Identification of Patients at Very Low Risk of Local Recurrence After Breast-Conserving Surgery

• Published in: International journal of radiation oncology, biology, physics Vol. 89; no. 3; pp. 556 - 562
• Main Authors: Smith, Sally L., Truong, Pauline T., Lu, Linghong, Lesperance, Mary, Olivotto, Ivo A.
• Format: Journal Article
• Language: English
• Published: United States Elsevier Inc 01.07.2014
• Subjects: Age Factors; Aged; Aged, 80 and over; Antineoplastic Agents, Hormonal - therapeutic use; Axilla; Breast Neoplasms - drug therapy; Breast Neoplasms - pathology; Breast Neoplasms - radiotherapy; Breast Neoplasms - surgery; Confidence Intervals; DIAGNOSIS; Dose Fractionation; Female; Follow-Up Studies; HAZARDS; Hematology, Oncology and Palliative Medicine; HISTOLOGY; Humans; Lymph Node Excision; MAMMARY GLANDS; Mastectomy, Segmental - methods; Middle Aged; Multivariate Analysis; Neoplasm Grading; Neoplasm Recurrence, Local; Neoplasm Staging; Neoplasm, Residual; NEOPLASMS; Neoplasms, Second Primary - pathology; PATIENTS; Proportional Hazards Models; Radiology; RADIOLOGY AND NUCLEAR MEDICINE; RADIOTHERAPY; Radiotherapy, Adjuvant - methods; Risk; SURGERY; WOMEN
• ISSN: 0360-3016; 1879-355X; 1879-355X
• DOI: 10.1016/j.ijrobp.2014.03.016

To identify clinical and pathological factors that identify groups of women with stage I breast cancer with a 5-year risk of local recurrence (LR) ≤1.5% after breast-conserving therapy (BCS) plus whole-breast radiation therapy (RT). Study subjects were 5974 patients ≥50 years of age whose cancer was diagnosed between 1989 and 2006, and were referred with pT1 pN0 invasive breast cancer treated with BCS and RT. Cases of 5- and 10-year LR were examined using Kaplan-Meier methods. Recursive partitioning analysis was performed in patients treated with and without endocrine therapy to identify combinations of factors associated with a 5-year LR risk ≤1.5%. The median follow-up was 8.61 years. Median age was 63 years of age (range, 50 to 91). Overall 5-year LR was 1.5% (95% confidence interval [CI], 1.2%-1.9%) and 10-year LR was 3.4% (95% CI, 2.8%-4.0%). Of 2830 patients treated with endocrine therapy, patient subsets identified with 5-year LR ≤1.5% included patients with grade 1 histology (n=1038; LR, 0.2%; 95% CI, 0%-0.5%) or grade 2 histology plus ≥60 years of age (n=843; LR, 0.5%; 95% CI, 0%-1.0%). Ten-year LR for these groups were 0.8% (95% CI, 0.1%-1.6%) and 0.9% (95% CI, 0.2%-1.6%), respectively. Of 3144 patients treated without endocrine therapy, patients with grade 1 histology plus clear margins had 5-year LR ≤1.5% (n=821; LR, 0.6%; 95% CI, 0.1%-1.2%). Ten-year LR for this group was 2.2% (95% CI, 1.0%-3.4%). Histologic grade, age, margin status, and use of endocrine therapy identified 45% of a population-based cohort of female patients over age 50 with stage I breast cancer with a 5-year LR risk ≤1.5% after BCS plus RT. Prospective study is needed to evaluate the safety of omitting RT in patients with such a low risk of LR.