Background: The aim of this study was to detect prognostic factors in recurrent breast cancer metastasis.
Materials and methods: This retrospective cohort study employed data from 996 breast cancer patients of Isfahan Seyed-o-Shohada research center from 1998 to 2010. Stratified Cox proportional hazards model, marginal approach, was used to evaluate the prognostic value of estrogen receptor, progesterone receptor, tumor protein 53, human epidermal growth factor receptor type 2, diagnosis age, nodal ratio, tumor size, antigen Ki67, and cathepsin D. Survival curves were plotted using Kaplan-Meier method and log-rank test was carried out to compare survival in two categories of nodal ratio (≤0.25 vs. >0.25).
Results: In simple Cox regression model, age (P = 0.037), nodal ratio (P < 0.0001), and Ki67 (P = 0.032) were associated with hazard of distant metastasis. Multiple analysis showed that patients with greater nodal ratio had significantly higher adjusted hazard of recurrent metastasis (Hazard ratio: 2.756, 95% Confidence interval: 1.017-7.467; P = 0.046). Tumor size was not an independent prognostic factor for recurrent metastasis. Comparing survival curves, there was significant difference between two categories of nodal ratio in the first (P < 0.0001), second (P < 0.0001) and third (P = 0.024) metastasis; survival was higher in-patients with nodal ratio <0.25.
Conclusion: Our findings indicate that tumor size was insignificant; this raises the question about conventional premise of being a major prognostic factor for distant metastasis. Furthermore, nodal ratio is suggested to clinicians as a prognostic variable in follow-up of breast cancer patients; patients with higher nodal ratio have greater hazard of distant metastasis.
Keywords: Axillary nodal ratio; breast cancer; distant metastasis; marginal approach; prognostic factor; stratified cox proportional hazards model; tumor size.