How would you approach a patient with metastatic ER/PR+,HER2- breast cancer with linear leptomeningeal enhancement on MRI but negative CSF protein and cytology?
She had disease progression on palbociclib and letrozole. She also has a PIK3CA mutation however did not tolerate alpelisib due to Grade 3 hyperglycemia and depression.
Answer from: Medical Oncologist at Academic Institution
First, it is important to note that the sensitivity of CSF cytology depends on both the number of LPs and the volume of LP. For example, one LP has a sensitivity of only ~70%, while doing more than 3 LPs takes the sensitivity up to 98%. Similarly, withdrawing at least 10ml of CSF improves sens...