# Disparities in time to breast cancer surgery in New Zealand by level of neighbourhood deprivation: a population-based study

## TL;DR

This study finds that women in more deprived neighborhoods in New Zealand still face longer delays for breast cancer surgery, even after a national treatment plan aimed to reduce inequities.

## Contribution

The study evaluates the impact of New Zealand's Faster Cancer Treatment plan on reducing surgical delays for breast cancer by neighborhood deprivation levels.

## Key findings

- Women in the most deprived neighborhoods were more likely to experience delays beyond 31 days for breast cancer surgery.
- Despite the FCT plan, significant inequities in timely access to surgery persist, particularly for Māori and those in deprived areas.
- Adjusting for factors like ethnicity and treatment facility type reduced the observed disparity, but inequities remained.

## Abstract

The New Zealand (NZ) Faster Cancer Treatment (FCT) plan aims for equitable cancer treatment irrespective of sociodemographic factors. Research on its impact on breast cancer surgery times is limited. This study evaluates whether (1) there are differences by level of neighbourhood deprivation in time to surgery in women with early-stage (1–3a) breast cancer in NZ between 2000 and 2020 and (2) whether this association differs pre- and post- FCT implementation.

This retrospective analysis used Te Rēhita Mate Ūtaetae (NZ Breast Cancer Foundation National Register), a prospectively maintained national database of breast cancers. Logistic regression models evaluated differences by neighbourhood deprivation in time to surgery beyond 31 days (defined in the FCT as the longest acceptable delay in time to first treatment). Deprivation was measured using the NZ Deprivation (NZDep) Index, an area-based measure of socioeconomic deprivation in deciles (decile 1 = least deprived to decile 10 = most deprived) categorised into quintiles. Models were adjusted sequentially for potential contributing factors across five domains; demographic [age, ethnicity, urban or rural place of residence], mode of diagnosis [screening programme or symptomatic], tumour [stage, grade, receptors], treatment facility type [public/private hospital] and treatment [locoregional and systemic]. Subgroup analysis by pre- and post-FCT implementation date were undertaken.

Of the 20,322 women included in the analysis, 23.5% were in the least deprived neighborhoods (NZDep index 1–2) and 13.8% were in the most deprived neighborhoods (NZDep index 9–10) and 22.3% 21.0% 19.5% were in 3–4, 5–6 and 7–8, respectively. Overall, 73% of the women were NZ European, 10% Māori (indigenous NZ people), 7% Pacific (from the Pacific islands) and 10% were Asian. In the unadjusted model, compared to the least deprived quintile, all other NZDep index quintiles were more likely to experience delay beyond 31 days. In the maximally adjusted model, compared to the least deprived quintile, only women in the most deprived quintile were more likely to experience delay in time to surgery > 31 days (OR 1.31; 95% CI: 1.17, 1.47). Key contributing factors to this reduction in OR were ethnicity and treatment facility type. A marginal but non-significant reduction in time to surgery was observed in the post-FCT period.

Women residing in more deprived neighborhoods experienced greater delay in time to breast cancer surgery. Despite FCT implementation, urgent action is still needed to reduce inequities by deprivation in timely access to breast cancer surgery.

The online version contains supplementary material available at 10.1007/s10552-025-02032-0.