✓ The cell-surface receptor for hyaluronic acid, CD44, is expressed by both normal and malignant cells. Numerous CD44 isoforms have recently been identified that are derived by alternative ribonucleic acid splicing. The expression of some CD44 isoforms has been shown to be involved in tumor progression and metastatic spread in a rat carcinoma model and in human carcinomas. In the present study, CD44 isoform expression was evaluated by reverse transcriptase—polymerase chain reaction (PCR) analysis in frozen sections derived from three samples of normal brain tissue and from 40 brain tumors, including samples of glioblastoma multiforme, anaplastic astrocytoma, low-grade astrocytoma, cerebral primitive neuroectodermal tumor, medulloblastoma, metastatic colon carcinoma, and metastatic melanoma. Normal brain tissue adjacent to the tumors was also examined in 14 of 18 glioblastomas. In all normal brain and tumor samples, with the exception of metastases from colon carcinoma, PCR analysis demonstrated one prominent product that corresponded to the CD44H hematopoietic form of CD44. Metastases from colon carcinoma demonstrated two prominent PCR amplification products corresponding to CD44H and CD44R1. These results suggest that CD44H is the predominant isoform of this protein in normal human brain tissue and in human neuroectodermal tumors of varying degrees of malignancy. The ability of CD44H to mediate tumor cell motility and invasiveness (in contrast to CD44R1) suggests that the CD44 alternative splicing pattern of neuroectoderm-derived tumors may enhance their local biological aggressiveness and intracerebral spread. The lack of expression of larger molecular weight CD44 variants by primary brain tumors may also partially explain why these tumors rarely metastasize to distant sites.
Susumu Nagasaka, Kenneth K. Tanabe, Janet M. Bruner, Hideyuki Saya, Raymond E. Sawaya and Richard S. Morrison
Benjamin D. Fox, Hassan H. Amhaz, Akash J. Patel, Daniel H. Fulkerson, Dima Suki, Andrew Jea and Raymond E. Sawaya
Medical student exposure to neurosurgery is limited. To improve the educational interactions between neurosurgeons and medical students as well as neurosurgical medical student rotations or clerkships (NSCs) we must first understand the current status.
Two questionnaires were sent, one to every neurosurgery course coordinator or director at each US neurosurgery residency program (99 questionnaires) and one to the associated parent medical school dean's office (91 questionnaires), to assess the current status of NSCs and the involvement of neurosurgeons at their respective institutions.
We received responses from 86 (87%) of 99 neurosurgery course coordinators or directors and 64 (70%) of 91 medical school deans' offices. Most NSCs do not have didactic lectures (53 [62%] of 86 NSCs), provide their medical students with a syllabus or educational handouts (53 [62%] of 86), or have a recommended/required textbook (77 [90%] of 86). The most common method of evaluating students in NSCs is a subjective performance evaluation. Of 64 medical school deans, 38 (59%) felt that neurosurgery should not be a required rotation. Neurosurgical rotations or clerkships are primarily offered to students in their 4th year of medical school, which may be too late for appropriate timing of residency applications. Only 21 (33%) of 64 NSCs offer neurosurgery rotations to 3rd-year students.
There is significant room for improvement in the neurosurgeon-to–medical student interactions in both the NSCs and during the didactic years of medical school.
Brian J. Williams, Dima Suki, Benjamin D. Fox, Christopher E. Pelloski, Marcos V. C. Maldaun, Raymond E. Sawaya, Frederick F. Lang and Ganesh Rao
Stereotactic radiosurgery (SRS) is commonly used to treat brain metastases. Complications associated with this treatment are underreported. The authors reviewed a large series of patients who underwent SRS for brain metastases to identify complications and factors predicting their occurrence.
Prospectively collected clinical data from 273 patients undergoing SRS for 1 or 2 brain metastases at The University of Texas M. D. Anderson Cancer Center between June 1993 and December 2004 were reviewed. Patients who had received prior treatment for their tumor, including whole-brain radiation, SRS, or surgery, were excluded from the study. Data on adverse neurological and nonneurological outcomes following treatment were collected.
Three hundred sixteen lesions were treated. Complications were associated with 127 (40%) of 316 treated lesions. New neurological complications were associated with 101 (32%) of 316 lesions. The onset of seizure was the most common complication, occurring in 41 (13%) of 316 SRS cases. On multivariate analysis, progressing primary cancer (hazard ratio [HR] = 2.4, 95% CI 1.6–3.6, p < 0.001), tumor location in eloquent cortex (HR = 2.3, 95% CI 1.6–3.4, p < 0.001), and lower (< 15 Gy) SRS dose (HR = 2.1, 95% CI 1.1–4.2, p = 0.04) were significantly associated with new complications. On multivariate analysis, a tumor location in the eloquent cortex (HR = 2.5, 95% CI 1.6–3.8, p < 0.001) and progressing primary cancer (HR = 1.6, 95% CI 1.1–2.5, p = 0.03) were significantly associated with new neurological complications.
The authors showed that new neurological and nonneurological complications were associated with 40% of SRS treatments for brain metastases. Patients with lesions in functional brain regions have a significantly increased risk of treatment-related complications.