PURPOSE: To develop evidence-based guidelines for (1) prostate re-biopsy after radiation and (2) radiation therapy with rising prostate-specific antigen (PSA) levels after radical prostatectomy in the management of patients with localized prostatic cancer. DESIGN: The American Society of Therapeutic Radiology and Oncology (ASTRO) challenged a multidisciplinary consensus panel to address consensus on specific issues in each of the two topics. Four well-analyzed patient data sets were presented for review and questioning by the panel. The panel sought criteria that would be valid for patients in standard clinical practice as well as for patients enrolled in clinical trials. Subsequent to an executive session that followed these presentations, the panel presented its consensus guidelines. RESULTS AND CONCLUSIONS: Based on the data presented, the prostate re-biopsy negative rates ranged from 62% to 80% for patients with stage T1-2 tumors. The panel judged that prostate re-biopsy is not necessary as standard follow-up care and that the absence of a rising PSA level after radiation therapy is the most rigorous end point of total tumor eradication. Further, the panel judged that re-biopsy may be an important research tool. Based on the data presented, the long-term (5 years or more) PSA remission rate after salvage radiation therapy ranges from 27% to 45%. The panel requested results from prospective randomized trials to evaluate optimally this information. The panel judged that the total dose of radiation should be 64 Gy or slightly higher and that, in patients with or without radiation therapy, there is no standard role for androgen suppressant therapy for rising PSA values after prostatectomy.
Necrosis and vascular proliferation are the pathologic features that distinguish the most malignant infiltrative astrocytoma, glioblastoma (GBM), from those of lower grades. In GBM, hypercellular zones called pseudopalisades typically surround necrotic foci. Although these cells are known to secrete high levels of proangiogenic factors that promote tumor growth, their origins are ill defined. We propose that pseudopalisades represent differing stages and histologic samplings of astrocytoma cells migrating away from a hypoxic/anoxic focus, often triggered by a central vaso-occlusive event. This proposition is based on our findings that pseudopalisading cells are 5-50% less proliferative and 6-20 times more apoptotic than adjacent astrocytoma, indicating that cell accumulation does not result from increased proliferation or resistance to apoptosis. Coexisting inflammatory cells account for <2% of pseudopalisading cells and cannot account for hypercellularity. Pseudopalisading cells show nuclear expression of hypoxia-inducible factor 1 alpha, consistent with their hypoxic nature, and hypoxia induces a 20-60% increase in glioma cell migration in vitro. Hypoxic cells in vitro and pseudopalisades in GBM specimens show enhanced gelatinase activity, typical of an invasive phenotype. These results suggest that pseudopalisading cells are migrating at the periphery of a hypoxic center. To uncover a potential source of hypoxia and sequence of structural events leading to pseudopalisade formation, we performed a morphometric analysis of 234 pseudopalisades from 85 pretreatment GBMs. We found distorted, degenerating, or thrombosed blood vessels within the center of more than half the pseudopalisades, suggesting that at least a subset of pseudopalisades are two-dimensional histologic representations of tumor cells migrating away from a vaso-occlusive event.
