The pre-cancer or premalignant niche is a site in which high rates of oxidative stress, the circulation of pro-angiogenic factors, dysregulated immunity, aberrant cellular metabolism and/or tissue-specific events (e.g., injury, elevated levels of stress hormones, aromatase, etc.), come together to create a local environment conducive to malignant transformation and cancer progression [18,33]. This evidence concerns the gene CYP19A1 and cancer.