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Abstract
We investigated a prognostic impact of radiotherapy-induced lymphopenia (RIL) in breast cancer patients treated with breast-conservative surgery (BCS). We included 531 breast cancer patients who were treated with BCS and adjuvant radiotherapy. None of these received (neo)adjuvant chemotherapy. Pre- and post- absolute lymphocyte counts (ALC) were reviewed before and after radiotherapy. The primary endpoint was to evaluate recurrence-free survival (RFS) according to the pre-to-post ALC ratio. Binary logistic regression model was used to identify risk factors for RIL. Either continuous or categorical (> 2.4) pre-to-post ALC ratio was associated with RFS. In 531 patients receiving whole breast irradiation (WBI) and regional nodal irradiation (RNI), RFS was significantly reduced in the patients with high pre-to-post ALC ration (> 2.4). In multivariable analysis, low pre-to-post post ALC ratio was significantly related to decreased RFS in the multivariable analysis (HR 2.293, 95% CIs 1.110-4.735, P = 0.025). In 452 patients treated with WBI alone, high pre-to-post ALC ratio was still significantly associated with decreased RFS in the multivariable analysis (HR 2.708, 95% CIs 1.016-7.218, P = 0.046). In binary logistic regression analysis, RNI was only significant risk factor for clinically meaningful RIL. Our findings show that a markedly decrease in ALC during radiotherapy has a negative prognostic impact.

Affiliations

Chang Ik Yoon # 1, Jawon Hwang # 2, Dooreh Kim 1, Jung Hwan Ji 2 3, Janghee Lee 4, Soong June Bae 2 3, Joon Jeong 2 3, Jee-Suk Chang 5, Yeona Cho 5, Hye Sun Lee 6, Jee Ye Kim 7, Sung Gwe Ahn 8 9
1Department of Surgery, College of Medicine, Seoul St Mary's Hospital, The Catholic University of Seoul, Seoul, Republic of Korea.
2Department of Surgery, Gangnam Severance Hospital, Yonsei University College of Medicine, 211 Eonju-ro, Dogok 1(il)-dong, Gangnam-gu, Seoul, 06273, Republic of Korea.
3Institute for Breast Cancer Precision Medicine, Yonsei University College of Medicine, Seoul, Republic of Korea.
4Department of Surgery, Hallym University Dongtan Sacred Heart Hospital, Hwaseong, Republic of Korea.
5Department of Radiation Oncology, Gangnam Severance Hospital, Yonsei University College of Medicine, Seoul, Republic of Korea.
6Biostatistics Collaboration Unit, Yonsei University College of Medicine, Seoul, Republic of Korea.
7Division of Breast Surgery, Department of Surgery, Breast Cancer Center, Yonsei Cancer Center, Severance Hospital, Yonsei University College of Medicine, 50-1 Yonsei-ro, Sinchon-dong, Seodaemun-gu, Seoul, 03722, Republic of Korea. JEEYE0531@yuhs.ac.
8Department of Surgery, Gangnam Severance Hospital, Yonsei University College of Medicine, 211 Eonju-ro, Dogok 1(il)-dong, Gangnam-gu, Seoul, 06273, Republic of Korea. asg2004@yuhs.ac.
9Institute for Breast Cancer Precision Medicine, Yonsei University College of Medicine, Seoul, Republic of Korea. asg2004@yuhs.ac.
#Contributed equally.