In this study, known anticancer/genotoxic properties of two different “molecule parts,” (i) triorganotin and (ii) isothiocyanate, combined into recently synthesized (commercially inaccessible) tributyltin isothiocyanate (TBT-ITC) and triphenyltin isothiocyanate (TPT-ITC), underwent investigation of their cytotoxic effects in both human estrogen-receptor-positive MCF 7 and human triple-negative MDA-MB-231 breast carcinoma cell lines. The gene discussed is ESR1; the disease is breast carcinoma.