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Biomedical subjects

W K Hong

Publications and source records attributed to W K Hong.

At least 181 records · Page 10Linked to original sources
PubMed1996

DPC4, a candidate tumor suppressor gene, is altered infrequently in head and neck squamous cell carcinoma.

DPC4, a candidate tumor suppressor gene, was identified recently at chromosome 18q21.1. Frequent homozygous deletion or mutations of the gene were observed in pancreatic carcinomas. To investigate the role of this gene in head and neck squamous cell carcinomas (HNSCCs), we examined 16 HNSCC cell lines from 11 patients and 20 primary HNSCCs for alterations of the gene by sequencing all 11 exons of the gene. Fourteen cell lines from 10 patients showed monomers at marker D18s46 (l8q21.1). Full-length cDNA was detectable in all cell lines by reverse transcription-PCR. A nonsense mutation was identified at codon 526 (GAA to TAA, glutamine to termination) in two cell lines (UMSCC22A and UMSCC22B) derived from the primary tumor and lymph node metastasis of the same patient. Loss of heterozygosity was found in 7 of 15 (47%) informative primary tumors at D18s46, whereas only one polymorphism was observed in both tumor and normal tissues from the same patient (at codon 525; ATT to GTT, isoleucine to valine). Our data indicate that although DPC4 is altered infrequently in HNSCC, it may play some role in the tumorigenesis of a small subset of HNSCCs.

Base Sequence↗
PubMed1996

p53 expressions: predicting recurrence and second primary tumors in head and neck squamous cell carcinoma.

BACKGROUND: The survival rate for head and neck squamous cell carcinoma remains poor despite therapeutic advances over the last two decades. For patients with disease confined to the head and neck, there are two major and biologically distinct patterns of treatment failures after definitive therapy: recurrence of primary disease and development of second primary tumors. Understanding the biological basis of patterns of treatment failure after definitive therapy is needed to guide the development of adjuvant treatment and strategies to prevent second primary tumors. PURPOSE: To determine whether expression of the p53 protein has prognostic significance and/or is associated with patterns of treatment failure, we examined protein expression in primary tumor specimens of patients with head and neck squamous cell carcinoma. METHODS: Immunohistochemical analysis with a monoclonal antibody (DO7) specific for p53 protein was used to detect expression of the protein in formalin-fixed, paraffin-embedded tumor samples from 69 head and neck cancer patients treated with definitive local therapy (surgery and/or radiotherapy) between January 1980 and October 1983 at The University of Texas M. D. Anderson Cancer Center. We quantitated p53 protein expression and assessed its association with duration of patient survival, patterns of treatment failure (recurrence of primary tumor and development of second primary tumor), and other clinical parameters. All reported P values resulted from two-sided statistical tests. RESULTS: We found detectable levels of p53 protein expression in the tumor cell nuclei of 41 of 69 patients. Thirty-six (52%) of 69 patients whose tumors exhibited p53 protein expression in greater than or equal to 10% of the cell nuclei were grouped as p53 positive, and 33 (48%) of 69 patients whose tumors exhibited less than 10% nuclear expression were groups as p53 negative. The clinical characteristics of the patients in the p53-positive, and p53-negative groups were well balanced. Overall survival was significantly lower, and the times to tumor recurrence, to second primary tumors, and to any treatment failure were significantly shorter in the p53-positive group that in the p53-negative group (P=.0002, P=.047, P=.003, and P=.0009, respectively), mainly because the p53 positivity was associated with earlier development of tumor recurrence and second primary tumors. The rate of second primary tumor development per person per year was also significantly higher in the p53-positive group that in the p53-negative group. By use of multivariate analysis according to the Cox regression model, p53 expression status was identified as the most significant predictor of overall survival duration (P=.007), time to tumor recurrence (P=.053), time to second primary tumors (P=.035), and time to any treatment failure (P=.004). CONCLUSIONS: The expression of p53 protein in primary head and neck squamous cell carcinoma was significantly predictive of shorter survival because of its association with earlier development of both tumor recurrence and second primary tumors. Thus, p53 expression may be a valuable marker for identifying individuals at high risk of developing a recurrence of primary disease and second primary tumors who may benefit from adjuvant therapy and chemoprevention after definitive local therapy.

Adult↗
PubMed1996

Regional metastases in patients with advanced laryngeal cancer. Department of Veterans Affairs Laryngeal Cancer Study Group.

OBJECTIVES: To determine patterns of regional metastases in patients with advanced squamous cell carcinoma of the larynx and the effect of these patterns on regional and distant tumor recurrence and disease-free and overall survival. METHODS: One hundred fifty-nine patients treated with conventional surgery and radiation in the Veterans Affairs Cooperative Study were studied. Ninety-three of the patients underwent modified or classic radical neck dissection. Median follow-up was 5 years. Patient data collected included age, gender, alcohol consumption, tobacco use, and performance status. Tumor variables evaluated included TNM classification, tumor site, surface area, presence of ulceration and invasion, and histologic growth pattern. Histologically positive regional lymph nodes were examined for level, number, site, and extracapsular spread. Outcome variables included time and location of recurrence, distant metastases, and survival. RESULTS: Regional metastases were more common in supraglottic than glottic or subglottic tumors (P < .001) and in tumors with larger surface dimensions (P = .004). Cervical metastases were associated with decreased disease-free interval (P < .001) and survival (P = .001) and increased distant metastases (P < .001). Presence of 3 or more positive nodes predicted distant recurrence (P < .001) and decreased survival (P < .001, multivariate analysis). An analysis of lymph node involvement (levels I-V) indicated that level 1 and 5 involvement was a significant prognostic factor. Age, sex, race, and tobacco or alcohol use were not associated with number or extent of regional metastases. CONCLUSIONS: These findings confirm the prognostic importance of number and level of lymph nodes in advanced laryngeal cancer. The association of distant metastases with number and level of regional nodes indicates a use for these variables in considering adjuvant chemotherapy.

Carcinoma, Squamous Cell↗
PubMed1996

Strategy and planning for chemopreventive drug development: clinical development plans II.

This is the second publication of Clinical Development Plans from the National Cancer Institute, Division of Cancer Prevention and Control, Chemoprevention Branch and Agent Development Committee. The Clinical Development Plans summarize the status of promising chemopreventive agents regarding evidence for safety and chemopreventive efficacy in preclinical and clinical studies. They also contain the strategy for further development of these drugs, addressing pharmacodynamics, drug effect measurements, intermediate biomarkers for monitoring efficacy, toxicity, supply and formulation, regulatory approval, and proposed clinical trials. Sixteen new Clinical Development Plans are presented here: curcumin, dehydroepiandrosterone, folic acid, genistein, indole-3-carbinol, perillyl alcohol, phenethyl isothiocyanate, 9-cis-retinoic acid, 13-cis-retinoic acid, l-selenomethionine and 1, 4-phenylenebis(methylene)selenocyanate, sulindac sulfone, tea, ursodiol, vitamin A, and (+)-vorozole. The objective of publishing these plans is to stimulate interest and thinking among the scientific community on the prospects for developing these and future generations of chemopreventive drugs.

Animals↗
PubMed1996

Molecular and cellular biomarkers for field cancerization and multistep process in head and neck tumorigenesis.

One way to explain the development of head and neck cancer is through the theories of field cancerization, i.e., the exposure of an entire field of tissue to repeated carcinogenic insult, and multistep process, i.e., development of multiple cancers in a predisposed filed through a series of recognizable stages. Recent molecular genetic studies of histologically normal and premalignant epithelia of high-risk subjects and studies of malignant tumors in aerodigestive tract epithelia have identified a continuum of accumulated specific genetic alterations that possibly occur during the clonal evolution of tumors, namely, during the multistep process. Second primary or multiple primary tumors arise in the same fields as independent clones, with similar but unique molecular genetic and/or cellular alterations. Consequently, the assessment of these genetic and phenotypic alterations has been integrated into clinical chemoprevention trials in an effort to identify biomarkers that are also risk predictors and intermediate end points. This review covers candidate biomarkers of the processes of field cancerization and multistep tumor development in aerodigestive tract epithelia, including general and specific genetic markers, proliferation markers, and squamous differentiation markers.

Biomarkers, Tumor↗
PubMed1996

Frequent microsatellite alterations at chromosomes 9p21 and 3p14 in oral premalignant lesions and their value in cancer risk assessment.

To better understand genetic alterations in oral premalignant lesions, we examined 84 oral leukoplakia samples from 37 patients who had been enrolled in a chemoprevention trial. The samples were analyzed for two microsatellite markers located at chromosomes 9p21 and 3p14. Loss of heterozygosity (LOH) at either or both loci was identified in 19 of the 37 (51%) patients. Of these 19 patients, seven (37%) have developed head and neck squamous cell carcinoma (HNSCC) while only one of 18 (6%) of patients without LOH developed HNSCC. Our data suggest that clonal genetic alterations are common in oral premalignant lesions; that multiple genetic alterations have already occurred in oral premalignant lesions, allowing at least a focal clonal expansion; and that losses of the 9p21 and 3p14 regions may be related to early processes of tumorigenesis in HNSCC. These genetic alterations in premalignant tissues may serve as markers for cancer risk assessment.

Adult↗
PubMed1996

Retrovirus-mediated wild-type p53 gene transfer to tumors of patients with lung cancer.

A retroviral vector containing the wild-type p53 gene under control of a beta-actin promoter was produced to mediate transfer of wild-type p53 into human non-small cell lung cancers by direct injection. Nine patients whose conventional treatments failed were entered into the study. No clinically significant vector-related toxic effects were noted up to five months after treatment. In situ hybridization and DNA polymerase chain reaction showed vector-p53 sequences in posttreatment biopsies. Apoptosis (programmed cell death) was more frequent in posttreatment biopsies than in pretreatment biopsies. Tumor regression was noted in three patients, and tumor growth stabilized in three other patients.

Aged↗
PubMed1996

A phase I investigation of the sequential use of methotrexate and paclitaxel with and without G-CSF for the treatment of solid tumors.

BACKGROUND: Paclitaxel is a novel agent with significant activity in several solid tumors. Preclinical data suggested that methotrexate prior to paclitaxel would be synergistic. To determine the qualitative and quantitative toxicity of this regimen we performed a phase I study in patients with solid tumors. PATIENTS AND METHODS: Patients with solid tumors previously treated with no more than two prior chemotherapy regimens were given methotrexate intravenously on day 1, followed by paclitaxel, as a 24-hour infusion on day 2. The starting dose (level '0') was 40 mg/m2 for methotrexate and 135 mg/m2 for paclitaxel. RESULTS: After achieving a maximum tolerated dose, additional patients were enrolled with the addition of G-CSF 5 mu g/kg/d on days 4-13. At the starting dose level, dose-limiting toxicity consisting of neutropenic fever occurred in 3 of 4 patients. At dose level -1, methotrexate 30 mg/m2 and paclitaxel 110 mg/m2, neutropenic fever occurred in 7 of 10 patients during the first course. At dose level -2, methotrexate 23 mg/m2 and paclitaxel 85 mg/m2, neutropenic fever occurred in 1 of 7 patients. To abrogate the neutropenia we explored the same combination with the addition of G-CSF. Neutropenic fever remained the only dose-limiting toxicity. At dose level '0' with G-CSF, 1 of 7 patients developed dose-limiting toxicity. At dose level 1 plus G-CSF, methotrexate 40 mg/m2 and paclitaxel 170 mg/m2, dose-limiting neutropenic fever occurred in 4 of 6 patients. Partial responses occurred in 4 of 41 patients entered on this study. Pharmacokinetic data suggested that methotrexate did not increase paclitaxel levels. CONCLUSION: The combination of methotrexate and paclitaxel is feasible, but neutropenic fever, even with the addition of G-CSF prevents further escalations of paclitaxel beyond 135 mg/m2 following methotrexate.

Antineoplastic Combined Chemotherapy Protocols↗
PubMed1996

A phase II study of ifosfamide in recurrent squamous cell carcinoma of the head and neck.

Chemotherapy has not significantly altered the overall survival of patients with recurrent squamous cell carcinoma of the head and neck; therefore, the development of new agents is essential. The purpose of the current phase II study was to define the efficacy of ifosfamide in the treatment of recurrent squamous cell carcinoma of the head and neck. All patients were required to have squamous cell carcinoma of the head and neck that had recurred following surgery or radiotherapy or both. Patients may have received prior chemotherapy. Patients were initially treated with ifosfamide 2 g/m2/day for 4 days (dose level 0). Dose level-1 was 2 g/m2/day for 3 days, and dose level-2 was 2 g/m2/day for 2 days. All patients received mesna 400 mg/m2/day prior to and 1,200 mg/m2/day as a continuous infusion after ifosfamide. Thirty-eight patients were enrolled in the study. Five patients were inevaluable for toxicity or response. Overall, the regimen was well tolerated, with grade 4 granulocytopenia the only significant toxicity occurring in 16 patients. Overall, eight of 31 evaluable patients (25.8%) had a major response. Only one of the 10 patients (10%) with prior chemotherapy responded, but seven of the 21 patients (33.3%) with no prior chemotherapy had major responses. Ifosfamide is an active agent in recurrent squamous cell carcinoma of the head and neck. Further studies of ifosfamide in combination with other agents, particularly as induction therapy in patients with locally advanced disease, are warranted.

Adult↗
PubMed1996

Treatment of patients with small-cell lung cancer refractory to etoposide and cisplatin with the topoisomerase I poison topotecan.

PURPOSE: This study was designed to assess the anti-tumor activity of topotecan (TPT) in patients with small-cell lung cancer (SCLC) refractory to etoposide. PATIENTS AND METHODS: Refractoriness to etoposide was defined as lack of response to etoposide-containing frontline therapy, or progression during or within 3 months of the last dose of etoposide-containing frontline or second-line therapy. Other eligibility criteria were presence of measurable disease, Zubrod scale performance status (PS) < or = 2, < or = two prior chemotherapy regimens, and adequate renal and liver function. TPT was administered at a dose of 1.25 mg/m2/d for 5 days over 30 minutes every 21 days. RESULTS: Thirty-two patients were registered, of whom 28 are fully assessable. All patients had been treated with frontline etoposide and cisplatin. Three patients (11%) achieved a partial remission (PR) (durations, 7, 8, and 19 weeks) and two (7%) achieved a minor response; five patients (17%) had stable disease and 18 (65%) had progressive disease. One of the three patients who achieved a PR had failed to respond to frontline cisplatin and etoposide. The overall median survival duration was 20 weeks. Grade 3 to 4 granulocytopenia and thrombocytopenia occurred after 70% and 31% of courses administered, respectively. No grade 3 to 4 non-hematological toxicities were observed. Grade 1 or 2 nonhematological toxicities (in percentage of patients) consisted of nausea (41%, 8%) and vomiting (25%, 11%), and alopecia (100%). CONCLUSION: TPT at the dose and schedule used has modest antitumor activity in SCLC patients refractory to etoposide and cisplatin, which indicates that clinical resistance to the topoisomerase II poison etoposide does not confer cross-sensitivity to the topoisomerase I poison TPT. TPT is well tolerated, with myelosuppression of short duration being the most common and limiting toxicity.

Adult↗
PubMed1996

Phase II study of topotecan in patients with advanced non-small-cell lung cancer previously untreated with chemotherapy.

PURPOSE: This study was designed to assess the anti-tumor activity of topotecan (TPT) in patients with advanced non-small-cell lung cancer (NSCLC) previously untreated with chemotherapy. PATIENTS AND METHODS: Patients with stage IIIB or IV NSCLC with measurable disease in nonradiated fields were eligible. Other eligibility criteria were Zubrod performance status (PS) < or = 2 and adequate renal and liver function. TPT was administered at a dose of 1.5 mg/m2/d for 5 days over 30 minutes every 21 days. Of 48 registered patients, 40 were fully assessable. Nineteen patients had adenocarcinoma (AD), 14 squamous carcinoma (SCC), and seven poorly differentiated carcinoma. RESULTS: Six patients (15%) achieved a partial remission (PR) (durations: 8, 14, 18, 28, 56, and 61 weeks) and four patients a minor response; 10 patients had stable disease and 20 patients progressive disease. The PR rate was 36% (five of 14 patients) in patients with SCC versus 4% (one of 26 patients) in those with other histologies (P = .014). The overall median survival time was 38 weeks and 30% of patients were alive at 1 year. Grade 3 to 4 granulocytopenia and thrombocytopenia occurred after 76% and 10% of courses administered, respectively. No grade 3 to 4 nonhematologic toxicities were observed. Grade 1 or 2 nonhematologic toxicities consisted of nausea (46% and 5%), vomiting (31% and 7%), and fatigue (53% and 16%). CONCLUSION: TPT at the dose and schedule used has moderate antitumor activity in NSCLC; its activity is mostly limited to patients with SCC. TPT is well tolerated, with myelosuppression of short duration being the most common and limiting toxicity.

Adenocarcinoma↗
PubMed1996

Screening and chemoprevention of gynecologic tumors.

The challenges in cancer prevention for primary care health professionals are to apply effectively and efficiently the technologies that prevent disease occurrence and progression. The opportunity for providing preventive services in the medical care setting would appear to be potentially achievable, but it requires consideration of economic, organizational, and conceptual barriers. Studies of potential deterrents of optimal use of cancer screening tests have emphasized the leadership role of physicians. Physician advocacy of cancer screening guidelines or assigning priority to counseling about high-risk behaviors will be influenced by the critical and balanced presentation of scientific evidence on the safety and efficacy of preventive interventions. Chemoprevention refers to the use of pharmacologic or natural agents, currently under investigation, to prevent or delay the development of cancer in ostensibly healthy persons with specified risk factors or precancerous conditions.

Feasibility Studies↗
PubMed1996

A statistical analysis of the reliability and classification error in application of the mutagen sensitivity assay.

In vitro mutagen hypersensitivity, determined with the bleomycin assay, has been found to be an independent risk factor for developing primary upper aerodigestive tract cancers, lung cancers, and second malignant tumors. The average number of chromatid breaks per cell (b/c) is derived from evaluating an arbitrarily set number of metaphases (usually 50) in each sample. The reliability of such an approach is of key importance in large-scale epidemiological studies. Because evaluating metaphases is a time-consuming task, it is desirable to know the minimum number of readings needed to reach an acceptable reliability. Statistical analyses were performed in 160 observations for which b/c values were determined by the same observer scoring 100 consecutive metaphases per sample. The b/c values were between 0.14 and 1.30 (mean, 0.61). The b/c values were separately calculated for the first and second sets of 50 metaphases. There was essentially no difference in the mean b/c values between the first and second 50 readings (difference, -0.002). The correlation between the two sets of readings was 0.72. The SE of the b/c values, based on scoring 50 metaphases, was 0.15. When scoring 100 metaphases, the SE decreased to 0.11. After evaluating the first 50 metaphases, the theoretical gain in reducing the SE was <1% with each additional reading. When 0.8 was used to dichotomize the mean b/c value into bleomycin-resistant or bleomycin-hypersensitive groups, sensitivity and specificity of reading 50 metaphases were above 75% and 95% when compared to 100 readings. A simulated case control study showed that there is a 15% attenuation in estimating the odds ratio with 50 readings. The findings suggest that the conventional method of reading 50 metaphases can yield an acceptable reliability in our setting and may be applied to other cancer epidemiology studies.

Algorithms↗
PubMed1996

Retinoic acid receptor- and retinoid X receptor-selective retinoids activate signaling pathways that converge on AP-1 and inhibit squamous differentiation in human bronchial epithelial cells.

Human bronchial epithelial (HBE) cells undergo squamous differentiation in response to a variety of conditions in tissue culture, and retinoid treatment has been shown to reverse this process. Retinoids mediate their effects through the retinoic acid and retinoid X nuclear receptors (RAR and RXR, respectively), which form RAR-RXR heterodimers, RXR homodimers, and heterodimers of RXR and certain orphan receptors. These receptor dimers bind to distinct response elements, activating separate pathways. In this study, we investigated the roles of RAR and RXR signaling pathways in the inhibition of HBE squamous differentiation. After induction of squamous differentiation by confluent growth, HBE cells were treated with retinoids that selectively activate RARs (E-4-[2-(5,5,8,8-tetramethyl-5,6,7,8-tetrahydro-2-naphthaienyl)-1- propenyl] benzoic acid), RXRs (4-[1-(5,5,8,8-tetramethyl-5,6,7,8-tetrahydro-2-naphthyl)ethenyl]benzoic acid), or both RARs and RXRs (9-c/s retinoic acid). These retinoids inhibited the mRNA expression of the squamous differentiation markers transglutaminase type I, involucrin, keratin 5, and keratin 13, suggesting that inhibition of HBE squamous differentiation could be mediated by activation of either RAR or RXR signaling pathways. We examined the role of AP-1 as a potential effector of these retinoid pathways. AP-1 transcriptional activity was reduced markedly by these retinoids, and a concomitant, but proportionally smaller, reduction in AP-1 DNA binding was observed. Furthermore, treatment of squamous HBE cells with the retinoid SR11238, which inhibited AP-1 without activating retinoid receptor transcriptional properties, reduced the expression of transglutaminase type I and involucrin. These findings support the hypothesis that, in HBE cells, RAR and RXR signaling pathways inhibit AP-1 transcriptional activity, and this contributes to retinoid-induced reversal of HBE squamous differentiation.

Alitretinoin↗
PubMed1996

Cervical human papillomavirus infection and intraepithelial neoplasia: a review.

Cervical human papillomavirus (HPV) infections and intraepithelial neoplasias are precursors to cervical cancer, the second most common cancer in women worldwide. HPV satisfies the epidemiologic criteria for causality; the role of other cofactors is under study. Natural history studies show that most low-grade lesions (productive HPV infections) regress or persist, whereas high-grade lesions (those with integrated HPV DNA) progress. Immunobiologic studies demonstrate that infection peaks in the early 20s, leading to a 10- to 20-year period of persistent infection, before finally progressing to a preinvasive or invasive lesion. Papanicolaou (Pap) screening has lowered the morbidity and mortality from cervical cancer in every country in which screening programs have been introduced. The diagnostic strategy for an abnormal Pap smear includes colposcopy; the role of HPV DNA testing in screening or diagnosis remains unclear. Patients are treated with cervical ablation, cone biopsy, or chemopreventive agents. Efforts to strengthen screening and prevention, as well as new directions for research, are needed.

Female↗
PubMed1996

Detection of chromosome instability of tissue fields at risk: in situ hybridization.

Many human tumors are thought to develop along a multistep pathway in tissues that have encountered long periods of carcinogen exposure and thus have accumulated genetic hits in functional targets relevant to tumor evolution. The cumulative degree of genetic change is dependent on both exogenous (e.g., degree of carcinogen exposure) and endogenous factors (e.g., metabolism of procarcinogens, repair or misrepair capacity, proliferation properties of the tissue, capability of damaged cells to survive). Thus one approach to risk estimation is to measure the accumulated amount of genetic damage in a target tissue at risk for tumor development. Since one cannot predict the exact site of the future tumor, the risk assay must detect a generalized ongoing process of genetic instability from small, random biopsies. The technique of chromosome in situ hybridization involves the use of chromosome- or region-specific probes and provides an ability to directly visualize genetic change (e.g., random or clonal chromosome polysomy and monosomy) on thin tissue sections (where tissue architecture is maintained) or exfoliated cells. Analyses of normal and premalignant lesions adjacent to tumors (e.g., head and neck, lung, bladder, cervix, breast) have demonstrated that chromosome instability can be detected in the field of the tumor (i.e., in normal and premalignant cells in a tissue at 100% risk of tumor development) and the degree of chromosome instability increases with the degree of histologic progression toward cancer. Analyses of premalignant lesions (e.g., oral leukoplakia and erythroplakia from individuals at risk for aerodigestive tract cancer) by chromosome in situ hybridization have uncovered varying degrees of chromosome instability. However, approximately half of those individuals who showed a high degree of chromosome instability in biopsies subsequently developed aerodigestive tract cancer. Of interest, half of these tumors have developed away from the biopsied site, suggesting that the detection of a chromosome instability process in one aspect of the tissue might yield risk information for the total tissue field. These studies also suggest that chromosome in situ hybridization might be useful for identifying individuals with high tumor risk who might benefit from chemopreventive intervention.

Bronchi↗