Determination of GFR is a cornerstone of the curative and palliative management of patients with carboplatin-responsive cancer such as lung, ovary, triple-negative– and germline BRCA1/2 mutation–positive breast cancer, and seminomas.18-27 Carboplatin doses are most commonly calculated using the Calvert equation,1 which is a linear relationship between GFR and dose. Here, BRCA1 is linked to cancer.