Fiona McKenzie

Cancer disparities in indigenous Polynesian populations: Māori, Native Hawaiians, and Pacific people

Polynesia consists of several islands that are scattered across a vast triangle in the Pacific, and include New Zealand, Hawaii, and the Pacific islands. There are reported differences in the types of cancer and epidemiologies seen among communities in these islands, the reasons for which are diverse and complex. In this Review, we describe patterns of cancer incidence, mortality, and survival in indigenous populations compared with populations of European origin in Polynesia, and highlight the limited available data for Pacific populations. Additionally, we document the current knowledge of the underlying biology of cancers in these populations, and report risk factors that differ between ethnicities, including smoking, viral infections, and obesity. Disparities in measures of health are highlighted, as are evident differences in knowledge of tumour biology and cancer management between majority and minority populations.

Do lifestyle or social factors explain ethnic/racial inequalities in breast cancer survival?

Despite numerous studies documenting ethnic inequalities in breast cancer survival between minority and majority ethnic groups worldwide, reasons for these inequalities remain unclear. The authors performed a systematic review of published literature to identify studies that investigated the explanatory power of smoking, alcohol consumption, body mass index (BMI), and socioeconomic position (SEP) on ethnic inequalities in breast cancer survival. Sixteen studies were included in the review. From 5 studies, the authors found that differences in breast cancer survival between ethnic groups may be in part explained by BMI, but there was little evidence to implicate smoking or alcohol consumption as explanatory factors of this inequality. From 12 studies, the authors found that SEP explains part of the ethnic inequality in all-cause survival but that it was not evident for breast-cancer-specific survival. SEP explains more of the disparities among African-American versus white women in the United States compared with other ethnic comparisons. Furthermore, given social patterning of BMI and other lifestyle habits, it is possible that results for SEP and BMI are measuring the same effect. In this review, the authors make suggestions regarding the role of epidemiology in facilitating further research to better inform the development of effective policies to address ethnic differences in survival.

Healthy lifestyle and risk of breast cancer among postmenopausal women in the European Prospective Investigation into Cancer and Nutrition cohort study.

Breast cancer is the most common cancer among women and prevention strategies are needed to reduce incidence worldwide. A healthy lifestyle index score (HLIS) was generated to investigate the joint effect of modifiable lifestyle factors on postmenopausal breast cancer risk. The study included 242,918 postmenopausal women from the multinational European Prospective Investigation into Cancer and Nutrition (EPIC) cohort, with detailed information on diet and lifestyle assessed at baseline. The HLIS was constructed from five factors (diet, physical activity, smoking, alcohol consumption and anthropometry) by assigning scores of 0–4 to categories of each component, for which higher values indicate healthier behaviours. Hazard ratios (HR) were estimated by Cox proportional regression models. During 10.9 years of median follow‐up, 7,756 incident breast cancer cases were identified. There was a 3% lower risk of breast cancer per point increase of the HLIS. Breast cancer risk was inversely associated with a high HLIS when fourth versus second (reference) categories were compared [adjusted HRu2009=u20090.74; 95% confidence interval (CI): 0.66–0.83]. The fourth versus the second category of the HLIS was associated with a lower risk for hormone receptor double positive (adjusted HRu2009=u20090.81, 95% CI: 0.67–0.98) and hormone receptor double negative breast cancer (adjusted HRu2009=u20090.60, 95% CI: 0.40–0.90). Findings suggest having a high score on an index of combined healthy behaviours reduces the risk of developing breast cancer among postmenopausal women. Programmes which engage women in long term health behaviours should be supported.

Case-control study of high risk occupations for bladder cancer in New Zealand

We conducted a nationwide case‐control study of bladder cancer in adult New Zealanders to identify occupations that may contribute to the risk of bladder cancer in the New Zealand population. A total of 213 incident cases of bladder cancer (age 25–70 years) notified to the New Zealand Cancer Registry during 2003 and 2004, and 471 population controls, were interviewed face‐to‐face. The questionnaire collected demographic information and a full occupational history. The relative risks for bladder cancer associated with ever being employed in particular occupations and industries were calculated by unconditional logistic regression adjusting for age, sex, smoking and socio‐economic status. Estimates were subsequently semi‐Bayes adjusted to account for the large number of occupations and industries being considered. An elevated bladder cancer risk was observed for hairdressers (odds ratio (OR) 9.15 95% Confidence Interval (95%CI) 1.60–62.22), and sewing machinists (OR 3.07 95%CI 1.35–6.96). Significantly increased risks were not observed for several other occupations that have been reported in previous studies, including sales assistants (OR 1.03 95%CI 0.64–1.67), painters and paperhangers (OR 1.42 95%CI 0.56–3.60), sheet metal workers (OR 0.39, 95%CI 0.15–1.00), printing trades workers (OR 1.11 95%CI 0.41–3.05) and truck drivers (OR 1.36 95%CI 0.60–3.09), although the elevated odds ratios for painters, printers and truck drivers are consistent with excesses observed in other studies. Nonsignificantly increased risks were observed for tailors and dressmakers (OR 2.84 95%CI 0.62–13.05), rubber and plastics products machine operators (OR 2.82 95%CI 0.75–10.67), building workers (OR 2.15, 95%CI 0.68–6.73), and female market farmers and crop growers (OR 2.05 95%CI 0.72–5.83). In conclusion, this study has confirmed that hairdressers and sewing machinists are high risk occupations for bladder cancer in New Zealand, and has identified several other occupations and industries of high bladder cancer risk that merit further study.

High risk occupations for non-Hodgkin’s lymphoma in New Zealand: case–control study

Objectives: Previous studies into occupational risk factors for non-Hodgkin’s lymphoma (NHL) in New Zealand have indicated that farmers and meat workers are at increased risk for these neoplasms. A new nationwide case–control study was conducted to assess whether previously observed associations persist and to identify other occupations that may contribute to the risk of NHL in the New Zealand population. Methods: A total of 291 incident cases of NHL (age 25–70 years) notified to the New Zealand Cancer Registry during 2003 and 2004, and 471 population controls, were interviewed face-to-face. The questionnaire collected demographic information and a full occupational history. The relative risk for NHL associated with ever being employed in particular occupations and industries was calculated by unconditional logistic regression adjusting for age, sex, smoking, ethnicity and socioeconomic status. Estimates were subsequently semi-Bayes adjusted to account for the large number of occupations and industries being considered. Results: An elevated NHL risk was observed for field crop and vegetable growers (OR 2.74, 95% CI 1.04 to 7.25) and horticulture and fruit growing (OR 2.28, 95% CI 1.37 to 3.79), particularly for women (OR 3.44, 95% CI 0.62 to 18.9; OR 3.15, 95% CI 1.50 to 6.61). Sheep and dairy farming was not associated with an increased risk of NHL. Meat processors had an elevated risk (OR 1.97, 95% CI 0.97 to 3.97), as did heavy truck drivers (OR 1.98, 95% CI 0.92 to 4.24), workers employed in metal product manufacturing (OR 1.92, 95% CI 1.12 to 3.28) and cleaners (OR 2.11, 95% CI 1.21 to 3.65). After semi-Bayes adjustment the elevated risks for horticulture and fruit growing, metal product manufacturing and cleaners remained statistically significant, representing the most robust findings of this study. Conclusions: This study has confirmed that crop farmers and meat workers remain high risk occupations for NHL in New Zealand, and has identified several other occupations and industries of high NHL risk that merit further study.

Lung cancer and occupation: A new zealand cancer registry‐based case–control study

BACKGROUNDnThere are many proven and suspected occupational causes of lung cancer, which will become relatively more important over time, as smoking prevalence decreases.nnnMETHODSnWe interviewed 457 cases aged 20-75 years notified to the New Zealand Cancer Registry during 2007-2008, and 792 population controls. We collected information on demographic details, potential confounders, and employment history. Associations were estimated using logistic regression adjusted for gender, age, ethnicity, smoking, and socio-economic status.nnnRESULTSnAmong occupations of a priori interest, elevated odds ratios (ORs) were observed for sawmill, wood panel and related wood-processing plant operators (OR 4.63; 95% CI 1.05-20.29), butchers (OR 8.77, 95% CI 1.06-72.55), rubber and plastics products machine operators (4.27; 1.16-15.66), heavy truck drivers (2.24; 1.19-4.21) and workers in petroleum, coal, chemical and associated product manufacturing (1.80; 1.11-2.90); non-significantly elevated risks were also observed for loggers (4.67; 0.81-27.03), welders and flame-cutters (2.50; 0.86-7.25), pressers (5.74; 0.96-34.42), and electric and electronic equipment assemblers (3.61; 0.96-13.57). Several occupations and industries not of a priori interest also showed increased risks, including nursing associate professionals (5.45; 2.29-12.99), enrolled nurses (7.95; 3.10-20.42), care givers (3.47; 1.40-8.59), plant and machine operators and assemblers (1.61; 1.20-2.16), stationary machine operators and assemblers (1.67; 1.22-2.28), food and related products processing machine operators (1.98; 1.23-3.19), laborers and related elementary service workers (1.45; 1.05-2.00), manufacturing (1.34; 1.02-1.77), car retailing (3.08; 1.36-6.94), and road freight transport (3.02; 1.45-6.27).nnnCONCLUSIONSnCertain occupations and industries have increased lung cancer risks in New Zealand, including wood workers, metal workers, meat workers, textile workers and drivers. Am. J. Ind. Med. 54:89-101, 2011.

Leukaemia and occupation: a New Zealand Cancer Registry-based case–control Study

BACKGROUNDnTo examine the association between occupation and leukaemia.nnnMETHODSnWe interviewed 225 cases (aged 20-75 years) notified to the New Zealand Cancer Registry during 2003-04, and 471 controls randomly selected from the Electoral Roll collecting demographic details, information on potential confounders and a comprehensive employment history. Associations between occupation and leukaemia were analysed using logistic regression adjusted for gender, age, ethnicity and smoking.nnnRESULTSnElevated odds ratios (ORs) were observed in agricultural sectors including horticulture/fruit growing (OR: 2.62, 95% confidence interval (CI): 1.51, 4.55), plant nurseries (OR: 7.51, 95% CI: 1.85, 30.38) and vegetable growing (OR: 3.14, 95% CI: 1.18, 8.40); and appeared greater in women (ORs: 4.71, 7.75 and 7.98, respectively). Elevated ORs were also observed in market farmers/crop growers (OR: 1.84, 95% CI: 1.12, 3.02), field crop/vegetable growers (OR: 3.98, 95% CI: 1.46, 10.85), market gardeners (OR: 5.50, 95% CI: 1.59, 19.02), and nursery growers/workers (OR: 4.23, 95% CI: 1.34, 13.35); also greater in women (ORs: 3.48, 7.62, 15.74 and 11.70, respectively). These elevated ORs were predominantly for chronic lymphocytic leukaemia (CLL). Several associations persisted after semi-Bayes adjustment. Elevated ORs were observed in rubber/plastics products machine operators (OR: 3.76, 95% CI: 1.08, 13.08), predominantly in plastic product manufacturing. CLL was also elevated in tailors and dressmakers (OR: 7.01, 95% CI: 1.78, 27.68), cleaners (OR: 2.04, 95% CI: 1.00, 4.14) and builders labourers (OR: 4.03, 95% CI: 1.30, 12.53).nnnCONCLUSIONSnThese findings suggest increased leukaemia risks associated with certain agricultural, manufacturing, construction and service occupations in New Zealand.

Prognostic factors in women with breast cancer: inequalities by ethnicity and socioeconomic position in New Zealand

ObjectiveTo investigate differences in breast cancer prognostic factors between ethnic and socioeconomic groups in New Zealand.MethodsWe analyzed all 21,586 breast cancer cases on the New Zealand Cancer Registry (July 1994–June 2004). Māori, Pacific, and non-Māori/non-Pacific women were categorized according to ethnicity on the Registry. Deprivation was analyzed as quintiles of the New Zealand Deprivation Index 2001, an area-based measure of socioeconomic position. Logistic regression was used to estimate age-adjusted odds ratios (OR) (95% confidence intervals (CI)).ResultsMāori and Pacific women were more likely to have non-local stage, less well differentiated cancer, larger tumors and positive human epidermal growth factor receptor-type 2 (HER-2) status than non-Māori/non-Pacific women. Māori were less likely and Pacific women more likely than non-Māori/non-Pacific women to have negative oestrogen (ER) and progesterone receptor (PR) status. Adjusting for deprivation did not materially alter the results.Women living in more deprived areas had a higher risk of non-local stage and larger tumors. These associations were only partially explained by ethnicity. There was no relationship between tumor grade, ER, PR or HER-2 status and deprivation.ConclusionsOur results confirm that Māori, Pacific and low socioeconomic women present with poor prognosis breast tumors.

Cigarette Smoking and Risk of Breast Cancer in a New Zealand Multi-Ethnic Case-Control Study

Background The association between breast cancer and tobacco smoke is currently unclear. The aim of this study was to assess the effect of smoking behaviours on the risk of breast cancer among three ethnic groups of New Zealand women. Methods A population-based case-control study was conducted including breast cancer cases registered on the New Zealand Cancer Registry between 2005 and 2007. Controls were matched by ethnicity and 5-year age-group. Logistic regression was used to estimate the association between breast cancer and smoking at different time points across the lifecourse, for each ethnic group. Estimated odds ratios (OR) were adjusted for established risk factors. Results The study comprised 1,799 cases (302 Māori, 70 Pacific, 1,427 non-Māori/non-Pacific) and 2,540 controls (746 Māori, 191 Pacific, 1,603 non-Māori/non-Pacific). There was no clear association between smoking and breast cancer for non-Māori/non-Pacific women, although non-Māori/non-Pacific ex-smokers had statistically significant increased risk of breast cancer when smoking duration was 20 years or more, and this remained significant in the fully adjusted model (OR 1.31, 95% CI 1.03 to 1.66). Māori showed more consistent increased risk of breast cancer with increasing duration among current smokers (<20 years OR 1.61, 95% CI 0.55 to 4.74; 20+ years OR 2.03, 95% CI 1.29 to 3.22). There was a clear pattern of shorter duration since smoking cessation being associated with increased likelihood of breast cancer, and this was apparent for all ethnic groups. Conclusion There was no clear pattern for cigarette smoking and breast cancer incidence in non-Māori/non-Pacific women, but increased risks were observed for Māori and Pacific women. These findings suggest that lowering the prevalence of smoking, especially among Māori and Pacific women, could be important for reducing breast cancer incidence.

Investigating reasons for ethnic inequalities in breast cancer survival in New Zealand.

Objective. This study investigated the role that demographic and tumour factors play in explaining ethnic inequalities in breast cancer survival. Design. Breast cancer cases notified to the New Zealand Cancer Registry (NZCR) from April 2005 to April 2007 were followed up to April 2009. Māori, Pacific and non-Māori/non-Pacific women were categorised according to ethnicity on the NZCR. Deprivation was analysed as quintiles of the New Zealand area-based index of socio-economic position. Relative survival rates were estimated using ethnic-specific life tables. Missing values were imputed and excess mortality modelling was used to estimate the contribution of demographic and tumour factors to ethnic inequalities in survival. Results. There were 2968 breast cancer cases (76.5% non-Māori/non-Pacific, 17% Māori, and 6.5% Pacific) included and 433 recorded deaths. Relative survival rates at 4 years were 91.5% (95% confidence interval (CI) 89.7 to 92.9) for non-Māori/non-Pacific, 86.2% (CI 80.3 to 90.4) for Māori, and 79.6% (CI 68.2 to 87.2) for Pacific women. Using non-Māori/non-Pacific as the reference group, the age-adjusted hazard ratio (HR) dropped for Māori from 1.76 (CI 1.22 to 2.48) to 1.43 (CI 0.97 to 2.10) when further adjusted by deprivation. For Pacific the HR dropped from 2.49 (CI 1.57 to 3.94) to 1.94 (CI 1.20 to 3.13). Inequalities persisted after adjustment for subtype variables (ER/PR/HER2), but adjusting for access to care variables (extent/size) eliminated the ethnic inequalities in excess mortality. Conclusion. Ethnic disparities in breast cancer survival in New Zealand can be attributed to deprivation and differential access to health care rather than differences in breast cancer subtypes.