A loop of cancer-stroma-cancer interaction promotes peritoneal metastasis of ovarian cancer via TNFα-TGFα-EGFR.

Peritoneum is the most common site for ovarian cancer metastasis. Here we investigate how cancer epigenetics regulates reciprocal tumor-stromal interactions in peritoneal metastasis of ovarian cancer. Firstly, we find that omental stromal fibroblasts enhance colony formation of metastatic ovarian cancer cells, and de novo expression of transforming growth factor-alpha (TGF-α) is induced in stromal fibroblasts co-cultured with ovarian cancer cells. We also observed an over-expression of tumor necrosis factor-alpha (TNF-α) in ovarian cancer cells, which is regulated by promoter DNA hypomethylation as well as chromatin remodeling. Interestingly, this ovarian cancer-derived TNF-α induces TGF-α transcription in stromal fibroblasts through nuclear factor-κB (NF-κB). We further show that TGF-α secreted by stromal fibroblasts in turn promotes peritoneal metastasis of ovarian cancer through epidermal growth factor receptor (EGFR) signaling. Finally, we identify a TNFα-TGFα-EGFR interacting loop between tumor and stromal compartments of human omental metastases. Our results therefore demonstrate cancer epigenetics induces a loop of cancer-stroma-cancer interaction in omental microenvironment that promotes peritoneal metastasis of ovarian cancer cells via TNFα-TGFα-EGFR.

Hysterectomy for recurrent postmenopausal bleeding revisited: missed sclerosing stromal ovarian tumour.

Sclerosing stromal tumour of the ovary is rare. Patients present with menstrual irregularities, pelvic pain, abdominal distension, and presence of a large pelvic mass during their twenties or thirties. We report a rare case of an ovarian sclerosing stromal tumour with an atypical presentation, in that it gave rise to recurrent postmenopausal bleeding.

Dysregulation of microRNA-204 mediates migration and invasion of endometrial cancer by regulating FOXC1.

MicroRNAs (miRNAs) regulate mRNA stability and protein expression, and certain miRNAs have been demonstrated to act either as oncogenes or tumor suppressors. Differential miRNA expression signatures have been documented in many human cancers but the role of miRNAs in endometrioid endometrial cancer (EEC) remains poorly understood. This study identifies significantly dysregulated miRNAs of EEC cells, and characterizes their impact on the malignant phenotype. We studied the expression of 365 human miRNAs using Taqman low density arrays in EECs and normal endometriums. Candidate differentially expressed miRNAs were validated by quantitative real-time PCR. Expression of highly dysregulated miRNAs was examined in vitro through the effect of anti-/pre-miRNA transfection on the malignant phenotype. We identified 16 significantly dysregulated miRNAs in EEC and 7 of these are novel findings with respect to EEC. Antagonizing the function of miR-7, miR-194 and miR-449b, or overexpressing miR-204, repressed migration, invasion and extracellular matrix-adhesion in HEC1A endometrial cancer cells. FOXC1 was determined as a target gene of miR-204, and two binding sites in the 3'-untranslated region were validated by dual luciferase reporter assay. FOXC1 expression was inversely related to miR-204 expression in EEC. Functional analysis revealed the involvement of FOXC1 in migration and invasion of HEC1A cells. Our results present dysfunctional miRNAs in endometrial cancer and identify a crucial role for miR-204-FOXC1 interaction in endometrial cancer progression. This miRNA signature offers a potential biomarker for predicting EEC outcomes, and targeting of these cancer progression- and metastasis-related miRNAs offers a novel potential therapeutic strategy for the disease.

CHD5 Downregulation Associated with Poor Prognosis in Epithelial Ovarian Cancer.

BACKGROUND: The CHD5 gene located on 1p36 encodes a protein-chromodomain helicase DNA-binding protein 5. CHD5 has been shown to be a tumor suppressor gene candidate. This study investigated the involvement of CHD5 in ovarian cancer and its clinicopathological significance. METHODS: CHD5 expression in ovarian cancer and its counterpart were determined by quantitative RT-PCR. The correlation of CHD5 expression to clinicopathological features of the tumor was analyzed. RESULTS: CHD5 expression was downregulated by at least twofold in 32 of 72 (41%) invasive epithelial ovarian carcinomas when compared to 12 controls in Hong Kong Chinese women. CHD5 downregulation was correlated to clinical status (p < 0.05), but not to patient age, tumor type and grade, recurrence and clinical stage (p > 0.05). Survival analysis showed that patients with CHD5 downregulation in their tumors were associated with shorter disease-free and total survival times compared to those without CHD5 downregulation (p < 0.05). Cox proportional-hazards regression analysis indicated that downregulation of CHD5 is an independent adverse prognostic factor in ovarian cancer. CONCLUSION: This study shows that CHD5 is downregulated in a certain number of ovarian cancers and appears to be an adverse predictor candidate of ovarian cancer disease-free and total survival.

Is aortic lymphadenectomy necessary in the management of endometrial carcinoma?

OBJECTIVE: To evaluate the role of aortic lymphadenectomy in the management of endometrial carcinoma. METHODS: Clinical notes of 163 patients with endometrial carcinoma were reviewed. All patients had peritoneal cytology, total abdominal hysterectomy, bilateral salpingo-oophorectomy and pelvic lymphadenectomy with or without aortic lymphadenectomy. RESULTS: Seventy-five (46.0%) patients had pelvic lymphadenectomy alone whereas 88 (54.0%) had both pelvic and aortic lymphadenectomy. Thirty-five (21.5%) patients had nodal metastases with positive pelvic and aortic nodes in 26 (16.0%) and 24 (27.3%) patients, respectively. Isolated aortic metastases were found in 17 cases (19.3%). Among 35 patients with nodal metastases, recurrence developed in 15 (42.9%) patients and all except one died within five to 50 months. The remaining patients had a median disease-free period of 55 months (13-93 months). The recurrence rate was higher (63.6%) among patients with upper aortic lymph node metastases, and all those who recurred died of disease within seven to 28 months. CONCLUSIONS: Our data suggest that aortic lymphadenectomy provides both diagnostic and therapeutic value in the management of endometrial carcinoma with high metastatic risk. After surgical removal and adjuvant radiotherapy, patients with nodal metastases achieved a better survival chance.

Identification of molecular markers and signaling pathway in endometrial cancer in Hong Kong Chinese women by genome-wide gene expression profiling.

Endometrial cancer is the third most common gynecologic malignancy and the ninth most common malignancy for females overall in Hong Kong. Approximately 80% or more of these cancers are endometrioid endometrial adenocarcinomas. The aim of this study was to reveal genes contributing to the development of endometrioid endometrial cancer, which may impact diagnosis, prognosis and treatment of the disease. Whole-genome gene expression analysis was completed for a set of 55 microdissected sporadic endometrioid endometrial adenocarcinomas and 29 microdissected normal endometrium specimens using the Affymetrix Human U133 Plus 2.0 oligonucleotide microarray. Selected genes of interest were validated by quantitative real-time-polymerase chain reaction (qRT-PCR). Pathway analysis was performed to reveal gene interactions involved in endometrial tumorigenesis. Unsupervised hierarchical clustering displayed a distinct separation between the endometrioid adenocarcinomas and normal endometrium samples. Supervised analysis identified 117 highly differentially regulated genes (>or=4.0-fold change), which distinguished the endometrial cancer specimens from normal endometrium. Twelve novel genes including DKK4, ZIC1, KIF1A, SAA2, LOC16378, ALPP2, CCL20, CXCL5, BST2, OLFM1, KLRC1 and MBC45780 were deregulated in the endometrial cancer, and further validated in an independent set of 56 cancer and 29 normal samples using qRT-PCR. In addition, 10 genes were differentially regulated in late-stage cancer, as compared to early-stage disease, and may be involved in tumor progression. Pathway analysis of the expression data from this tumor revealed an interconnected network consisting of 21 aberrantly regulated genes involved in angiogenesis, cell proliferation and chromosomal instability. The results of this study highlight the molecular features of endometrioid endometrial cancer and provide insight into the events underlying the development and progression of endometrioid endometrial cancer.

Gene expression pattern associated with radiotherapy sensitivity in cervical cancer.

UNLABELLED: The objective of the present preliminary study was to determine if a difference in the pattern of gene expression exists between tumors that were subsequently found to be sensitive to radiotherapy and tumors found to be resistant to radiotherapy. PATIENTS AND METHODS: A total of 16 patients with invasive squamous cell carcinoma of the uterine cervix were included in this study. All patients were treated with standardized radiotherapy alone. Ten of the tumors were clinically radiosensitive and six were radioresistant. Total RNA, extracted from tumor specimens obtained prior to treatment, was hybridized onto an oligonucleotide microarray with probe sets complementary to over 20,000 transcripts. The genes were first subjected to a statistical filter to identify genes with statistically significant differential expression levels between those that were radiosensitive and those that were radioresistant. A back-propagation neural network was then constructed to model the differences so that patterns could be easily identified. RESULTS: Although a number of genes were found to express differentially between radiosensitive and radioresistant tumors; the 10 most discriminating genes were used to construct the model. Using the expressions from these 10 genes, we found that neural networks constructed from random subsets of the whole data were capable of predicting radiotherapy responses in the remaining subset, which appears stable within the dataset. DISCUSSION: This study shows that such an approach has the potential to differentiate tumor radiosensitivity, although confirmation of such a pattern using other larger independent datasets is necessary before firm conclusions can be drawn.

Prospective self-controlled study on prevention of hysteroscopic dissemination in endometrial carcinoma.

Patients diagnosed to have endometrial carcinoma without prior hysteroscopic examination were recruited from March 2000 to August 2003. Normal saline was used to distend the uterine cavity during the hysteroscopic examination to look for endocervical spread before the definitive surgical treatment. We performed laparotomy, clamped both fallopian tubes, and collected peritoneal washing before the hysteroscopic examination was performed. Peritoneal washing was collected once more after the hysteroscopic examination. Hysteroscopic assessment was performed in 103 patients. Of them, 10 patients were excluded from the study due to previous history of tubal sterilization or blockage. The final analysis was confined to 93 patients. Positive peritoneal cytology was found in 10 (10.8%) patients and this finding was significantly related to the tumor grading (P = 0.023), adnexal involvement (P = 0.003), cervical invasion (P = 0.01), and the presence of peritoneal seedlings (P = 0.001). In five of the 10 patients with positive peritoneal cytology before the hysteroscopic examination, malignant cells could also be recovered in the peritoneal washing collected after the hysteroscopic examination. For patients with negative peritoneal cytology before hysteroscopy, none exhibited positive peritoneal cytology after the procedure. Our data suggested that complete occlusion of both fallopian tubes can effectively prevent the dissemination of endometrial malignant cells into the peritoneal cavity during hysteroscopy.

The value of pelvic and para-aortic lymphadenectomy in endometrial cancer to avoid unnecessary radiotherapy.

The case histories of 95 patients with endometrial carcinoma treated between July 1998 and December 2002 were reviewed. These patients were staged according to FIGO classification and included peritoneal cytology, total abdominal hysterectomy/bilateral salpingo-oophorectomy (TAHBSO), and pelvic with or without para-aortic lymphadenectomy. The FIGO surgical stages were as follow: IA, 9 (9.5%); IB, 35 (36.8%); IC, 16 (16.8%); IIB, 10 (10.5%); IIIA, 5 (5.3%); IIIB, 1 (1.1%); IIIC, 19 (20.0%). In addition to TAHBSO, 47 (49.5%) patients had pelvic lymphadenectomy whereas 48 (50.5%) had both pelvic and para-aortic lymphadenectomy. Nineteen (20.0%) of 95 patients had nodal metastases. Positive pelvic and para-aortic lymph nodes were found in 15 (15.8%) of 95 and 12 (25.0%) of 48 patients, respectively. According to the result of the lymphadenectomy, 19 (20.0%) patients had their surgical stage upgraded to stage IIIC and 61 (64.2%) patients had a change in their management plan. Twelve (12.6%) patients required extended field irradiation due to para-aortic nodal metastases and 49 (51.6%) patients with negative nodes avoided postoperative external radiotherapy. By defining the lymphatic spread via surgical staging, postoperative radiotherapy can be recommended to patients with nodal metastases, while it can be withheld from those patients with negative nodes, irrespective of the presence of risk factors.

Expression of apoptotic regulators and their significance in cervical cancer.

Insufficient apoptosis is implicated in many human cancers, including cervical carcinoma. The objectives of this study were to explore changes of apoptosis-regulating gene expression and their clinical significance in cervical cancer. The expression of apoptosis-regulating genes, including five Bcl-2 family and two caspase family members, was evaluated in 43 cervical invasive squamous cell carcinomas, using immunohistochemistry. Specimens in which >or=10% of the neoplastic cells showed cytosolic immunoreactivity were considered to be immunopositive. Results were correlated with clinico-pathologic characteristics of the subjects. All seven apoptotic regulators examined were positive in a proportion of the tumors. The percentage of cases expressing Bax was higher in the patients without evidence of disease after treatment than in the patients alive with disease or who died of disease (P<0.05). A significant difference in disease-free survival was detected between Bax-positive and -negative groups (P<0.05), and in overall survival between Mcl-1-positive and -negative groups (P<0.05). Significant association between the seven markers tested was only found for caspase 3 and Bak immunoreactivity in cervical carcinoma (P<0.05). The results demonstrate expression of multiple apoptosis-modulating proteins in cervical cancer. There appears to be complex regulation of apoptosis protein levels in association with clinical behavior of cervical squamous cell carcinoma.

Cervical intraepithelial neoplasia is associated with increased polyamine oxidase and diamine oxidase concentrations in cervical mucus.

OBJECTIVE: The aim of this study was to establish whether reactive oxygen species, generated during oxidation of amines, catalyzed by polyamine oxidase (PAO) and diamine oxidase (DAO) in cervical secretions may play a role in the etiology of cervical cancer. METHODS: Cervical mucus was obtained from women attending the gynecological outpatient department: 139 with and 154 without cytological evidence of cervical intraepithelial neoplasia were recruited. The mucus was freeze dried in liquid nitrogen, weighed, and later resuspended for assay of PAO and DAO concentrations using a chemiluminescence method. The two groups were compared by group sequential analysis using PEST3 software. RESULTS: Patients with a colposcopic diagnosis of a high-grade squamous intraepithelial lesion (SIL) had significantly higher enzyme activities than control cases (L(N)PAO 1.37 (0.37) versus 1.18 (0.35): Student t test: P < 0.001; L(N)DAO 1.37 (0.36) versus 1.15 (0.37): Student t test: P < 0.001). CONCLUSION: It is probable that this rise in enzyme activity precedes cytological changes and plays some part in the etiology of cervical cancer, as the cells that undergo premalignant change are normally squamous in origin, whereas mucus is a product of columnar epithelium. Higher enzyme activity in patients with SIL than in controls may be a reflection of higher risk of exposure to amine substrates in semen through multiple sexual partners.

Hysteroscopic dissemination of endometrial carcinoma using carbon dioxide and normal saline: a retrospective study.

OBJECTIVE: The aim of this study was to compare the likelihood of disseminating endometrial carcinoma cells into the peritoneal cavity by hysteroscopic examination using carbon dioxide (CO(2)) or normal saline (NS) as the distension medium. METHODS: A retrospective study of 162 consecutive patients with endometrial carcinoma treated at a university teaching hospital from 1994 to 1999 was undertaken. All patients had a hysteroscopic examination, using either CO(2) or NS as the distension medium, as part of the investigation for abnormal uterine bleeding or in determining whether the uterine cervix was invaded by tumor. Peritoneal fluid for cytology was collected immediately upon entry into the abdominal cavity. Positive peritoneal cytology was considered the primary statistical endpoint. RESULTS: Among 162 patients, 39 cases were excluded from the study because of macroscopic intraperitoneal diseases (n = 32) or pathology other than endometrioid adenocarcinoma (n = 7). Another 3 cases were excluded because both distension mediums had been used in the hysteroscopy. Analysis was therefore based on the data of 120 patients. There was no statistically significant difference between the two groups of patients undergoing hysteroscopy using either CO(2) (n = 70) or NS (n = 50) with regard to age, pathologic stage, International Federation of Gynecology and Obstetrics grading, myometrial invasion, tumor size, cervical involvement, nodal involvement, and 2-year progression-free survival. However, there was a mean of 13.0 plus minus 5.0 days (range 3-21 days) time gap between laparotomy for definitive surgery and CO(2) hysteroscopy compared to immediate laparotomy after NS hysteroscopy (P < 0.001). Positive peritoneal cytology was noticed in 8 (6.7%) patients of which 7 were in the NS group and 1 was in the CO(2) group. Positive cytology was significantly more common among patients after hysteroscopy using NS than CO(2) (14.0% versus 1.4%, odds ratio = 11.2, 95% confidence interval = 1.3-94.5, P = 0.009). The presence of positive peritoneal cytology was not associated with age, tumor grade, tumor size, myometrial invasion, cervical involvement, or nodal metastasis. All 8 patients with positive cytology received no additional treatment and are disease free at 12 to 34 months of follow-up. CONCLUSIONS: Our data suggested that endometrial malignant cells were introduced into the peritoneal cavity during hysteroscopy and might be more likely after the use of NS rather than CO(2). This report emphasizes the need for prospective evaluation for further clarification of this hypothesis. The clinical significance of the dissemination awaits the long-term follow-up of these patients.

The effect of continuous combined hormone replacement therapy on arterial reactivity in postmenopausal women with established angina pectoris.

Most epidemiological studies have suggested that the administration of estrogen reduces cardiovascular risk in healthy postmenopausal women. More recently, however, in the large Heart Estrogen/progestin Replacement Study (HERS), it was unexpectedly found that in women with established cardiovascular disease, there was overall no difference in cardiovascular events between those treated with combined oestrogen/progestin hormone replacement therapy and those on placebo. The aim of this study was to examine the effect of combined hormone replacement therapy on arterial reactivity in women with existing angina pectoris. Seventy-four postmenopausal women with angina pectoris were recruited into a 16 week double-blind, placebo-controlled study of treatment with 2 mg of estradiol combined with 1 mg of norethisterone acetate daily. The median endothelium-dependent change in arterial relaxation increased from 5.00 to 7.69% in the treatment group and decreased from 5.57 to 3.64% in the controls. The median endothelium-independent change in arterial relaxation increased from 6.49 to 7.27% in the treatment group and decreased from 4.39 to 2.07% in the controls. The changes in arterial relaxation between the treatment and control groups were not statistically significant. The administration of estrogen/progestin did not significantly improve either endothelium-dependent or -independent arterial relaxation in postmenopausal women with established cardiovascular disease. We have previously shown that estrogen/progestin treatment improves endothelium dependent relaxation in healthy women. The results of our study provide one possible explanation for the clinical findings of the HERS study. In women with established cardiovascular disease, arterial relaxation does not increase significantly in response to treatment with combined hormone replacement therapy.

Aberrant expression of p21(WAF1/CIP1) and p27(KIP1) in cervical carcinoma.

An immuno-histochemical study of p21 and p27 expression in cervical carcinoma was performed in 73 patients. Positive p21 and p27 staining was detected in 35.6 and 11% of tumour tissues, respectively. p21 expression was significantly correlated with advanced disease stage and negative human papilloma virus infection whilst positive p27 staining was not correlated with any clinical and pathological parameters studied. Kaplan-Meier estimation indicated that survival might be related to disease stage, tumour grade and p21 expression. Cox regression analysis confirmed that advanced stage disease and poorly differentiated tumour are independent prognostic factors for cervical carcinoma.

Preoperative hysteroscopic assessment of cervical invasion by endometrial carcinoma: a retrospective study.

OBJECTIVE: The aim of this study was to evaluate the efficacy of hysteroscopy, using normal saline (NS) or carbon dioxide (CO2) as the distention medium, in assessing tumor invasion of the uterine cervix by endometrial carcinoma. METHODS: A retrospective study was conducted in 200 consecutive patients with endometrial carcinoma diagnosed from 1993 to 2000. Prior to definitive surgical treatment, hysteroscopy was performed using either NS or CO2 as the distention medium to determine whether the tumor had spread to the cervix. The uterine specimens obtained after hysterectomies were cut open for gross examination. Tumor invasion of the cervix as determined by hysteroscopy and gross examinations was compared with the pathological findings. RESULTS: Tumor invasion of the cervix was found in 41 (20.5%) cases on pathological examination. Hysteroscopy has an accuracy of 92.5% (185/200), a sensitivity of 68.3% (28/41), and a specificity of 98.7% (157/159), with a PPV of 93.3% (28/30) and a NPV of 92.4% (157/170) in determining cervical involvement. Assessment by gross inspection had 93.0% (186/200) accuracy, 68.3% (28/41) sensitivity, 99.4% (158/159) specificity, 96.6% (28/29) PPV, and 92.4% (158/171) NPV. There was no significant difference between the two assessment methods. When the results of hysteroscopy performed with different distention mediums were compared, the use of NS had a higher accuracy in determining tumor spread to the cervix (96.8% vs 88.7%, P = 0.03) and NPV (96.4% vs 88.4%, P < 0.05) than the use of CO2. CONCLUSIONS: Hysteroscopic assessment and gross examination of the uterine specimen had similar efficacy in detecting cervical invasion by endometrial carcinoma. Hysteroscopic examination using NS is more accurate than that which uses CO2.

Anti-ischemic action of estrogen-progestogen continuous combined hormone replacement therapy in postmenopausal women with established angina pectoris: a randomized, placebo-controlled, double-blind, parallel-group trial.

The benefit of treating postmenopausal women with established cardiovascular disease with combined estrogen-progestogen hormone replacement therapy (HRT) is controversial. This study investigated the effect of treatment with estradiol and norethisterone acetate on exercise tolerance and on the frequency and severity of ischemic attacks in postmenopausal women with stable angina pectoris. A total of 74 Chinese women were recruited for this 16-week double-blind, placebo-controlled trial. They were randomly allocated into two groups; one group received placebo/placebo/placebo and the other group received placebo/estrogen-progestogen/placebo. Estrogen-progestogen continuous combined HRT increased both time to 1-mm ST depression (99.1 s, p < 0.05) compared with a mean decrease of 22.9 s with placebo (p < 0.05), and total exercise duration also showed a significant increase (32.7 s, p < 0.05) after treatment compared with placebo (2.5 s, p < 0.05). In addition, the total number of ischemic events/24 h during ambulatory electrocardiographic monitoring decreased by 0.82 events after treatment (p < 0.05) compared with an increase in the placebo group (0.94), a highly significant difference (p = 0.006). These results suggest that the administration of this particular combined hormone replacement preparation may have a beneficial effect on myocardial ischemia in postmenopausal women with established coronary disease.

The effects of follicular fluid and platelet-activating factor on motion characteristics of poor-quality cryopreserved human sperm.

PURPOSE: To evaluate the effects of follicular fluid and platelet-activating factor on sperm motion characteristics of cryopreserved oligospermic and normospermic samples. METHODS: Sperm motion characteristics were evaluated prior to cryopreservation, immediately after thawing and following incubation in human tubal fluid, follicular fluid, or 1-microM platelet-activating factor cultures. Sixteen oligospermic samples and 20 normospermic samples were examined. Sperm motion characteristics were analyzed manually according to WHO criteria (1999) and also with an automated videomicrography system. RESULT(S): Incubation in follicular fluid increased overall motility and the percentage of sperm with fast progressive motility in normospermic but not oligospermic samples. Incubation with platelet-activating factor increased overall motility and the percentage of sperm showing nonprogressive motility in both oligospermic and normospermic samples. CONCLUSION(S): The stimulatory effects of culture in follicular fluid as seen in normospermic samples do not show a significant benefit in oligospermic cryopreserved samples. Platelet-activating factor and follicular fluid increase motility via different mechanisms. Incubation of oligospermic cryopreserved sperm with PAF increases the number of motile sperm, thereby enabling easier identification of viable sperm for intracytoplasmic sperm injection in samples with severe asthenozoospermia.

Alteration of cyclin D1 and CDK4 gene in carcinoma of uterine cervix.

Amplification and overexpression of cyclin D1 and CDK4 genes in cervical carcinoma were studied by semi-quantitative differential polymerase chain reaction assay and an immunostaining technique, respectively. Amplifications of cyclin D1 and CDK4 genes were found in 24% (27/113) and 26% (29/112) of tumors, respectively. Overexpression of cyclin D1 and CDK4 was demonstrated in 32% (21/66) and 73% (45/62) of tumors, respectively. No tumor showed CDK4 gene mutation on single strand conformational polymorphism. Sixteen percent (8/49) of the tumor specimens showed neither amplification nor overexpression. Disease stage, tumor grade and overexpression of cyclin D1 were found to be independent poor prognostic factors in cervical carcinoma.

Whole blood mercury concentrations in sub-fertile men in Hong Kong.

We aimed to investigate the association between whole blood mercury concentrations and semen quality in sub-fertile men. Fifty-nine male partners of infertile couples attending the Assisted Reproduction Unit of the Chinese University of Hong Kong between 1997 and 1998 were recruited into our study. Blood was taken from each subject for whole blood mercury concentration and hormone profile. Semen samples were obtained for computer assisted semen analysis using the Hobson sperm tracker. The semen parameters and hormone profile were compared between subjects with normal and those with elevated mercury concentrations. Twenty-one subjects (35.6%) had a whole blood mercury concentration higher than the normal range (0-50 nmol/l). All parameters of the semen analysis including the concentration of sperm, percentage of morphologically normal sperm, percentage of motile sperm, curvilinear velocity, straight-line velocity, average path velocity, and amplitude of lateral head displacement, were reduced in those with elevated blood mercury concentrations, although the difference was not statistically significant. We failed to demonstrate a statistically significant effect on the measurement of semen quality, but other adverse effects cannot be excluded. From a public heath perspective, these findings confirm that mercury toxicity is a potentially serious problem affecting the local community.