Mary Jane Sneyd

Meta-analysis of observational studies of serum 25-hydroxyvitamin D levels and colorectal, breast and prostate cancer and colorectal adenoma.

Epidemiological studies have suggested a reduced risk of several cancers associated with high vitamin D status. We performed a systematic review with meta‐analyses of observational studies of serum 25‐hydroxyvitamin D level and colorectal, breast and prostate cancer and colonic adenoma. The literature of December 2009 was searched without language restriction. The meta‐regression analysis was done to compute dose‐response effects. Because in case‐control studies, serum 25‐hydroxyvitamin D level is measured after the diagnosis of cancer, separate analyses for case‐control and prospective studies were done. We identified 35 independent studies. The seven studies on colorectal adenomas were heterogeneous in terms of endpoint and control for major confounding factors, and we did not perform a meta‐analysis of these data. The summary relative risk (SRR) and (95% confidence interval) for a 10 ng/ml increase in serum 25‐hydroxyvitamin D was 0.85 (0.79; 0.91) for colorectal cancer (2,630 cases in 9 studies); 0.89 (0.81;0.98) for breast cancer (6,175 cases in 10 studies); and 0.99 (0.95;1.03) for prostate cancer (3,956 cases in 11 studies). For breast cancer, case‐control studies (3,030 cases) had major limitations and obtained SRR of 0.83 (0.79; 0.87) whereas SRR of prospective studies (3,145 cases) was 0.97 (0.92; 1.03). For colorectal and breast cancer, differences between cases and controls in the season of blood draw or in overweight/obesity or physical inactivity could not explain the results. In conclusion, a consistent inverse relationship between serum 25‐hydroxyvitamin D levels and colorectal cancer was found. No association was found for breast and prostate cancer.

High prevalence of vasectomy in New Zealand

The aim of this study was to examine the prevalence of vasectomy and associated factors in New Zealand, based on interviews with men. Participants were randomly selected from European men, aged between 40 and 74 years, on the general electoral roll. Telephone interviews were completed with 1225 men between 1997 and 1999. Overall, the prevalence of vasectomy was 44% (95% CI, 37-52%), adjusted to the age distribution of all New Zealand men aged 40-74 years. The prevalence ranged from 57% of men aged 40-49 years to 15% of those aged 70-74 years. Catholic men had a significantly lower odds of vasectomy, and there was a trend in increasing odds of vasectomy with increasing number of marriages and level of education of the wife. The results confirm a very high prevalence of vasectomy among New Zealand men. Comparison with earlier surveys based on interviews of women showed an increasing prevalence of vasectomy in each birth cohort from the 1920s to the 1950s. Vasectomy has been popular with men across all socioeconomic groups. New Zealand is an ideal country in which to study consequences of vasectomy.

Melanoma in Maori, Asian, and Pacific Peoples in New Zealand

New Zealand Maori, Pacific, and Asian people develop melanoma less frequently than New Zealand Europeans, but little is known about melanomas that develop in these people. We examined the characteristics of melanoma in these minority ethnic groups in New Zealand. In 2007, all first primary melanomas diagnosed from January 1996 to December 2006 were extracted from the New Zealand Cancer Registry database. Melanoma was more commonly diagnosed in Maori than Asian or Pacific peoples. Age-adjusted incidence rates increased annually from 1996 to 2006 by 0.37 per 100,000 in the total population and 0.20 per 100,000 in Maori, a 12% (from 30.9 to 34.6) and 90% (from 2.3 to 4.3) increase, respectively, over the 11 years. Nodular melanoma occurred more often in Maori (15.9%) and Pacific peoples (17.1%) compared with Asians (8.7%) and New Zealand Europeans (10.5%). In Pacific peoples, acral lentiginous melanoma (22.9%) was the most common subtype. The median thickness of melanoma was 0.78 mm in New Zealand Europeans, 1.2 mm in Maori, 2.5 mm in Pacific peoples, and 0.73 mm in Asians (P < 0.001, difference in medians). Thirty-seven percent of melanomas in Pacific peoples were >4 mm thick compared with 7.9% in New Zealand Europeans. About 13% of Asians and 11% of Pacific peoples, compared with 4% of New Zealand Europeans with melanoma, were diagnosed by histology of metastases rather than the primary lesion. Minority ethnicities in New Zealand have a higher than expected risk of thick and more advanced melanoma, with poorer prognosis. Melanoma campaigns should include messages that incorporate the unique features of melanoma in minorities. (Cancer Epidemiol Biomarkers Prev 2009;18(6):1706–13)

Ethnic differences in prostate cancer survival in New Zealand: a national study

ObjectiveTo examine disease-specific survival from prostate cancer by ethnic group in New Zealand.MethodsAnalyses were based on the 7,733 men with histologically confirmed prostate cancer diagnosed from the start of 1996 to the end of 1999 in New Zealand. Five-year adjusted prostate-specific mortality rates and hazard ratios were calculated for Maori, Pacific, and European men.ResultsIn univariate analyses, Maori and Pacific men had higher mortality particularly in the first year after a diagnosis of prostate cancer than did European men. The strongest prognostic factors for prostate cancer were Gleason score and age. When survival analyses by ethnic group were adjusted for age and Gleason score the disparities in survival for Maori men and Pacific men with low-grade prostate cancers remained, with European men having the best survival.ConclusionsSeveral possible explanations have been proposed to explain the survival disparities by ethnicity in New Zealand. Differentials in Gleason grade of disease by ethnic group explain a lot of these disparities. Further data on stage of disease at diagnosis, co-morbidity, treatment, access to health services, and behavioral and environmental factors are needed to resolve these issues.

School Milk and Risk of Colorectal Cancer: A National Case-Control Study

To determine whether school milk consumption in childhood decreased the risk of adult colorectal cancer, the authors conducted a national population-based, case-control study of 562 cases and 571 controls. The authors identified new cases of colorectal cancer in 2007 among people aged 30-69 years from the New Zealand Cancer Registry. Controls were randomly selected from the electoral rolls and frequency matched to cases in 5-year age groups. Participation in school milk programs was associated with a reduced odds ratio for colorectal cancer (odds ratio (OR) = 0.70, 95% confidence interval (CI): 0.51, 0.96). Odds ratios decreased with increasing numbers of bottles of milk drunk compared with no school milk (for 1-799 bottles, OR = 1.04, 95% CI: 0.66, 1.67; for 800-1,199 bottles, OR = 0.81, 95% CI: 0.51, 1.29; for 1,200-1,599 bottles, OR = 0.62, 95% CI: 0.41, 0.93; for 1,600-1,799 bottles, OR = 0.57, 95% CI: 0.37, 0.90; and for 1,800 or more bottles, OR = 0.62, 95% CI: 0.41, 0.96). Participation in school milk programs in New Zealand was associated with a 2.1% reduction (95% CI: 0.7, 3.5) in the odds ratio for colorectal cancer for every 100 half-pint bottles drunk (1 half-pint bottle = 284 mL).

Bias in breast cancer research in the screening era

Screening aims to detect breast cancer at an earlier stage than would occur if symptoms developed. The characteristics of breast cancer that are detectable at screening depend on both the physical properties of the screening test and specific anatomical features of breast cancer. As a result, breast cancer detected by screening is a select subset of all breast cancer existing in the population. Therefore, biomedical, clinical and epidemiological research into breast cancer using populations with access to screening can result in major bias. The biases, with examples, are explained.

Risk factors for prostate cancer: A national case-control study.

Statutory notification of cancer in New Zealand provided an opportunity to investigate risk factors for prostate cancer in a large national population‐based case‐control study. We analyzed data obtained from telephone interviews with 923 cases and 1,224 controls. For inclusion in the study, all subjects had to have been married at some time. We found an increased risk of prostate cancer among those with a history of prostate cancer in first degree relatives (RR 2.6; 95% CI, 1.9–3.7) and an increased risk of prostate cancer with length of marriage among men married only once and still married at interview. For a consecutive subgroup of 550 cases and 819 controls, data on height and weight at age 20 and at 5 years before interview were collected. Men less than or equal to 1.7 m in height at age 20 years had a lower risk of prostate cancer than men taller at that age. There was no association between weight or body mass index and risk of prostate cancer.

Clinical and Histologic Factors Associated With Melanoma Thickness in New Zealand Europeans, Maori, and Pacific Peoples

Thickness is the major prognostic indicator for patients with melanoma. In many countries, the incidence of thick melanoma has not decreased. To reduce mortality, knowledge of the characteristics associated with melanoma depth is needed.

PSA testing and digital rectal examination in New Zealand

Objective: To investigate the use of digital rectal examination and prostate specific antigen (PSA) testing in a population‐based sample of men in New Zealand.

Epidemic of Non-Hodgkin Lymphoma in New Zealand Remains Unexplained

Background. Non-Hodgkin lymphoma (NHL) incidence rates have increased considerably in New Zealand. Methods. Incidence and mortality rates for NHL from 1981 to 2010 were calculated. Trends in age-specific rates were analysed and age-period-cohort models fitted to explore generation-specific changes in incidence and mortality. Results. NHL incidence increased by 67% for men and 74% for women between the 1981–1985 and 2006–2010 time periods in New Zealand. For women born about 1936 and men born about 1946, NHL incidence and mortality have diverged suggesting an improved prognosis for recent generations. Conclusion. The strong generation effects suggest that an exposure before 25 years of age is of major importance in determining the lifetime risk of NHL in New Zealand. NHL incidence rates in New Zealand will continue to increase in the future and probably more in females than males, as generations with increased risk age. Current hypotheses for the cause of NHL do not explain the trends observed. A decline in the prevalence of a protective factor may have also contributed to these trends. Examination of trends for subtypes of NHL and innovative testable hypotheses that may explain these trends are needed.