Improved stage and survival for patients in the Aotearoa New Zealand colorectal cancer screening program 2012-2019.

BACKGROUND: Colorectal cancer (CRC) screening was introduced in Aotearoa New Zealand at Waitematā District Health Board (WDHB) in late 2011. This study reviewed patterns of disease, treatment received, and survival of patients with national bowel screening program (NBSP)-detected CRC versus non-NBSP patients at WDHB 2012-2019.

METHODS: Data collected retrospectively for all patients with adenocarcinoma of the colon or rectum at WDHB 2012-2019. Patient records were manually reviewed. Chi-square, Fisher's exact test and the Mann Whitney U-test used as appropriate. Kaplan-Meier and Cox proportional hazards regression modelling for survival analysis.

RESULTS: 1667 patients included (360 NBSP and 1307 non-NBSP). 863 (51.8%) were male. Median age at diagnosis 73 years (range 21-100); NBSP patients were younger (median 68 vs. 76 years, P < 0.001). NBSP patients had significantly lower T, N, M and overall TNM stage than non-BSP patients. Median survival estimate on Kaplan-Meier analysis was 94 months for all patients. Statistically significant (P < 0.05) predictors of mortality on multi-variate regression analysis included increasing overall TNM stage compared with stage I (stage II HR 1.63 (95% CI 1.14-2.34), stage III HR 2.86 (95% CI 2.03-4.03), stage IV HR 7.73 (95% CI 5.59-10.68)), diagnosis within NBSP (HR 0.51 (95% CI 0.37-0.71)), increasing age in years (HR 1.03 (95% CI 1.02-1.03)), urgent/emergency surgery (HR 1.66 (95% CI 1.36-2.01)) and formal resection of primary tumour (HR 0.31 (95% CI 0.25-0.38)).

CONCLUSION: Patients diagnosed within the Aotearoa New Zealand NBSP were found to be younger and have earlier stage CRC. Diagnosis within the NBSP is an independent predictor of survival for patients with CRC.