Identification of occupational cancer risks in British Columbia. Part I: Methodology, descriptive results, and analysis of cancer risks, by cigarette smoking categories of 15,463 incident cancer cases.

To identify occupational cancer risk factors, lifetime occupational, smoking, and alcohol-consumption histories were collected by means of a self-administered questionnaire from 15,463 male cancer patients aged 20 years and over as ascertained from the British Columbia population-based cancer registry; all cases were histologically confirmed. The study methodology, descriptive results, and cancer risks from cigarette smoking are reported. Assessment of questionnaire validation and reliability showed very high correlations between all variables analysed. Non-response bias, assessed among 221 non-responders and 432 matched controls, revealed no statistically significant differences for smoking status, education, or for 11 usual (longest-held job) occupational groups, except for managerial occupations and for four pooled groups that represented 6.7% of all occupations. Except for pancreatic cancer, a significant relationship was found for all cancer sites known to be strongly associated with cigarette smoking.

Identification of occupational cancer risks in British Columbia. Part II: A population-based case-control study of 1516 Prostatic cancer cases.

We have, as part of a program aimed at detecting occupational risk factors in British Columbia, collected lifetime occupational histories from 15,643 incident cancer cases, of whom 1519 had a diagnosis of prostate cancer. Occupational risks for this cancer site are examined using this large data set, and the results are presented in this report.

Basal cell carcinoma of the periocular region.

BACKGROUND: Basal cell carcinomas of the periocular area present a particular challenge because of the likelihood of damage to vital structures. OBJECTIVE: More than 10-years experience of treating basal cell carcinomas by Mohs micrographic surgery was reviewed. METHODS: Chart analysis of 233 periocular basal cell carcinomas was performed. All patients were contacted either in clinical follow-up or by telephone review. RESULTS: Two hundred and thirty-three periocular basal cell carcinomas were analyzed out of a total of 3, 192 basal cell carcinomas treated during this period (7.3%). Patients ranged in age from 17 to 102 years with a mean age of 58.8 years and a median of 59.0 years. Of the patients, 54.5% were female. Mohs micrographic surgery was the prime therapy in 177 patients (75. 9%). Of the lesions, 48.5% occurred in the medial canthal area, 35. 2% on the lower eyelid, 10.7% on the upper eyelid, and 5.6% on the lateral canthus. There was no significant difference between the left/right distribution in males and females. The average follow-up time was 34 months (standard deviation 26.38 months). A cumulative rate of no recurrence tabulated by modified life table analysis was 0.9864. CONCLUSION: This study further documents the problems associated with basal cell carcinoma of the periocular area as well as the value of Mohs micrographic surgery as treatment.

Cohort mortality study of pulp and paper mill workers in British Columbia, Canada.

The authors studied a cohort of 30,157 male pulp and paper workers in British Columbia, Canada. Of these, 20,373 worked in kraft mills only, 5,249 in sulfite mills only, and 4,535 in both kraft and sulfite mills. All workers with at least 1 year of employment on January 1, 1950, or thereafter until December 31, 1992, were studied. Standardized mortality ratios (SMRs) were used to compare the mortality rates of the cohort with those of the Canadian male population. Ninety percent confidence intervals (CIs) for the SMRs were obtained. Cancer risks significantly associated with work duration and time from first employment of 15 years or more were observed: 1) total cohort: pleura (SMR = 3.61, 90% CI 1.42-7.58); kidney (SMR = 1.69, 90% CI 1.13-2.43); brain (SMR = 1.51, 90% CI 1.03-2.16); 2) workers in kraft mills only: kidney (SMR = 1.92, 90% CI 1.04-3.26); 3) workers in sulfite mills only: Hodgkin's disease (SMR = 4.79, 90% CI 1.29-12.37); 4) workers ever employed in both kraft and sulfite mills: esophagus (SMR = 1.91, 90% CI 1.00-3.33). These malignancies have been associated with the following known or suspected carcinogens to which pulp and paper workers may have been exposed: asbestos (pleura), biocides (kidney), formaldehyde (kidney, brain, Hodgkin's disease), hypochlorite (esophagus). A nested case-control study with detailed exposure assessment is under way to help determine whether excess risks for specific cancers reflect exposure among subsets of workers.

Seven fractions of twice daily high dose-rate brachytherapy for node-negative carcinoma of the mobile tongue results in loss of therapeutic ratio.

From June 1989 to December 1993, a Phase I/II protocol using high dose-rate (HDR) interstitial brachytherapy for early stage node-negative squamous cell carcinoma of the mobile tongue was undertaken to assess the toxicity and efficacy of this modality. A total of 27 patients were treated: T1-10 patients, T2-15 patients, and T3-two patients. Seven fractions x 6.5 Gy of HDR brachytherapy were given on a twice daily schedule, with a minimum interval time of 6 h, over a period of 3.5 days. The actuarial tumor control probability after HDR brachytherapy was 53% at 5 years. Local control rates for the T1 and T2 tumors were lower than comparable historical controls treated at our institution using low dose-rate (LDR) radium or cesium needle implants and iridium wire implants. This is despite the fact that the HDR schedule was calculated by the linear quadratic formula to have equal tumor killing effects as 60 Gy in 6 days of LDR radiation. In addition, there was a trend towards higher incidence of severe complications for the HDR patients compared to historical controls treated with LDR. We would caution against the use of this schedule of HDR brachytherapy until further studies are done.

Sunlight exposure, pigmentary factors, and risk of nonmelanocytic skin cancer. I. Basal cell carcinoma.

BACKGROUND AND DESIGN: Basal cell carcinoma (BCC) of the skin is the most common neoplasm in white populations, and solar radiation is generally accepted to be the dominant environmental risk factor for this disease. However, little information is available on the nature of the relationship between BCC and sunlight. The purpose of this study was to evaluate the nature of the relationship between sunlight exposure, pigmentary factors, and BCC of the skin. A population-based case-control study of 226 male patients with BCC diagnosed from January 1, 1983, through December 31, 1984, and 406 randomly selected male control subjects was conducted in Alberta, Canada. The study was conducted using a standardized questionnaire, administered in person by trained interviewers. Data were analyzed using conditional logistic regression methods. RESULTS: After controlling for other host and pigmentary factors, the risk of BCC was increased in subjects with light skin color and those who freckled in childhood. A history of severe sunburn in childhood also increased risk. Subjects of southern European ethnic origin were at significantly lower risk of BCC. Surprisingly, no association was seen between mean annual cumulative summer sunlight exposure and risk of BCC. A significantly increased risk of BCC was seen in subjects with increased recreational sunlight exposure in adolescence and childhood (age, 0 to 19 years), although an inverse relationship was seen with lifetime recreation exposure. The relationship with childhood sun exposure was most pronounced among sun-sensitive subjects whose skin tended to burn rather than tan in the sun. CONCLUSIONS: The lack of association between cumulative sun exposure and BCC contradicts conventional wisdom about the cause of this tumor, and the increased risk with sun exposure at age 0 to 19 years suggests that childhood and adolescence may be critical periods for establishing adult risk for BCC.

Sunlight exposure, pigmentation factors, and risk of nonmelanocytic skin cancer. II. Squamous cell carcinoma.

INTRODUCTION AND DESIGN: Squamous cell carcinoma of the skin (SCC), a common cancer in white populations, is related to sunshine exposure; however, relatively little information is available on how timing and character of exposure affect the relationship. The purpose of this study was to investigate the nature of the relationship of SCC to individual solar UV exposure after control for phenotype and pigmentary factors. All newly diagnosed cases of SCC were in men aged 25 through 79 years, ascertained in the province of Alberta from January 1, 1983, through December 31, 1984, who were approached for participation; 80% completed a standardized etiologic interview that was conducted in their homes by a trained interviewer. Control subjects were chosen at random from the Alberta Health Care Insurance Plan subscribers list, matched only by sex (male) and age (within a 5-year age group). The response rate among controls was 71%. RESULTS: Subjects with pale skin and red hair had an elevated risk of SCC. Subjects whose mother was of southern European ancestry had a reduced risk of SCC. After accounting for pigmentary factors, no association was seen between risk of SCC and cumulative lifetime sun exposure. However, a strong trend toward increasing risk was seen with increasing chronic occupational sun exposure in the 10 years prior to diagnosis. CONCLUSION: The results suggest that recent sun exposure (in the 10 years prior to diagnosis) may be important in accounting for individual risk of SCC.

Mortality among female registered nurses and school teachers in British Columbia.

The mortality profile of female nurses and teachers in British Columbia (BC) was examined using age-standardized proportional mortality ratios (PMRs) calculated for the period 1950-1984. Lowered overall mortality among nurses was seen for degenerative heart disease and for cerebrovascular accidents. Significantly elevated PMR values were observed for cancer of the breast and ovary in nurses of age 20-65 years. PMRs were significantly elevated for cancer of the pancreas and leukemia among those age 20 years and older. Elevated values were also observed for motor vehicle accidents and suicide among nurses in both age groups. Lower than expected mortality from degenerative heart disease and cerebrovascular accidents was seen in working age teachers (age 20-65 years). However, elevated PMRs were detected for carcinoma of the colon, breast, endometrium, brain, and melanoma. Among those 20 years and over, significantly elevated PMRs were also observed for cancers of the ovary and other digestive organs. Elevated PMRs were found for motor vehicle and aircraft accidents. Mortality from cirrhosis of the liver was lower than anticipated in both teachers and nurses. A number of significant PMRs declined when deaths of "homemakers" were withdrawn from the comparison group used to generate PMR values, suggesting that risk of death from various causes among women working outside the home differ from those seen in women who are predominantly in the home.

Rate of death from cervical cancer among native Indian women in British Columbia.

OBJECTIVE: To compare the rates of death from cervical cancer among native Indian women and non-native women in British Columbia from 1953 to 1984. DESIGN: Retrospective analysis of data retrieved from the British Columbia Division of Vital Statistics. MAIN OUTCOME MEASURES: Age-standardized death rate and relative rate. RESULTS: The rate of death from cervical cancer was significantly higher among the native women than among the non-native women throughout the study period. No deaths from cervical cancer were recorded in women under 20 years of age. Among those 20 to 64 the relative rate increased from 3.83 in 1953-62 to 6.53 in 1973-84; among those 65 or more it decreased slightly. For the entire study period the relative rate for women 20 to 64 years old was 5.95 and for those 65 or older 2.98. CONCLUSION: The rate of death from cervical cancer among native women in British Columbia is unacceptably high, probably because the provincial screening program does not reach as many native women as it does non-native women.

Mortality patterns in female domestic workers.

To investigate mortality patterns for domestic workers, proportional mortality ratios (PMRs) were calculated for the 1,382 female domestic workers who died in British Columbia at age 20 years or over between 1950 and 1984. This group experienced fewer deaths than expected from cerebrovascular accidents (PMR = 84) and hypertension (PMR = 39). The proportion of deaths from cirrhosis was higher than expected (PMR = 152). An excess of observed deaths was also noted for all accidents (PMR = 126), accidents due to environmental factors (PMR = 439), and homicide (PMR = 235). Mortality from pneumonia was elevated for domestic workers aged 20 to 65 (PMR = 180). Further studies using more sophisticated epidemiologic methods are necessary to evaluate whether these deaths are a result of occupational exposures or of poor socioeconomic conditions.

Carcinoid tumour of the gastrointestinal tract: prognostic factors and disease outcome.

This study represents retrospective analysis of 87 patients with a carcinoid tumour of the gastrointestinal tract seen and followed in the British Columbia Cancer Agency (BCCA) from 1960 to 1986. In 49 cases, the primary site was the small bowel. The rest of the cases were distributed as follows: 11 appendix, 10 rectum, 5 stomach, and 7 undetermined. We extrapolated the Dukes' and modified Astler-Coller surgicopathological classifications used for colorectal cancer for use in our cases of carcinoid tumour of the gastrointestinal tract. A strong correlation was found, using this staging, with disease-specific survival. Other prognostic factors included histologic differentiation, the presence of macroscopic residual disease after initial surgery, and level of 5-hydroxyindoleacetic acid (5-HIAA) in urine. Among 51 patients with surgically grossly removed disease, there was a tendency for the development of distant and distant/locoregional recurrence more often than locoregional recurrence alone. The liver was the commonest site of distant recurrence. Analysis of the effect of radiotherapy or chemotherapy on carcinoid tumour of the gastrointestinal tract proved unsuccessful because only a small portion of the patients had this treatment, and it was used mainly for palliation.

Mortality among British Columbia pilots.

We studied the mortality experience of all pilots who died in the province of British Columbia between 1950 and 1984, using proportional mortality ratios (PMR) and proportional cancer mortality ratios (PCMR). There were 341 deaths during that time in males whose usual occupation was listed as pilot. The PMR for aircraft accidents was significantly elevated (PMR = 3196, 95% C.I. 2810, 3634), and the PMR for atherosclerotic heart disease was significantly depressed (PMR = 47, 95% C.I. 30, 70). Although based on small numbers of deaths, and not statistically significant, elevated PCMRs were seen for cancers of the colon, brain, and nervous system, as well as for Hodgkin's disease. These findings suggest the need for further epidemiologic studies of commercial airline pilots.

Occupational associations among British Columbia male cancer patients.

In a study of 6,389 male cancer patients diagnosed and treated at the Cancer Control Agency of British Columbia from 1950-1975, several associations were detected between occupation and specific cancers. Elevated risks for lung cancer were seen in miners, metal processors and machinists, while a reduced risk was seen in farmers. Lip cancer excesses were detected in individuals involved in several outdoor occupations, and melanoma excesses were seen for three groups of predominantly indoor workers. These results confirm previous findings in the literature, whereas the following associations have not been previously reported. Fishermen were found to have an excess of Hodgkin's Disease (RR = 3.0, 95% C.I. = 1.4,6.5), engineers are at an elevated risk of cancer of the pancreas (RR = 4.2, C.I. = 1.8,9.9), and forestry workers have an elevated risk of bladder cancer (RR = 1.7, C.I. = 1.1,2.6). Further studies will be needed to replicate the new associations detected here.

Identification of occupational cancer risks using a population-based cancer registry.

The study of Xuan Wei fuel use and lung cancer mortality and also the interim case-control study suggested an association between domestic smoky coal use and Xuan Wei lung cancer. The collaborative studies of physical characterization, chemical analysis, and toxicology further substantiated this linkage. The Xuan Wei residents who used smoky coal inhaled extremely high concentrations of mostly submicron-sized particles, which can be inhaled and deposited effectively deep in the lung. These fine particles were composed mostly of organic compounds (72%), including mutagenic and carcinogenic organic compounds, especially in the aromatic and polar fractions. These residents were exposed to polycyclic aromatic compounds, such as benzo[a]pyrene, at comparable or higher levels than those measured in coke oven plants and other occupational environments (International Agency for Research on Cancer 1984). In comparison with wood and smokeless coal combustion emissions, the organic extracts of smoky coal emission particles showed much higher activity of genotoxicity and carcinogenicity. These results all point to a strong etiological link between the complex organic mixtures from smoky coal emissions and Xuan Wei lung cancer. This study and studies reported by other investigators (de Koning et al. 1984) suggested little association between indoor open-fire wood smoke and lung cancer. The less efficient lung deposition of the larger particles from wood combustion, as well as the lower concentrations of biologically active organic compounds, may contribute to the low rate of lung cancer in the wood-burning communes. As to the smokeless coal emissions, the lower particulate concentration and the lower organic content of the particles emitted may also contribute to the low lung cancer rate in the commune using this fuel. In conclusion, the complex organic mixtures from combustion emissions are genotoxic and carcinogenic in animal and in vitro assays. The magnitude of the cancer risks from the complex organic mixtures in man depends on the degree of the exposure, the types of the compounds contained in the mixtures, and the concentrations of these biologically active compounds present in the combustion emissions.

Pathologic prognostic factors for cutaneous malignant melanoma: the Western Canada Melanoma Study.

An analysis of data for histopathologic factors influencing survival was conducted on 798 cases of invasive cutaneous malignant melanoma. On univariate analysis, a number of factors influenced survival; however, when these factors were examined using a proportional-hazards model, sex and log of depth of penetration were the only factors governing survival. Moreover, these factors were only important in patients with lesions up to 4 mm in depth with no evidence of other disease. For patients with solitary lesions deeper than 4 mm, or patients with regional or distant disease, none of the factors examined in our study was of predictive value for survival assessment.

Symptoms and time to presentation and treatment in ocular melanoma: the Western Canada Melanoma Study.

Reports on all ocular melanomas newly diagnosed between Apr. 1, 1979, and Mar. 31, 1981, were obtained from the cancer registries of British Columbia, Alberta, Saskatchewan and Manitoba. Of the 90 cases, 87 were in patients aged 20 to 79 years, 64 of whom were interviewed about their initial symptoms. Three symptoms--loss of part of the visual field (in 33% of patients), photopsia (in 20%) and blurred vision (in 20%)--emerged as the main indicators of disease. In 17% of cases the tumour was discovered as an incidental finding on ocular examination. The length of delay before consulting a physician was generally short in symptomatic patients, with 85% reporting that they saw a physician within 3 months of onset of the first symptom. Of the 30 patients who received definitive treatment 4 months or more after initial presentation, 13 were seen by general practitioners who delayed before referring the patient to an ophthalmologist. Continuing medical education is needed to ensure earlier referral to ophthalmologists by general practitioners of patients with ocular melanoma.