ESR1 and cancer: This is an important consideration as the presence of intratumoral T cells has been shown to correlate with improved survival in patients with several cancer types such as ovarian, colon, lung, melanoma, and breast cancers.[32], [33], [34], [35], [36], [37] Moreover, tumor infiltrating lymphocytes have been shown to predict response to anthracycline-based chemotherapy in estrogen receptor-negative breast cancer.[38].