Risk stratification and outcomes can be improved for women with ductal carcinoma in situ (DCIS), according to two studies presented at the 2012 ASCO Annual Meeting.
RTOG 9804
Findings from the Radiation Therapy Oncology Group (RTOG) 9804 trial suggested that even for DCIS patients whose prognosis is already favorable, radiation therapy is highly beneficial.1 “For patients with ‘good risk’ disease, the addition of radiation significantly reduced the risk of local failure,” said Beryl McCormick, MD, of Memorial Sloan-Kettering Cancer Center, New York.
The study was conducted among 585 patients with small, low-grade asymptomatic tumors who underwent lumpectomy and achieved adequate resection margins. The patients were randomly assigned to observation or radiation therapy; 62% also received tamoxifen. Radiation therapy was initiated within 12 weeks of surgery and consisted of 42.5 to 50.4 Gy with no boost.
Dr. McCormick reported that the actuarial 5-year rate of local failure (invasive or noninvasive) was 3.2% in the observation arm and 0.4% in the radiation arm, for an 86% reduction in risk (P = .002). With radiation, there were no local failures within the quadrant of the primary tumor, but in the observation arm, two-thirds of the failures occurred there. Contralateral cancers, disease-free survival, and overall survival were similar between the arms.
Adverse events were comparable, and only 0.7% of the radiated group experienced late grade 3 or higher radiation therapy toxicity.
DCIS Score Adds Prognostic Information
In a separate presentation, investigators reported that the new DCIS score independently predicted the risk of ipsilateral recurrence or invasive disease.2 The score is modeled on the Oncotype DX recurrence score, using the same validated technique but a different 12-gene signature.
The score divided patients into a high-risk group, which had a 27% risk of recurrence at 10 years; an intermediate-risk group, which had a 24% risk; and a low-risk group, whose risk was 12%.
In a subgroup analysis of the prospective validation study, E5194, each 50-point increase in DCIS score was associated with more than a doubling in the risk of recurrence of DCIS or invasive disease (HR = 2.41; P = .02), according to Sunil S. Badve, MBBS, FRCPath, of Indiana University School of Medicine, Indianapolis.
The study followed 327 DCIS patients treated with wide local excision; 29% received tamoxifen and none received radiation therapy.
Further Findings
Tumor size and postmenopausal status were also independent predictors, but the score was only moderately correlated with histologic grade and with the percentage of cells showing comedo necrosis, and was poorly correlated with tumor size. There was no correlation between the score and patient’s age, menopausal status, DCIS histologic pattern or margin status.
“The DCIS score provides independent information on ipsilateral breast risk beyond clinical and pathologic variables,” Dr. Badve said, noting that it will help identify a subset of patients who may be at increased risk despite their profile based on traditional criteria. ■
Disclosure: Dr. McCormick reported no potential conflicts of interest. Dr. Badve has served as a consultant or advisor for Genomic Health.
References
1. McCormick B, Winter K, Hudis C, et al: RTOG 9804: A prospective randomized trial for “good risk” ductal carcinoma in situe, comparing radiation to observation. 2012 ASCO Annual Meeting. Abstract 1004. Presented June 5, 2012.
2. Badve SS, Gray RJ, Baehner FL, et al: Correlation between the DCIS score and traditional clinicopathologic features in the prospectively designed E5194 clinical validation study. 2012 ASCO Annual Meeting. Abstract 1005. Presented June 5, 2012.
