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R Dufresne

Publications and source records attributed to R Dufresne.

3 recordsLinked to original sources
PubMed1992

Localized carcinoma of the external ear is an unrecognized aggressive disease with a high propensity for local regional recurrence.

Management problems in patients with recurrent squamous cell carcinoma (SCC) of the external ear (pinna) have prompted a review of the management and treatment outcomes of patients who present with localized disease. Forty patients were seen over a 15-year period (1972 to 1991). Thirty-six were men, and 4 were women, with an age range from 43 to 93 years (average age: 71 years). Presenting TNM status was stage 0 in 2 patients, stage I in 15 patients, stage II in 13 patients, stage III in 2 patients, stage IV in 4 patients, and unknown stage in 4 patients. Thirty-six patients had clinically negative nodes at presentation (N0), and 4 had palpable nodes (N+). The primary treatment was local excision in 13 patients, Mohs' micrographic surgery in 16 patients, local excision plus external beam radiotherapy in 4 patients, and radical resection (parotidectomy/neck dissection/mastoidectomy) with or without radiotherapy in 5 patients. Two patients with stage IV disease died after diagnosis and prior to treatment, and two other patients with stage IV disease received palliative chemotherapy. Twenty patients developed recurrence from 2 months to 8 years. It included nine local recurrences, eight regional recurrences (parotid/neck/mastoid), and three distant metastases (lung or brain). After treatment of the recurrences in 20 patients, 8 are alive 15 months to 16 years later, 2 patients died of other diseases, and 10 patients died of SCC. The recurrences were managed by reoperation, radiotherapy, or chemotherapy. From the results of this study, we conclude that localized carcinoma of the external ear has a high propensity for local and regional failure and merits more aggressive treatment of the primary lesion and elective treatment of the regional lymph nodes and parotid gland in high-risk patients.

Adult↗
PubMed1989

The relation between problem categorization and problem solving among experts and novices.

These investigations were conducted to examine the relationship between problem-solving ability and the criteria used to decide that two classical mechanics problems would be solved similarly. We began by comparing experts and novices on a similarity judgment task and found that the experts predominantly relied on the problems' deep structures in deciding on similarity of solution, although the presence of surface-feature similarity had a clear adverse effect on performance. The novices relied predominantly on surface features, but were capable of using the problems' deep structures under certain conditions. In a second experiment, we compared groups of novices, at the same level of experience, who tended to employ different types of reasoning in making similarity judgments. Compared to novices who relied predominantly on surface features, novices who made greater use of principles tended to categorize problems similarly to how experts categorized them, as well as score higher in problem solving. These results suggest that principles play a fundamental role in the organization of conceptual and procedural knowledge for good problem solvers at all levels.

Adult↗