I have a growing fibroadenoma mammae (non-dangerous tumor), what to do?

Leave alone: Fibroademomas represent the effect of hormones on breast tissue. In the 30's the effect produces reaction on breast tissue producing fibroadenomas which are benign and should be left unless they continue to enlarge to form a giant lesion. When the breast tissue stops responding the hormone effect acts on the milk ducts to produce cysts. These lesions rarely convert to malignancy.

See breast surgeon: Fibroadenomas are generally benign and do not require any treatment. If it is increasing in size,the recommendation is to remove it. In rare cases, it can be a phyllodes, which is like a fibroadenoma but tend to grow large. Find a breast surgeon who can evaluate you and provide a recommendation or follow you clinically.