Anne-Marie Ugnat

Occupational risk factors for brain cancer in Canada

Objective: We sought to examine the impact of occupational exposure on brain cancer risk. Methods: Mailed questionnaires were used to collect information on lifetime employment history, occupational exposure to 18 chemicals, and other risk factors for 1009 incident cases of brain cancer and 5039 control subjects in Canada in 1994 to 1997. Results: People exposed to asphalt and welding had respective odds ratio (and 95% confidence interval) of 1.29 (1.02–1.62) and 1.26 (0.98–1.45). An increased risk of brain cancer might be associated with exposure to asbestos, benzene, mineral or lubricating oil, isopropyl oil, and wood dust and with following occupations: teaching; protective service; metal processing and related jobs, and metal shaping and forming; knitting in textile processing; construction trades; and transport equipment operating. Conclusions: Our study suggests a possible role for occupational exposure in the etiology of brain cancer.

Association of cigarette smoking with the risk of ovarian cancer

Cigarette smoking may be associated with ovarian cancer risk. This association may differ by histological type. The authors conducted a population‐based case‐control study in Canada of 442 incident cases of ovarian cancer and 2,135 controls 20–76 years of age during 1994–1997 to examine this association, overall and by histological type. Compared to women who never smoked, those who smoked had higher odds (odds ratio [OR] = 1.22; 95% confidence interval [CI] = 0.98–1.53) of having ovarian cancer, and the OR was larger for ex‐smokers (1.30; 95% CI = 1.01–1.67) than for current smokers (1.10; 95% CI = 0.81–1.49). The association with cigarette smoking was stronger for mucinous tumors (OR = 1.77; 95% CI = 1.06–2.96) than for nonmucinous tumors (OR = 1.13; 95% CI = 0.89–1.44). In addition, the odds of smokers having mucinous tumors increased with years of smoking (OR = 1.36, 1.88, 1.19, 4.89 for <20, 21–30, 31–40 and >40 years, respectively; p for trend = 0.002), number of cigarettes smoked per day (OR = 1.55, 1.89, 2.28 for <10, 11–20 and >20 cigarettes/day, respectively; p for trend = 0.014) and smoking pack‐years (OR = 1.13, 2.65, 1.77 and 2.39 for <10, 11–20, 21–30 and >30 pack‐years, respectively; p for trend = 0.004). Our data suggest that cigarette smoking is associated with an increased risk of ovarian cancer, especially for mucinous types.

Cancer Incidence Patterns Among Chinese Immigrant Populations in Alberta

This study examines the incidence of cancer among Chinese immigrants to Alberta in comparison to the incidence in Canadian-born Alberta residents and in people of Chinese origin still living in China. Cancer cases among Chinese immigrants and Canadian-born Alberta residents were identified from the Alberta Cancer Registry (1974–1993). Incidence rates for Shanghai (1975–1992) were obtained from the International Agency for Research on Cancer (IARC) publications. Direct age-standardized incidence rates (ASIRs) were calculated using the “world standard population.” Descriptive analysis and Poisson regression modelling were employed to obtain the rate ratios for certain cancer sites among the three populations. For males, the overall incidence of cancer (excluding non-melanoma skin cancer) was lowest in Chinese immigrants while being similar in Canadian-born Alberta residents and Chinese living in Shanghai (197 vs. 224 and 232/100,000). For females, the overall incidence in Chinese immigrants was lower than Canadian-born Alberta residents but similar to that in Chinese living in Shanghai (154 vs 200 and 150/100,000). For cancers that are common in China (stomach and esophagus), the incidence rates for Chinese immigrants were more similar to those for Canadian-born residents than to rates for Shanghai. However, the incidence of liver cancer was very high in the immigrants, suggesting the possible presence of an initiating event during childhood or early adulthood. For cancers that are traditionally uncommon in China (breast and prostate), rates for immigrants were mid-way between those of the two comparison groups. This study supports observations that the risk of cancer in immigrants tends towards the risk of people in the new host country.

Histology-related variation in the treatment and survival of patients with lung carcinoma in Canada

OBJECTIVES The aim of the study was to examine histologic differences in lung cancer treatment and survival, and to define recent survival trends in Ottawa, Canada. METHODS From 1994 to 2000, 3,237 patients with invasive lung cancer were registered at the Ottawa Regional Cancer Centre (ORCC) and were followed up to 31 December 2001. Five-year relative survival rates (RSRs) and relative excess risks (RERs) of dying were calculated by stage and dominant initial treatment modalities for major cellular histologies using a relative survival model. RESULTS The overall 5-year survival rate was 14%, and female patients had significantly better survival. Patients with stage I and II non-small cell lung cancer (NSCLC) who were treated by surgery alone were more likely to survive (5-year RSRs were 72 and 48%, respectively) than those who received other treatments. Patients with stage III NSCLC had a 5-year survival rate of 9% after chemotherapy plus radiotherapy, whereas stage IV patients who received only chemotherapy had better survival for up to 2 years than patients with other treatments. In cases of limited-stage small cell lung cancer (SCLC), survival was better for patients who received chemotherapy plus radiotherapy than for those who received only chemotherapy. CONCLUSIONS The relatively superior survival of surgical patients with stage I NSCLC implies that a considerable number of patients have the potential to be treated successfully. The overall poor survival of lung cancer patients suggests a need for more national public health emphasis on lung cancer prevention, improved screening and early diagnosis, and better treatment.

Survival Patterns for the Top Four Cancers in Canada: The Effects of Age, Region and Period

This study examined the variations in survival rates (1989–1991) and the trends (1969–1991), by sex, age and province, for patients diagnosed with breast, colorectal, lung or prostate cancer in Canada and compared the Canadian rates with those of nine American SEER registries. Five-year age-standardized relative survival rates (ASRs) were calculated, and the trends were estimated from variance-weighted linear regression of the ASRs for five periods of diagnosis (1969–1973, 1974–1978, 1979–1983, 1984–1988 and 1989–1991). In 1989–1991, the ASR varied among provinces for each cancer except female colorectal cancer. The lowest survival rates were observed in the youngest patients (15–44) for breast and prostate cancers, and in the oldest patients (75–99) of both sexes for lung and colorectal cancers. Over the five periods, a major trend toward improved survival was observed for breast, prostate and colorectal cancers (P<0.008), whereas no changes were seen for lung cancer. The ASRs in the western region were higher than in the Atlantic region over time (P<0.02) for each cancer. From the third period onward, the ASRs for Canadian patients with lung cancer were similar to those for the US patients and lower than for Canadian patients with breast, prostate or colorectal cancer. The observed increases in ASR for breast and prostate cancer are likely due to the increased use of screenings and the improved treatment modalities.