There is a very small subset of women with fibrocystic tendency who are at increased risk, based upon findings at biopsy or on mammography. Most women are not at increased risk. Even for early stage disease, many physicians recommend additional systemic therapy. This might be Tamoxifen or it might be chemotherapy. The purpose of this additional systemic therapy is to kill any circulating breast cancer cells and prevent spread.
Cysts are just collections of fluid.
They can be detected on physical examination or on ultrasound. Aspirating the fluid collapses the cyst and makes the lump go away. These simple cysts have no relationship to breast cancer that we know of. The crucial thing is to be certain that the lump is just a cyst. That is why confirming the diagnosis with ultrasound and aspiration is so important.