My approach is best described as aggressive. While I'm always pleased to see alternate opinions because I am not certain of anything, I'm motivated by the occurance of breast cancer metastasized to the brain a neighbor, a renter and a relative. All of these women had breast cancer over 30 years earlier and were assured of the cureative effect of treatment.
Until I had cancer myself, I couldn't understand how these intelligent women hadn't had followup testing. Now I understand that the follow up is not encouraged expecially after five years. And is sometimes denied by medical providers. Most cancers don't end up directly in the brain and in these cases there were different stops along the way where cancers would have been detected. Undetected brain cancer is a painful madness. In all three women it was behaviour that alerted medical professionals to the cancers, too late.
Worse is the number of chemotherapeutic agents that enhance metastasis. https://www.ncbi.nlm.nih.gov/pmc/articles/PMC6616300/#:~:text=Chemotherapeutic%20drugs%2C%20cisplatin%2C%20paclitaxel%2C,6%2C%20and%20VEGF%2DA.
Now I'am beginning to understand that PET/CTs are uncommonly used before or after beast cancer.