Biomedical subjects

H P Lee

Publications and source records attributed to H P Lee.

At least 19 recordsLinked to original sources

PubMed1999

Primary endodermal sinus tumor of the omentum.

Endodermal sinus tumor (EST) is a rare neoplasm which usually arises in the testis or ovary. But extragonadal EST is well recognized and may arise in a wide array of sites such as the mediastinum, vagina, and brain. We report a case of primary EST of the omentum and to our knowledge it is the first case of omental EST in the literature. A 45-year-old woman with a history of abdominal distension was treated with total abdominal hysterectomy with bilateral salpingo-oophorectomy and infracolic omentectomy, followed by four cycles of BEP (bleomycin, etoposide, cisplatin) combination chemotherapy. Microscopically, the tumor exhibited typical patterns of EST and stained for alpha-fetoprotein and cytokeratin. She has remained free of disease for 10 months of follow-up. According to previous studies, debulking surgery and BEP chemotherapy were used as primary therapy with good results. The subject of extragonadal EST is reviewed, and the possible histogenesis of this tumor at such a rare site is discussed.

Antineoplastic Combined Chemotherapy Protocols↗

PubMed1998

Identification of antigenic differences between the phosphorylated and nonphosphorylated forms of the E7 protein of human papillomavirus type 16.

To analyze the antigenic properties of the human papillomavirus type 16 E7 oncoprotein, two monoclonal antibodies, VD6 and IB10, that have different reactivities to the E7 protein were generated. While the VD6 antibody reacted strongly with E7 protein in CaSki cell extracts, the other antibody, IB10, showed much weaker reactivity with E7. This reactivity increased in a dose-dependent manner in the presence of the casein kinase II-specific inhibitor DRB (5,6-dichloro-1-beta-D-ribofuranosylbenzimidazole). Antigenic site estimation and an in vitro phosphorylation assay, using bacterially expressed E7 protein, demonstrated that the weak reactivity of IB10 was related to the phosphorylation status of the E7 protein. Phosphorylation of E7 reduced considerably the reactivity of IB10 but did not affect the reactivity of VD6, which reacts with the N-terminal portion of E7. In immunoprecipitation (IP) assays, IB10 precipitated weakly the E7 protein from CaSki cell extracts. Together, these data suggest that unphosphorylated E7 protein shows distinct antigenic character compared to its phosphorylated form under denaturing conditions; however, under native conditions, the phosphorylated and nonphosphorylated E7 proteins have some antigenic cross-reactivity.

Animals↗

PubMed1998

The effects of interaction between familial and reproductive factors on breast cancer risk: a combined analysis of seven case-control studies.

In this paper, a combined analysis was performed to study the interaction between familial risk and reproductive life factors. In particular, the interaction between familial risk and breast cell mitotic activity (BCMA), as assessed by duration of ovarian activity, was investigated because of the potential importance of mitotic activity on genetically susceptible cells. The present analysis included 3152 cases and 4404 controls in seven case-control studies from four countries. The interaction effect was estimated in each study separately, then combined using two different methods: a multivariate weighted average and a Bayesian random-effects model. The main effects of reproductive life factors on the risk of breast cancer were in agreement with the previous findings. In particular, an increased duration of BCMA before the first childbirth and over life was found to increase the risk of breast cancer (P < 0.001). Slightly increasing but non-significant, familial risks were observed with increasing number of children (P = 0.17), increasing age at first childbirth (P > 0.2) and increasing duration of BCMA (P > 0.2). There was no modification in familial risk with age at menarche and no clear pattern with menopause characteristics. A weak influence of reproductive and menstrual factors on the familial risk emerged from the present study.

Adult↗

PubMed1998

Lung cancer among Chinese females in Singapore 1968-1992: time trends, dialect group differences and implications for aetiology.

BACKGROUND: Chinese females are distinguished internationally as having relatively high lung cancer incidence rates despite a low prevalence of cigarette smoking. In Singapore, this population comprises several dialect groups which have origins in different regions in China, each with its own traditional cultural practices. METHODS: An analysis of 4029 incident cases of the disease notified to the Singapore Cancer Registry for 1968-1992 was undertaken to provide some insight into important aetiologic factors among these women. RESULTS: The age-standardized incidence rate of lung cancer rose from 17.3 per 100,000 woman-years in 1968-1972 to 23.0 in 1978-1982 before falling off in more recent years. Age-period-cohort analysis indicated significant period and birth cohort effects, with the risk being highest for women born around 1908. Between the major dialect groups, Cantonese women had a significantly high rate compared with Hokkiens (relative risk [RR] = 2.6, 95% CI: 2.4-2.8). Histologically, there appears to be an increase in the proportion of adenocarcinomas diagnosed over this period (25.8% in 1968-1972 to 51.3% in 1988-1992). CONCLUSION: Our results suggest that traditional practices which have decreased over the years, and are more prominent among Southern Chinese, may play a part in the aetiology of lung cancer locally.

Adenocarcinoma↗

PubMed1998

The clear cell variant of epithelioid intravenous leiomyomatosis of the uterus: report of a case.

A case of very rare uterine clear cell epithelioid leiomyomatosis is reported. The patient presented with a recurrent pelvic mass after hysterectomy 2 years earlier. The recurrent tumor was located mainly in the vessels of the broad ligament as worm-like plugs. The reviewed hysterectomy specimen showed a typical multi-lobulated intramural mass together with worm-like plugs within the myometrial vessels. Computer tomography exhibited metastatic nodules in both lungs. According to an histological examination, all the tumor cells were of epithelioid type and contained abundant clear cytoplasm. Characteristic large, thick-walled blood vessels were observed. Immunohistochemical staining and ultrastructural examination supported smooth-muscle origin in this case. Electron microscopic study revealed that the clear cytoplasm was attributed to the presence of numerous dilated mitochondria that had lost their cristae. The patient is still alive with the disease 28 months after surgery.

Female↗

PubMed1998

Doses to patients in routine X-ray examinations in Malaysia.

A collaborative national survey initiated by the University of Malaya and the Ministry of Health was conducted from 1993 to 1995 to establish baseline patient dose data for seven common types (12 projections) of X-ray examinations in Malaysia. A total of 12 randomly selected public hospitals and 867 patients were included in this survey. The entrance surface doses (ESD) received by the patients were measured using thermoluminescent dosemeters (TLDs) attached to the patient's skin. Histograms are presented showing wide, positively skewed distributions of measured entrance surface doses for each examination. Mean, median, first and third quartile values of ESD and median effective dose are reported. Survey results are generally comparable with those reported in the UK, USA and by the International Atomic Energy Agency (IAEA). The results also provide information on dose level for a lower weight population (mean weight 60 kg) compared with the international reference dose values based on a 70 kg standard. The findings support the importance of the on-going national quality assurance programme to ensure doses are kept to a level consistent with optimum image quality. The data will also be useful for the formulation of national guidance levels as recommended by the IAEA. Furthermore, this study provides patient dosimetry information on healthcare level II countries.

Adult↗

PubMed1998

A randomized trial of the use of print material and personal contact to improve mammography uptake among screening non-attenders in Singapore.

The Singapore Breast Screening Project was a nationwide study inviting a random sample of women between the ages of 50 and 64 years for mammography at one of two hospital-based screening centres over two years. The current study was undertaken to determine if (1) mailed health educational material alone, or (2) the same material delivered during a home visit made to the subject and her family would increase the uptake among Singapore women who had not responded to two previous invitations for mammographic screening as part of the Project. This randomized trial employed a standard second reminder letter (R), the same letter packaged with health education material designed for the project (RP) and the addition of a home visit to make contact with the woman and her family (RV). The outcome measure of interest was the proportion of women in each group subsequently attending for screening. The study population comprised 1500 non-attenders whose names appeared consecutively in the database of the larger screening centre in this Project. These were randomized into three groups of 500 each. In total, they broadly resembled the national population in ethnic composition (72.3% Chinese, 17.8% Malays, 9.0% Indians and 0.8% Others). By the end of the project, 7.0% of women in group R and 7.6% in group RP responded to the invitation. In group RV, 428 homes were visited at least once and contact was made with the subject and her family member in 306 (71.5%) cases. Subsequently, 13.3% of the women visited attended for screening. The rate ratio for attendance in group RP compared with group R was 1.09 (95% CI 0.70 to 1.70) and for group RV compared with R, 1.90 (1.27 to 2.84). When analyzed by groups originally assigned to, women in group RV remained significantly more likely to attend than those in groups R or RP. The marginal cost of a home visit, based on this study, was $25.04 per additional woman screened. Our results suggest that the response to a second reminder is generally low and that additional print material does not improve screening attendance in this group of initial non-attenders. Personal contact with the family through a home visit appears to increase uptake, and may be helpful particularly among women who have less frequent contact with the health care system.

Aged↗

PubMed1998

Isoflavonoid levels in spot urine are associated with frequency of dietary soy intake in a population-based sample of middle-aged and older Chinese in Singapore.

Soy products contain high amounts of isoflavonoids, which have been shown to exhibit possible cancer-protective properties. Chinese populations in Asia, in particular, have a high level of soy intake and a relatively low risk of hormone-dependent cancers. In this study, we assessed the distributions of dietary soy isoflavonoids (daidzein, genistein, and glycitein) and urinary soy isoflavonoids and their metabolites (daidzein, genistein, glycitein, equol, and O-desmethylangolensin) among 147 Singapore Chinese (76 men and 71 women) ages 45-74 years, who are participants of the Singapore Cohort Study on diet and cancer. Urinary values were measured from spot samples collected 10-20 months following recruitment, when usual dietary habits were assessed by a structured food frequency/portion size questionnaire administered in person. Dietary levels of daidzein and genistein were comparable within individuals and about seven times higher than the level of dietary glycitein. All three dietary isoflavonoids showed an approximately 3.5-fold difference between the 25th and 75th percentile values. Similarly, daidzein was the most abundant and glycitein the least abundant of the five isoflavonoid compounds in urine. There was a 4.9-fold difference between the 25th and 75th percentile values for the sum of the five urinary isoflavonoids. Among study subjects, there were statistically significant, dose-dependent associations between frequency of overall soy intake and levels of urinary daidzein (two-sided P = 0.03) and sum of urinary daidzein, genistein, and glycitein (two-sided P = 0.04). In contrast, there were no associations between frequency of overall soy intake and levels of the two daidzein metabolites (equol and O-desmethylangolensin) in urine (two-sided P = 0.85 and 0.34, respectively). We suggest that within the range of exposures experienced by Singapore Chinese, urinary level of daidzein or the sum of daidzein, genistein, and glycitein obtained from a spot sample can serve as a biomarker of current soy consumption in epidemiological studies of diet-disease associations.

Aged↗

PubMed1998

Population-based mammographic screening in Singapore: what are participants' views?

Mammographic screening for breast cancer has been shown to be an effective tool for reducing mortality from the disease in many studies in the West, if high technical quality and acceptance by the target population are achieved. The objective of the Singapore Breast Screening Project was to determine if the same results could be obtained among local women by inviting a random sample of 69,500 women aged 50 to 64 years for a screening mammogram over two years. To date, the compliance rate among the women invited has been 41.7%. The objective of the present substudy was to determine participants' views on the accessibility and acceptability of organised mammographic screening. Of the three hundred women interviewed, 85% were satisfied with the information given prior to the visit, while 67% needed to change the original appointment given. The majority were satisfied with aspects of the visit such as waiting time, privacy and explanation given during the test. However, 35.1% reported at least moderate discomfort during mammography. A substantial proportion (39.7%) of attenders felt that there was very little hope of cure even if cancer was detected early. When asked the most important reason for attending, most indicated they had taken the opportunity for a free check-up to be assured they were well. Almost all (95.7%) reported a willingness to be screened again, but most would not be willing to pay for a mammogram at the current rates.

Appointments and Schedules↗

PubMed1998

Urinary total isothiocyanate (ITC) in a population-based sample of middle-aged and older Chinese in Singapore: relationship with dietary total ITC and glutathione S-transferase M1/T1/P1 genotypes.

Isothiocyanates (ITCs), degradation products of glucosinolates (which occur naturally in a variety of cruciferous vegetables), have been shown to exhibit chemopreventive activity. These compounds are metabolized in vivo to form the corresponding dithiocarbamates, which are the major urinary metabolites of ITCs, by a pathway involving the glutathione S-transferase (GST) class of enzymes. Using a newly developed assay that measures total ITC (primarily ITC conjugates) in urine, we examined the relationships between cruciferous vegetable intake (obtained from a food frequency/portion size questionnaire administered in person); dietary total ITC level; GSTM1, GSTT1, and GSTP1 genotypes; and levels of total ITC in spot urine samples collected from 246 Singapore Chinese (111 men and 135 women), ages 45-74 years, who are participants of the Singapore Cohort Study on diet and cancer. Consumption level of cruciferous vegetables was high in study subjects (mean consumption = 345 times per year, mean daily intake = 40.6 g), which was >3 times the comparable level of intake in the United States. Mean daily intake of total ITC among study subjects was 9.1 micromol, and there was a 2.5-fold difference between the 25th and 75th percentile values. Seventy-three % of study subjects tested positive for ITC in urine, and there was a 4-fold difference between the 25th and 75th percentile values among the positive subjects. There was a highly significant positive association between dietary intake and urinary excretion levels of total ITC (two-sided P = 0.0003) that was stronger than the association between overall cruciferous vegetable intake and urinary ITC level, which also was statistically significant (P = 0.0004). There was no difference in urinary ITC levels between GSTM1-null and GSTM1-positive study subjects (P = 0.61) or between subjects with differing GSTP1 genotypes (P = 0.77), but urinary excretion of ITC was significantly higher among GSTT1-positive subjects, relative to GSTT1-null subjects (P = 0.006). The strength of the association between GSTT1 genotype and urinary total ITC level was highly dependent on the level of cruciferous vegetable consumption (or dietary ITC level) in study subjects. Among subjects in the lowest tertile of cruciferous vegetable intake, there was little evidence of an association between GSTT1 genotype and urinary total ITC level (P = 0.67). In contrast, there was a strong and statistically significant association between GSTT1 genotype and urinary total ITC among subjects in the highest tertile of cruciferous vegetable intake (P = 0.02), whereas those in the middle tertile of cruciferous vegetable consumption exhibited an association of intermediate strength (P = 0.04). These results suggest the presence of GSTT1 inducers in cruciferous vegetables.

Age Factors↗

PubMed1997

Comparing a sample proportion with a specified population proportion based on the mid-P method.

A common practice for determining whether a sample proportion is statistically different from a specified population proportion is using the exact probability procedure. However, it produces overly conservative confidence intervals and p-values. A stand-alone executable program is written for applying alternative approaches based on the mid-P and bootstrap methods.

Confidence Intervals↗

PubMed1997

Major sequence variants in E7 gene of human papillomavirus type 16 from cervical cancerous and noncancerous lesions of Korean women.

Geographic specificity of nucleotide sequence variations in the coding and noncoding regions of HPV 16 genome has been reported. Little has been known, however, regarding whether these naturally occurring sequence variations of HPV 16 may result in marked differences in biological properties, such as oncogenic potential. This study was performed to identify sequence variants in the HPV 16 E7 gene derived from Korean women with cervical cancerous and noncancerous lesions, and to assess the association between the sequence variant and the cervical cancer. We examined E7 variants of HPV 16 in a total of 157 patients with no cervical disease (NCD, n = 87) or cervical neoplasia (cervical intraepithelial neoplasia 3, n = 21; cervical carcinoma, n = 49), using the nested polymerase chain reaction (PCR) and the PCR-directed sequencing methods with outer consensus and inner type-specific primers. Forty-two (NCD, n = 9; CIN 3, n = 6; cervical carcinoma, n = 27) of 157 cervical samples contained HPV 16 E7 DNA, but only 8 had prototype sequences. Four variants of the HPV 16 E7 gene were identified. The variant with a single nucleotide change at position 647 (A --> G, Asn --> Ser) was found in about 60% of DNA samples with HPV 16. The second most common variant, found in 16.7% of cases, had three silent mutations at positions 732 (T --> C), 789 (T --> C), and 795 (T --> G). Two other variants were detected, one in a patient with cervical cancer and the other in a patient with no cervical disease. One had a single nucleotide change at position 666 (G --> A) and the other had one silent mutation at position 796 (T --> C). The most common variant in Korea has a change of nucleotide affecting the predicted amino acid related with high antigenicity and binding to retinoblastoma protein. There was a statistically significant trend for this variant to be more frequently detected in cancerous lesions of the uterine cervix than in noncancerous lesions. These data suggest that naturally occurring sequence variants of HPV 16 E7 gene may have different oncogenic properties.

Adult↗

PubMed1997

Factors determining acceptability of mammography in an Asian population: a study among women in Singapore.

Population-based mammographic screening has been shown to be effective in reducing breast cancer mortality in the West. In Singapore, a project carried out to determine the effectiveness of implementing such a program locally invited 28,000 women between the ages of 50 and 64 years for mammography. The current study, which was part of this larger project, was intended to determine factors contributing to the acceptance of mammographic screening among women in Singapore. A questionnaire was administered in-person to 300 attenders and 260 non-attenders. The respondents were compared with respect to basic demographic characteristics, previous preventive behavior, informal social support, and attitudes towards early detection. We found that screening attenders were more likely to be Chinese than Malays (14 percent of the population) or Indians (seven percent), and to be working outside the home (adjusted odds ratio [OR]) = 4.5, 95 percent confidence interval [CI] = 2.6-7.9). A greater proportion of attenders had a history of other screening tests such as the Pap smear (OR = 4.7, CI = 2.6-8.7 for recent smear compared with never having had a smear). They were also more likely to indicate a sense of personal susceptibility to cancer, but did not differ from non-attenders in terms of believing in cancer prevention, or of preferring to be told if they did have cancer. The strongest independent predictor of attendance, however, was encouragement by her spouse or family member. For women in this population to be persuaded effectively to participate in mammographic screening, it would be important to convince family members of the benefits of the test. At the same time, education targeted specifically at women of the appropriate age group should address the issue of the personal relevance of screening for breast cancer.

Breast Neoplasms↗

PubMed1997

The relationship between dietary fat intake and risk of colorectal cancer: evidence from the combined analysis of 13 case-control studies.

The objective of this study was to examine the effects of the intake of dietary fat upon colorectal cancer risk in a combined analysis of data from 13 case-control studies previously conducted in populations with differing colorectal cancer rates and dietary practices. Original data records for 5,287 cases of colorectal cancer and 10,470 controls were combined. Logistic regression analysis was used to estimate odds ratios (OR) for intakes of total energy, total fat and its components, and cholesterol. Positive associations with energy intake were observed for 11 of the 13 studies. However, there was little, if any, evidence of any energy-independent effect of either total fat with ORs of 1.00, 0.95, 1.01, 1.02, and 0.92 for quintiles of residuals of total fat intake (P trend = 0.67) or for saturated fat with ORs of 1.00, 1.08, 1.06, 1.21, and 1.06 (P trend = 0.39). The analysis suggests that, among these case-control studies, there is no energy-independent association between dietary fat intake and risk of colorectal cancer. It also suggests that simple substitution of fat by other sources of calories is unlikely to reduce meaningfully the risk of colorectal cancer.

Adult↗

PubMed1997

Radiological findings in serous surface papillary carcinoma of the ovary. Case reports.

Serous surface papillary carcinoma (SSPC) is a malignant tumor originating from the surface epithelium of the ovary, and is characterized by macroscopic normal ovaries accompanied by diffuse peritoneal dissemination. Therefore diagnosis of SSPC cannot usually be made preoperatively. We report on two cases of SSPC in which US, CT, and MR demonstrated nodularities along the surface of the normal-sized ovaries, adjacent organs and pelvic peritoneum in addition to findings of peritoneal seeding. These imaging findings may suggest the correct preoperative diagnosis of SSPC.

Cystadenocarcinoma, Papillary↗

PubMed1997

Risk factors associated with uterine cervical cancer in Korea: a case-control study with special reference to sexual behavior.

OBJECTIVE: A hospital-based case-control study was conducted to identify characteristics of women at high risk of developing cervical cancer with special reference to sexual behavior in Korea. METHODS: Histologically confirmed cases of invasive cervical cancer were selected from the Department of Gynecology, Seoul National University Hospital between September 1992 to May 1995 (n = 203). Women with normal pap smear tests and women free of past history of any malignancies were regarded as controls (n = 827). Information on risk factors were collected by both a self-administered questionnaire and a direct interview. RESULTS: Uterine cervical cancer risk was higher in women with a less educated spouse (Ptrend = 0.0003), women with a family history of cervical cancer (adjusted odds ratio [OR] = 2.20., 95% confidence interval [CI] 1.21-4.01), women of shorter height (Ptrend = 0.02), women with early age at first full term pregnancy (Ptrend = 0.0005), and women who have had multiple full term pregnancies (Ptrend = 0.006) by the multiple linear logistic analysis. Particularly noteworthy was a significant decreasing trend in the adjusted OR with the age at first sexual intercourse increasing (Ptrend = 0.002) after adjusting the number of sexual partners. The husband's indecent sexual history showed a borderline significance (Ptrend = 0.07). CONCLUSIONS: This study confirmed that the risk factors of cervical cancer in Korea are similar with those found in other countries.

Adult↗

PubMed1996

Non-Hodgkin's lymphoma in an Asian population: 1968-1992 time trends and ethnic differences in Singapore.

BACKGROUND: Non-Hodgkin's lymphoma has increased in incidence in many countries, particularly in the West. Advances in diagnostic methods and the understanding of the disease over time pose a challenge to the interpretation of these trends. The aim of this study was to determine if the disease has increased in Singapore, a newly industrialized Asian country, and to examine the possible factors that may account for any observed changes. METHODS: Data from the population-based Singapore Cancer Registry for the period 1968 to 1992 were reviewed to determine time trends based on sex and ethnic group. The Poisson regression model was fitted to the cross-tabulated data to obtain the adjusted incidence density ratios. RESULTS: A total of 1988 cases of non-Hodgkin's lymphoma were included in the analysis. There was an overall increase in incidence among both Chinese and Malaysians. However, the rate of increase was greater in females (age-standardized rate from 1.8 per 100,000 in 1968-1972 to 4.5 per 100,000 in 1988-1992) than in males (3.2 per 100,000 to 5.9 per 100,000 in the same time periods). Between ethnic groups, Malay females were at higher overall risk compared with their Chinese counterparts (incidence density ratio 1.32; 95% confidence interval, 1.08-1.61). Although a substantial proportion of patients diagnosed with Hodgkin's disease between 1968 and 1972 were reclassified on review, using present criteria, as having non-Hodgkin's lymphoma, it is unlikely that this, and other recent changes in histologic interpretation, could have accounted for an increase of this magnitude. CONCLUSIONS: Non-Hodgkin's lymphoma has increased in incidence among the Chinese and Malay populations in Singapore. The pattern of increase differs from that of the common cancer sites, and suggests the need to look for environmental and genetic factors that have not yet been elucidated.

China↗

PubMed1996

Breast cancer in Singapore: trends in incidence 1968-1992.

BACKGROUND: Breast cancer is the most commonly occurring cancer among women in Singapore, a country which has experienced significant changes in lifestyle over the past three decades. The increase in incidence of the disease is a matter of some concern. METHODS: Data from the population-based Singapore Cancer Registry for 1968-1992 were used to determine time trends, inter-ethnic differences and the contributions of age, period and cohort effects to the incidence of the disease. RESULTS: Our results revealed an average annual increase of 3.6% over the 25-year period for all women, form 20.2 per 100,000 women in the period 1968-1972 to 38.8 per 100,000 in 1988-1992. There was a statistically significant difference between the three major ethnic groups, the rate of increase being highest in Malays (4.4%) and lowest in Indians (1.4%). The overall increase was attributable to a strong cohort effect that remained significant when adjusted for time period for Chinese women and for all ethnic groups combined. The risk was observed to increase in successive birth cohorts from the 1890s to 1960s. CONCLUSIONS: Our results suggest that breast cancer incidence rates are likely to continue to increase more sharply in the future as women born after the mid-20th century reach the high-risk age groups. They also suggest the pattern by which important aetiological factors for the disease in our population have exerted their effects, and provide support for the role of demographic and lifestyle changes as possible risk factors.

Adult↗