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Purpose To assess the associations between ovarian cancer and depot medroxyprogesterone acetate (DMPA), intrauterine contraceptive devices (IUDs), and partner vasectomy. Methods We undertook a New Zealand-wide population-based case-control study. During 2013-2015, 205 eligible cases were identified from the cancer registry (152 [74%] participated) and 1,735 eligible controls were randomly selected from the electoral roll (837 [48%] participated). A postal questionnaire was used to gather information. Results Ever-use of vasectomy was inversely associated with ovarian cancer in age-adjusted analysis, but not in multivariable analysis (OR = 0.67, 95% CI = 0.46–0.96, and OR = 0.82; 95% CI = 0.54–1.23, respectively). A suggestive trend towards lower risk with longer duration of reliance on partner vasectomy was observed (P-trend = 0.08). Ever-use and duration of use of DMPA were not associated with ovarian cancer. Although ever-use of IUDs was not associated with ovarian cancer, duration of use of IUDs was associated with higher risk (P-trend = 0.04). There were also statistically significant inverse associations between ovarian cancer and use of oral contraceptives, parity, and breastfeeding. Conclusions Prolonged use of IUDs may increase the risk of ovarian cancer. It is also possible that an inverse association exists between ovarian cancer and partner vasectomy.

Objectives The prevention of colorectal cancer (CRC) attainable from introducing once-in-a-lifetime flexible sigmoidoscopy (FSIG) screening was assessed. Study design This is a review of relevant available information for the assessment of the impact and resource demands of FSIG in New Zealand. Methods The reduction in bowel cancer incidence achievable by one-off FSIG screening from 50 to 59 years of age, an age group for which bowel screening is not currently offered, was reviewed. The prevention of CRC attainable from an offer of screening at 55 years of age in New Zealand was also estimated. The number and cost of the FSIG screening procedures required and referrals for colonoscopies and the savings in treatment were calculated. Results Annually, about 27,500 FSIG screening procedures would be required if 50% of those turning 55 years of age accepted an offer of once-in-a-lifetime FSIG screening. This would result in three–four-fold fewer people being referred for colonoscopy than in the national 2-yearly faecal immunochemical test (FIT) screening programme and subsequently reduce demand for colonoscopy from a false-positive FIT. The number of CRC cases prevented would increase over 17 years to more than 300 per year by 2033. After 10–15 years of screening, the annual savings in health service costs, primarily from CRC prevented, were sufficient to completely fund the FSIG screening. Conclusions Inclusion of FSIG screening in the national bowel screening programme would significantly reduce both the incidence and mortality of CRC in New Zealand, reduce the colonoscopy demand of current bowel screening and reduce long-term health service costs.

Introduction Our objective was to evaluate the impact on the incidence of cervical cancer in New Zealand of 5-yearly human papillomavirus (HPV) primary screening compared with 3-yearly cytology. Materials and methods Unbiased estimates of the screening test sensitivity of HPV and cytology screening, and screening coverage, were used to calculate the reduction in cervical cancer incidence obtained by current cytology screening and the new HPV screening policy. Results HPV screening in New Zealand is predicted to increase the incidence of cervical cancer in women being screened by 81.7% (95% CI: 38.9%-124.7%). The overall increase in the population incidence of cervical cancer in New Zealand was estimated to be 46.7% (95% CI 42.6%-50.8%), leading to about 57 more women developing cervical cancer each year. Conclusions The results indicate that lengthening the screening interval concurrently with changing to HPV testing may reduce the protection from invasive cervical cancer for women. Women in New Zealand should continue to be screened by cytology every 3 years. Changes to screening policy should be carefully designed so that changes in screening effectiveness can be accurately measured.

To investigate regional variation in myeloma incidence in New Zealand in order to inform aetiological investigations.All new registrations of myeloma (1991-2016) were extracted from the New Zealand Cancer Registry. Ethnic classifications used prioritised ethnicity. For geographical groupings, 74 Territorial Local Authority (TLA) categories for 2006 and population densities were used. Negative binomial regression was used to estimate incidence rate ratios, 95% confidence intervals and p-values.Between 1 January 1991 and 31 December 2016, 7,083 myelomas were registered. The Clutha TLA had a significantly lower incidence than the New Zealand average. Compared to Clutha, many regions had a significantly higher incidence, but there was no clear spatial pattern. The highest incidence rate was for Māori men in the North Island. Women had significantly lower incidence than men of the same ethnic group and in the same area.As both extremes of myeloma incidence occurred in rural areas, and as all TLAs (except one, Horowhenua) in the two lowest risk categories were rural, it seems unlikely that farming confers an increased risk. Results suggest that some other factor is driving the differences in myeloma incidence by ethnic group. We have provided a baseline of the geographical burden of myeloma in New Zealand.

Background Myeloma survival has greatly increased over past decades. We investigated trends in survival over time in New Zealand by age, ethnicity, and geography and thus examined potential inequalities among these population subgroups. Methods From data supplied by the New Zealand Ministry of Health, all new diagnoses of multiple myeloma (ICD-10 code C90) between 1990 and 2016 were extracted, as well as their matched mortality data. Cox’s proportional hazards regression and competing risks regression were used to estimate multivariable survival functions. Results Between 1 January 1990 and 1 December 2015, 6642 myeloma cases were registered by the New Zealand Cancer Registry. Although survival from myeloma increased substantially from 1990–1994 to 2010–2015, 5-year survival was still only about 60% in 2010–2015. The greatest improvement in survival was for people aged 60–69 years at diagnosis. Using Cox’s proportional hazards regression, Māori showed an increased risk of myeloma death but this was predominantly due to differences in competing risks among ethnic groups. Competing risks analysis found the greatest improvement in myeloma survival in Pacific Islanders, and in 2010–2015 Māori had better survival than other ethnicities. Myeloma survival improved significantly over time in all regional health authorities but in all time periods the Central and Southern regions had significantly poorer survival than the Midland region. Conclusions Improvements in myeloma survival have been unequal across subgroups and regions in New Zealand. Detailed information about utilization of chemotherapeutic agents and transplantation in New Zealand is not available. This information, as well as more detailed hematological data, is essential to further explore the relationships and reasons for differing myeloma survival in population subgroups of New Zealand.

Introduction The new cervical screening policy in Australia replaces 2-yearly cytology with 5-yearly human papillomavirus (HPV) screening. However, 2 of 5 randomized trials that have reported the number of women with cervical cancer found the incidence rate of invasive cervical cancer during follow-up to be higher for HPV compared with cytology screening. Therefore, we have estimated the possible impact of the new policy on cervical cancer incidence in Australia. Materials and Methods Available estimates of the relative protection from cytology screening, estimates of the coverage of the 2-yearly cytology screening policy of the Australian national cervical screening program, and estimates of screening test sensitivity were used to estimate the change in the incidence of cervical cancer from the introduction of the new policy. Results HPV screening 5-yearly was predicted to increase the annual incidence of cervical cancer in women screened to 121% (95% CI: 73%-169%) of current incidence after 10 years. The overall incidence of cervical cancer in Australia was predicted to increase by 39.2% (95% CI: 34.0%-44.4%) with an additional 222 women developing cervical cancer each year after 10 years. Conclusions Measures of the screening sensitivity of HPV testing and cervical cytology suggest the introduction of 5-yearly HPV primary screening may increase the incidence cervical cancer in Australia.

The data presented here were obtained for a New Zealand nationwide population-based case-control analysis undertaken to assess the association between ovarian cancer and depot medroxyprogesterone acetate (DMPA), intrauterine contraceptive devices (IUDs), and vasectomy of a woman's sexual partner (Chesang et al., 2021). The research involved women aged 35 to 69 years. Controls were randomly selected from the New Zealand electoral roll. Cases were women with a diagnosis of incident ovarian cancer recruited from the New Zealand Cancer Registry and had to be listed on the electoral roll. Data collection was conducted between 1st May 2013 and 31st October, 2015. A structured postal questionnaire was used to gather information. Data were analysed using IBM Statistical Package for the Social Sciences (IBM SPSS statistics 22). Odds ratios adjusted for age were calculated using the method of Mantel and Haensze (Rosner et al., 2007). For multivariable analyses, binary logistic regression was used. Description of study participants and age-adjusted and multivariable analyses of the association between ever-use and specifics of use of DMPA, IUDs, and vasectomy were presented in a journal article (Chesang et al., 2021). Here, we present data from analyses of the risk of ovarian cancer by histological type associated with the use of DMPA, IUDs and ever having had a vasectomised partner. In addition, analyses assessing the association between ovarian cancer and these contraceptives restricted to ever-users and never-users of hormonal contraceptives (defined as oral contraceptives or DMPA) are presented. Data from analyses of the association between history of tubal ligation and the risk of ovarian cancer are also presented. These data, including the findings of a related study (Chesang et al., 2021) and the raw data, can be included in a collaborative analysis of existing studies undertaken to assess the association between IUDs, long-acting progestogen-based contraceptives, and partner vasectomy and the risk of ovarian cancer.

Objectives We investigated potential causes of the high incidence rate of colorectal cancer (CRC) in New Zealand. Study design A national population-based case-control study of 806 cases and 1025 controls was conducted to determine the risk factors for CRC in this population. Methods Information about family history of CRC, ethnicity, diet, school milk consumption, exercise, and height and weight at age 20 years were collected by a self-administered questionnaire from cases and controls. Results Response rates were 84% for cases and 65% for controls. Increasing preference for low-fat food alternatives was associated with reducing odds ratios (OR) for CRC (Ptrend Conclusions A preference for low-fat food may ameliorate an increased risk of CRC from the consumption of processed meat.

Background Myeloma, one of the most common haematological malignancies worldwide arises in the bone marrow. Incidence rates vary by age and ethnicity but reasons behind these trends are unknown. Treatment of myeloma has changed significantly over recent decades, resulting in longer survival and decreased mortality. Methods From data supplied by the Ministry of Health, all new registrations of and deaths from myeloma between 1985 and 2016 were extracted. Trends in age-specific rates were assessed using the method of Armitage. Age-standardised rates were calculated, and trends in age-adjusted rates analysed using the Mantel-Haenszel extension chi-square test. Age-adjusted incidence and mortality rate ratios were calculated. Myeloma-specific survival was visualised using Kaplan-Meier curves and multivariable hazard ratios calculated using Cox regression. Results Between 1985 and 2016, 7826 New Zealanders were registered with myeloma. Over this time the age-specific incidence of myeloma increased significantly for men, who had higher rates than women. Myeloma mortality was highest in Maori men. Men had higher mortality rates than women in all time periods. Since 1995–1999, mortality has decreased in women whereas in men it has declined since about 2000–2004. Survival has increased significantly since 1990 but Maori still have a higher risk of death than non-Maori. Conclusion The patterns of variation in myeloma incidence, mortality and survival, as well as their trends over time may be used to assist research into the causes and management of myeloma in New Zealand.

Purpose To compare freedom from biochemical failure (FFBF) of French Polynesian (FP) and Native European (NE) prostate cancer patients after definitive conformal radiotherapy (RT). Patients and methods Data were reviewed from medical records of 152 consecutive patients (46 FP and 106 NE) with clinically localised prostate cancer treated with definitive RT. Neoadjuvant androgen deprivation therapy (ADT) was used in 22% of cases. Definition for biochemical failure was a rise by 2ng/mL or more above the nadir prostate-specific antigen (PSA) level. The median follow-up was 34months. Results In comparison to NE patients, FP patients were younger ( p =0.002) with a higher low-risk proportion ( p =0.06). Probability of 5-year FFBF was 77% in the NE cohort and 58.0% in the FP cohort ( p =0.017). Univariate analysis showed that FP ethnicity was associated with worse prognosis in high-risk tumours ( p =0.004). Cox multivariate analysis showed that factors associated with FFBF were risk category ( p p =0.03), independently of ADT and radiation dose. Conclusion FP ethnicity was an independent prognostic factor for biochemical relapse after definitive conformal RT for prostate cancer.

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).

To examine disease-specific survival from prostate cancer by ethnic group in New Zealand. Analyses 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. In 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. Several 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.

A high response rate has long been regarded as one of the hallmarks of a ‘good’ epidemiological study. However, the validity of results from studies that require participants to complete questionnaires, have an interview or provide a biological specimen is becoming increasingly jeopardized by decreasing participation. One analysis showed that cooperation rates (participants interviewed/number eligible that were contacted) in published population-based case–control studies declined by 3.33% per year in cases and 5.15% per year in controls from 1991 to 2003. In such studies, cooperation rates of 70% and response rates [participants interviewed/(participants interviewedþ eligible non-participantsþ people of presumed but unconfirmed eligibility)] of 50% are not uncommon today. Furthermore, and maybe because of declining rates, only a minority of studies published sufficient information for either cooperation or response rates to be calculated. A fundamental tenet of a case–control study design is that the controls should be selected randomly, and independently of exposure status, from the source population from which the cases were drawn and thus be representative of the exposure experience of the source population. Poor response rates by themselves do not create selection bias any more than high response rates guarantee unbiased estimates, but by endangering representativeness, low participation can provide more opportunity for bias to occur. Selection bias develops if the selection probabilities are different for cases and controls based on their exposure status. Since odds ratios maybe biased due to low participation, should we discard case–control studies as a valid study design?

Background New Zealand and Australia have the highest melanoma incidence rates worldwide. In New Zealand, both the incidence and thickness have been increasing. Clinical decisions require accurate risk prediction but a simple list of genetic, phenotypic and behavioural risk factors is inadequate to estimate individual risk as the risk factors for melanoma have complex interactions. In order to offer tailored clinical management strategies, we developed a New Zealand prediction model to estimate individual 5-year absolute risk of melanoma. Methods A population-based case–control study (368 cases and 270 controls) of melanoma risk factors provided estimates of relative risks for fair-skinned New Zealanders aged 20–79 years. Model selection techniques and multivariate logistic regression were used to determine the important predictors. The relative risks for predictors were combined with baseline melanoma incidence rates and non-melanoma mortality rates to calculate individual probabilities of developing melanoma within 5 years. Results For women, the best model included skin colour, number of moles > =5 mm on the right arm, having a 1st degree relative with large moles, and a personal history of non-melanoma skin cancer (NMSC). The model correctly classified 68% of participants; the C-statistic was 0.74. For men, the best model included age, place of occupation up to age 18 years, number of moles > =5 mm on the right arm, birthplace, and a history of NMSC. The model correctly classified 67% of cases; the C-statistic was 0.71. Conclusions We have developed the first New Zealand risk prediction model that calculates individual absolute 5-year risk of melanoma. This model will aid physicians to identify individuals at high risk, allowing them to individually target surveillance and other management strategies, and thereby reduce the high melanoma burden in New Zealand.

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.

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.

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.

Few studies have been performed to evaluate the effect of skin surveillance on melanoma risk. This population-based case-control study was carried out to confirm the association of phenotype with melanoma and to investigate the effect of surveillance by skin examination on the risk of melanoma in New Zealand. Cases were patients with a first diagnosis of in-situ or invasive cutaneous malignant melanoma from three regions of New Zealand. Controls were selected at random from the electoral rolls and frequency-matched by age. Participants included men and women of European origin aged between 20 and 79 years. A strong association was found between host phenotypic factors (red hair, fair skin, many freckles on the face, and numbers of moles) and melanoma risk. These effects were largely independent of each other. The relative risk of melanoma was significantly reduced after skin examination by one's self, partner or a health professional; this reduction in risk remained after adjustment for phenotype, mole counts, skin reaction to sun, and exposure to sun. People who attended a 'skin check clinic' had a non-significant increase in risk of melanoma.

ContextVasectomy is a common method of contraception, but concern exists about a reported association with risk of prostate cancer.ObjectiveTo examine whether vasectomy increases risk of prostate cancer.Design, Setting, and ParticipantsNational population-based case-control study of 923 new cases of prostate cancer among men aged 40 to 74 years from the New Zealand Cancer Registry who were on the general electoral roll. Controls (n = 1224) were randomly selected from the general electoral roll, with frequency matching to cases in 5-year age groups. Cases (3-15 months after diagnosis) and controls were interviewed by telephone between January 1997 and November 1999.Main Outcome MeasuresRelative risk (RR) of prostate cancer for men who had had a vasectomy vs those who had not.ResultsThere was no association between prostate cancer and vasectomy (RR, 0.92; 95% confidence interval [CI], 0.75-1.14) nor with time since vasectomy (RR, 0.92; 95% CI, 0.68-1.23 for ≥25 years since vasectomy). Adjustment for social class, geographic region, religious affiliation, and a family history of prostate cancer did not affect these RRs.ConclusionsVasectomy does not increase the risk of prostate cancer, even after 25 years or more.

In a national case-control study, 891 New Zealand women aged 25 to 54 with newly diagnosed breast cancer were compared with 1,864 control subjects selected at random from the electoral rolls. The relative risk of breast cancer for current drinkers of alcohol, compared with women who had never drunk alcohol, was 1.0 (95% confidence interval 0.64 to 1.7). For ex-drinkers the relative risk was 1.3 (95% confidence interval 0.74 to 2.5). Women drinking up to 14 drinks per week had no increase in risk, while the relative risk in those consuming more than 14 drinks per week was 1.8 (95% confidence interval 0.87 to 3.8). There was no evidence of effect modification by age at diagnosis, menopausal status, body mass index, or any of the other variables examined. While these results provide little support for the hypothesis that moderate alcohol consumption increases the risk of breast cancer, they are not inconsistent with the weak associations that have been found in many other studies. Possible explanations for such a relationship are considered.

Rats have been fed semi-synthetic diets containing 4 and 20% (w/w) corn oil for periods of 9–12 weeks covering two lactations. 1. 2. The mean maternal and pup weights at day-14 of the second lactation on the diets were not significantly different. 2. 3. The milk fatty acids of the rats on the high-fat diet contained 39 mol% linoleic acid and only 20 mol% medium-chain acids compared with over 40% for the low-fat diet. 3. 4. With the exception of “malic” enzyme, none of five enzymes assayed in mammary supernatants was significantly altered by the diet fed. 4. 5. These results suggest that the synthesis of these enzymes in the mammary gland is insensitive to dietary lipid.