How often is monitoring needed?
Labs (blood tests) may be checked before the start of treatment, every two weeks during the first two cycles, then prior to the start of each cycle thereafter. Labs often include: Complete Blood Count (CBC), Comprehensive Metabolic Panel (CMP), magnesium, phosphorous, plus any others your doctor may order.
How often is imaging needed?
Imaging may be checked before treatment, then as often as every two months for the first 18 months, then every three months thereafter. Imaging may include: magnetic resonance imaging (MRI) or computerized tomography (CT) scans.
Electrocardiograms (ECG, or EKG) are typically done prior to starting treatment, approximately two weeks after starting treatment, before Cycles 2 and 3, then at the discretion of your doctor thereafter. DEXA (dual energy x-ray absorptiometry) scans may be performed to monitor your bone mineral density (bone strength).
How might blood test results/imaging affect treatment?
Depending upon the results, your doctor may advise to continue ribociclib and anastrozole as planned, reduce the dose of future ribociclib treatments (there are no dose reduction recommendations for anastrozole), delay the next dose until the side effect goes away, discontinue ribociclib but continue anastrozole, or switch to an alternative therapy.
Electrolytes and liver function will be monitored using a CMP blood test. If the serum potassium or magnesium are low, your doctor may prescribe potassium or magnesium supplements to help prevent heart rhythm problems. If the liver function decreases, your doctor may delay therapy or reduce the dose of ribociclib.
If the echocardiogram (ECG, EKG) shows a prolonged QTc interval, your doctor may recommend to hold therapy until the ECG returns to normal. In addition, the dose of ribociclib may be decreased.
Neutropenia will be monitored using a CBC blood test. If the neutrophil count decreases, your doctor may delay therapy for one or more weeks, and resume ribociclib at a reduced dose. Stopping treatment for neutropenia is rare and occurs in about 1% of patients taking ribociclib.