Breast biomarkers evolution between primary and distant metastasis: incidence and significance

Aims To evaluate the evolution when breast cancer (BC) is classified as three clinical profiles and five clinical profiles by incorporating human epidermal growth factor 2 (HER2)‐low to the biomarkers’ profile. Methods and results BC with distant metastasis that has document hormonal receptors (HR) (positive, negative) and HER2 (positive, low, zero) results were included ( n = 161). Cases were categorised into three clinical profiles (HR‐positive/HER2‐negative, HER2‐positive and TNBC) and five (HR‐positive/HER2‐zero, HR‐positive/HER2‐low, HR‐negative/HER2‐zero, HR‐negative/HER2‐low, HR‐positive or negative/HER2‐positive). Evolution occurred in 22.4% cases when three clinical profiles were analysed and 36.6% considering five clinical profiles. There were no statistically significant differences among the three clinical profiles in overall survival (OS). When five clinical profiles were analysed, HR‐negative/HER2‐zero had the worst OS with HzR = 6.82 and 95% confidence interval (CI) =1.19, 39.23, P = 0.031. In the multivariable analysis, ER‐positive was associated with HER2 discordance less than oestrogen receptor (ER)‐negative with odds ratio (OR) = 0.354 and 95% CI = 0.14–0.88, P = 0.025. In the multivariable analysis, patients with Eastern Cooperative Oncology Group 2+ had worse OS with hazard ratio (HzR) = 5.54 and 95% CI = 2.4–12.79, P < 0.0001. HR concordant had better OS with HzR = 0.34 and 95% CI = 0.2–0.63, P = 0.0004. HER2 conversion from low to zero had worse OS than HER2 concordance with HzR 2.66 and 95% CI = 1.21–5.83, P = 0.015. Conclusions Five‐profile classification provides a more accurate idea about the rate of potential change in treating BC in the metastatic setting.