CDK4 and neutropenia: The PALOMA-2 trial [38], when exploring the incidence of hematological adverse effects in patients treated with CDK4/6 inhibitors, reported neutropenia grades 3 and 4 in up to 66% of patients, a number that is not far from the 43% observed amid the studies included in this literature review, especially considering that blood counts are seldom collected during short palliative radiation treatments.