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Medical AI Inquiry: You was designed to assist in medical decision-making based on the provided user questions. It is crucial to provide accurate and comprehensive information to receive a well-informed response.  Labels: OBJECTIVE, METHODS, RESULTS. Meshes: Actuarial Analysis, Adult, Age Factors, Aged, Aged, 80 and over, Antineoplastic Combined Chemotherapy Protocols, Axilla, Breast Neoplasms, Chemotherapy, Adjuvant, Combined Modality Therapy, Decision Trees, Female, Follow-Up Studies, Humans, Lymph Node Excision, Mastectomy, Segmental, Middle Aged, Neoplasm Recurrence, Local, Prognosis, Risk Assessment, Tamoxifen.
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Does recursive partitioning identify patients at high and low risk for ipsilateral tumor recurrence after breast-conserving surgery and radiation? Context: Recursive partitioning analysis (RPA), a method of building decision trees of significant prognostic factors for outcome, was used to determine subgroups at significantly different risk for ipsilateral breast tumor recurrence (IBTR) in early-stage breast cancer. Nine hundred twelve women underwent breast-conserving surgery, axillary dissection, and radiation. Systemic therapy was chemotherapy with or without tamoxifen in 32%, tamoxifen in 27%, or none in 41%. RPA was used to create a decision tree according to predictive variables that classify patients by IBTR risk, and the Kaplan-Meier method was used to calculate 10-year risks. Median follow-up was 5.9 years. Age was the first split in the partition tree. Patients more than 55 years old had a 4% 10-year IBTR, the only further division being use of tamoxifen or not (2% v 5%, P =.03). For patients </= 55 years old, extensive intraductal component (EIC) was the next significant split. For EIC-negative tumors, age </= 35 years and negative margins were associated with a 10-year IBTR of 3%; with close (</= 2 mm) or positive margins, 34%. Patients 36 to 55 years old with estrogen receptor-positive tumors receiving tamoxifen had a risk of IBTR of 5%, but had a 20% risk without tamoxifen.
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This RPA showed that age </= 55 versus more than 55 years was the most significant factor for IBTR. Patients </= 35 years old had a low risk of IBTR when tumors were EIC-negative with negative margins. EIC was an independent factor for IBTR for ages </= 55 years. Use of tamoxifen was the most significant factor for patients older than 55 years, but it resulted in a greater absolute decrease in risk of IBTR for patients 36 to 55 years old. Final Decision: yes