Osimertinib With or Without Bevacizumab in Treating Patients With EGFR Positive Non-small Cell Lung Cancer and Brain Metastases

Inclusion Criteria: * Non-small cell lung cancer (NSCLC) with an activating EGFR mutation (exon 19 deletion, L858R point mutation, or any other mutation known to be associated with EGFR TKI sensitivity); presence of an activating EGFR mutation may be documented in tumor tissue or by plasma testing if performed in a Clinical Laboratory Improvement Act (CLIA)-certified laboratory * No prior treatment with an EGFR TKI; patient may have received prior chemotherapy for early-stage or advanced disease but this is not required; prior immunotherapy is not allowed * Patients must have at least one measurable CNS lesion that is asymptomatic, untreated, and does not require local therapy at the time of enrollment; measurable CNS disease is defined as a brain metastasis that can be accurately measured in at least one dimension (longest diameter to be recorded) as \>= 5 mm (\>= 0.5 cm) with brain magnetic resonance imaging (MRI); if the lesion is 5-10 mm in size and is the only measurable disease, MRI imaging must be performed with 1.5 mm slice thickness or less; a history of previously treated brain metastases is allowed, however any lesion present at the time of whole brain radiotherapy or included in the stereotactic radiotherapy field (or within 2 mm of the treated lesion) will NOT be considered "untreated" unless it is new or documented to have progressed unequivocally since treatment * Patients are not required to have measurable systemic (i.e. non-CNS) disease; if present, measura…