A ductal carcinoma in situ nomogram that provides an individualized risk estimate of recurrence after breast-conserving surgery can help inform treatment decisions and reduce over-and undertreatment of noninvasive breast cancer, according to a study published July 12 online in the Journal of Clinical Oncology.
“While the mortality associated with ductal carcinoma in situ is minimal, the risk of ipsilateral breast tumor recurrence after breast-conserving surgery is relatively high,” stated Kimberly Van Zee, MD, surgeon in the Breast Cancer Surgical Service at Memorial Sloan-Kettering Cancer Center in New York City. Radiation therapy and antiestrogen agents can reduce the risk of ipsilateral breast tumor recurrence, but “[the treatments] have never been proven to improve survival, and in themselves carry rare but serious risks,” wrote Zee and colleagues.
To help address the ambiguity surrounding these treatment options, researchers developed a nomogram that integrates 10 clinicopathologic variables to offer physicians and patients an individualized estimate of ipsilateral breast tumor recurrence risk for five and 10 years after surgery.
The study--conducted at Memorial Sloan-Kettering Cancer Center--included 1,681patients treated with breast-conserving surgery for ductal carcinoma in situ from 1991 to 2006.
The researchers built ten clinical, pathologic and treatment variables into a nomogram estimating the probability of ipsilateral breast tumor recurrence at five and 10 years following breast-conserving surgery. Variables included the patient's age, family history, clinical presentation, margin status and histopathological features such as nuclear grade and presence of necrosis. Van Zee and colleagues tested the nomogram for discrimination and calibration using bootstrap resampling.
Factors that carried the greatest influence on risk of ipsilateral breast tumor recurrence in the model included adjuvant radiation therapy or endocrine therapy, age, margin status, number of excisions and treatment time period, according to the authors, who noted that the nomogram demonstrated good calibration and discrimination for prediction of five and 10-year ipsilateral breast tumor recurrence risk.
Until now, physicians had no way of integrating all of the known risk factors for recurrence to present an individualized absolute risk estimate to their patients, explained the authors.
"For the first time, using readily available information, a patient and her oncologist can estimate her individualized risk, and then use this tool to help in the decision-making process regarding treatment options … Given that nomograms have been repeatedly shown to be more accurate at risk estimation than expert opinion, it is very helpful to have mathematical models to integrate available information and improve the decision-making process for our patients," concluded Van Zee.