The ductal carcinoma in situ (DCIS) Score, a multigene expression assay, quantifies the risk of local recurrence and invasive local recurrence for women with DCIS treated with surgical excision, researchers reported in the Journal of the National Cancer Institute. “The DCIS Score can aid clinical decision making by identifying those patients with a lower DCIS Score for whom surgical excision alone may be adequate and those patients with a lower DCIS score for whom adding treating after surgical excision should be considered,” the researchers stated.
The DCIS Score was developed and validated in a multistep strategy “based in part on evidence that quantitative expression of genes from the 21-gene Oncotype Recurrence Score (hereafter referred to as the Recurrence Score) may be useful for predicting local recurrence in DCIS,” investigators reported. The DCIS Score was calculated from seven cancer-related genes and five reference genes.
To validate the DCIS Score, researchers looked at the association between the DCIS Score as a continuous variable and the risk of developing ipsilateral breast event—defined as local recurrence of DCIS or invasive carcinoma—among women who were treated with surgical excision but without radiation in the Eastern Cooperative Oncology Group (ECOG) E5194 study. Eligible patients had either low-grade or intermediate-grade DCIS with tumor size ≤ 2.5 cm or high-grade DCIS with tumor size ≤ 1.0 cm. “Protocol specifications included a minimum negative margin width of at least 3 mm or no tumor on reexcision,” the researchers noted.
An ipsilateral breast event developed in 46 of the 327 patients with adequate tissue for analysis; 26 had DCIS only and 20 had invasive carcinoma. “The continuous DCIS Score was statistically significantly associated with the risk of developing an [ipsilateral breast event] (hazard ratio [HR] = 2.31, 95% confidence interval [CI] = 1.15 to 4.49; P = .02) when adjusted for tamoxifen use (prespecified primary analysis) and with invasive [ipsilateral breast event] (unadjusted HR = 3.68, 95% CI = 1.34 to 9.62; P = .01),” the researchers reported.
“For the prespecified DCIS risk groups of low, intermediate, and high, the 10-year risks of developing an [ipsilateral breast event] were 10.6%, 26.7%, and 25.9%, respectively, and for an invasive [ipsilateral breast event], 3.7%, 12.3%, and 19.2%, respectively (both log rank P ≤ .006). In multivariable analyses, factors associated with [ipsilateral breast event] risk were DCIS Score, tumor size, and menopausal status (all P ≤ .02),” the authors added.
“In contrast with the DCIS Score, the Recurrence Score was not statistically significantly associated with developing an [ipsilateral breast event],” the investigators stated. “No statistically significant association was seen for developing a contralateral breast cancer for either the DCIS Score or the Recurrence Score.”
A Controversial Issue
Given that the management of DCIS is controversial, “a straightforward approach to selecting the optimum therapy—defined here as the minimum needed to avoid recurrence, particularly with an invasive component—is needed,” according to an accompanying editorial by Christine D. Berg, MD, of the School of Medicine, University of Queensland, Australia, and formerly of the National Cancer Institute. The DCIS assay “does appear to be a step forward,” Dr. Berg stated. “The clinical applicability of this assay for all women who present with DCIS remains to be determined,” she added.
“Although the information provided by the DCIS Score may be useful in the correct setting and application, it is not a definitive guide,” and does not address the using or not using radiation therapy, Shivani Duggal, MD, and Thomas B. Julian, MD, of Allegheny General Hospital in Pittsburgh, commented in another editorial. “The DCIS Score should complement traditional clinical and pathologic factors used to guide decision-making in the treatment of DCIS.” ■
Solin LJ, et al: J Natl Cancer Inst 105:701-710, 2013.
Berg CD: J Natl Cancer Inst 105:680-681, 2013.
Duggal S, Julian TB: J Natl Cancer Inst 105:681-683, 2013.