Can uterine fibroids lead to cancer?

Not directly . Fibroids are a result of high estrogen levels. High estrogen can be caused by excessive carbohydrate intake (via competetive inhibition of glucoronidase enzyme) therefore a low carb diet is beneficial to reduce estrogen and help shrink fibroids. You may also have low iodine, thyroid problems, low progesterone. All of these things should be evaluated. High estrogen levels can cause cancer.
Very rarely. Fibroids are benign tumors that only very rarely may become malignant.