Growth factor practice patterns among pediatric oncologists: results of a 1998 Pediatric Oncology Group Survey. Economic Evaluation Working Group the Pediatric Oncology Group.

The American Society of Clinical Oncology (ASCO) guidelines on growth factor (GF) use recommend applying adult-derived guidelines in pediatric oncology. An ASCO survey of adult oncology GF use determined the preference for first degree prophylaxis (use of GF when febrile neutropenia [FN] is expected to be high in untreated patients), second-degree prophylaxis (administration of GF after a documented episode of FN on a previous cycle of chemotherapy), and intervention in the treatment of FN. Similar preferences have not been evaluated in pediatrics. The purpose of this study was to (1) characterize GF use in pediatric oncology; (2) correlate use patterns with demographic factors; and (3) compare the Pediatric Oncology Group (POG) and ASCO surveys. The ASCO survey was revised for use within pediatric oncology and was mailed to the physician membership of POG; 341 were returned (86% completion rate). Comparisons were made with the ASCO survey. Most (76%) physicians said GF use was determined by protocol requirements and most (70%) patients were entered on POG protocols. GF use as first-degree prophylaxis was selected 40% of the time, which was significantly greater than in adults; this was most influenced by anticipated duration of neutropenia (> or =7 days). The severity of the initial clinical course (e.g., neutropenia, infection) influenced use in second-degree prophylaxis; dose reduction alone was never selected. For FN, GF use was 45%, with lower preferences in uncomplicated FN (16%-38%) compared with complicated FN (66%). POG respondents endorse greater use of GF for first-and second-degree prophylaxis but less use in uncomplicated FN than do ASCO respondents. These patterns may reflect different strategies, including the role of chemotherapy, value of dose intensity, and perceived toxicity of regimens. Given these differences, adult-based guidelines may not be appropriate for pediatrics.

Response of facial and rubrospinal neurons to axotomy: changes in mRNA expression for cytoskeletal proteins and GAP-43.

Neurons confined within the mammalian CNS usually do not regenerate after axonal injury, while axonal regeneration is the rule in the PNS. It has been hypothesized that this may be related to differences in the microenvironment of the PNS versus CNS and to differences in the neuronal response to injury. In order to test the latter hypothesis, we compared changes in gene expression after axotomy in two populations of neurons: rat facial motoneurons and rat rubrospinal neurons. In situ hybridization with cDNA probes for the medium and light neurofilament protein revealed a reduced mRNA content in both facial and rubrospinal neurons at all times investigated (i.e., 1, 2, and 3 weeks after axotomy). On the other hand, mRNAs for actin and tubulin were increased in both neuronal populations during the first week after axotomy. While this increase was sustained in facial motoneurons for several weeks, total tubulin mRNA and actin mRNA were decreased in rubrospinal neurons at 2 and 3 weeks after axotomy, coincident with their atrophy. The developmentally regulated T alpha 1 tubulin mRNA, which was previously shown to be reexpressed in facial motoneurons after axotomy, was elevated severalfold in axotomized rubrospinal neurons, and increased levels persisted in some rubrospinal neurons as late as 7 weeks after axotomy. Similarly, the developmentally regulated GAP-43 mRNA increased in both axotomized facial and rubrospinal neurons, and increased levels were sustained in some axotomized rubrospinal neurons for at least 7 weeks. The response of rubrospinal neurons to axotomy in the cervical spinal cord is, in the first week, qualitatively similar to the response of facial motoneurons. However, by 2 weeks after axotomy there is a generalized reduction in mRNA levels for all three cytoskeletal proteins that is associated with neuronal atrophy. During this period, mRNA levels for the two specific markers of the growth state, T alpha 1 tubulin and GAP-43, remain elevated. Thus, axotomy of rubrospinal neurons appears to set in motion two independent events. First, an axotomy signal initiates a cell-body reaction similar to that of PNS neurons, including increased mRNA levels for T alpha 1 tubulin and GAP-43. Later, a generalized cellular atrophy and decrease in mRNA levels occur without reversing the specific responses of T alpha 1 and GAP-43 to axotomy. We conclude that the failure of rubrospinal neurons to regenerate is not due to a failure to initiate gene-expression changes characteristic of regenerating peripheral neurons.(ABSTRACT TRUNCATED AT 400 WORDS)