title: Comparative risk of leptomeningeal disease after resection or stereotactic radiosurgery for solid tumor metastasis to the posterior fossa.
abstract: OBJECTIVE
  The authors tested the hypothesis that patients with metastatic posterior fossa lesions (MPFLs) treated with resection have a higher risk of leptomeningeal disease (LMD) than those with MPFLs treated with stereotactic radiosurgery (SRS).
  
  
  METHODS
  Between 1993 and 2004, 379 patients with MPFLs were treated with resection or SRS at The University of Texas M. D. Anderson Cancer Center. The authors' primary study outcome was the incidence of LMD, as diagnosed with cerebrospinal fluid cytological analysis and/or neuroimaging.
  
  
  RESULTS
  Resection was performed in 260 patients, whereas 119 patients underwent SRS. The median patient age was 56 years, 51% of patients were male, and 93% had a Karnofsky Performance Scale score>or=70. The most common primary cancers were those of the lung, breast, and kidney, as well as melanoma. Leptomeningeal dissemination of cancer occurred in 33 patients: 26 in the resection group and 7 in the SRS group (resection group: rate ratio [RR] 2.06, 95% confidence interval [CI] 0.89-4.75, p=0.09). Piecemeal tumor resection (137 cases) was associated with a significantly higher risk of LMD than en bloc resection (123 cases; RR 3.4, 95% CI 1.43-8.12, p=0.006) or SRS (RR 3.37, 95% CI 1.41-8.04, p=0.006), and there was no significant difference in the risk for LMD between en bloc resection and SRS (en bloc resection: RR 0.98, 95% CI 0.34-2.81, p=0.98). The multivariate RR and significance associated with piecemeal resection, however, were consistent, with a strong effect (RR 2.45, 95% CI 1.19-5.02, p=0.02) and no indication of biases associated with tumor size, location, or cystic/necrotic appearance.
  
  
  CONCLUSIONS
  There is an increased risk of LMD after piecemeal resection of an MPFL. This increase, although clinically and statistically significant, is not as alarming as previously reported and is absent when en bloc removal is achieved. Further assessment of the role of resection in a controlled prospective setting is warranted.
authors.affiliation: Department of Neurosurgery, The University of Texas M. D. Anderson Cancer Center, Houston, Texas 77030-4009, USA. dsuki@mdanderson.org
authors.forename: Dima
authors.initials: D
authors.lastname: Suki
authors.forename: Hiba
authors.initials: H
authors.lastname: Abouassi
authors.forename: Akash J
authors.initials: AJ
authors.lastname: Patel
authors.forename: Raymond
authors.initials: R
authors.lastname: Sawaya
authors.forename: Jeffrey S
authors.initials: JS
authors.lastname: Weinberg
authors.forename: Morris D
authors.initials: MD
authors.lastname: Groves
mesh_terms: D000293:Adolescent; D000328:Adult; D000368:Aged; D000369:Aged, 80 and over; D001099:Arachnoid / Q000473:pathology*; D001932:Brain Neoplasms / Q000556:secondary* / Q000601:surgery; D001943:Breast Neoplasms / Q000473:pathology; D002528:Cerebellar Neoplasms / Q000556:secondary / Q000601:surgery; D002648:Child; D003388:Cranial Fossa, Posterior; D005260:Female; D006801:Humans; D007680:Kidney Neoplasms / Q000473:pathology; D008175:Lung Neoplasms / Q000473:pathology; D008297:Male; D008545:Melanoma / Q000556:secondary; D008577:Meningeal Neoplasms / Q000473:pathology* / Q000556:secondary; D008875:Middle Aged; D009366:Neoplasm Seeding; D010841:Pia Mater / Q000473:pathology*; D011149:Pons / Q000601:surgery; D016634:Radiosurgery / Q000009:adverse effects; D012307:Risk Factors; D015996:Survival Rate; D016896:Treatment Outcome