Pongsatorn Supaattagorn; Radiation Oncology Department, Ubonratchathani Cancer CenterTawin Chottetanaprasith; Radiation Oncology Department, Ubonratchathani Cancer CenterThanut Khuayjarernpanishk; Radiation Oncology Department, Ubonratchathani Cancer CenterSirilak Ngoeiwikit; Radiation Oncology Outpatient Department, Ubonratchathani Cancer CenterChuenchom Songyai; Radiation Oncology Outpatient Department, Ubonratchathani Cancer CenterKanittha Promsumlee; Radiation Oncology Outpatient Department, Ubonratchathani Cancer CenterMutita Sappsarn; Radiation Oncology Outpatient Department, Ubonratchathani Cancer Center2011-02-212011-02-212010-04-182010-04-18Journal of Thai Society of Therapeutic Radiology and Oncology - วารสารมะเร็งวิวัฒน์; Vol. 16 No. 1 January – June 2010; 51 - 54http://imsear.searo.who.int/handle/123456789/131240The addition of radiation after mastectomy or breast conservative surgery in high risk breast cancer women can reduces the risk of locoregional recurrence. Weekly CBC is a routine monitor during the period of radiation. But the CBC abnormalities or bone marrow suppression is not much observed in our clinical practice.The purpose of this retrospective study was to evaluate the necessary of this routine practice. We had collected the CBC abnormalities in 122 stage I-III breast cancer patients who received postoperative radiation with or without preceding adjuvant chemotherapy in 2008.The finding showed that 27 % ,12.2 % and 2.4 % of patients had Hb \< 10 g% , ANC \< 1,500/mm3 and PLT \< 100,000 /mm3 in any weeks during radiation period. The mean duration between adjuvant chemotherapy and starting date of radiation were 4 weeks and 4.8 weeks in the patients who had abnormal CBC and no abnormal CBC respectively. Most of these abnornormalities occurred in the first 3 weeks of radiation.In our conclusion, routine CBC entired radiation period may not be necessary. CBC monitor in the first few weeks and clinical evaluation may be suffi cient.en-USThai Society of Therapeutic Radiology and Oncology, Bangkok, ThailandOriginal Article