11 years) or median time to recurrence (13 months, range 6–50 months) between the two study groups. Of the 11,864 genes analyzed, 14 showed a statistically significant difference in expression between the two groups (figure); six genes had increased expression and eight genes had decreased expression in patients with normal CA-125 levels at recurrence. The gene functions were consistent with known CA-125/MUC16 biology, including regulation of transcription and DNA binding, which would affect growth, mobility, and invasion. Conclusions: Gene expression profiles vary between advancedstage, platinum-sensitive HGSOC patients who recur with and without elevated CA-125 levels. These findings may indicate inherent differences in tumor biology. Further evaluation of the functional significance of this variable gene expression may lead to better stratification and monitoring approaches based on primary tumor genomics.
Objectives: To evaluate performance of an in vitro chemotherapy drug response assay in BRCA1/2-deficient patients with primary ovarian cancer (OVCA). Methods: Retrospective review of newly diagnosed OVCA patients undergoing primary staging/debulking surgery with performance of commercially available in vitro chemosensitivity assays (CSTA). All patients were offered genetic counseling and testing. Progressionfree survival (PFS) and overall survival (OS) were analyzed. Comparative analysis was performed using Fisher's exact test. PFSs were analyzed using Kaplan–Meier curves. Results: A total of 140 patients met inclusion criteria and had adequate follow-up information. Deleterious mutations in BRCA1 and BRCA2 were found in 8.6% (12/140) and 6.4% (9/140) of patients, respectively, with 25.7% (25/140) patients negative for BRCA mutation. The remaining 59.3% (83/140) declined testing. All patients underwent primary chemotherapy with a platinum agent and a taxane. The mean age at diagnosis was 55 and 61 years in BRCA1/2 mutated and negative/not tested patients (neg/NT). The majority of patients were diagnosed with stage III/IV disease: 71.4% (15/21) BRCA and 80.7% (96/119) neg/NT patients. BRCA1/2 patients had a trend toward improved PFS when compared to PFS in neg/NT (19 vs 26) (P =0.08). There were no statistically significant differences in CTSA between BRCA1/2 and neg/NT patients: carboplatin (73.7% response vs 61.6% response, P = 0.43), cisplatin (64.3% vs 49.3% P = 0.39), carboplatin with paclitaxel (80% vs 80%, P = 1.00), carboplatin with docetaxel (83.3% vs 85.3%, P = 1.00), carboplatin with gemcitabine (77.3% vs 76.7%, P = 1.00), doxorubicin (20.0% vs 33.7%, P = 0.37), gemcitabine (35.0% vs 32.3%, P = 0.80), paclitaxel (57.9 vs 56.4%, P = 1.00), and docetaxel (37.5% vs 34.4%, P = 0.78). Conclusions: In this review of primary OVCA patients tested with CTSA, no significant difference in chemosensitivities based on BRCA mutation status was observed. Although BRCA mutation has been linked to increased platinum sensitivity, this was not demonstrated based on the drug assay. An in vivo mechanism not evaluated by in vitro assay may account for clinically observed increased platinum sensitivity. doi:10.1016/j.ygyno.2014.03.217
Figure: 198 — Poster Session A Inhibition of chaperone-mediated autophagy may be a novel approach to increase platinum susceptibility in ovarian cancer cell lines L.A. Spoozak1, C. Park1, M.R. Ewart1, G.L. Goldberg2, A.M. Cuervo1. 1 Albert Einstein College of Medicine, Bronx, NY, USA, 2Albert Einstein College of Medicine/Montefiore Medical Center, Bronx, NY, USA.
doi:10.1016/j.ygyno.2014.03.216
Objectives: Chaperone-mediated autophagy (CMA) assures lysosomal degradation of specific damaged cytosolic proteins. Our group has previously shown that CMA is upregulated in different types of cancer cells and is required for lung and melanoma tumor growth. We hypothesized that upregulation of CMA may underlie chemotherapy resistance in serous ovarian cancer by removing cellular damage generated by the treatment. Methods: CMA and macroautophagy (MA) activity were assessed in ovarian cancer cell lines with different sensitivities to cisplatin and in formalin-fixed tumor specimens using biochemical and image-based procedures. Markers of both pathways were measured by immunoblot,
82
Abstracts / Gynecologic Oncology 133 (2014) 2–207
immunofluorescence, and immunohistochemistry (IHC). MA activity was assessed by LC3B flux assay and CMA activity using a photoactivatable fluorescent reporter. CMA was inhibited using RNA interference against LAMP-2A, the CMA lysosomal receptor. Changes in protein expression between knockdown cells and control were assessed. Cell proliferation and cell viability were measured using standard assays to analyze changes in susceptibility to chemotherapy. Results: Tumor IHC revealed significantly increased expression of LAMP-2A for all ovarian cancer stages, while LC3 was decreased in all stages compared to control. MA activity was comparable in control and platinum-sensitive cell lines, but it was reduced in the platinumresistant cell line. CMA markers and activity were increased in the ovarian cancer cells compared to control but most notably in the platinum-resistant cell line. Blockage of CMA by LAMP-2A knockdown decreased proliferation rates of both cancer cell lines and partially restored cisplatin sensitivity in the platinum-resistant cell line. We are currently investigating the molecular changes induced by the blockage of CMA in the platinum-resistant cells that contributed to their increased sensitivity. Conclusions: Inhibition of chaperone-mediated autophagy may be a novel approach to increase chemotherapy susceptibility of platinumresistant ovarian cancers. doi:10.1016/j.ygyno.2014.03.218
199 — Poster Session A The management of peritoneal surface malignancies: Single-center initial experience M.A.F. Seoud, F. Jamali, A. Shamesseddine, M.J. Khalifeh. American University of Beirut Medical Center, Beirut, Lebanon. Objectives: Peritoneal carcinomatosis (PC) has been traditionally considered a terminal disease, with median survivals reported in the literature of 6 to 12 months. Cytoreductive surgery (CRS) and hyperthermic intraperitoneal chemotherapy (HIPEC) have gradually gained acceptance as the standard of care in the management of selected cases of PC. Excellent results have been achieved in well-selected patients, but there is a very steep learning curve when starting a new program. Methods: A program for the multidisciplinary treatment of peritoneal surface malignancies of gastrointestinal or gynecologic origin was initiated in January 2010 at the American University of Beirut Medical Center. Patients enrolled in the program were treated using multimodality therapy with combinations of systemic therapy, cytoreductive surgery (CRS), and HIPEC. We present the results of our initial experience using a retrospective review of a prospectively collected database. Results: Twenty-three patients were treated with CRS and HIPEC. There were 10 male and 13 female patients. The most common indication (35%) was PC of colorectal origin, followed closely by pseudomyxoma (30%), ovarian malignancies (22%), gastric cancer (8%), and mesothelioma (4%). The mean duration of surgery was 480 min. Mean Peritoneal Cancer Index was 26. Twenty-one (91%) patients had a complete cytoreduction. Major morbidity and mortality rates were 35% and 4.3%, respectively. Mean hospital stay was 16 days. At a mean follow-up of 18 months, median survival has not been reached. Conclusions: We report the successful establishment of an active peritoneal surface malignancy multidisciplinary treatment program with excellent early results that are comparable to those published by reputable centers in the literature. Careful patient selection, a multidisciplinary approach, and proper surgical training and technique are essential for the success of such a program. doi:10.1016/j.ygyno.2014.03.219
200 — Poster Session A The mTOR inhibitor RAD001 exhibited more efficacy against ovarian cancer ascites after pharmacologic inhibition of Mirk kinase X. Deng1, J. Hu1, M.J. Cunningham2, E.A. Friedman1. 1Upstate Medical University, Syracuse, NY, USA, 2GYN Oncology of CNY, PC, East Syracuse, NY, USA. Objectives: The PI3K/PTEN/Akt/mTOR pathway is one of the most frequently deregulated signaling pathways in ovarian cancer and is often responsible for the chemoresistance characterizing recurrent ovarian cancers. Several inhibitors of this pathway have shown limited clinical responses due to upregulation of other survival pathways in complex feedback loops. Because pharmacologic inhibition of mTOR causes Akt or PI3K upregulated expression of Mirk/dyrk1B kinase, we determined whether pharmacologic inhibition of Mirk kinase would enhance the toxicity of mTOR inhibitors toward ovarian cancer ascites taken from patients. Mirk is expressed in most ovarian cancers, and depletion or pharmacologic inhibition of Mirk forces ovarian cancer cells to enter the cycle with elevated reactive oxygen species (ROS) levels, leading to cell death. Methods: Ascites were maintained as nonadherent multicellular aggregates or spheroids by culture in serum-free spheroid media in ultralow-attachment dishes. Specimens were obtained from eight patients with newly diagnosed epithelial ovarian cancer. Results: A Mirk/dyrk1B kinase inhibitor increased the sensitivity of three ovarian cancer cell lines to the mTOR inhibitor RAD001 (everolimus). Spheroids from these lines, like ascites spheroids, were largely quiescent, mostly in G0/G1, and enriched in Mirk/dyrk1B kinase and the quiescence proteins p130/Rb2 and the CDK inhibitor p27. Inhibition of Mirk/dyrk1B kinase led to a decrease in spheroid quiescence markers, an increase in ROS levels, and up to a sevenfold decrease in spheroid volume and viable cell numbers. Significantly, treatment of eight of eight patient-derived ovarian cancer ascites with a Mirk/dyrk1B kinase inhibitor together with the mTOR inhibitor RAD001 led first to an induction of apoptosis markers, then to a disruption of spheroid structure, and finally to loss in viable tumor cells. The Mirk inhibitor, at the concentration that killed patient-derived ovarian cancer ascites cells in vitro, had no detectable toxicity in mice, but reduced the size of xenografts up to threefold. Conclusions: The mTOR inhibitor RAD001 was more effective against ovarian cancer ascites when Mirk/dyrk1B kinase was inhibited. doi:10.1016/j.ygyno.2014.03.220
201 - Poster Session A The usefulness of ovarian cancer risk scoring in the discrimination of an isolated pelvic mass L.R. Eiriksson1, H.C. Millar2, G.K. Lennox2, C.J.M. Reade2, F. Leung2,3, E.P. Diamandis2,3,4, V. Kulasingam2,4, K.J. Murphy5, S.E. Ferguson5, M.Q. Bernardini5. 1Juravinski Hospital and Cancer Centre, Hamilton Health Sciences, Hamilton, ON, Canada, 2University of Toronto, Toronto, ON, Canada, 3Mount Sinai Hospital, Toronto, ON, Canada, 4University Health Network, Toronto, ON, Canada, 5Princess Margaret Hospital, Toronto, ON, Canada. Objectives: Treatment by a gynecologic oncologist improves survival for women with ovarian cancer. When patients present with a pelvic mass, risk-scoring systems are commonly applied to predict the likelihood of benign vs malignant disease based on menopausal status, tumor markers, and ultrasound findings. The objective of this study was to determine the usefulness of the Risk of Malignancy Index (RMI) to guide appropriate referral in patients with an isolated pelvic mass using a prospective population-based cohort. Methods: All patients presenting to our institution from February 2011 through November 2012 with known ovarian cancer, BRCA