Biomedical subjects

T H Cheung

Publications and source records attributed to T H Cheung.

At least 37 records · Page 2Linked to original sources

PubMed2000

Comparison of dynamic helical CT and dynamic MR imaging in the evaluation of pelvic lymph nodes in cervical carcinoma.

OBJECTIVE: This study compares dynamic helical CT with dynamic MR imaging in the evaluation of pelvic lymph nodes in cervical carcinoma. SUBJECTS AND METHODS: Women with biopsy-proven cervical carcinoma prospectively underwent dynamic helical CT and MR imaging before surgery. A metastatic node on CT and MR imaging was defined as a rounded soft-tissue structure greater than 10 mm in maximal axial diameter or a node with central necrosis. Imaging results were compared with pathology, and receiver operating characteristic curves for size and shape were plotted on a hemipelvis basis. Nodal density and signal intensity on CT and MR images, respectively, were reviewed for differences between benign and malignant disease. RESULTS: A total of 949 lymph nodes were found at pathology in 76 hemipelves in 43 women, of which 69 lymph nodes (7%) in 17 hemipelves (22%) were metastatic. Sensitivity, specificity, positive and negative predictive values, and accuracy of helical CT and MR imaging in the diagnosis of lymph node metastasis on a hemipelvis basis was 64.7%, 96.6%, 84.6%, 90.5%, and 89.5% and 70.6%, 89.8%, 66. 7%, 91.4%, and 85.5%, respectively. Receiver operating characteristic curves for helical CT and MR imaging gave cutoff values of 9 and 12 mm in maximal axial diameter, respectively, in the prediction of metastasis. Central necrosis had a positive predictive value of 100% in the diagnosis of metastasis. Signal intensity on MR imaging and density-enhancement pattern on CT in patients with metastatic nodes did not differ from those in patients with negative nodes. CONCLUSION: Helical CT and MR imaging show similar accuracy in the evaluation of pelvic lymph nodes in patients with cervical carcinoma. Central necrosis is useful in the diagnosis of metastasis in pelvic lymph nodes in cervical cancer.

Adult↗

PubMed1999

Allelic loss on chromosome 1 is associated with tumor progression of cervical carcinoma.

BACKGROUND: Alterations in chromosome 1 are common in human malignancies. The frequency of loss of heterozygosity (LOH) on chromosome 1 in cervical carcinoma and its clinical significance are not clearly understood. METHODS: LOH on chromosome 1 was studied in 100 cervical carcinomas by the polymerase chain reaction (PCR) using 29 highly polymorphic microsatellite markers spaced approximately 10 centimorgans apart. Loci with high frequencies of LOH were identified and the findings were correlated with clinicopathologic characteristics. RESULTS: LOH on chromosome 1 at 1 or more loci was detected in 93% of tumors. The frequencies of LOH at locus D1S2829 (1p31), D1S2663 (1p36.3), and D1S2725 (1q25) exceeded 30%, and 12 other loci exhibited frequencies of LOH of 20-30%. Advanced stage tumors had a significantly higher percentage of informative microsatellite markers with LOH than early stage tumors. Of the 29 microsatellite markers studied, 4 loci had a significantly higher frequency of LOH in Stage III and IV tumors than in earlier stage tumors. CONCLUSIONS: Frequent aberrations on chromosome 1 in cervical carcinoma suggest that inactivation of tumor suppressor genes is important in cervical tumorigenesis. Higher frequencies of LOH in Stage III and IV tumors suggest that chromosome 1 changes are late events in cervical carcinoma. The findings of this study are consistent with earlier reports that suggest that tumor suppressor genes are present at 1p36.3 and 1p31. To the authors' knowledge, the high frequency of LOH mapped to 1q25 has not been reported previously. Its significance awaits further clarification.

Adenocarcinoma↗

PubMed1999

Methylation of p16INK4A in primary gynecologic malignancy.

The p16INK4A gene mapped on band p21 of chromosome 9 can be inactivated via multiple mechanisms including homozygous deletion, point mutation and promoter hypermethylation in various human tumors. A polymerase chain reaction (PCR) based analysis was performed to examine methylation of the p16INK4A gene promoter in 196 primary gynecologic malignancies including 98 cervical, 49 endometrial and 49 ovarian carcinomas. Methylation of p16INK4A was detected in 31% of cervical, 20% of endometrial, and 4% of ovarian carcinomas, respectively. The incidence of p16INK4A methylation in patients with cervical and endometrial carcinomas at advanced stages (stages III-IV) was statistically higher than those at early stages (stages I-II). There were also significant differences in the incidence of p16INK4A methylation in both cancers between the patients who had died of their disease or were alive with evidence of disease, and those without evidence of disease. The results indicate that methylation of the p16INK4A gene is present in a proportion of primary gynecologic malignancies and this alteration may be associated with poor outcome in cervical and endometrial carcinomas.

Adult↗

PubMed1999

Clinical use of serum c-erbB-2 in patients with ovarian masses.

The c-erbB-2 (Her-2/neu) gene product has a large extracellular domain (ECD) and part of which could be identified in the serum. We measured the serum level of c-erbB-2 ECD in 93 patients, who presented with ovarian masses, with an enzyme immunoassay test and an elevated level was found in 5.5, 16.7 and 38% of patients with benign, borderline and malignant ovarian neoplasms, respectively. This serum marker may reflect the overexpression of c-erbB-2 gene in tumor tissues, which is associated with poor prognosis. However, measurement of c-erbB-2 ECD when used alone or in combination with CA 125 is not useful in differentiating benign from malignant ovarian tumors.

Adult↗

PubMed1999

Comparison of laparoscopic sonography with surgical pathology in the evaluation of pelvic lymph nodes in women with cervical cancer.

OBJECTIVE: This study compared laparoscopic sonography with surgical pathology in the evaluation of pelvic lymph nodes in women with cervical cancer. SUBJECTS AND METHODS: Intraoperative laparoscopic sonography of pelvic lymph nodes was performed in 31 women with biopsy-proven cervical cancer. A lymph node that was rounded (longitudinal-transverse axis ratio of <2) or showed absence of central hilum was defined as positive for metastasis. For comparison, lymph nodes from each hemipelvis were grouped anatomically into paraaortic, common, internal, and external iliac chains during evaluation on laparoscopic sonography and on surgical pathologic examination. RESULTS: Pelvic dissection in 31 women yielded 630 lymph nodes. There were 54 metastatic nodes in 12 women. Laparoscopic sonography revealed 32 (59%) of all pathologically metastatic lymph nodes. Sensitivity on laparoscopic sonography when comparing groups by hemipelves was 93.3% and by anatomic lymph node chains was 76.2%. Metastatic nodes were most commonly located in the common iliac region and were characteristically rounded, hypoechoic, showed absence of central hilum, and occasionally showed central necrosis. Nine (28%) of 32 metastatic lymph nodes revealed by laparoscopic sonography measured 1 cm or less. Six benign nodes in four patients were also visualized with laparoscopic sonography. CONCLUSION: Laparoscopic sonography achieved a sensitivity exceeding 90% in the detection of metastatic lymph nodes in the hemipelves of women with cervical cancer. Laparoscopic sonography is a feasible and promising technique for the evaluation of pelvic lymph nodes in women with cervical cancer and merits further evaluation.

Adult↗

PubMed1998

Expression of p16INK4 and retinoblastoma protein Rb in vulvar lesions of Chinese women.

The protein products of the two tumor suppressor genes located on 9p and 13p, p16INK4 and Rb, respectively, play an important role in regulation of the cell cycle and are implicated in tumorigenesis. We examined 49 cases of benign vulvar lesions, vulvar intraepithelial neoplasia (VIN), and squamous cell carcinoma with immunohistochemical staining to determine expression of p16INK4 and Rb. All and 86% of benign lesions expressed Rb and p16INK4, respectively; 40% each of VIN I and VIN III expressed p16INK4 and Rb, respectively; and 37 and 68% of squamous cell carcinomas expressed p16INK4 and Rb, respectively. The combination of the lack of p16INK4 and/or Rb expression increased from benign lesions (14.3%), through VIN I (60%) and VIN III (60%), to invasive squamous cell carcinoma (72%), thus supporting the postulation that alterations in p16INK4 or Rb could be significant events in progression of disease. The loss of Rb expression also increased from stage I carcinoma (16.7%) through stage II (26.7%) and III (44.4%), to IV (50%), suggesting that Rb may play an important role in tumor progression. A larger study on VIN lesions and genetic coding is suggested to further investigate the role of p16INK4, Rb, and other factors in tumorigenesis and progression of vulvar cancers.

Carcinoma, Squamous Cell↗

PubMed1998

New development of laparoscopic ultrasound and laparoscopic pelvic lymphadenectomy in the management of patients with cervical carcinoma.

OBJECTIVES: The objectives of this study were to evaluate the use of laparoscopic ultrasonography (USG) in combination with laparoscopic pelvic lymphadenectomy in the management of patients with cervical carcinoma. METHODS: A technique for detecting pelvic and para-aortic lymph node metastases through laparoscopic USG was developed. Laparoscopic USG was done prior to pelvic lymphadenectomy performed either laparoscopically or by laparotomy. Laparoscopic USG findings were compared with pathologic findings. RESULTS: The sensitivity and specificity of laparoscopic USG in detecting pelvic lymph node metastases were 91 and 100%, respectively. Metastatic pelvic lymph nodes could be completely removed through laparoscopes in 7 of 11 patients, with no complications. CONCLUSION: Laparoscopic USG is highly sensitive in detecting metastatic pelvic lymph nodes. Detection and removal of metastatic pelvic lymph nodes laparoscopically allow quick recovery from the operation and early commencement of radiotherapy.

Adult↗

PubMed1998

MTAP gene deletion in endometrial cancer.

A gene (MTAP) that encodes the enzyme 5'-deoxy-5'-methylthioadenosine (MTA) phosphorylase has been identified on chromosome 9p21 and cloned. The substrate of this enzyme, MTA, inhibits aminopropyltransferases that synthesize polyamines from putrescine and decarboxylated S-adenosylmethionine. This enzyme normally cleaves MTA to adenine and 5'-methylthioribose-1-phosphate, which are recycled to adenine nucleotides and methionine, respectively. Cancers with deletions of the MTAP gene may be especially susceptible to chemotherapeutic regimes which interfere with purine or methionine utilization. The purpose of this study was to determine deletion of the MTAP gene in endometrial cancer using a polymerase chain reaction-based method. Therefore, 50 endometrial adenocarcinomas were studied. Partial or total deletions of the MTAP gene were detected in 7 (14%) of these cancers. There were no significant relationships between gene deletion and patient age, pathological grade or clinical stage (p > 0.05). The findings indicate that deletion of the MTAP gene does occur in a subgroup of endometrial cancer. The present work may be extended to the development of molecular diagnosis of MTAP gene deletion in other cancers and assist in selecting appropriate chemotherapy.

Adult↗

PubMed1997

Frequent loss of heterozygosity of chromosome 3 short arm detected by PCR-based microsatellite polymorphisms in cervical squamous cell carcinoma.

Karyotypic studies have shown that genetic aberrations of the short arm of chromosome 3 (3p) may be involved in the pathogenesis of cervical carcinoma. In this study we analyzed nine polymorphic microsatellite repeats on 3p using a PCR-based assay for loss of heterozygosity (LOH) in 64 invasive squamous cell carcinomas of the cervix. These markers encompass chromosome region 3p13-25. LOH at one or more loci was detected in 46 (79%) out of the 58 informative cases. The incidence of LOH at locus D3S643 (3p13) was the highest among nine markers examined. The difference between the frequency of LOH at D3S643 in early stage (I-II) disease (43%) and those with advanced stage (stage III-IV) (79%) was statistically significant (P < 0.05). The results indicate that tumor suppressor gene(s) that play a role in cervical cancer may be located on the short arm of chromosome 3, likely near or at 3p13. The LOH at 3p13 appears to be a late event in tumor progression and may serve as an indicator for a less favorable clinical outcome.

Carcinoma, Squamous Cell↗

PubMed1997

p16INK4 and p15INK4B alterations in primary gynecologic malignancy.

Chromosome 9 abnormalities have been found in primary tumors and cell lines from human gynecologic malignancy. Alterations of p16INK4 and p15INK4B genes mapped on the band p21 of chromosome 9 have been detected in various human tumors, but the role of these genes as tumor suppressors in vivo appear to be dependent on tumor type. Polymerase chain reaction (PCR)-based analysis was performed to search for lesions of these genes in 202 primary gynecologic malignancies. Homozygous deletions of p16INK4 were detected in 7 of 128 (5%) cervical, 1 of 41 (2%) endometrial, 2 of 27 (7%) ovarian, and 3 of 6 (50%) vulvar carcinomas, while homozygous deletions of p15INK4B were detected in 19 of 128 (15%) cervical, 1 of 41 (2%) endometrial, 9 of 27 (33%) ovarian, and 3 of 6 (50%) vulvar carcinomas, respectively. No mutations were found in exon 2 of p16INK4 from 161 cases of gynecologic malignancy without deletion of p16INK4. All 3 cases of vulvar carcinoma showing homozygous deletions of p16INK4 and p15INK4B were at advanced clinical stage (stage III-IV), while all 7 cases of cervical carcinoma and 2 cases of ovarian carcinoma showing homozygous deletion of p16INK4 were at early stage (stage I-II). The results indicate that homozygous deletions of p16INK4 and/or p15INK4B genes may play a role in a subset of primary gynecologic malignancy.

Carrier Proteins↗

PubMed1997

C-myc mutation detected by polymerase chain reaction--heteroduplex in cervical cancer.

To evaluate both the incidence of c-myc gene mutation and the relationship of this finding to the clinico-pathologic characteristics of patients with cervical cancer, a polymerase chain reaction (PCR)-based heteroduplex gel electrophoresis method was used to screen DNA extracted from 102 cervical invasive carcinomas referred to the Department of Obstetrics and Gynaecology, The Chinese University of Hong Kong. C-myc mutation was detected and then characterised by sequencing of PCR products in 4 cases (4%). The incidence of c-myc mutation in patients with advanced stage tumours (stage III-IV, 11% was statistically higher than in those with early stages (stage I-II, 1%, p = 0.05). There was also a significant difference in the incidence of c-myc mutation among the patients who had died of their disease (10%), were alive with evidence of disease (25%), and those without evidence of disease (0%, p = 0.0003). These findings indicate that the c-myc mutation is not common in cervical cancer, but where it exists, it may be associated with cancer progression and poorer outcome. Whether the c-myc mutation is an adjunct prognostic indicator in cervical cancer remains to be established in a larger study.

Base Sequence↗

PubMed1997

c-fos overexpression is associated with the pathoneogenesis of invasive cervical cancer.

The molecular genetics of human cervical cancer remains to be defined to a significant extent. The current study examined the prevalence and significance of proto-oncogene c-fos overexpression in cervical cancer. Immunohistochemical staining of c-fos oncoprotein was performed in 27 invasive cervical carcinomas and 30 cervical intraepithelial neoplasias (CINs) managed in our department. Eight normal cervical specimens were used as controls. In the patients with invasive cervical cancer, 8 were stage I, 12 were stage II, and 7 had stage III-IV disease. Three of the cancers were well differentiated, 18 were moderately differentiated and 6 were poorly differentiated. Twenty invasive cervical carcinomas (59%) and 3 CIN (10%) showed overexpression of c-fos. The difference is statistically significant (p < 0.001). No statistically significant relationship was found between c-fos overexpression and clinical stage, histological grade, or survival in invasive cervical cancer. In this population, c-fos overexpression appears to be common in invasive cervical cancer and correlated with the ability of the tumor to become invasive, but is not associated with the progression of cervical cancer.

Female↗

PubMed1996

Coincidental renal cell and endometrial carcinoma: a case report.

A case of renal cell carcinoma and coexistent endometrial carcinoma is reported. The renal tumor in the lower pole of left kidney was detected by staging preoperative ultrasound scan and was confirmed to be a multilocular cystic renal cell carcinoma. There were two separate foci of moderately differentiated endometrial cancer in the endometrial cavity. Microscopic tumor deposits were also found in the left ovary and the right obturator pelvic lymph nodes. The multicentric involvement of endometrial cavity is uncommon and even rarer is the association with renal cell carcinoma. To the best of our knowledge, this is the first report of an association between renal cell carcinoma and endometrial cancer. This case demonstrates the importance of complete preoperative investigation before any definitive surgery for cancer. Without the abdominal ultrasound scanning, the asymptomatic renal cell carcinoma would probably have been undetected.

Adenocarcinoma↗

PubMed1996

Gonadoblastoma in patient with Turner's syndrome.

A 15-year-old phenotypic female referred for the investigation of primary ammenorrhea, was found to have a 45,XO karyotype and an ovarian cyst. She demonstrated some of the features of Turner's syndrome, as well as virilization. On laparotomy, she was found to have bilateral gonadoblastomas. She was treated with total abdominal hysterectomy and bilateral salpingo-oophorectomy. Subsequently, repeated chromosomal analysis detected the presence of Y chromosomes, which was confirmed by the use of polymerase chain reaction (PCR). The difficulties encountered in searching for the Y chromosome in patients with gonadoblastoma are discussed. Prophylactic gonadectomy is suggested in those cases associated with atypical features.

Adolescent↗

PubMed1996

HER-2/neu gene amplification in cervical cancer in Chinese women of Hong Kong and China.

OBJECTIVE: To determine the amplification of proto-oncogene HER-2/neu in invasive cervical cancer and its relationship with the stage of disease, grade of tumor and prognosis of patients. METHODS: In this retrospective study 70 women with invasive cervical squamous cell carcinoma were included. DNA was extracted from the paraffin-embedded tumor tissue. The amplification of HER-2/neu was studied using a differential polymerase reaction (PCR) technique. Assessment of significance was performed using Peason's Chi-square test and Fisher's exact test. RESULTS: Eleven of the 70 cases (16%) showed an amplification of HER-2/neu but there was no relation between amplification and tumor histologic grading (p = 0.408) or clinical staging (p = 0.180). Follow-up information in 67 patients was available. The incidence of amplification in the patients who were alive with disease was not statistically different from that in the patients who were alive with no evidence of disease (p = 0.315). The incidence of amplification in the patients who died of disease was higher than that in the patients who were still alive, but statistical significance did not reached (p = 0.062). CONCLUSION: The results suggest that HER-2/neu amplification does exist in a subgroup of invasive cervical cancer and may play a role in cervical carcinogenesis. The role as independent prognostic factor has to be evaluated by further prospective studies.

Base Sequence↗

PubMed1996

Transrectal ultrasound in the evaluation of cervical carcinoma and comparison with spiral computed tomography and magnetic resonance imaging.

38 women with biopsy proven untreated cervical carcinoma were prospectively studied with transrectal ultrasound (TRUS), spiral computed tomography (SCT) and magnetic resonance imaging (MRI). 20 women had radical hysterectomy and pelvic lymphadenectomy with detailed histological evaluation of the parametra. The echographic features of cervical carcinoma on TRUS are a hypoechoic (60%) or isoechoic (40%) (relative to normal uterine muscle/cervical stroma), poorly defined mass lesion with indistinct margins in an enlarged cervix. This relatively high percentage of isoechoic tumours and relative lack of contrast resolution may pose a problem in the identification of some tumours, and to our knowledge has not been previously reported. Further limitations of TRUS are in the evaluation of advanced cervical cancer, due to bulky tumours rendering poor access to the parametrium and pelvic sidewall. The overall accuracy in staging of early cervical cancer (less than stage 2b) was 85% for examination under anaesthesia (EUA), 75% for TRUS, 65% for MRI and 50% for SCT. The positive predictive value in evaluating the parametra in this group of patients was also lower for SCT (14%) and MRI (33%) compared with TRUS (100%). In the evaluation of advanced cervical cancer (stage 2b or higher), there was poor correlation between TRUS and EUA, with MRI showing the best correlation with EUA. We conclude that SCT is inferior to both TRUS and MRI in the staging of early stage cervical cancer.

Adult↗

PubMed1995

Frequent ras gene mutations in squamous cell cervical cancer.

Eighty samples of cervical invasive squamous cell carcinoma were examined for ras gene mutations using polymerase chain reaction (PCR) followed by restriction enzyme digestion. We found 28 (35%) cervical cancers contained ras mutations at H-ras codon 12, 49 (61%) at K-ras codon 12, and 5 (6%) at K-ras codon 13. There were no significant differences in incidence of the ras gene mutations among different histologic grades or clinical stages of the cancer (P > 0.05). This result suggests that ras mutation may be an important step involved in a substantial number of cervical carcinoma. The interaction of ras with other genes and/or events may also be involved in pathogenesis of this malignancy.

Alleles↗

PubMed1995

Sarcoma botryoides of the cervix treated with limited surgery and chemotherapy to preserve fertility.

Sarcoma botryoides rarely arises in the uterine cervix. It usually presents in the adolescent age group and is treated primarily by surgery followed by adjuvant chemotherapy. It has been reported in the literature that is possible to limit surgery to local excision in stage I cases, when the tumor is confined to the cervix. In an attempt to preserve reproductive function in a young female patient, we performed cervicectomy alone, followed by adjuvant chemotherapy. After 36 months follow-up she remains well, suggesting that limited excision with adjuvant chemotherapy may be sufficient for early-stage disease.

Adult↗