Trends in colorectal cancer mortality by ethnicity and socio-economic position in New Zealand, 1981-99: one country, many stories.
ABSTRACT Ethnicity and socio-economic position are important determinants of colorectal cancer (CRC) mortality. In this paper, we determine trends in colorectal cancer mortality by ethnicity and socio-economic position in New Zealand.
Cohort studies of the entire New Zealand population for 1981-84, 1986-89, 1991-94 and 1996-99 (linking Census and mortality datasets) allowed direct determination of trends in CRC mortality by income and education. For ethnicity, we used routine unlinked Census and mortality data, but with correction factors applied for undercounting of Mâori and Pacific deaths.
ETHNICITY: CRC mortality trends varied markedly. There were small (10-20%) decreases among non-Mâori non-Pacific people, a 50% increase among Mâori, and up to 10-fold increase among Pacific people. By 1996-99, all three ethnic groups had similar CRC mortality. SOCIO-ECONOMIC POSITION: For females, differences in CRC mortality by education and income increased over time e.g. poor females had a 40% higher CRC mortality than rich females in 1996-99, compared with no difference in 1981-84 (p for trend 0.04). In men, increases in inequality were seen by income but not education.
The observed ethnic trends probably reflect differential trends in exposure to etiological risk factors. Social inequalities in colorectal cancer mortality appear to be increasing.
Article: Survival disparities in Indigenous and non-Indigenous New Zealanders with colon cancer: the role of patient comorbidity, treatment and health service factors.[show abstract] [hide abstract]
ABSTRACT: Ethnic disparities in cancer survival have been documented in many populations and cancer types. The causes of these inequalities are not well understood but may include disease and patient characteristics, treatment differences and health service factors. Survival was compared in a cohort of Maori (Indigenous) and non-Maori New Zealanders with colon cancer, and the contribution of demographics, disease characteristics, patient comorbidity, treatment and healthcare factors to survival disparities was assessed. Maori patients diagnosed as having colon cancer between 1996 and 2003 were identified from the New Zealand Cancer Registry and compared with a randomly selected sample of non-Maori patients. Clinical and outcome data were obtained from medical records, pathology reports and the national mortality database. Cancer-specific survival was examined using Kaplan-Meier survival curves and Cox hazards modelling with multivariable adjustment. 301 Maori and 328 non-Maori patients with colon cancer were compared. Maori had a significantly poorer cancer survival than non-Maori (hazard ratio (HR)=1.33, 95% CI 1.03 to 1.71) that was not explained by demographic or disease characteristics. The most important factors contributing to poorer survival in Maori were patient comorbidity and markers of healthcare access, each of which accounted for around a third of the survival disparity. The final model accounted for almost all the survival disparity between Maori and non-Maori patients (HR=1.07, 95% CI 0.77 to 1.47). Higher patient comorbidity and poorer access and quality of cancer care are both important explanations for worse survival in Maori compared with non-Maori New Zealanders with colon cancer.Journal of epidemiology and community health 02/2010; 64(2):117-23. · 3.04 Impact Factor
Article: The burden of cancer risk in Canada's indigenous population: a comparative study of known risks in a Canadian region.[show abstract] [hide abstract]
ABSTRACT: Canadian First Nations, the largest of the Aboriginal groups in Canada, have had lower cancer incidence and mortality rates than non-Aboriginal populations in the past. This pattern is changing with increased life expectancy, a growing population, and a poor social environment that influences risk behaviors, metabolic conditions, and disparities in screening uptake. These factors alone do not fully explain differences in cancer risk between populations, as genetic susceptibility and environmental factors also have significant influence. However, genetics and environment are difficult to modify. This study compared modifiable behavioral risk factors and metabolic-associated conditions for men and women, and cancer screening practices of women, between First Nations living on-reserve and a non-First Nations Manitoba rural population (Canada). The study used data from the Canadian Community Health Survey and the Manitoba First Nations Regional Longitudinal Health Survey to examine smoking, binge drinking, metabolic conditions, physical activity, fruit/vegetable consumption, and cancer-screening practices. First Nations on-reserve had significantly higher rates of smoking (P < 0.001), binge drinking (P < 0.001), obesity (P < 0.001) and diabetes (P < 0.001), and less leisure-time physical activity (P = 0.029), and consumption of fruits and vegetables (P < 0.001). Sex differences were also apparent. In addition, First Nations women reported significantly less uptake of mammography screening (P < 0.001) but similar rates for cervical cancer screening. Based on the findings of this retrospective study, the future cancer burden is expected to be high in the First Nations on-reserve population. Interventions, utilizing existing and new health and social authorities, and long-term institutional partnerships, are required to combat cancer risk disparities, while governments address economic disparities.International Journal of General Medicine 01/2011; 4:699-709.
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ABSTRACT: Incidence rates of colorectal cancer (CRC) in New Zealand rank among the highest worldwide. Internationally, there has been evidence of a shift in colon cancer from left- to right-sided. The objective of this study was to determine trends in left- and right-sided colon and rectal cancers incidence by sex, age and ethnicity. Using datasets created by linking data from the New Zealand Cancer Registry to the census data, we analysed a total of 47,694 CRCs from 1981 to 2004. Cancers were divided into right-sided colon (cecum to the splenic flexure); left-sided colon (descending and sigmoid colon); and rectal (rectosigmoid junction and rectum). Left- and right-sided colon, and rectal cancer incidence rates increased by 13-20% among men. In women, colon cancer rates increased by 25% for right-sided cancers, decreased by 8% for left-sided cancers and remained unchanged for rectal cancers. This corresponds with an increase in right-sided cancers from 57% to 65% of total colon cancers in women. The incidence of all CRCs increased at a faster rate among Māori than non-Māori. We identified a left- to right-sided shift in colon cancer limited to women over the age of 65. While Māori trends in site distribution parallel those of their non-Māori counterparts, the rapid increase in Māori incidence rates is noteworthy. It is unclear why such shifts in CRC site distribution are occurring.ANZ Journal of Surgery 04/2012; 82(4):258-64. · 1.25 Impact Factor