both supratentorial and infratentorial brain metastases. Adjuvant chemother- apy after the index procedure was per- formed in 103 patients (56%) KPS was equal or greater than 70 in 90% of the patients. At the time of the index proce- dure, 118 patients (64%) had ‘progres- sive’ systemic disease and 65 patients had ‘stable’ disease or ‘no evidence of disease (NED)’. Analysis of factors affecting the incidence of LMC LMC occurred in 27 out of 183 patients (14%) with the median time to LMC of 8.0 months (range, 2-26 months) (Fig. 1). LMC was diagnosed only by typical MRI findings for ten patients, only by cytology for two patients, and by both CSF cytology and MRI for the remain- ing 15 patients. After diagnosed with LMC, 15 patients received intra-CSF chemotherapy. Four patients received WBRT only with or without spinal radi- ation and the remaining 8 patients de- ferred any further treatment. The distributions of the incidence of LMC according to various patients’ characteristics and the haz- ard ratios of these factors based on cumulative LMC incidences are presented in Table 2. The incidence of LMC was significantly higher in the SR group than the WBRT group, as 10 of 27 (37%) patients were diag- nosed with LMC. The hazard ratio (HR) for development of LMC in the SR group compared to WBRT was 2.95 (95% CI, 1.33-6.54; p=0.008) (Fig. 2). The incidence of LMC was higher in the younger age group (<40 years old) compared with that in patients aged 40 years or older as 8 out of 24 younger age pa- tients developed LMC after the index procedure. However, the difference was not statistically significant at 0.05 (HR=2.36, 95% CI, 0.98-5.65, p=0.055). The time from diagnosis to brain me- tastasis (<12 versus ≥12 months), tumor volume (≤4.0 versus >4.0 mL3), number of lesions (single versus multiple), location of tumor (supratentorial versus infratentorial), adjuvant che- motherapy, KPS (≥70 versus <70) and systemic disease status (NED or stable versus progressing) were not significantly asso- ciated with the incidence of LMC in univariable analysis. Multivariable analysis of factors affecting the incidence of LMC Among the factors analyzed univariately for the cumulative incidence of LMC, variables with a p-value less than 0.2 were included in the multivariable Cox proportional hazards model (Table 3). Leptomeningeal Carcinomatosis from Brain Metastases of Breast Cancer | JM Jung, et al. Table 1. Characteristics of patients with who underwent surgical resection or whole brain radiation therapy for brain metastases of breast cancer Characteristics Age (range) Follow-up (range) Time from diagnosis to brain metastasis (range) Tumor volume (range) All patients (n=183) 52.0 (28-80) 6.3 months (1-51) 41 months (1-271) 4.0 cm3 (0.01-105.00) Surgical resection (n=27) 50 (33-77) 8.0 (1-36) 35 months (6-120) 10.9 cm3 (1.00-105.00) WBRT (n=156) 52.0 (28-80) 5.8 (1-51) 44 months (1-271) 3.1 cm3 (0.01-72.20) p-value 0.392 0.081 0.312 <0.001 No. of lesions Single 58 (32) 21 (78) 37 (24) <0.001 Multiple 125 (68) 6 (22) 119 (76) Location Supratentorial 52 (28) 22 (81) 30 (19) <0.001 Infratentorial* 131 (72) 5 (19) 126 (81) Adjuvant chemotherapy No 80 (44) 10 (37) 70 (45) 0.449 Yes 103 (56) 17 (63) 86 (55) KPS ≥70 164 (90) 24 (89) 140 (90) 0.893 <70 19 (10) 3 (11) 16 (10) Systemic disease status NED & stable 65 (36) 16 (60) 49 (31) 0.005 Progressing 118 (64) 11 (41) 107 (69) Numbers in parenthesis, not specified elsewhere, represents column percentage. *Multiple lesions distributing both supra- and infratentorial area are classified into “Infratentorial”. WBRT : wholebrain radiation therapy, KPS : Karnofsky Performance Status, NED : no evidence of disease 1.0 C0.8 M L t u to0.6 h i w n ito0.4 r o p o r P0.2 0.0 0 10 20 30 40 Time from index procedure (months) 50 Fig. 1. Kaplan-Meier curve for time to development of LMC after treat- ment of the parenchymal brain metastases plotted for 183 patients in our study. Y-axis represents the proportion of patients without LMC at each follow-up time at the X-axis. 27 patients developed LMC (14%) during the follow-up. LMC : leptomeningeal carcinomatosis. Among the preoperative characteristics, the index procedure was still significant and the younger age group gained statistical significance in this multivariable analysis. The administration of adjuvant chemotherapy and NED/stable systemic disease status significantly reduced the cumulative incidence of LMC in multivariable analysis even though these variables were not significant at the p-value 0.05 in the univariable analysis. Com- 195