Lysine-specific demethylase KDM3A regulates ovarian cancer stemness and chemoresistance.

This corrects the article DOI: 10.1038/onc.2016.320.

Lysine-specific demethylase KDM3A regulates ovarian cancer stemness and chemoresistance.

Ovarian cancer is the leading cause of death among all gynecological malignancies due to the development of acquired chemoresistance and disease relapse. Although the role of cancer stem cells (CSCs), a subset of tumor cells with the self-renewal and differentiation capabilities, in therapeutic resistance is beginning to be better understood, the significance of epigenetic regulatory mechanisms responsible for integrating the stemness with drug resistance remain poorly understood. Here we identified that lysine demethylase KDM3A as a critical regulator of ovarian cancer stemness and cisplatin resistance by inducing the expressions of pluripotent molecules Sox2 and Nanog and anti-apoptotic B-cell lymphoma 2 (Bcl-2), respectively. In addition, KDM3A induces ovarian cancer growth while antagonizing cellular senescence by repressing the expression of cyclin-dependent kinase inhibitor, p21Waf1/Cip1. The underlying mechanism of the noted biological processes include KDM3A-mediated stimulation of Sox2 expression, and demethylating p53 protein and consequently, modulating its target genes such as Bcl-2 and p21Waf1/Cip1 expression. Consistently, KDM3A depletion inhibited the growth of subcutaneously implanted cisplatin-resistant human ovarian cancer cells in athymic nude mice. Moreover, KDM3A is abundantly expressed and positively correlated with Sox2 expression in human ovarian cancer tissues. In brief, our findings reveal a novel mechanism by which KDM3A promotes ovarian CSCs, proliferation and chemoresistance and thus, highlights the significance of KDM3A as a novel therapeutic target for resistant ovarian cancer.

PON3 is upregulated in cancer tissues and protects against mitochondrial superoxide-mediated cell death.

To achieve malignancy, cancer cells convert numerous signaling pathways, with evasion from cell death being a characteristic hallmark. The cell death machinery represents an anti-cancer target demanding constant identification of tumor-specific signaling molecules. Control of mitochondrial radical formation, particularly superoxide interconnects cell death signals with appropriate mechanistic execution. Superoxide is potentially damaging, but also triggers mitochondrial cytochrome c release. While paraoxonase (PON) enzymes are known to protect against cardiovascular diseases, recent data revealed that PON2 attenuated mitochondrial radical formation and execution of cell death. Another family member, PON3, is poorly investigated. Using various cell culture systems and knockout mice, here we addressed its potential role in cancer. PON3 is found overexpressed in various human tumors and diminishes mitochondrial superoxide formation. It directly interacts with coenzyme Q10 and presumably acts by sequestering ubisemiquinone, leading to enhanced cell death resistance. Localized to the endoplasmic reticulum (ER) and mitochondria, PON3 abrogates apoptosis in response to DNA damage or intrinsic but not extrinsic stimulation. Moreover, PON3 impaired ER stress-induced apoptotic MAPK signaling and CHOP induction. Therefore, our study reveals the mechanism underlying PON3's anti-oxidative effect and demonstrates a previously unanticipated function in tumor cell development. We suggest PONs represent a novel class of enzymes crucially controlling mitochondrial radical generation and cell death.

CA125 levels are a weak predictor of optimal cytoreductive surgery in patients with advanced epithelial ovarian cancer.

The utility of preoperative CA125 to predict optimal primary tumor cytoreduction in patients with advanced (stages IIIC and IV) epithelial ovarian cancer is controversial. In this paper, we retrospectively review patients with stage IIIC and IV epithelial ovarian cancer who underwent primary cytoreductive surgery from 1989 to 2001. Ninety-nine patients were identified and included in the analysis. All patients had preoperative CA125 levels measured. Operative and pathology reports were reviewed. Optimal cytoreduction was defined as largest volume of residual disease < 1 cm in maximal dimension. Mean values were compared with t-test on a log scale when needed. The optimal cut-point for discriminating between those with vs. without optimal cytoreduction was determined using the receiver operator curve (ROC) method. Optimal cytoreduction was achieved in 73% of patients. Among patients with optimal cytoreductive status the mean CA125 level was 569, while among patients with suboptimal cytoreduction the mean CA125 level was 1520 (P < 0.007). A CA125 level of 912 was identified as the optimal cut-point to distinguish the two groups. Using this CA125 level, the sensitivity of this test in predicting optimal cytoreduction was 58% and the specificity was 54%. The positive predictive value of CA125 for optimal cytoreduction was 78% and the negative predictive value was 31%. We conclude that CA125 level is a weak positive and negative predictor of optimal cytoreductive surgery in patients with advanced epithelial ovarian cancer. The CA125 level should not be used as a primary predictor of the outcome of cytoreductive surgery and should be viewed in the context of all other preoperative features.

FIGO stage III and IV uterine papillary serous carcinoma: impact of residual disease on survival.

The objective of this study was to assess the impact of surgical cytoreduction on the survival of patients with uterine papillary serous carcinoma (UPSC). Patients added to the institutional tumor registries between January 1980 and September 2001 with the diagnosis of UPSC were reviewed. The records of 43 patients who underwent surgical cytoreduction for FIGO stage III and IV disease were reviewed. The median survival of UPSC patients with microscopic residual disease was significantly improved compared to those with macroscopic residual disease following primary surgical cytoreduction. We conclude that primary surgical cytoreduction resulting in microscopic residual disease is associated with an improvement in recurrence-free survival and overall survival in women with UPSC.

NID67, a small putative membrane protein, is preferentially induced by NGF in PC12 pheochromocytoma cells.

In an effort to identify genes involved in neuronal differentiation, we have used representational difference analysis (RDA) to clone cDNAs that are preferentially induced by nerve growth factor (NGF) vs. epidermal growth factor (EGF) in PC12 pheochromocytoma cells. We now report the cloning of a previously unknown primary response gene, NID67. In addition to a robust induction by NGF and FGF, both of which cause PC12 cells to differentiate, NID67 is strongly induced by forskolin, A23187 and ATP. EGF, TPA and KCl induce NID67 only weakly. NID67 mRNA is most abundant in heart, ovary and adrenal. Modest levels are present in most brain regions, testis, thyroid, thymus, pituitary, kidney and intestine; little NID67 is present in skeletal muscle and cerebellum. The NID67 cDNA contains a 180 bp open reading frame (ORF) that encodes a 60 amino acid protein. The central 29 amino acids are very hydrophobic and very likely comprise a transmembrane domain. Mouse and human NID67 cDNAs contain an ORF similar to NID67; the rat and human protein sequences are 85% identical whereas the rat and mouse sequences are 92% identical. In vitro transcription and translation reactions confirmed that the ORF we identified produces a 6000 Da protein product. Several small membrane proteins are similar to NID67; they contain a transmembrane domain and little more. All of these proteins participate in forming or regulating ion channels. NID67 may play a similar role in cellular physiology.

Expression of the urokinase plasminogen activator receptor is transiently required during "priming" of PC12 cells in nerve growth factor-directed cellular differentiation.

We previously identified the urokinase plasminogen activator receptor (UPAR) as a gene induced by nerve growth factor (NGF), but not by epidermal growth factor (EGF), in PC12 cells (Farias-Eisner et al. [2000] J. Neurosci. 20:230-239). Antisense oligonucleotides for the UPAR mRNA or an antibody directed against UPAR protein, added simultaneously with NGF, block NGF-induced morphological and biochemical differentiation of PC12 cells. In this report, we show that anti-UPAR antibody blocks morphological differentiation and the expression of two NGF-specific secondary response genes, collagenase-1 and transin, in PC12 cells only during the first 2 hr following NGF exposure. These data suggest that induced UPAR expression is required only over a short period of time following exposure to NGF for the differentiation program in PC12 cells to proceed. For two models of "primed" PC12 cells, we found that UPAR expression and function are not required for NGF-induced differentiation. UPAR and the secondary response genes collagenase-1 and transin are not induced in "primed" PC12 cells in response to NGF, and anti-UPAR antibody does not block morphological differentiation in these cells. Our data suggests that UPAR is required only transiently during the "priming" of PC12 cells in NGF-induced PC12 cell differentiation.

Searching for depolarization-induced genes that modulate synaptic plasticity and neurotrophin-induced genes that mediate neuronal differentiation.

We identify and characterize two classes of immediate-early genes: (i) genes, induced by depolarization in neurons, that play a role in depolarization-induced neuronal plasticity and (ii) genes, induced in neuronal precursors by neurotrophins, that play a causal role in neurotrophin-directed neuronal differentiation. We use rat PC12 pheochromocytoma cells to identify (i) genes preferentially induced by [depolarization or forskolin] versus [Nerve Growth Factor (NGF) or Epidermal Growth Factor (EGF)] and (ii) genes preferentially induced by NGF versus EGF. We describe (i) a collection of genes preferentially induced by depolarization/forskolin in PC12 cells and by kainic acid in vivo, and (ii) a collection of genes preferentially induced by NGF. The synaptotagmin IV gene encodes a synaptic vesicle protein whose level is modulated by depolarization. NGF preferentially induces the urokinase-plasminogen activator receptor in PC12 cells. Antisense oligonucleotide and anti-UPAR antibody experiments demonstrate that NGF-induced UPAR expression is required for NGF-driven PC12 cell differentiation.

The urokinase plasminogen activator receptor (UPAR) is preferentially induced by nerve growth factor in PC12 pheochromocytoma cells and is required for NGF-driven differentiation.

Nerve growth factor (NGF)-driven differentiation of PC12 pheochromocytoma cells is a well studied model used both to identify molecular, biochemical, and physiological correlates of neurotrophin-driven neuronal differentiation and to determine the causal nature of specific events in this differentiation process. Although epidermal growth factor (EGF) elicits many of the same early biochemical and molecular changes in PC12 cells observed in response to NGF, EGF does not induce molecular or morphological differentiation of PC12 cells. The identification of genes whose expression is differentially regulated by NGF versus EGF in PC12 cells has, therefore, been considered a source of potential insight into the molecular specificity of neurotrophin-driven neuronal differentiation. A "second generation" representational difference analysis procedure now identifies the urokinase plasminogen activator receptor (UPAR) as a gene that is much more extensively induced by NGF than by EGF in PC12 cells. Both an antisense oligonucleotide for the UPAR mRNA and an antibody directed against UPAR protein block NGF-induced morphological and biochemical differentiation of PC12 cells; NGF-induced UPAR expression is required for subsequent NGF-driven differentiation.

Cancer of the uterine cervix.

The overall five-year survival of cervical cancer is only 40% worldwide despite the development of effective screening modalities. Paramount to this issue is access to appropriate medical care which remains limited to high-risk populations throughout the world. While surgery and radiation remain the mainstays of current treatment, new therapies based on the association of cervical cancer with the human papillomavirus are currently under investigation.

Dysgerminoma: the role of conservative surgery.

Twenty-five cases of pure ovarian dysgerminoma treated at UCLA Medical Center between 1958 and 1992 were reviewed retrospectively. Patterns of recurrence and overall survival were analyzed with regard to primary surgery (conservative versus nonconservative), use of adjuvant therapy, and stage of disease. Fourteen patients (56%) underwent conservative surgical therapy defined as preservation of the contralateral ovary, 10 patients (40%) had nonconservative primary surgery, and one patient (4%) had chemotherapy as primary treatment. Three patients (12%) received adjuvant chemotherapy and nine patients (36%) received postoperative radiation therapy. Fifteen patients (60%) had stage I disease, four (16%) stage II, and three each (12%) had stage III and IV disease. Nine patients (36%) experienced recurrence of disease. Seven of these nine patients (78%) had stage I disease and all seven had undergone conservative primary surgery with preservation of the contralateral ovary. Six of the seven had received no adjuvant therapy. Only one of these seven patients experienced recurrence in the preserved ovary. She was found to have a dysgenetic ovary and an XY karyotype. Three patients with recurrent disease had received radiation therapy after primary surgery. Twenty patients (80%) were alive without disease at follow-up, two patients (8%) were alive with disease, and three (12%) had died of disease. There was no statistically significant difference in recurrence rates between those patients treated with conservative surgery and those treated with nonconservative surgery, although the total number of patients with recurrences was greater in the former group. Our data suggest that a conservative surgical approach is the preferred treatment in patients with pure dysgerminoma of the ovary who desire future fertility. Lack of adjuvant chemotherapy or radiation therapy, rather than type of initial surgery, may be associated with a higher risk of recurrence.

The chemistry and tumoricidal activity of nitric oxide/hydrogen peroxide and the implications to cell resistance/susceptibility.

The mechanism of cytotoxicity of the NO donor 3-morpholino-sydnonimine toward a human ovarian cancer cell line (OVCAR) was examined. It was found that the NO-mediated loss of cell viability was dependent on both NO and hydrogen peroxide (H2O2). Somewhat surprisingly, superoxide (O2) and its reaction product with NO, peroxynitrite (-OONO), did not appear to be di- rectly involved in the observed NO-mediated cytotoxicity against this cancer cell line. The toxicity of NO/H2O2 may be due to the production of a potent oxidant formed via a trace metal-, H202-, and NO-dependent process. Because the combination of NO and H2O2 was found to be particularly cytotoxic, the effect of NO on cellular defense mechanisms involving H2O2 degradation was investigated. It was found that NO was able to inhibit catalase activity but had no effect on the activity of the glutathione peroxidase (GSHPx)-glutathione reductase system. It might therefore be expected that cells that utilize primarily the GSHPx-glutathione reductase system for degrading H2O2 would be somewhat resistant to the cytotoxic effects of NO. Consistent with this idea, it was found that ebselen, a compound with GSHPx-like activity, was able to protect cells against NO toxicity. Also, lowering endogenous GSHPx activity via selenium depletion resulted in an increased susceptibility of the target cells to NO-mediated toxicity. Thus, a possible NO/H2O2/metal-mediated mechanism for cellular toxicity is presented as well as a possible explanation for cell resistance/susceptibility to this NO-initiated process.

What is the role of reassessment laparoscopy in the management of gynecologic cancers in 1995?

One hundred fifty-four patients with a diagnosis of ovarian, primary peritoneal, or fallopian tube carcinoma underwent 181 reassessment procedures to detect persistent or recurrent disease between January 1, 1989 and December 31, 1994 at Cedars-Sinai Medical Center. One hundred four laparoscopic procedures were performed. Eleven of these procedures were converted to laparotomy due to severe adhesions. Therefore, a total of 88 reassessment laparotomies were performed during the study period. Fifty-seven of 93 laparoscopies and 69 of 88 laparotomies were done as second-look procedures. There was no significant difference between the two groups with respect to patient age, tumor histology, degree of primary cytoreduction, and tumor stage or grade. Significant differences were found between laparoscopy and laparotomy groups in the following outcome variables evaluated: estimated blood loss (33.9 ml vs 164.9 ml, P = 0.0001), operative time (81.3 min vs 130.4 min, P = 0.0001), days of hospitalization (0.3 days vs 6.8 days, P = 0.0001), and direct cost/case ($2765 vs $5420, P = 0.0001). Despite obtaining 50% fewer biopsies with laparoscopy than laparotomy, the ability to detect disease was similar between these two groups: 47.3% vs 55.7% for all procedures and 52.6% vs 53.6% in the patients undergoing second-look procedures. Major complications in the laparoscopy group included transverse colon perforation (1), small bowel perforation (2), enterocutaneous fistula (1), and a retroperitoneal hematoma (1). Major complications in the laparotomy group included cystotomy (1), left ureteral injury (1), enterotomy (2), and SBO (4). Laparoscopy, when technically feasible, appears equally as effective as laparotomy in detecting persistent or recurrent malignant disease with less blood loss, less days spent in the hospital, less financial burden, and no increase in patient morbidity.

Endocervical sampling by Kevorkian curette or Pipelle aspiration device: a randomized comparison.

OBJECTIVE: Our purpose was to compare two means of endocervical sampling-the Kevorkian curette and the Pipelle aspiration device (Unimar Co., Wilton, Conn.)-with respect to patient discomfort, tissue volume, and specimen adequacy for diagnosis. STUDY DESIGN: Fifty-two women undergoing investigation of abnormal cervical cytologic results were assigned randomly to endocervical sampling by Kevorkian or Pipelle instruments. Pain associated with the procedure was assessed by having each subject indicate her pain level on a visual analog scale. Tissue volume was graded by examination of the microscopic slides by two investigators blinded to assignment. Adequacy for diagnosis was evaluated by reviewing pathology reports. RESULTS: Subjects having Pipelle endocervical aspiration (n = 24) had significantly lower mean (+/- SEM) pain scores (27 +/- 5 vs 48.5 +/- 7, p = 0.02) than those in whom the Kevorkian instrument was used (n = 28). However, there were no significant differences in tissue volume obtained or in proportions considered adequate for diagnosis. CONCLUSIONS: Use of the Pipelle instrument was associated with less patient discomfort than Kevorkian curettage for endocervical sampling while providing similar tissue volume and adequacy for diagnosis.

The importance of communication between the pathologist and the clinician in caring for patients receiving gynecologic treatment.

These cases clearly illustrate the importance of communication between the pathologist and gynecologist or gynecologic oncologist to deliver optimal patient care. It is not only important for the pathologist and gynecologist to review the pathologic diagnosis before implementing treatment plans, it is also imperative that the gynecologist provide the pathologist with a thorough history. As part of this communication process, the pathologist conveys abnormalities of histology as well as uncertainties, such as that which occurred in the mucinous cystadenocarcinoma case. By maintaining open communication, the patient receiving gynecologic treatment will receive the best possible care.

The influence of tumor grade, distribution, and extent of carcinomatosis in minimal residual stage III epithelial ovarian cancer after optimal primary cytoreductive surgery.

The purpose of this study was to determine the influence of tumor grade, distribution, and extent of carcinomatosis in minimal residual epithelial ovarian cancer after primary optimal cytoreductive surgery. Between 1978 and 1990, 112 patients with stage III epithelial ovarian cancer underwent primary cytoreductive surgery and had minimal residual disease, i.e., < 5 mm maximum diameter of residual tumor nodules. Seventy-eight patients (70%) had operative reports that contained sufficient detail to be included in this study. We retrospectively reviewed histopathological reports to determine tumor grade, operative and clinical notes to determine one predominant distribution pattern of residual metastases (pelvic/omental, diaphragmatic, or intestinal/mesenteric), and the approximate extent of residual disease (no gross disease, scattered nodules, or extensive carcinomatosis). Standard actuarial survival analysis was performed, and the log-rank chi 2 was used. At the mean follow-up time of 24.4 months, survival was 65% for grade 2 or 3 disease versus 93% for grade 1 (log-rank P < 0.01). Survival was 66% for residual disease in the intestines/mesentery versus 70 and 81% for residual disease in the diaphragm and pelvis/omentum, respectively (log-rank P < 0.03). Survival was 48% for residual extensive carcinomatosis versus 76 and 93% for minimal residual nodules and no gross residual, respectively (log-rank P < 0.001). In conclusion, in women who have minimal residual ovarian cancer after primary cytoreductive surgery, tumor grade and the distribution and extent of carcinomatosis can independently affect survival. The shortest survival correlated with high-grade tumor and extensive carcinomatosis predominantly involving the intestines and mesentery.

Nitric oxide is an important mediator for tumoricidal activity in vivo.

When cultured in vitro, peritoneal macrophages, obtained from mice previously inoculated with bacillus Calmette-Guérin, release nitric oxide, which is cytostatic and/or cytolytic for tumor cells. However, it is not known whether nitric oxide has antitumor effects in vivo. Here we demonstrate that nitric oxide is an important mediator of host resistance to syngeneic and xenogeneic ovarian tumor grafts in C3HeB/FeJ mice. A murine ovarian teratocarcinoma cell line, utilized to study the mechanism of bacillus Calmette-Guérin-induced host resistance to a syngeneic ovarian tumor, proliferated when transplanted intraperitoneally. Marked tumoricidal activity was observed, however, when these murine ovarian teratocarcinoma cells were transplanted 8 days after intraperitoneal bacillus Calmette-Guérin inoculation. In studies related to xenogeneic ovarian tumor grafts, tumoricidal activity was observed after intraperitoneal transplantation of a human epithelial ovarian cancer cell line, NIH:OVCAR-3. This cell line proliferates only in athymic nude (immunologically incompetent) mice. In both sets of experiments, tumoricidal activity was reduced by inhibition of nitric oxide synthesis. These results demonstrate the tumoricidal action of nitric oxide in vivo.

Surgical management of ovarian cancer.

Although several surgical approaches to the diagnosis and management of epithelial ovarian cancer are now standard, surprisingly few prospective data exist to support many of these procedures. However, retrospective data have accumulated over the past decade, much of it very recent, which allow clinicians to make informed decisions regarding most of the commonly performed procedures. This review is an attempt to critically evaluate the best available data regarding the following procedures: primary surgical staging, primary cytoreductive surgery, second look laparotomy and secondary cytoreductive surgery, and palliative surgery for relief of bowel obstruction. We conclude that there is evidence to support the continued use of primary surgical staging and primary cytoreductive surgery. However, data in support of second look laparotomy and secondary cytoreductive surgery are lacking, and we recommend that these procedures not be performed on a routine basis. Finally, we conclude that palliative surgery is hazardous at best and results in questionable benefits for most patients.

Conservative and individualized surgery for early squamous carcinoma of the vulva: the treatment of choice for stage I and II (T1-2N0-1M0) disease.

We studied the outcome of patients undergoing radical local excision (modified radical vulvectomy) with inguinal-femoral lymphadenectomy through separate groin incisions for stage I and II invasive squamous carcinoma of the vulva. The purpose was to determine whether less radical and more individualized surgery is consistent with local control and cure. We have reported previously our experience using radical local excision and modified radical vulvectomy in stage I disease (Obstet. Gynecol. 63, 155 (1984)) and with separate groin incisions (Obstet. Gynecol. 58, 574 (1981)). This current report expands our experience with stage I and adds stage II patients treated over the past decade. Seventy-four patients were studied retrospectively over the 5-year period ending in January 1990. Reviews of both patient charts and histopathology reports were correlated with recurrence and survival. Factors analyzed included FIGO stage and grade, histology, lesion size and depth of invasion, surgical procedure, radiotherapy, lymph node status, interval to and site of recurrence, and survival. Thirty-nine patients had stage I disease and 35 had stage II. The primary operation was a radical local excision (modified radical vulvectomy) in 56 patients and radical vulvectomy in 18 patients; 13 underwent ipsilateral inguinal-femoral lymphadenectomy and 58 bilateral lymphadenectomy, each through separate groin incisions. The survival of those treated conservatively (97 and 90% for stages I and II, respectively) is the same as those undergoing a radical vulvectomy (100 and 75% for stages I and II, respectively) with only the presence of inguinal-femoral lymph node metastases impacting negatively on survival. In the entire group, the survival for negative and positive nodes was 98 and 45%, respectively. In conclusion, conservative, modified, and individualized vulvectomy in both stage I and II disease is associated with the same outcome and survival as radical vulvectomy, and lymph node status is the most important prognostic factor.

The etiology and management of diarrhea in the gynecologic oncology patient.

PURPOSE: We determined the etiology and evaluated the usefulness of diagnostic tests in 42 gynecologic oncology patients with diarrhea. METHODS: All inpatients who developed diarrhea during treatment for gynecologic cancer were prospectively evaluated during the 12-month study period ending June 1992. Diarrhea was defined as five or more loose stools per 24 hr lasting for 48 hr or more. Diagnostic tests were complete blood cell count; electrolytes; stool for occult blood, white blood cells, and Clostridia difficile toxin; and stool culture for Shigella, Salmonella, Yersinia, and Campylobacter. RESULTS: During the study period 351 women with gynecologic cancer received inpatient care. Forty-two (12%) patients developed diarrhea. One patient had three episodes and another had two episodes of diarrhea. There were 39 evaluable patients; 3 patients were excluded due to incomplete tests. The only cause of bacterial-associated diarrhea was C. difficile, which occurred in 4 of 39 (10.3%) patients. No patient had community-acquired diarrhea, and 1 patient had diarrhea due to Crohn's Disease. Surgery was performed on 265 patients; 29 of 265 (10.9%) developed postoperative diarrhea. Eighty-six patients had medical treatment and 13 (15.1%) developed diarrhea. The distribution by admission status of patients with diarrhea did not differ statistically from the patients without diarrhea. The four patients with C. difficile-associated diarrhea received appropriate therapy at the time of diagnosis. Nevertheless, the mean (SD) duration of C. difficile-associated diarrhea (342 (103) hr) was significantly longer than the mean (SD) duration of diarrhea not associated with this pathogen (79 (32) hr). The difference between the sample means is 263 hr with a 95% confidence interval for the difference between the means of 218 and 308 hr. Electrolyte abnormalities occurred in 20 patients (51%). Fecal leukocytes were present in 11 (28%) patients and occult blood in 5 (12.8%) of the 39 patients. Neither study was predictive for the presence of C. difficile. CONCLUSION: Hospital-acquired diarrhea in gynecologic oncology patients is common, although specific bacterial pathogens requiring antibiotic therapy account for only 10% of cases. Diagnostic tests for infectious causes besides C. difficile are infrequently useful and may be omitted unless the condition persists more than 72 hr.