A New Predictive Model for Breast Cancer Survival in New Zealand: Development, Internal and External Validation, and Comparison With the Nottingham Prognostic Index

Background: Women diagnosed with breast cancer, their doctors, and their families, would find a valid estimate of her prognosis helpful in planning treatment and support. Assessing prognosis is complex as many factors influence it. Several predictive models have been produced, but none has been developed or tested on patients in New Zealand (NZ). Aim: We aimed to develop and validate a NZ predictive model (NZPM) for breast cancer, and compare its performance to a widely used UK-developed model, the Nottingham Prognostic Index (NPI). Methods: We developed a model to predict 10-year breast cancer-specific survival, using data collected prospectively in the largest population-based breast cancer registry in NZ (Auckland, 9182 patients), and assessed its performance in this data set (internal validation) and in an independent NZ population-based series of 2625 patients in Waikato (external validation). The data included all women with primary invasive breast cancer diagnosed from 1 June 2000 to 30 June 2014, with follow-up to death or to 31 December 2014. We used multivariate Cox proportional hazards regression to assess predictors and to estimate the probability of breast cancer mortality within 10 years, and therefore 10-year survival, for each patient. We assessed observed survival by the Kaplan-Meier method. We assessed discrimination by the C-statistic, and calibration by comparing predicted and observed survival rates for patients in 10 groups ordered by predicted 10-year survival. We compared this NZPM with the NPI in the validation data set. Results: The final NZPM used continuous variables of age, tumor size, and number of positive lymph nodes, and categorical variables of ethnicity, tumor stage, tumor grade, ER and PR receptors, HER2 status, and histologic type of tumor. Discrimination was good: C-statistics were 0.84 for internal validity and 0.83 for independent external validity. For calibration, for both internal and external validity, the predicted 10-year survival probabilities in 10 groups of patients, ordered by predicted survival, were all within the 95% confidence intervals (CI) of the observed Kaplan-Meier survival probabilities. The NZPM showed good discrimination even within the prognostic groups defined by the NPI. Conclusion: These results for the NZPM show good internal and external validity, transportability, potential clinical value, and its clear superiority over the NPI. Further research will assess other potential predictors, other outcomes, performance in specific subgroups of patients, and compare the NZPM to other models, which have been developed in other countries and have not yet been tested in NZ.

EGFR Mutation Testing of Nonsquamous NSCLC in New Zealand: Trends, Selectivity and Effects on the Prevalence of EGFR Mutation

Background: Given the benefits in using epidermal growth factor receptor (EGFR) tyrosine kinase inhibitors (TKI), clinical practice guidelines recommend EGFR mutation testing of nonsquamous non–small cell lung cancer (NSCLC). However, not all patients get tested, which may have an impact on the prevalence of EGFR mutation previously estimated. Aim: To determine the trends of EGFR mutation testing in patients with nonsquamous NSCLC in New Zealand, and to explore the possible associations between the proportions tested, selectivity and the prevalence of EGFR mutation. Methods: This population-based study involves all patients who were diagnosed with nonsquamous NSCLC in the four health regions of New Zealand between January 2010 and July 2016. We identified eligible patients from the New Zealand Cancer Registry and obtained information on EGFR testing from TestSafe, a clinical information sharing service. We then calculated the proportions of patients tested for EGFR mutation and computed selectivity indices for eleven periods. We used a log-linear model to assess the associations between the proportions tested, selectivity and the prevalence of EGFR mutation. Results: Of the 2986 patients involved in this analysis, 1280 (42.9%) were tested for EGFR mutation. The proportion tested increased from 3.7% in 2010 to 74.0% in 2016. Testing was more prevalent in younger age group, female, Asian and patients with adenocarcinoma, and when specimens for testing was available. Such selectivity, however, decreased from 2010 to 2016. The prevalence of EGFR mutation varied widely across the periods, ranging from 16.8% in January-June 2014 to 43.8% in 2010. It was negatively associated with the proportion tested ( P = 0.02), and positively associated with the selectivity of testing ( P = 0.03). The log linear models estimated that the prevalence of EGFR mutation would be at most 16.1% (95% CI: 9.5%–27.1%) if 100% of patients were tested. Conclusion: In New Zealand, the uptake of EGFR mutation testing has improved over time but there is still room for improvement. Incomplete and selective testing may result in an overestimation of the prevalence of EGFR mutation in patients with nonsquamous NSCLC.

Chronic neck pain following car crashes: a population-based study from Auckland, New Zealand

BACKGROUND

  In a setting with a 'no fault' universal government-funded accident compensation system, we undertook a study to (i) estimate the prevalence and predictors of chronic neck pain in car occupants surviving serious injury-producing crashes and (ii) compare the longer-term health-related quality of life of crash survivors with and without neck discomfort.

METHODS

  A prospective cohort study recruited hospitalized survivors aged ≥16 years and non-hospitalized drivers of cars involved in serious crashes in Auckland over a 10-month period. Participants completed a structured questionnaire at recruitment and 5 and 18 months later.

RESULTS

  Of the 268 participants, 50 (18.7%) reported neck pain or stiffness at 5 and 18 months following the crash. Of these, 70% noted the discomfort led to limitations in work and recreation. Depressive and post-traumatic stress symptoms at 5 months were associated with an increased risk of moderate to severe neck discomfort at 18 months. Participants with and without neck discomfort had significantly reduced health-related quality of life based on Short Form-36 scores.

CONCLUSION

  Significant neck discomfort limiting usual function is relatively common up to 18 months following crashes. The reductions in health status among crash survivors with and without neck pain reveal the complexities in attributing longer-term adverse outcomes to a particular condition in the absence of an appropriate comparison group. The findings indicate the need to manage judiciously comorbid conditions while prioritizing efforts to support crash survivors' return to their usual social roles and activities.