COMT and vitamin D deficiency: Previous research has presented evidence elucidating potential mechanisms contributing to the racial disparity in tumor development and progression, including a higher incidence of vitamin D deficiency in Black patients [89,90]; higher levels of aromatase (CYP19), progesterone receptor A (PR-A), and lower levels of retinoic acid receptor-α (RARA) [89,90]; and increased polymorphism of the genes ER (estrogen receptor), CYP17 (cytochrome P450C17α), and COMT, which are involved in estrogen synthesis, in tumors from Black women [89,90].