Empiric dose reduction of pegfilgrastim in breast cancer patients receiving cytotoxic chemotherapy

20636 Background: Pegfilgrastim greatly reduces the incidence of febrile neutropenia in patients receiving myelosuppressive chemotherapy, but is associated with side effects such as bone pain often requiring analgesics. Empiric dose reduction from 6mg to 4mg administered on the day after chemotherapy was used to ameliorate pain while maintaining count recovery in these patients. Methods: We retrospectively reviewed 25 female breast cancer patients who were undergoing adjuvant or neoadjuvant chemotherapy with pegfilgrastim support who had empiric dose reductions because of bone pain with concomitant normal or high leukocyte counts during recovery. Data of blood counts, complaints of bone pain and analgesic use were collected. Weekly complete blood counts (CBC’s) were analyzed. White cell counts and ANC before and after pegfilgrastim dose reduction and treatment delays post dose reduction were recorded. Results: Median age was 52 yrs (5 < 40, 6 < 50, 6 < 60, 4 < 70 while 2 were more than 70); 18 were African Americans, 7 Caucasians; 4 stage I, 13 were stage II and 8 were stage III. Seven patients received neoadjuvant chemotherapy and 18 received it in the adjuvant setting. Thirteen patients (52%) were estrogen receptor positive; 56% patients received Doxorubicin and cyclophosphamide (60/600 mg/m2) followed by docetaxel (100 mg/m2). Median number of cycles given was 7 (range 4–10) and total number of CBC’s recorded were 397. After dose reduction, the highest white cell count noted on day 8 of the cycle was 48,600 and 41,300 on day 15; 8 patients had WBC >20,000. The lowest nadir WBC count after dose reduction was 800 with an ANC of 200 on day 8. Seven patients required narcotics for pain control at standard dose of pegfilgrastim. None of the 25 patients experienced bone pain after dose reduction. We were able to give 100% of the planned doses without dose delays in all cases after a dose reduction to 4 mg per cycle. Conclusions: From this small experience, it appears that dose reduction may be a viable and safe option to avoid the undesirable side effects of pegfilgrastim especially bone pain in patients receiving cytotoxic chemotherapy. A prospective well designed study in appropriately selected patients is warranted to investigate the optimal dose in these patients. No significant financial relationships to disclose.