The presence of DCIS adjacent to invasive breast tumor and a younger age at diagnosis are associated with increased risk of ipsilateral breast tumor recurrence.
The presence of ductal carcinoma in situ (DCIS) adjacent to invasive breast tumor and a younger age at diagnosis are associated with increased risk of ipsilateral breast tumor recurrence (BTR), according to a new study published in JAMA Oncology.
Relapse of high-grade invasive tumors was more frequent during the first 5 years post diagnosis, but this declined with time. The study authors led by Conny Vrieling, MD, PhD, of the Clinique des Grangettes in Geneva, Switzerland, noted that patients should be closely monitored in these first 5 years.
Vrieling and coauthors analyzed the long-term impact of prognostic factors on ipsilateral BTR among 1,616 breast cancer patients who underwent breast-conserving surgery and 50-Gy whole-breast irradiation in the European Organisation for Research and Treatment of Cancer (EORTC) “boost no boost” trial. The median follow-up was 18.2 years. Prior to this new analysis, the known risk factors for relapse included tumor size and nodal presence, younger age, mammographic density, margin status, peritumoral vascular invasion, and molecular subtype.
In this study, the 20-year cumulative incidence rate of ipsilateral BTR was 15% (160 recurrence events); for patients 40 years and younger, between 41 and 50 years, and 50 years and older, the rates were 34%, 14%, and 11%, respectively. The rates were 18% and 9% for tumors with and without DCIS (P < .001).
High-risk patients under age 50 who were randomized to an additional 16-Gy boost of radiation had a further reduced 20-year ipsilateral BTR incidence rate (31% to 15%; P < .001).
Among the 124 high-risk patients with estrogen receptor (ER)- and progesterone receptor (PR)-negative breast cancer, 16 events of local recurrence occurred during the follow-up period. Younger age particularly affected relapse risk in this population: the 15-year cumulative incidence rates of ipsilateral BTR were 34%, 19%, and 6% in patients 40 years and younger, those between 41 and 50 years, and those 50 years and older, respectively. The presence of DCIS did not further affect these rates.
Among the 464 with ER-positive low-grade tumors, there were 43 relapse events. The 15-year cumulative incidence rates of ipsilateral BTR were 34% in patients 40 years and younger and 10% in those older than 40 years (P < .001). The presence of DCIS partly affected local recurrence rates: the 15-year cumulative incidence rates of ipsilateral BTR were 14% in patients with additional DCIS and 7% in patients without DCIS (P = .02).
“Although the absolute benefit of a [radiation] boost is likely much smaller now than that observed in the study, certain women clearly remain at high risk of ipsilateral BTR after breast-conserving surgery,” wrote Laurie W. Cuttino, MD, of Virginia Commonwealth University, and Charlotte Dai Kubicky, MD, PhD, of Oregon Health & Science University, in an accompanying editorial. Younger patients, patients with high-grade tumors, and those with ER-negative tumors should receive a boost after whole-breast radiotherapy, while older patients with low-grade, ER-positive tumors with clear surgical margins do not benefit from the addition of a boost, they concluded.