J Korean Neurosurg Soc 52 | September 2012 tients, CSF testing was not performed. Risk factors for the development of LMC It is known that certain biological features of breast cancer af- fect clinical finding including LMC. Several reports have sug- gested a higher risk for brain metastasis in HER-2 positive and triple negative (TN) breast subtypes than in hormone receptor (HR) positive subtypes6,19,20). Lee et al.18) reported a different dis- tribution of subtypes of breast cancer between PBM with LMC and PBM without LMC, and a worse prognosis of patients with TN. However, the direct comparison of incidence of LMC ac- cording to the subtypes of breast cancer was not made. Several studies suggested that mechanical spread of tumor cells to the CSF space could contribute to the development of LMC. Some studies reported an increased incidence of LMC after posterior fossa tumor surgery compared with supratento- rial lesions25,35). Other studies observed a higher incidence of LMC after SR compared with non-surgical treatment31-33). Nor- ris et al.25) suggested that the more chance of CSF exposure in patients receiving posterior fossa tumor removal was responsi- ble for the increased development of LMC. Suki et al.33) report- ed increased incidence of LMC in patients with PBM, whose tumor was removed in a piecemeal manner than en-bloc exci- sion. Thus, authors investigated the incidence of LMC after SR of PBM according to the proximity to CSF pathway and suggest- ed the PBM not entirely surrounded by brain parenchyma should be removed in caution not to spill the tumor by piece- meal removal or using Cavitron ulatrsonographic aspirator1). In our study, the SR group showed a significantly higher incidence of LMC than the WBRT group, which is in accordance with previous finding. However, the PBM location whether or not the lesions involved posterior fossa, did not affect the risk of de- velopment of LMC. This result may reflect not tumor location itself but a chance for CSF exposure to be responsible for devel- opment of LMC. Known prognostic factors for the survival of breast cancer patients include axillary nodal status, tumor size/type/grade, lymphatic/vascular invasion, proliferation markers, ethnicity and patient age at diagnosis. Many studies, which evaluated the influence of age on outcome in breast cancer have been small and had conflicting results. Two relatively large trials have, how- ever, demonstrated a worse prognosis for patients younger than 35 years of age, even after adjustment for other prognostic fac- tors4,39). Studies suggested different and aggressive biological be- haviors of younger age breast cancer. A different distribution of molecular phenotypes in the population of young women with breast cancer compared to the general population of women with breast cancer was reported7). Young age appears to be an independent risk factor and the median age of patients with brain metastases is about 5 years younger than those without brain metastases6). In our study, an age of younger than 40 years was an independent risk factor for development of LMC in pa- tients with PBM from breast cancer. This propensity is in accor- dance with the observation of Lee et al.18), where the age of PBM from breast cancer patients with LMC was significantly young- er than those without LMC although the variables were not ad- justed. The role of systemic chemotherapy to prevent CNS metasta- sis has not yet been proven. However, a recent study reported a favorable outcome showing significantly prolonged survival in patients with PBM from breast cancer who received chemo- therapy, compared with the patients without chemotherapy16). These finding leave a possibility that the chemotherapy directly reduce PBM from breast cancer or LMC, in addition to prolong- ing patient’s survival by decreasing the systemic cancer burden. In our study, the patients in a direction of reduced systemic can- cer burden (i.e. patients with stable or NED of systemic cancer and patients with systemic chemotherapy) showed a decreased risk for the development of LMC after treatment for their PBM from breast cancer. The role of WBRT for preventing CNS recurrence after SR of PBM was proven in a randomized controlled clinical trial27). However, it is unclear whether or not this “CNS recurrence” in- cluded LMC, and we could not find any study that compared not the local recurrence rate, but the risk of LMC after SR in pa- tients with or without WBRT9,10). An 11% incidence of LMC in the WBRT only group in our study is the first presented figure indicating the natural risk for the development of LMC without SR. But in this cohort, we did not have a group of patients, who had PBM from breast cancer without WBRT. Thus, to evaluate the role of WBRT for preventing the development of LMC, a further well controlled cohort study is needed. CONCLUSION This retrospective analysis revealed an increased risk for the development of LMC after SR of PBM from breast cancer com- pared with WBRT. The young age (<40) and systemic cancer burden in terms of progressing systemic could be additional risk factors for LMC, whereas continued systemic chemothera- py after the index procedure may reduce the incidence of LMC in patients with PBM from breast cancer. References 1. Ahn JH, Lee SH, Kim S, Joo J, Yoo H, Lee SH, et al. : Risk for leptomen- ingeal seeding after resection for brain metastases : implication of tumor location with mode of resection. J Neurosurg 116 : 984-993, 2012 2. 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