We noted that the number of receptors assessed substantially affects the cost comparison: biomarker analysis by STRAT4 costs US$ 38.23 (175.6%) or 13.76 (29.8%) more per patient than by immunohistochemistry at laboratories that only assess estrogen receptor status or estrogen and progesterone receptor status (relative to assessing three breast cancer biomarkers), respectively. The gene discussed is ESR1; the disease is breast carcinoma.