The Radiation Therapy Oncology Group (RTOG) initiated a phase I/II study of intraoperative radiotherapy (IORT) in advanced or recurrent rectal cancer to assess therapeutic efficacy, toxicity, and establish quality control guidelines prior to beginning a phase III trial. From October 1985 through December 1989, 87 patients with histologically proven adenocarcinoma of the rectum or rectosigmoid with recurrent/persistent disease after surgery or those primarily inoperable were entered by 14 institutions. Of 86 evaluable patients, 42 patients received IORT either alone (n = 15) or in combination with external beam (n = 27). Local control was dependent on the amount of residual disease prior to IORT, with 2-year actuarial local control of 77% if no gross residual disease remained vs. 10% with gross residual disease (P = 0.001). For the recurrent/residual group (n = 33), this observation was also significant with a 2-year actuarial local control rate of 64% if no gross residual remained vs. 10% with gross residual disease (P = 0.004). Local control translated into an improved survival for all patients and the recurrent/residual group with 2-year actuarial survival of 88% and 89% if no gross residual disease remained vs. 48% and 45% with gross residual disease, respectively (P = .0005, 0.006). Six patients (14.6%) experienced four grade 3 and three grade 4 complications as a possible result of IORT during follow-up with a 2-year actuarial risk of major complications of 16%. We conclude that IORT is feasible within a cooperative group and can be performed with acceptable complication rates. A phase III trial to demonstrate a therapeutic advantage for IORT over external beam alone is currently in progress.
We apply a version of our web-based literature-mapping system to PNAS for 1971-2002, as indexed by the National Library of Medicine and the Institute for Scientific Information. Given a single input term from a user, a medical subject heading, a cocited author, or a cocited journal, PNASLINK rapidly displays views in which that term and the other 24 terms that most frequently co-occur with it in a bibliographic database are interrelated in ways suggesting fruitful combinations for document retrieval. The interrelationships are produced by two algorithms, pathfinder networks and Kohonen-style self-organizing maps. PNASLINK displays are themselves interactive interfaces that can retrieve documents from digital libraries (e.g., PNAS Online). This style of visualizing knowledge domains is called ''localized'' because it does not attempt to map the indexing of literatures in full but concentrates on the top terms in an ''associative thesaurus'' reflecting user interests. It also permits swift remappings, as the user recognizes terms worth pursuing. PNASLINK is illustrated with maps drawn from the literature of population genetics. Some comparative and evaluative comments are added, one from a domain expert indicating that the face validity of the system may be tempered by insufficient specificity in the indexing terms being mapped.
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