Sanjeewa Seneviratne

Accuracy and completeness of the New Zealand Cancer Registry for staging of invasive breast cancer

PURPOSE Population based cancer registries are an invaluable resource for monitoring incidence and mortality for many types of cancer. Research and healthcare decisions based on cancer registry data rely on the case completeness and accuracy of recorded data. This study was aimed at assessing completeness and accuracy of breast cancer staging data in the New Zealand Cancer Registry (NZCR) against a regional breast cancer register. METHODOLOGY Data from 2562 women diagnosed with invasive primary breast cancer between 1999 and 2011 included in the Waikato Breast Cancer Register (WBCR) were used to audit data held on the same individuals by the NZCR. WBCR data were treated as the benchmark. RESULTS Of 2562 cancers, 315(12.3%) were unstaged in the NZCR. For cancers with a known stage in the NZCR, staging accuracy was 94.4%. Lower staging accuracies of 74% and 84% were noted for metastatic and locally invasive (involving skin or chest wall) cancers, respectively, compared with localized (97%) and lymph node positive (94%) cancers. Older age (>80 years), not undergoing therapeutic surgery and higher comorbidity score were significantly (p<0.01) associated with unstaged cancer. The high proportion of unstaged cancer in the NZCR was noted to have led to an underestimation of the true incidence of metastatic breast cancer by 21%. Underestimation of metastatic cancer was greater for Māori (29.5%) than for NZ European (20.6%) women. Overall 5-year survival rate for unstaged cancer (NZCR) was 55.9%, which was worse than the 5-year survival rate for regional (77.3%), but better than metastatic (12.9%) disease. CONCLUSIONS Unstaged cancer and accuracy of cancer staging in the NZCR are major sources of bias for the NZCR based research. Improving completeness and accuracy of staging data and increasing the rate of TNM cancer stage recording are identified as priorities for strengthening the usefulness of the NZCR.

Treatment delay for Māori women with breast cancer in New Zealand

Objectives. To identify differences in delay for surgical treatment of breast cancer between ethnic groups and to evaluate the role of health system, sociodemographic and tumour factors in ethnic inequities in breast cancer treatment. Methods. A retrospective analysis of prospectively collected data from the Waikato Breast Cancer Register for cancers diagnosed in the Waikato region in New Zealand (NZ) from 1 January 2005 to 31 December 2010. Results. Approximately 95% (1449 out of 1514) of women with breast cancer diagnosed in the Waikato over the study period were included. Of women undergoing primary surgery (n = 1264), 59.6% and 98.2% underwent surgery within 31 and 90 days of diagnosis, respectively. Compared with NZ European women (mean 30.4 days), significantly longer delays for surgical treatment were observed among Māori (mean = 37.1 days, p = 0.005) and Pacific women (mean = 42.8 days, p = 0.005). Māori women were more likely to experience delays longer than 31 (p = 0.048) and 90 days (p = 0.286) compared with NZ European women. Factors predicting delays longer than 31 and 90 days in the multivariable model included public sector treatment (OR 5.93, 8.14), DCIS (OR 1.53, 3.17), mastectomy (OR 1.75, 6.60), higher co-morbidity score (OR 2.02, 1.02) and earlier year of diagnosis (OR 1.21, 1.03). Inequities in delay between Māori and NZ European women were greatest for women under 50 years and those older than 70 years. Conclusion. This study shows that significant inequities in timely access to surgical treatment for breast cancer exist in NZ, with Māori and Pacific women having to wait longer to access treatment than NZ European women. Overall, a high proportion of women did not receive surgical treatment for breast cancer within the guideline limit of 31 days. Urgent steps are needed to reduce ethnic inequities in timely access to breast cancer treatment, and to shorten treatment delays in the public sector for all women.

Ethnic differences in timely adjuvant chemotherapy and radiation therapy for breast cancer in New Zealand: a cohort study

BackgroundIndigenous and/or minority ethnic women are known to experience longer delays for treatment of breast cancer, which has been shown to contribute to ethnic inequities in breast cancer mortality. We examined factors associated with delay in adjuvant chemotherapy and radiotherapy for breast cancer, and its impact on the mortality inequity between Indigenous Māori and European women in New Zealand.MethodsAll women with newly diagnosed invasive non-metastatic breast cancer diagnosed during 1999–2012, who underwent adjuvant chemotherapy (n = 922) or radiation therapy (n = 996) as first adjuvant therapy after surgery were identified from the Waikato breast cancer register. Factors associated with delay in adjuvant chemotherapy (60-day threshold) and radiation therapy (90-day threshold) were analysed in univariate and multivariate models. Association between delay in adjuvant therapy and breast cancer mortality were explored in Cox regression models.ResultsOverall, 32.4% and 32.3% women experienced delays longer than thresholds for chemotherapy and radiotherapy, respectively. Higher proportions of Māori compared with NZ European women experienced delays longer than thresholds for adjuvant radiation therapy (39.8% vs. 30.6%, p = 0.045) and chemotherapy (37.3% vs. 30.5%, p = 0.103). Rural compared with urban residency, requiring a surgical re-excision and treatment in public compared with private hospitals were associated with significantly longer delays (p < 0.05) for adjuvant therapy in the multivariate model. Breast cancer mortality was significantly higher for women with a delay in initiating first adjuvant therapy (hazard ratio [HR] =1.45, 95% confidence interval [CI] 1.05-2.01). Mortality risks were higher for women with delays in chemotherapy (HR = 1.34, 95% CI 0.89-2.01) or radiation therapy (HR = 1.28, 95% CI 0.68-2.40), although these were statistically non-significant.ConclusionsIndigenous Māori women appeared to experience longer delays for adjuvant breast cancer treatment, which may be contributing towards higher breast cancer mortality in Māori compared with NZ European women. Measures to reduce delay in adjuvant therapy may reduce ethnic inequities and improve breast cancer outcomes for all women with breast cancer in New Zealand.

Impact of mammographic screening on ethnic and socioeconomic inequities in breast cancer stage at diagnosis and survival in New Zealand: a cohort study

BackgroundIndigenous Māori women experience a 60% higher breast cancer mortality rate compared with European women in New Zealand. We explored the impact of differences in rates of screen detected breast cancer on inequities in cancer stage at diagnosis and survival between Māori and NZ European women.MethodsAll primary breast cancers diagnosed in screening age women (as defined by the New Zealand National Breast Cancer Screening Programme) during 1999–2012 in the Waikato area (n = 1846) were identified from the Waikato Breast Cancer Register and the National Screening Database. Stage at diagnosis and survival were compared for screen detected (n = 1106) and non-screen detected (n = 740) breast cancer by ethnicity and socioeconomic status.ResultsIndigenous Māori women were significantly more likely to be diagnosed with more advanced cancer compared with NZ European women (OR = 1.51), and approximately a half of this difference was explained by lower rate of screen detected cancer for Māori women. For non-screen detected cancer, Māori had significantly lower 10-year breast cancer survival compared with NZ European (46.5% vs. 73.2%) as did most deprived compared with most affluent socioeconomic quintiles (64.8% vs. 81.1%). No significant survival differences were observed for screen detected cancer by ethnicity or socioeconomic deprivation.ConclusionsThe lower rate of screen detected breast cancer appears to be a key contributor towards the higher rate of advanced cancer at diagnosis and lower breast cancer survival for Māori compared with NZ European women. Among women with screen-detected breast cancer, Māori women do just as well as NZ European women, demonstrating the success of breast screening for Māori women who are able to access screening. Increasing breast cancer screening rates has the potential to improve survival for Māori women and reduce breast cancer survival inequity between Māori and NZ European women.

Differences in Breast Cancer Survival between Public and Private Care in New Zealand: Which Factors Contribute?

Background Patients who received private health care appear to have better survival from breast cancer compared to those who received public care. This study investigated if this applied to New Zealand women and identified factors that could explain such disparities. Methods This study involved all women who were diagnosed with primary breast cancer in two health regions in New Zealand, covering about 40% of the national population, between June 2000 and May 2013. Patients who received public care for primary treatment, mostly surgical treatment, were compared with those who received private care in terms of demographics, mode of presentation, disease factors, comorbidity index and treatment factors. Cox regression modelling was performed with stepwise adjustments, and hazards of breast cancer specific mortality associated with the type of health care received was assessed. Results Of the 14,468 patients, 8,916 (61.6%) received public care. Compared to patients treated in private care facilities, they were older, more likely to be Māori, Pacifika or Asian and to reside in deprived neighbourhoods and rural areas, and less likely to be diagnosed with early staged cancer and to receive timely cancer treatments. They had a higher risk of mortality from breast cancer (hazard ratio: 1.95; 95% CI: 1.75, 2.17), of which 80% (95% CI: 63%, 100%) was explained by baseline differences, particularly related to ethnicity, stage at diagnosis and type of loco-regional therapy. After controlling for these demographic, disease and treatment factors, the risk of mortality was still 14% higher in the public sector patients. Conclusions Ethnicity, stage at diagnosis and type of loco-regional therapy were the three key contributors to survival disparities between patients treated in public and private health care facilities in New Zealand. The findings underscore the need for more efforts to improve the quality, timeliness and equitability of public cancer care services.

Breast Cancer Characteristics and Survival Differences between Maori, Pacific and other New Zealand Women Included in the Quality Audit Program of Breast Surgeons of Australia and New Zealand

BACKGROUND The Quality Audit (BQA) program of the Breast Surgeons of Australia and New Zealand (NZ) collects data on early female breast cancer and its treatment. BQA data covered approximately half all early breast cancers diagnosed in NZ during roll-out of the BQA program in 1998-2010. Coverage increased progressively to about 80% by 2008. This is the biggest NZ breast cancer database outside the NZ Cancer Registry and it includes cancer and clinical management data not collected by the Registry. We used these BQA data to compare socio-demographic and cancer characteristics and survivals by ethnicity. MATERIALS AND METHODS BQA data for 1998-2010 diagnoses were linked to NZ death records using the National Health Index (NHI) for linking. Live cases were followed up to December 31st 2010. Socio-demographic and invasive cancer characteristics and disease-specific survivals were compared by ethnicity. RESULTS Five-year survivals were 87% for Maori, 84% for Pacific, 91% for other NZ cases and 90% overall. This compared with the 86% survival reported for all female breast cases covered by the NZ Cancer Registry which also included more advanced stages. Patterns of survival by clinical risk factors accorded with patterns expected from the scientific literature. Compared with Other cases, Maori and Pacific women were younger, came from more deprived areas, and had larger cancers with more ductal and fewer lobular histology types. Their cancers were also less likely to have a triple negative phenotype. More of the Pacific women had vascular invasion. Maori women were more likely to reside in areas more remote from regional cancer centres, whereas Pacific women generally lived closer to these centres than Other NZ cases. CONCLUSIONS NZ BQA data indicate previously unreported differences in breast cancer biology by ethnicity. Maori and Pacific women had reduced breast cancer survival compared with Other NZ women, after adjusting for socio-demographic and cancer characteristics. The potential contributions to survival differences of variations in service access, timeliness and quality of care, need to be examined, along with effects of co- morbidity and biological factors.

Screening for gestational diabetes mellitus in southern Asian women

Aim:  To compare fasting plasma glucose (FPG) against 2‐h postprandial plasma glucose (PPPG), following a carbohydrate meal, for screening of gestational diabetes mellitus (GDM) in southern Asian women with one or more risk factors.

Ethnic, socio-demographic and socio-economic differences in surgical treatment of breast cancer in New Zealand.

Indigenous Māori are known to experience inferior quality cancer care compared with non‐Indigenous Europeans in New Zealand. However, limited data are available on ethnic/socio‐economic differences in surgical treatment of breast cancer, or reasons for such variations within the local context. We investigated ethnic/socio‐economic differences in rates of mastectomy, sentinel node biopsy (SNB), post‐mastectomy breast reconstruction and definitive local therapy for breast cancer in New Zealand.

Breast cancer biology and ethnic disparities in breast cancer mortality in new zealand: a cohort study.

Introduction Indigenous Māori women have a 60% higher breast cancer mortality rate compared with European women in New Zealand. We investigated differences in cancer biological characteristics and their impact on breast cancer mortality disparity between Māori and NZ European women. Materials and Methods Data on 2849 women with primary invasive breast cancers diagnosed between 1999 and 2012 were extracted from the Waikato Breast Cancer Register. Differences in distribution of cancer biological characteristics between Māori and NZ European women were explored adjusting for age and socioeconomic deprivation in logistic regression models. Impacts of socioeconomic deprivation, stage and cancer biological characteristics on breast cancer mortality disparity between Māori and NZ European women were explored in Cox regression models. Results Compared with NZ European women (n=2304), Māori women (n=429) had significantly higher rates of advanced and higher grade cancers. Māori women also had non-significantly higher rates of ER/PR negative and HER-2 positive breast cancers. Higher odds of advanced stage and higher grade remained significant for Māori after adjusting for age and deprivation. Māori women had almost a 100% higher age and deprivation adjusted breast cancer mortality hazard compared with NZ European women (HR=1.98, 1.55-2.54). Advanced stage and lower proportion of screen detected cancer in Māori explained a greater portion of the excess breast cancer mortality (HR reduction from 1.98 to 1.38), while the additional contribution through biological differences were minimal (HR reduction from 1.38 to 1.35). Conclusions More advanced cancer stage at diagnosis has the greatest impact while differences in biological characteristics appear to be a minor contributor for inequities in breast cancer mortality between Māori and NZ European women. Strategies aimed at reducing breast cancer mortality in Māori should focus on earlier diagnosis, which will likely have a greater impact on reducing breast cancer mortality inequity between Māori and NZ European women.

Breast cancer inequities between Māori and non-Māori women in Aotearoa/New Zealand

Māori women have one of the highest incidences of breast cancer in the world. This high incidence is generally unexplained although higher rates of obesity and alcohol intake are modifiable risk factors that may be important. Māori women are less likely to attend mammographic breast screening and are likely to be diagnosed with more advanced disease. This is one of the reasons for the excess mortality. Another factor is differences in the treatment pathway. Māori women are more likely to experience delay in receiving treatment, are less likely to receive radiotherapy, are more likely to be treated with a mastectomy and are less likely to adhere to long-term adjuvant endocrine therapy. However, genetic factors in Māori women do not seem to impact significantly on mortality. This review looks at the inequity between Māori and non-Māori women and addresses the causes. It proposes ways of reducing inequity through primary prevention, increased participation in breast screening and greater standardisation of the treatment pathway for women newly diagnosed with breast cancer. We believe that health system improvements will decrease barriers to health care participation for Māori women and suggest that further research into identifying and modifying obstacles within health systems is required.