Biomedical subjects

Nhu D Le

Publications and source records attributed to Nhu D Le.

13 recordsLinked to original sources

PubMed2006

Comparison of two indices of exposure to polycyclic aromatic hydrocarbons in a retrospective aluminium smelter cohort.

BACKGROUND: The association between coal tar-derived substances, a complex mixture of polycyclic aromatic hydrocarbons, and cancer is well established. However, the specific aetiological agents are unknown. OBJECTIVE: To compare the dose-response relationships for two common measures of coal tar-derived substances, benzene-soluble material (BSM) and benzo(a)pyrene (BaP), and to evaluate which among these is more strongly related to the health outcomes. METHODS: The study population consisted of 6423 men with > or =3 years of work experience at an aluminium smelter (1954-97). Three health outcomes identified from national mortality and cancer databases were evaluated: incidence of bladder cancer (n = 90), incidence of lung cancer (n = 147) and mortality due to acute myocardial infarction (AMI, n = 184). The shape, magnitude and precision of the dose-response relationships and cumulative exposure levels for BSM and BaP were evaluated. Two model structures were assessed, where 1n(relative risk) increased with cumulative exposure (log-linear model) or with log-transformed cumulative exposure (log-log model). RESULTS: The BaP and BSM cumulative exposure metrics were highly correlated (r = 0.94). The increase in model precision using BaP over BSM was 14% for bladder cancer and 5% for lung cancer; no difference was observed for AMI. The log-linear BaP model provided the best fit for bladder cancer. The log-log dose-response models, where risk of disease plateaus at high exposure levels, were the best-fitting models for lung cancer and AMI. CONCLUSION: BaP and BSM were both strongly associated with bladder and lung cancer and modestly associated with AMI. Similar conclusions regarding the associations could be made regardless of the exposure metric.

Air Pollutants, Occupational↗

PubMed2006

Cancer risk in aluminum reduction plant workers (Canada).

A 14-year update to a previously published historical cohort study of aluminum reduction plant workers was conducted [1]. All men with three or more years at an aluminum reduction plant in British Columbia (BC), Canada between the years 1954 and 1997 were included; a total of 6,423 workers. A total of 662 men were diagnosed with cancer, representing a 400% increase from the original study. Standardized mortality and incidence ratios were used to compare the cancer mortality and incidence of the cohort to that of the BC population. Poisson regression was used to examine risk by cumulative exposure to coal tar pitch volatiles (CTPV) measured as benzene soluble materials (BSM) and benzo(a)pyrene (BaP). The risk for bladder cancer was related to cumulative exposure to CTPV measured as BSM and BaP (p trends <0.001), and the risk for stomach cancer was related to exposure measured by BaP (p trend BaP <0.05). The risks for lung cancer (p trend <0.001), non-Hodgkin lymphoma (p trend <0.001), and kidney cancer (p trend <0.01) also increased with increasing exposure, although the overall rates were similar to that of the general population. Analysis of the joint effect of smoking and CTPV exposure on cancer showed the observed dose-response relationships to be independent of smoking.

Air Pollutants, Occupational↗

PubMed2005

Toluidine blue staining identifies high-risk primary oral premalignant lesions with poor outcome.

There is a pressing need for the development of visual aids that will facilitate the detection of oral premalignant lesions (OPLs) with a high-risk of progression. Preliminary data suggest that toluidine blue stain may be preferentially retained by OPLs with high-risk molecular clones. In this study, we monitored OPLs from 100 patients without any history of oral cancer for an average of 44 months in order to evaluate the association of toluidine blue status with clinicopathologic risk factors, molecular patterns (microsatellite analysis on seven chromosome arms: 3p, 9p, 4q, 8p, 11q, 13q, and 17p) and outcome. Toluidine blue-positive staining correlated with clinicopathologic risk factors and high-risk molecular risk patterns. Significantly, a >6-fold elevation in cancer risk was observed for toluidine blue-positive lesions, with positive retention of the dye present in 12 of the 15 lesions that later progressed to cancer (P = 0.0008). This association of toluidine blue status with risk factors and outcome was evident even when the analysis was restricted to OPLs with low-grade or no dysplasia. Our results suggest the potential use of toluidine blue in identifying high-risk OPLs.

Adult↗

PubMed2005

Identification of occupational cancer risks in British Columbia: a population-based case-control study of 1129 cases of bladder cancer.

OBJECTIVE: We collected information on lifetime occupational histories, smoking, and alcohol consumption from 15,463 incident cancer cases. Occupational risk factors for bladder cancer are presented in this report. METHOD: A matched case-control design was used. All cases were diagnosed with bladder cancers, with controls being internal controls consisting of all other cancer sites, excluding lung and unknown primary. Data were analyzed using conditional logistic regression for matched sets data and the likelihood ratio test. RESULTS: Excess bladder cancer risks was observed in a number of occupation and industries, particularly those involving exposure to metals, including aluminum, paint and solvents, polycyclic aromatic hydrocarbons, diesel engine emissions, and textiles. CONCLUSIONS: The results of our study are in line with those from the literature and further suggest that exposure to silica and to electromagnetic fields may carry an increased risk of bladder cancer.

Adult↗

PubMed2004

The efficacy of pilocarpine and bethanechol upon saliva production in cancer patients with hyposalivation following radiation therapy.

PURPOSE: Pilocarpine and bethanechol have been reported as potentially effective sialogogues for xerostomic patients. The purpose of the present study was to compare the efficacy of bethanechol to that of pilocarpine in patients with dry mouth following cancer therapy. STUDY DESIGN: Patients with documented hyposalivation were provided pilocarpine or bethanechol for 2-3 weeks in an open-label randomized crossover study. Baseline and weekly whole resting saliva (WRS) and whole stimulated saliva (WSS) were obtained for 5 minutes. Subjective response and side effects were recorded. RESULTS: Forty-two xerostomic patients who had received radiation therapy to the head and neck participated. The increase in the WRS and WSS with each medication independently was limited. Statistically significant increase in WRS was seen for both medications when all patients using either agent were analyzed, but no statistically significant increase in WSS was found.Twenty-seven patients completed the crossover protocol. No significant difference in the effect was noted between each of the 2 drugs whether they were prescribed as the first or second drug in the crossover. Statistically significant improvement in subjective report of saliva production/mouth wetness was seen for patients on either medication. This study suggests that subjective improvement in symptoms of dry mouth may be related to resting saliva production, and not to stimulated saliva production. No statistically significant differences in adverse side effects were reported between the medications prescribed. The most common side effects were minor and included frequent urination, dizziness, and increased sweating. CONCLUSIONS: The findings indicate that head and neck radiation-treated patients with established hyposalivation will respond minimally to systemic sialagogues and while they may experience an increase in resting saliva little change in stimulated saliva may occur. It is not known whether relatively small increases in saliva are beneficial in maintaining oral health; however, subjective improvement suggests improved quality of life. While it is not known if prolonged use of a sialagogue will have increased effects, the limited increase in saliva seen following the second drug of the crossover suggests that prolonged use of a sialagogue may further increase saliva production.

Adult↗

PubMed2004

Carcinoma of the tongue: a case series analysis of clinical presentation, risk factors, staging, and outcome.

OBJECTIVE: Oral cancer is primarily a disease of epithelial origin. The tongue is the most common site of oral cancer. Oropharyngeal cancer accounts for approximately 2% of all cancer deaths. The purpose of this study was to analyze a case series of patients with tongue cancer. STUDY DESIGN: The medical records of 322 consecutive patients diagnosed with squamous cell carcinoma (SCC) of the tongue treated from 1979-1994 were reviewed. RESULTS: Patients had a mean age of 61.1 years and a 1.5:1 male to female ratio. Approximately, half of the cancers were diagnosed at an advanced stage and most involved the base of the tongue. The majority of oral tongue tumors were diagnosed at an early stage and had more well-differentiated cell types than those of the base of the tongue. Localized discomfort was the most common complaint (66.5%), present for up to 6 months in patients prior to diagnosis and were related to the oral tongue in 90% of cases. Symptoms associated with base of tongue lesions included neck masses, dysphagia, ear pain, and weight loss. Seventy-nine percent of the patients smoked, 58% consumed alcohol on a daily basis, and 43% consumed more than 4 alcoholic drinks daily. Primary radiotherapy was the treatment of 49.6% lesions, of which 57% were at an early stage at diagnosis. The mean overall survival was 3 years and 5 months, with a 5-year overall survival of 40%. Patients with stage 1 tumors had a disease-specific survival of over 80%. The 5-year survival of patients with cancer of the oral tongue was 43% and cancer of the base of the tongue was 27%. CONCLUSION: The prognosis is poorer for patients presenting with advanced stage and with tumors involving the base of the tongue. Symptoms were more common in tumors of the oral tongue, which likely results in earlier diagnosis. Patients with SCC of the base of the tongue presented with advanced stage of disease and were typically poorly differentiated lesions.

Adolescent↗

PubMed2004

Identification of occupational cancer risks in British Columbia: a population-based case-control study of 769 cases of non-Hodgkin's lymphoma analyzed by histopathology subtypes.

We have, as part of a program aimed at detecting occupational risk factors in British Columbia, collected lifetime occupational histories as well as information on lifetime cigarette smoking and alcohol consumption from 15,643 incident cancer cases, of whom 782 had a diagnosis of non-Hodgkin's lymphoma (NHL). Occupational risks for this cancer site are examined using a matched case-control study design, and the results are presented in this report for all cases and for histopathology subtypes. The results of our study indicate excess NHL risk, particularly for a number of occupations that involve exposures to electromagnetic fields, treated and fresh wood, metals, and solvents.

British Columbia↗

PubMed2003

Oral topical doxepin rinse: anesthetic effect in normal subjects.

Oral doxepin rinse has been reported to provide pain relief in patients with oral mucosal lesions due to cancer or cancer therapy. The purpose of this study was to assess the anesthetic effect of doxepin oral rinse in normal subjects to identify the duration of effect and to contrast the anesthetic effect with reported pain relief in patients with oral mucosal lesions. Normal volunteers were provided a solution of doxepin (5 mg/mL) for oral rinsing. Oral numbness and adverse effects were recorded for a period of 4 h after rinsing. Doxepin rinse resulted in mucosal anesthesia in all subjects. Sedation/fatigue was reported in four of seven subjects. There were no taste complaints and no nausea reported. The limited duration of numbness/anesthesia in normal subjects compared with prior studies showing pain relief for more than 3 h in patients with mucosal lesions, suggests that the extended duration of pain relief in patients was due to analgesic effects rather than anesthetic effects. The majority of normal subjects reported sedation after use, but this was less common in patients with mucosal lesions.

Adolescent↗

PubMed2002

3p14 and 9p21 loss is a simple tool for predicting second oral malignancy at previously treated oral cancer sites.

Treatment induces reactive changes that often resemble low-grade dysplasia at former oral cancer sites, complicating histopathological assessment. We tested a set of microsatellite markers shown previously to be predictive of progression for oral premalignant lesions for the ability to predict development of second oral malignancy (SOM). Sixty-eight oral leukoplakia at former cancer sites (with known outcome, 36 progressed to SOM) were evaluated for loss of heterozygosity at 19 loci on seven chromosome arms. 3p and/or 9p loss in these posttreatment leukoplakia was associated with a 26.3-fold increase in risk of developing SOM compared with those that retained both of these arms (P < 0.001), with 60% of cases with loss of heterozygosity developing SOM in 2 years. In contrast, histological diagnosis (moderate or severe dysplasia versus hyperplasia or mild dysplasia) had only a 1.7-fold increase in risk (P = 0.11). The identification of 3p and 9p loss in posttreatment lesions could serve as a simple and direct test for stratifying risk of SOM development.

Adolescent↗

PubMed2002

Carcinogenic and endocrine disrupting effects of cigarette smoke and risk of breast cancer.

BACKGROUND: Results of epidemiological studies, assessing the relation between smoking and breast cancer, have been inconclusive. Our aim was to assess the carcinogenic and possibly antioestrogenic effects of cigarette smoke on risk of breast cancer. METHODS: We sent a questionnaire to 1431 women younger than age 75 years who had breast cancer and were listed on the population-based British Columbia cancer registry between June 1, 1988, and June 30, 1989. We also sent questionnaires to 1502 age-matched controls, randomly selected from the 1989 provincial voters list. We obtained information on all known and suspected risk factors for breast cancer, and on lifetime smoking, alcohol consumption, and occupational history. We assessed the effect of smoking separately for premenopausal and postmenopausal women, adjusting for confounding variables. FINDINGS: 318 premenopausal women and 340 controls replied. Risk of breast cancer was significantly increased (adjusted odds ratio 1.69, 95% CI 1.13-2.51) in women who had been pregnant and who started to smoke within 5 years of menarche, and in nulliparous women who smoked 20 cigarettes daily or more (7.08, 1.63-30.8) and had smoked for 20 cumulative pack-years or more (7.48, 1.59-35.2). Postmenopausal women (700 breast cancer and 685 controls) whose body-mass index increased from age 18 to current and who started to smoke after a first fullterm pregnancy had a significantly reduced risk of breast cancer (0.49, 0.27-0.89). INTERPRETATION: Our results suggest that cigarette smoke exerts a dual action on the breast, with different effects in premenopausal and postmenopausal women. Our observations reinforce the importance of smoking prevention, especially in early adolescence, and draw attention to the timing of exposure in relation to susceptibility and refractory windows in the design of studies to investigate associations between environmental carcinogens or putative endocrine disruptors and risk of breast cancer.

Adult↗

PubMed2002

A Bayesian approach to case-control studies with errors in covariables.

We develop Bayesian methodology for the analysis of case-control data with covariate imprecision. The pretense that the distribution of the imprecisely measured covariate is discrete on a heuristically chosen support set leads to a method which is reasonably simple to implement, and can be applied to different study designs. The methodological development emphasizes the interplay between retrospective and prospective analysis. We illustrate the method on simulated data, and on data from a cancer study where smoking history is the imprecisely measured covariate.

Journal Article↗

PubMedDate not supplied

The effect of a disinfectant/coolant irrigant on microbes isolated from dental unit water lines.

The purpose of this study was to assess water samples from a hospital dental clinic to determine whether a disinfectant/coolant irrigant containing chlorhexidine (Lines, Micrylium Laboratories) affects the presence of microbial organisms in dental unit waterlines. Water samples from three hospital dental operatories were collected at baseline and after overnight treatment with a disinfectant-containing irrigant followed by sterile water irrigation. Saliva of treated patients and sterile water rinse specimens were collected from the waterlines of these operatories for three consecutive days, then weekly for eight weeks after treatment. Specimens were cultured to identify total heterotrophic plate counts as well as presence of Pseudomonas aeruginosa and Candida species. Baseline organism counts varied from 10(3) to 10(5) colony-forming units per milliliter. After treatment, no organisms were detected in waterline discharge. Decontamination of dental unit waterlines is possible using a disinfectant/irrigant followed by sterile water irrigation. The potential for contamination of the lines from patients' saliva may have been reduced due to use of anti-retraction valves and the disinfectant/sterile water irrigation, as conducted in this study.

Bacteria↗

PubMedDate not supplied

Patients with oropharyngeal cancer: a comparison of adults living independently and patients living in long-term care facilities.

The low survival rate of persons with oropharyngeal cancer (OPC) is directly related to the size of the primary tumor, lymph node involvement and to the smoking history. The association between medical independence and the survival rate of oral cancer is unclear. The purpose of this study was to assess the survival rate of institutionalized patients with oral cancer compared to those living independently. Information regarding gender, age, tobacco habits, disease characteristics, and survival status were recorded and statistically analyzed from 30 patients with oral cancer who were institutionalized compared to 543 patients with oral cancer who were non-institutionalized. Patients living in long-term care facilities (LTC) were significantly older than the independent patients (67% were 70 years or older versus 28% of independent patients) (p = 0.0001). No differences in smoking habits were noted between the two groups but more patients who were institutionalized stopped smoking at the time of diagnosis (p = 0.47). More patients who were institutionalized were diagnosed with positive lymph node involvement (p = 0.09). Significantly higher all-cause and disease-free 5-year survival rates were noted in the patients living independently, compared to the adults who were institutionalized (32% and 60% compared to 7% and 26% respectively; p < 0.05). The disease-specific 5-year survival was directly related to age (p = 0.001), size of the tumor (p = 0.001), and lymph node involvement (p < 0.001). Significant longer survival rates were observed for patients living independently. The more advanced disease seen in the patients who were institutionalized may be due to a delay in diagnosis, which may be associated with fewer symptoms, limited report of symptoms, a lack of attention or a misdiagnosis of the oral lesion.

Activities of Daily Living↗