Improvement in survival of breast cancer patients - trends over two time periods in a single institution in an Asia Pacific country, Malaysia

BACKGROUND: There is improvement in breast cancer survival in the developed world, but information on breast cancer survival trends in the Asia Pacific region is limited. The aim of the study was to evaluate survival trends and factors that affect survival in Malaysia.

METHODS: Two prospective groups of 423 and 965 newly diagnosed breast cancer patients in University of Malaya Medical Centre, Kuala Lumpur, Malaysia diagnosed in two time periods ie. 1993 to 1997 and in 1998 to 2002 were studied. Vital status was obtained from the National Registry of Births and Deaths. The overall survival was calculated from the date of diagnosis to the date of death from any cause. The survival differences between the two groups were analysed using the log-rank or Peto-Wilcoxon method. Survival estimates and independent prognostic factors were estimated by the Kaplan-Meier method and multivariate analysis using Cox proportional hazard models. P values less than 0.05 were considered statistically significant. Analyses were performed using SPlus 2000 Professional Release 2.

RESULTS AND DISCUSSION: Median follow-up for the two groups were 55 months (SD 29.2 months) in the first group and 52 months (SD 24.43) in the second group. There was improvement in 5-year observed survival from 58.4% (CI 0.54-0.63) to 75.7% (CI 0.73-0.79). The improvement in survival was significantly seen in all co-variates (p< 0.05) except for those aged 40 years and below (p= 0.27), tumour size 2 to 5 cm (p=0.11), grade 3 (p=0.32) and patients with Stage IV disease (p= 0.80). Stage of disease, lymph node (LN) involvement, size and grade were identified as independent prognostic factors in cohort one. For the second cohort; stage and LN involvement remained independent factors with the addition of ER status and ethnicity.

CONCLUSIONS: There was improvement in 5-year observed survival. Besides known prognostic factors, Malay ethnicity was an independent prognostic factor.