Validation of a Web-Based Predictive Nomogram for Ipsilateral Breast Tumor Recurrence After Breast Conserving Therapy

• Published in: Journal of clinical oncology Vol. 28; no. 5; pp. 718 - 722
• Main Authors: SANGHANI, Mona, TRUONG, Pauline T, ABI RAAD, Rita, NIEMIERKO, Andrzej, LESPERANCE, Mary, OLIVOTTO, Ivo A, WAZER, David E, TAGHIAN, Alphonse G
• Format: Journal Article
• Language: English
• Published: Alexandria, VA American Society of Clinical Oncology 10-02-2010
• Subjects: Adult; Aged; Biological and medical sciences; Breast Neoplasms - pathology; Breast Neoplasms - radiotherapy; Breast Neoplasms - surgery; British Columbia; Databases as Topic; Decision Support Techniques; Female; Gynecology. Andrology. Obstetrics; Humans; Internet; Kaplan-Meier Estimate; Mammary gland diseases; Mastectomy, Segmental; Medical sciences; Middle Aged; Models, Biological; Neoplasm Recurrence, Local; Nomograms; Original Reports; Predictive Value of Tests; Proportional Hazards Models; Radiotherapy, Adjuvant; Reproducibility of Results; Risk Assessment; Risk Factors; Time Factors; Treatment Outcome; Tumors; United States; United States; British Columbia; Validation; Mammary gland diseases; Ipsilateral; Relapse; Cancerology; Treatment; Nomogram; Breast tumor; Internet
• ISSN: 0732-183X; 1527-7755
• DOI: 10.1200/JCO.2009.22.6662

PURPOSE IBTR! version 1.0 is a web-based tool that uses literature-derived relative risk ratios for seven clinicopathologic variables to predict ipsilateral breast tumor recurrence (IBTR) after breast-conserving therapy (BCT). Preliminary testing demonstrated over-estimation in high-risk subgroups. This study uses two independent population-based datasets to create and validate a modified nomogram, IBTR! version 2.0. METHODS Cox regression modeling was performed on 7,811 patients treated with BCT at the British Columbia Cancer Agency (median follow-up, 9.4 years). Population-based hazard ratios were generated for the seven variables in the original nomogram. A modified nomogram was then tested against 664 patients from Massachusetts General Hospital (median follow-up, 9.3 years). The mean predicted and observed 10-year estimates were compared for the entire cohort and for four groups predefined by nomogram-predicted risks: group 1: less than 3%; group 2: 3% to 5%; group 3: 5% to 10%; and group 4: more than 10%. Results IBTR! version 2.0 predicted an overall 10-year IBTR estimate of 4.0% (95% CI, 3.8 to 4.2), while the observed estimate was 2.8% (95% CI, 1.6 to 4.7; P = .10). The predicted and observed IBTR estimates were: group 1 (n = 283): 2.2% versus 1.3%, P = .40; group 2 (n = 237): 3.8% versus 3.5%, P = .80; group 3 (n = 111): 6.7% versus 3.2%, P = .05; and group 4 (n = 33): 12.5% versus 8.7%, P = .50. CONCLUSION IBTR! version 2.0 is accurate in the majority of patients with a low to moderate risk of in-breast recurrence. The nomogram still overestimates risk in a minority of patients with higher risk features. Validation in a larger prospective data set is warranted.