Radiation therapy will improve outcomes for patients with ductal carcinoma in situ (DCIS), even if they are considered at low risk for recurrence, according to the Radiation Therapy Oncology Group (RTOG) 9804 trial.1 But the follow-up time is short, and the findings still leave some wiggle room, according to Harold J. Burstein, MD, of Dana-Farber Cancer Institute, and Steven J. Isakoff, MD, PhD, of Massachusetts General Hospital, Boston, who discussed the study at the Best of ASCO Boston meeting.
RTOG 9804 was conducted among 585 patients with small, low-grade asymptomatic tumors who underwent lumpectomy with adequate margins. The patients were randomly assigned to observation or radiation therapy (42.5–50.4 Gy with no boost); 62% also received tamoxifen.
Local failures (invasive or noninvasive) at 5 years occurred in 3.2% of the observation arm (primarily within the primary quadrant) vs 0.4% of the radiotherapy arm, for an 86% reduction in risk (P = .002). Contralateral cancers, disease-free survival, and overall survival were similar between the arms, and adverse events were comparable.
Findings Support Both Points of View
Dr. Isakoff contrasted the lower local failure rate in RTOG 9804 (3.2%) with that of the similar Eastern Cooperative Oncology Group (ECOG) 5194 trial2 in low-risk patients (10.5%), suggesting that shorter follow-up (5 vs 7 years) may account for the difference. “Beyond 5 years, the slope was still going up in the ECOG trial,” he noted.
Therefore, longer follow-up is required before a group can be clearly identified as not requiring radiotherapy due to sufficiently low risk, both specialists agreed.
Meanwhile, Dr. Burstein said the findings will support both the pro and con radiotherapy camps. “Physicians who want to give radiotherapy can look at the 86% risk reduction and highly significant P value, and contend that they can’t tell patients that radiation won’t benefit them. Physicians who think radiotherapy is unnecessary will say that we have identified a group with less than a 5% incidence of recurrence over 5 years, and wonder if we are helping them in a way that is clinically compelling,” he said.
“The question is not whether radiotherapy works, but whether there is benefit that makes sense,” Dr. Burstein concluded. “The debate will rage on and on.”
The findings may be most useful when they are put into context by patient age. Since the study has only 5 years of follow-up, and more events are likely to emerge in years 6 to 10, younger patients may need to take these points into consideration and opt for the extra protection. For older patients who do not want radiotherapy anyway, “You can point to the data and say their changes are excellent for a very good prognosis over the next 5 years,” he said.
Dr. Isakoff added that in the future, molecular tests may guide the treatment of DCIS patients. Meanwhile, he suggested, “Discussions with patients are required.” ■
Disclosure: Drs. Burstein and Isakoff reported no potential conflicts of interest.
References
1. McCormick B: RTOG 9804: A prospective randomized trial for “good risk” ductal carcinoma in situ, comparing radiation to observation. 2012 ASCO Annual Meeting. Abstract 1004. Presented June 5, 2012.
2. Hughes LL, Wang M, Page DL, et al: Local excision alone without irradiation for ductal carcinoma in situ of the breast: A trial of the Eastern Cooperative Oncology Group. J Clin Oncol 27:5319-5324, 2009.
