The Geographic Distribution of Liver Cancer in Canada Does Not Associate with Cyanobacterial Toxin Exposure.

BACKGROUND: The incidence of liver cancer has been increasing in Canada over the past decade, as has cyanobacterial contamination of Canadian freshwater lakes and drinking water sources. Cyanotoxins released by cyanobacteria have been implicated in the pathogenesis of liver cancer. OBJECTIVE: To determine whether a geographic association exists between liver cancer and surrogate markers of cyanobacterial contamination of freshwater lakes in Canada. METHODS: A negative binomial regression model was employed based on previously identified risk factors for liver cancer. RESULTS: No association existed between the geographic distribution of liver cancer and surrogate markers of cyanobacterial contamination. As predicted, significant associations existed in areas with a high prevalence of hepatitis B virus infection, large immigrant populations and urban residences. DISCUSSION AND CONCLUSIONS: The results of this study suggest that cyanobacterial contamination of freshwater lakes does not play an important role in the increasing incidence of liver cancer in Canada.

Effects of household socialization on youth susceptibility to smoke: differences between youth age groups and trends over time.

A Canadian biennial youth survey facilitated repeating investigation of susceptibility to smoke and household socialization. We operationalized susceptibility to smoke by 3 levels on the basis of intention and behavior. Variables consistently predicting greater susceptibility across time and age groups were sibling smoking, household restrictions, and vehicle smoke exposure. Gender was predictive among older youths. Household restrictions and emerging legislation to ban smoking in vehicles with youth passengers provide protection against secondhand smoke exposure and sustained resolve to remain smoke-free.

Differential role of estrogen receptor beta in early versus metastatic non-small cell lung cancer.

Although women have an increased susceptibility to lung cancer, they also have a favorable clinical outcome. This may in part be due to female specific genetic and hormonal factors. In the present study, expression of ER-beta was investigated by immunohistochemistry using tissue samples from two cohorts: non-small cell lung cancer (NSCLC) diagnosed in 1999 in Manitoba and advanced NSCLC patients from the NCIC-CTG BR.18 trial. In the Manitoba cohort assessable tissue samples available in 79 patients (32 females and 47 males) and the majority (75%) had early stage disease. Fifty-one percent of patients expressed high levels of ER-beta (defined by ≥60, the median immunohistochemistry score) and its expression was comparable in males and females. The 3-year overall survival of the group was 53% and males had significantly worse survival compared to females (HR=2.37, 95%CI 1.15­4.91, P=0.02). Higher ER-beta 1 expression was associated with better survival in both univariate (HR=0.41, 95%CI 0.21­0.80, P=0.009) and in multivariate (HR=0.37, 95%CI 0.18­0.77, P=0.008) analysis. In the NCIC-CTG cohort that were more often later stage, assessable tissue samples from 48 cases were available however higher ER beta 1 expression correlated with poorer survival (HR= 1.94, 95%CI 1.01­3.75 P=0.047). These results suggest a differential impact of ER-beta 1 expression on clinical outcome by disease stage, that needs to be explored further and may explain contradictory observations reported in the literature.