Pre-diagnosis:1. TNBC/HER2+ BC: once a year2. NSCLC/SCLC: every 4 months3. Melanoma: every 6 monthsAt 1st CNS diagnosis:As close to diagnosis of CNS metastases and no later than 6 weeks afterPost diagnosis:Every 3 months (+/- 1 month). Here, ERBB2 is linked to melanoma.