P51-3 Examination of CARG toxicity scores in palbociclib therapy for elderly patients with breast cancer

Abstract

Palbociclib is proven to be effective against hormone receptor-positive, metastatic and recurrent breast cancer and is being adopted as a standard treatment. In clinical practice, elderly patients with poor general condition are at risk for adverse events of palbociclib. Four hormone receptor-positive breast cancer patients, aged 70 years and above, who received palbociclib therapy, were enrolled in this study. The toxicity risk of Grade 3-5 (G3-5) predicted through the Cancer Aging Research Group (CARG) toxicity scores, a tool for predicting adverse events in cancer chemotherapy, were retrospectively compared with the actual adverse events. The median age (range) of four patients was 76.5 (70 to 83) years. The group included one case of Stage 4 cancer and three cases of postoperative recurrence. Three patients were undergoing one endocrine therapy regimen after recurrence, while the remaining one was not undergoing any endocrine therapy regimens. None of them had a history of chemotherapy. All had CARG scores of 8 (moderate risk), and their toxicity risk of G3-5 was 59%. The actual adverse events were neutropenia: G2 one case / G3 two cases / G4 one case, thrombocytopenia: G5 one case, and anemia: G4 / one case. The G3-5 incidence, as predicted by the GARG scores, was 100%, with a concordance rate of 75% with the actual adverse events. The progression-free survival of the three patients who were able to continue therapy was 218, 444, and 377 days, respectively, showing a sufficient response period. The 85-year-old patient who started with a reduced initial dose was hospitalized four weeks after administration on account of impaired consciousness with pancytopenia. The patient died of cerebral hemorrhage three days after the administration. Palbociclib therapy in elderly patients can have serious outcomes with a moderate-to-high risk of toxicity based on the CARG score. Close follow-up is thus recommended even after dose reduction.