Search

The Aramis method proposes a complete and efficient way to manage risk analysis by using the bow-tie representation. This paper shows how the bow-tie representation can also be appropriate for experience learning. It describes how a pharmaceutical production plant uses bow-ties for incident and accident analysis. Two levels of bow-ties are constructed: standard bow-ties concern generic risks of the plant whereas local bow-ties represent accident scenarios specific to each workplace. When incidents or accidents are analyzed, knowledge that is gained is added to existing local bow-ties. Regularly, local bow-ties that have been updated are compared to standard bow-ties in order to revise them. Knowledge on safety at the global and at local levels is hence as accurate as possible and memorized in a real time framework. As it relies on the communication between safety experts and local operators, this use of the bow-ties contributes therefore to organizational learning for safety.

Between October 1977 and December 1983, 379 consecutive patients have been treated for unilateral, non metastatic breast cancer, either with conservative (n = 205) or radical surgery (n = 174), with axillary dissection in all the cases. None of them had histologically proved lymph node involvement. Adjuvant radiotherapy was given in 268 cases. Estrogen receptor (ER) and progesterone receptor (PR) levels were measured on each tumor. Levels greater than 5 fmoles/mg cytosolic protein were considered as positive for both ER and PR. At 5 years, overall survival (OS) and disease-free survival (DFS) are respectively 88% and 79%. Unifactorial analysis using KAPLAN and MEIER estimates and Logrank test revealed that OS was significantly related to age, tumor size, histopathological grading, ER and PR. DFS was significantly related to the same factors. Menopausal status, number of intra mammary tumor foci, previous familial history of breast cancer were not significant. Multifactorial analysis revealed that DFS was significantly related to age (bad prognosis [bp]: less than or equal to 37 years old), tumor size, histopathological grading (bp: SBR = 3) and that OS was significantly related to tumor size and PR (bp: PR less than or equal to 5 fmoles/mg protein). A prognostic score was obtained which sampled our patients into 3 significantly different (P less than 0.0001) groups with high, intermediate and low risk of relapse. These results suggest that tumor size, histopathological grading and PR have their own prognostic weight in histologically node negative breast cancer. Grouping these factors together allows to define a high risk relapse group that could benefit from adjuvant treatment.