Breast cancer treatment modalities, treatment delays, and survival in Brunei Darussalam.

Introduction: Breast cancer remains a leading cause of cancer-related mortality globally. This study aims to examine the demographic variables and effects of different treatment modalities and treatment delays on overall and relative survival rates of breast cancer patients in Brunei Darussalam.

Methods: This retrospective study analysed data from the Brunei Darussalam Cancer Registry on breast cancer cases diagnosed and treated between 2013 and 2022. Statistical analyses included descriptive statistics to characterise the study population, Kaplan-Meier estimates to compare survival curves of different groups, Log rank tests to determine significant differences in survival rates among groups, and Cox Proportional Hazard (PH) models to estimate hazard ratios (HRs) and identify predictors of survival outcomes. Overall survival (OS) and relative survival (RS) rates were calculated.

Results: Out of the 431 women treated for breast cancer, the majority were diagnosed at the regional stage (45.7%), with 39.0% at the localised stage. Over half (55.4%) of the diagnoses occurred in women aged 40 to 59, while about a quarter (25.5%) were in the 60-69 age group. Surgery was the most common first-line treatment modality (55.9%), with a median time to treatment of 37 days, followed by chemotherapy (30.6%). More than half of the patients (62.9%) were treated within 60 days of diagnosis. Treatment varied by age and cancer stage, with younger patients more likely to undergo surgery and older patients more likely to receive chemotherapy or hormonal therapy. Survival rates were high for patients receiving only surgery (5-year RS: 98.7%, OS: 92.3%), and significant survival differences were found for cancer stage and treatment delay, with a HR of 2.5 for delays over 60 days. Multivariate analysis showed that patients with distant stage cancer had a significantly higher risk of death (HR = 15.3) compared to localised stage.

Conclusion: This study highlights the impact of treatment modalities and delays on breast cancer survival in Brunei Darussalam, emphasising the need for timely treatment to improve survival rates. Our findings suggest that ensuring breast cancer treatment initiation within two months post-diagnosis may enhance patient outcomes, supporting potential policy targets for timely access to care.