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Biomedical subjects

W H Chow

Publications and source records attributed to W H Chow.

At least 109 records · Page 6Linked to original sources
PubMed1996

Clinical features of hematopoietic malignancies and related disorders among benzene-exposed workers in China. Benzene Study Group.

Previous occupational cohort studies of benzene-exposed workers have for the most part used only death certificates to validate diagnoses of workers developing leukemia and other hematopoietic and lymphoproliferative malignancies and related disorders (HLD). In a follow-up study of 74,828 benzene-exposed workers and a comparison group of 35,805 nonexposed workers from 12 cities in China, we sought to characterized clinicopathologically and to confirm diagnoses of all cases of HLD. Using medical records, laboratory hematology results, and histopathology, U.S. and Chinese expert hematopathologists, blinded to exposure status, carried out a detailed review using standardized evaluation forms. Key among the findings were a notable diversity of malignant and nonneoplastic hematopoietic and lymphoproliferative disorders, documentation of excess myelodysplastic syndromes among benzene workers, and widespread dyspoiesis involving all hematopoietic cell lines. As sophisticated clinicopathologic characterization and corresponding classification schemes for HLD become increasingly widespread, it is recommended that future epidemiologic investigations of benzene workers incorporate similarly detailed morphologic evaluation. In extending follow-up of this cohort of young workers, we will continue to use all available clinical, laboratory hematology, and pathology data as well as cytogenetic and biochemical markers to characterized various HLD outcomes. These careful surveillance mechanisms should also provide additional insight into carcinogenic mechanisms of benzene and allow comparison of the molecular pathogenesis of HLD induced by benzene versus chemotherapy, radiation, or other exposure.

Adult↗
PubMed1996

Obesity and risk of renal cell cancer.

In a population-based case-control study including 449 directly interviewed cases and 707 controls, we assessed the risk of renal cell cancer associated with height, weight, body mass index (BMI), and frequency of weight changes. Odds ratios and 95% confidence intervals were estimated by using logistic regression models. Among women, risk increased with increasing usual BMI (P for trend < 0.001). A nearly 4-fold risk was found among the 10% of women with the highest usual BMI (odds ratio = 3.8; confidence interval = 1.7-8.4). Among men, no clear trend was observed with usual weight or BMI, although the highest risk (30-50%) generally was seen among those in the upper deciles of weight or BMI. There was no clear indication that excess BMI early or late in life disproportionately affected risks. Risk also was not related to patterns of weight fluctuations or use of diet pills. Our study supports previous observations linking renal cell cancer risk to increased BMI among women and suggests a weaker association in men. Given the increasing prevalence of obesity and the rising incidence of renal cell cancer in the United States, additional studies are needed to disentangle the effects of BMI from various correlates and to identify the mechanisms by which obesity affects risk.

Adult↗
PubMed1996

Nitrite, N-nitroso compounds, and other analytes in physiological fluids in relation to precancerous gastric lesions.

Levels of gastric juice nitrite, several urinary N-nitroso compounds, and other analytes were examined among nearly 600 residents in an area of Shandong, China, where precancerous gastric lesions are common and rates of stomach cancer are among the world's highest. Gastric juice nitrite levels were considerably higher among those with gastric juice pH values above 2.4 versus below 2.4. Nitrite was detected more often and at higher levels among persons with later stage gastric lesions, especially when gastric pH was high. Of those with intestinal metaplasia, 17.5% had detectable levels of gastric nitrite, while this analyte was detected in only 7.2% of those with less advanced lesions. Relative to those with undetectable nitrite, the odds of intestinal metaplasia increased from 1.5 (95% confidence interval = 0.6-4.1) to 4.1 (95% confidence interval = 1.8-9.3) among those with low and high nitrite concentrations, respectively. Urinary acetaldehyde and formaldehyde levels also tended to be higher among those with more advanced pathology, particularly dysplasia. However, urinary excretion levels of total N-nitroso compounds and several nitrosamino acids differed little among those with chronic atrophic gastritis and intestinal metaplasia and dysplasia, consistent with findings from recent studies in the United Kingdom, France, and Colombia. The data from this high-risk population suggest that elevated levels of gastric nitrite, especially in a high pH environment, are associated with advanced precancerous gastric lesions, although specific N-nitroso compounds were not implicated.

Adult↗
PubMed1996

Smoking and adrenal cancer mortality among United States veterans.

Adrenal cancer is a rare and heterogenous group of tumors the etiology of which is largely unknown. Tobacco use was suggested as a potential risk factor in a recent case-control study of adults dying from adrenal cancers, most of which were adrenocortical carcinomas. In a cohort study of nearly 250,000 United States veterans whose mortality was followed for up to 26 years, we evaluated the risk of adrenal cancer associated with tobacco use. Relative risks and corresponding 95% confidence intervals were calculated. A total of 27 adrenal cancer deaths were observed during the follow-up period. Relative to nonusers of any tobacco, risk was elevated 5-fold (relative risk = 5.1; confidence interval = 1.1-22.4) among current cigarette smokers, with risks further increased among those who smoked > 20 cigarettes/day (P for trend < 0.01). Nonsignificant increases in risk occurred among smokers of other forms of tobacco. This cohort study provides support for an etiological relationship between tobacco smoking and adrenal cancer, although further confirmatory studies are needed.

Adrenal Gland Neoplasms↗
PubMed1996

Underreporting and misclassification of urinary tract cancer cases on death certificates.

We compared the diagnoses for decreased cases with urinary tract cancer reported to the Surveillance, Epidemiology, and End Results (SEER) program with their underlying cause of death reported on death certificates. Deaths for a substantial proportion of cases were ascribed to noncancer causes (bladder, 48%; kidney, 28%; renal pelvis, 37%; and other urinary tract, 38%), which decreased with advancing stage at diagnosis and increased with length of survival. In general, cancer deaths were more likely to be recorded to the predominant subsite within an organ. Only 5.5% of renal pelvis cancer patients were recorded to have died of their illness, whereas 33.7% of their deaths were reported as due to kidney cancer. On the other hand, over 85% of urinary tract cancer deaths reported on the death certificates were confirmed by SEER diagnosis, although the extent of agreement varied by stage at diagnosis and age at death for kidney and renal pelvis cancers.

Adult↗
PubMed1996

Tea and cancer: a review of the epidemiological evidence.

Numerous recent reports of inhibition of carcinogenesis in experimental animals by tea or tea compounds raise the possibility that tea drinking may lower cancer risk in humans. Thus, studies around the world were reviewed to evaluate whether there is a consensus of epidemiologic evidence on the relation of tea drinking to cancer overall or to specific cancers. Ecological data suggest at most a modest benefit, since there is considerable international variation in tea consumption but generally small differences in cancer rates. More relevant case-control and cohort studies show mixed results. Detailed data from these studies on cancer risks according to amount and duration of tea intake are quite limited, and consistent dose-related patterns. have yet to emerge. Nevertheless, several investigations point to the possibility of lowered risks of digestive tract cancers among tea drinkers, especially those consuming green tea. Further research, particularly in population with wide ranges of tea consumption, is needed before definitive conclusions on tea's impact upon cancer risk can be reached.

Case-Control Studies↗
PubMed1995

International renal-cell cancer study. VIII. Role of diuretics, other anti-hypertensive medications and hypertension.

Risk of renal-cell cancer in relation to use of diuretics, other anti-hypertensive medications and hypertension was assessed in a multi-center, population-based, case-control study conducted in Australia, Denmark, Germany, Sweden and the United States, using a shared protocol and questionnaire. A total of 1,732 histologically confirmed cases and 2,309 controls, frequency-matched to cases by age and sex, were interviewed. The association between renal-cell cancer and the drugs was estimated by relative risks (RRs) and 95% confidence intervals (CIs). Risks were increased among users of diuretics and other anti-hypertensive medications. After adjustment for hypertension, risk for diuretics was reduced to unity, except among long-term (15+ years) users. Risk for use of non-diuretic anti-hypertensive drugs remained significantly elevated and increased further with duration of use. Overall risk was not enhanced when both classes of medications were used. Excess risk was not restricted to any specific type of diuretic or anti-hypertensive drug and no trend was observed with estimated lifetime consumption of any particular type of product. The RR for hypertension after adjustment for diuretics and other anti-hypertensive medications was 1.4 (95% CI = 1.2-1.7), although among non-users of any anti-hypertensive medications, there was little excess risk associated with a history of hypertension. Exclusion of drug use that first occurred within 5 years of cancer diagnosis or interview did not alter the associations. Our findings suggest small effects on renal-cell cancer risk associated with hypertension and use of diuretics and other anti-hypertensive medications. However, because of potential misclassifications of these highly correlated variables, it is difficult to distinguish the effect of treatment from its indication, hypertension.

Antihypertensive Agents↗
PubMed1995

The relation of gastroesophageal reflux disease and its treatment to adenocarcinomas of the esophagus and gastric cardia.

OBJECTIVE: To examine the relationship of gastrointestinal disorders and their treatment to the risk of adenocarcinomas of the esophagus and gastric cardia (AEC). DESIGN: A medical record-based case-control study, with data collected on a standardized form by a trained abstractor, blind to the case-control status. SETTING: A large prepaid health plan. SUBJECTS: Case patients were plan members newly diagnosed with histologically confirmed AEC from 1986 to 1992. For each of the 196 eligible case patients, one control was selected who matched for membership at time of diagnosis, sex, year of birth, and duration of membership. MAIN OUTCOME MEASURES: Association between AEC and history of gastroesophageal conditions and their treatment. Conditional logistic regression procedures were used for calculation of odds ratios (ORs) and corresponding 95% confidence intervals (Cls), with adjustment for race, smoking status, and body mass index. Medications were grouped into H2 antagonists (cimetidine, ranitidine, famotidine, and nizatidine) and anticholinergics (propantheline bromide, dicyclomine hydrochloride, Donnatal [combination of atropine sulfate, hyoscyamine sulfate, phenobarbital, and scopolamine hydrobromide], and Librax [combination of chlordiazepoxide hydrochloride and clidinium bromide]). RESULTS: Significant twofold or greater risks of AEC were associated with a history of esophageal reflux, hiatal hernia, esophagitis/esophageal ulcer, and difficulty swallowing. The ORs increased with increasing number of these conditions. Although a fourfold risk was linked to four or more prescriptions for H2 antagonists, the risk was reduced to 1.5 (95% Cl, 0.4 to 5.4) after adjusting for the predisposing conditions. Further analysis revealed that the excess risk was restricted to persons with a history of gastroesophageal reflux and related conditions. No association was observed for overall use of anticholinergics. However, after adjustment for predisposing conditions, ORs decreased with increasing number of prescriptions for anticholinergics (P for trend = .08) CONCLUSIONS: This study provides reassuring findings that use of H2 antagonists and anticholinergics does not increase AEC risk. It also quantifies the elevated risk of AEC associated with gastroesophageal reflux disease. Further research into reflux disease and the production of premalignant epithelial changes may help elucidate carcinogenic mechanisms and measures aimed at early detection and prevention of AEC.

Adenocarcinoma↗
PubMed1995

Analgesics and cancers of the renal pelvis and ureter.

To evaluate renal pelvis and ureter (RPU) cancer risk in relation to lifetime use of analgesics, a population-based case-control study was carried out in 3 areas of the United States. Among 502 cases and 496 controls diagnosed and interviewed during 1983-1986, no significant increases in risk were found for any of the non-prescription and prescription analgesics evaluated or among regular users of phenacetin, acetaminophen or aspirin. Neither cumulative lifetime ingestion nor duration of regular use of these 3 drugs, whether alone or in combination, was associated with significantly increased risk of RPU cancer, although a slight excess was observed among long-term users of acetaminophen. Risk was not increased among persons reporting highest cumulative dose and/or longest duration of phenacetin use. Although our study of RPU cancer is the largest to date, it was nonetheless limited by the small number of regular analgesic users and the relatively low response rates. Because of the relatively recent onset of widespread use of acetaminophen, its pharmacologic similarity to phenacetin, a known urothelial carcinogen, and the elevation in risk seen in long-term users, further surveillance of this analgesic is warranted.

Acetaminophen↗
PubMed1995

Reproductive factors and the risk of renal cell cancer among women.

In etiologic studies of renal cell carcinoma the role of reproductive variables and the use of exogenous hormones have not been well examined. In a population-based case-control study including 165 female cases and 227 controls, we assessed the risk of renal cell cancer associated with reproductive factors and use of oral contraceptives and menopausal hormones. Odds ratios were computed using logistic regression analyses. Risk was positively associated with number of births and inversely associated with age at first birth, with the largest increases in risk (more than 2-fold) among women with 5 or more births after age 25. After adjustment for age, smoking status, body mass index and age at first birth, women with 5 or more births had a 2-fold risk (OR = 2.2, 95% CI = 1.2-4.0) relative to those with 1 or 2 births. Age at first birth, however, was no longer a risk factor when the number of births was adjusted for. The association with parity was considerably stronger among women with a history of hypertension or above-median body mass index than among those without these conditions. In addition, risk was reduced among long-term oral contraceptive users but elevated among women who had had a hysterectomy or used menopausal hormones. Our findings suggest that reproductive factors, particularly the number of births, may play an etiologic role in renal cell cancer among women and deserve further study.

Adult↗
PubMed1995

Colorectal cancer trends by race and anatomic subsites, 1975 to 1991.

OBJECTIVES: To determine whether colorectal cancer rates among black men and women show the abrupt declines seen in whites since the mid-1980s and to determine how the cancer trends vary by anatomic subsites. DATA SOURCES: Mortality data from the National Center for Health Statistics, Hyattsville, Md, and incidence and survival data from the Surveillance, Epidemiology, and End Results program of the National Cancer Institute, Bethesda, Md. MAIN OUTCOME MEASURES: Trends in incidence, survival, and mortality rates. RESULTS: For white men and women, cancer incidence rates declined for the right colon, left colon, and rectum after 1985. Stage-specific incidence rates for white men and women for each subsite had generally similar patterns. Distant-disease incidence rates declined beginning in the late 1970s, whereas regional-disease rates increased until the early to mid-1980s and then declined. An exception is the right colon in men, for which the incidence rates of distant disease did not decline, although the regional-disease pattern was similar to other sites. For blacks, colorectal cancer incidence rates changed little in the 1980s for men or women. In particular, there were no significant declines in the cancer incidence rates of the colorectum or of subsites after 1985. Black colorectal cancer mortality trends showed gender and age differences. Black men had significantly increasing colorectal cancer mortality rates from 1975 through 1992, but the increase after 1985 was observed only in men 65 years of age and older. The colorectal cancer mortality rates did not increase overall in black women in the 1980s, but the mortality rates increased slightly in women 65 years of age and older while declining in women younger than 65 years. CONCLUSIONS: For whites, the trends in colorectal cancer rates by anatomic subsite support the contention that early-detection procedures, such as sigmoidoscopy and colonoscopy, are contributing to the declines in incidence and mortality rates since 1985. The absence in blacks of significant declines in colorectal incidence or mortality rates since 1985 suggests the need for a greater emphasis on early-detection programs in the black community, particularly for elderly blacks.

Black People↗
PubMed1995

Esophageal cancer and occupation in a cohort of Swedish men.

Using the Cancer Environment Registry of Sweden, which links the 1960 census information on employment with cancer incidence data from 1961-1979, we conducted a systematic, population-based assessment of esophageal cancer incidence by industry and occupation for men in Sweden. A general reduction in esophageal cancer incidence was found among agricultural and professional workers, whereas excess incidence was found among business, sales, and some craftsmen and production jobs. Elevated incidence was associated with several specific industries, including the food (SIR = 1.3, p < 0.05), beverage and tobacco (SIR = 1.8, p < 0.05) industries, vulcanizing shops within the rubber industry (SIR = 4.7, p < 0.01), and certain automotive building industries. Incidence also was increased among brewery workers (SIR = 4.2, p < 0.01) and butchers (SIR = 2.1, p < 0.01), and among individuals with certain service jobs, particularly waiters in the hotel and restaurant industry (SIR = 3.1, p < 0.01). Some of the occupational associations may be explained by lifestyle factors such as alcohol drinking and smoking, whereas others are specific and tend to support those of earlier investigations. This study adds to the evidence of a small but possibly important role of occupation in esophageal cancer etiology.

Adenocarcinoma↗
PubMed1995

Mitral valve prolapse causing severe mitral regurgitation in a patient with absent right pulmonary artery.

A 33-year-old man was investigated for dyspnea on exertion and the presence of a pansystolic murmur. Physical examination revealed dextrocardia confirmed by chest radiograph, which also showed oligemic right lung field. Subsequent cardiac catheterization revealed secundum atrial septal defect, persistent left sided superior vena cava, and severe mitral valve prolapse causing severe mitral regurgitation with pulmonary hypertension. The right pulmonary artery was absent. It is the first report of the association between severe mitral valve prolapse and absent right pulmonary artery.

Adult↗
PubMed1995

Cigarette smoking and alcohol consumption and the risk of pancreatic cancer: a case-control study in Shanghai, China.

Cancer of the pancreas has been rising in incidence in Shanghai, China since the early 1970s. In 1987-89, this malignancy ranked eighth in cancer incidence among men and ninth among women in Shanghai. To examine risk factors for this tumor in urban Shanghai, a population-based case-control study was conducted. Cases (n = 451) were permanent residents of Shanghai, 30 to 74 years of age, newly diagnosed with pancreatic cancer between 1 October 1990 and 30 June 1993. Deceased cases (19 percent) were excluded from the study. Controls (n = 1,552) were selected among Shanghai residents, frequency-matched to cases by gender and age. Cases and controls were interviewed about their demographic background and potential risk factors, including tobacco, alcohol and beverage consumption, diet, and medical history. Adjusted odds ratios (OR) and 95 percent confidence intervals (CI) were estimated using logistic regression models. Current cigarette smoking was associated with excess risk of pancreatic cancer in both men (OR = 1.6, CI = 1.1-2.2) and women (OR = 1.4, CI = 0.9-2.4). ORs increased significantly with number of cigarettes smoked per day, and with duration and pack-years of smoking. Risk increased three- to sixfold among those in the highest categories of cigarette consumption, while risk decreased with increasing years since smoking cessation. Former smokers who stopped smoking for 10 or more years had risks comparable to nonsmokers.

Adult↗