20 Years Later, Radiation Still Protecting Against DCIS Recurrence
NEW YORK (Reuters Health) – Rates of recurrence of ductal carcinoma in situ (DCIS) after breast-conserving surgery (BCS) remain lower 20 years after radiotherapy, according to results from the SweDCIS Trial.
“Today in Sweden, according to our national guidelines we do not give radiotherapy to women with a DCIS, grade 1 or 2, smaller than 15mm,” Dr. Fredrik Warnberg from Uppsala University in Sweden told Reuters Health. “We know that we can reduce the number of local recurrences even in this group, but the absolute benefit is very low and we think the disadvantage is larger than the gain.”
Among those disadvantages is a possible increase in contralateral cancers, his team noted October 13th online in the Journal of Clinical Oncology.
The Swedish DCIS trial began in 1987 to study the effect of radiotherapy after breast-conserving surgery for DCIS. Dr. Warnberg and colleagues now present data from 20 years out.
At the 10-year follow-up, local recurrences were reduced by 60% in the radiotherapy group, compared with controls, with most of the protection noted among women over age 60.
Now, at the 20-year follow-up, the cumulative risk of ipsilateral new breast events is 20.0% in the radiotherapy group, significantly lower than the 32.0% in the control group.
There were, however, more contralateral events in the RT arm (67 events) than in the control arm (48 events), although the difference was not statistically significant.
RT did not have any significant effect on breast cancer-specific death or overall survival.
As in the earlier analysis, the relative risk reduction in ipsilateral new breast events proved to be significant only in the older age groups (52 years and older). Moreover, women with smaller tumors (14 mm or less) with clear margins showed no apparent benefit from radiotherapy.
“We can inform the women that we do not improve their survival chances with radiotherapy but we know that we reduce local recurrences,” Dr. Warnberg said. “Based on this, we have to help them to make a decision. We can include age, size, and grade of the lesion, but the scientific knowledge for data on these variables is less valid.”
He concluded, “We will continue to look for subgroups where radiotherapy safely can be omitted. We will also look for subgroups where the best option might be a mastectomy, with or without a breast reconstruction. We will need to look at tumor biology in a new way, and we need to find that way.”
Dr. Noam VanderWalde from University of North Carolina Hospitals in Chapel Hill, who recently reviewed the role of adjuvant radiotherapy in older women with early breast cancer, told Reuters Health by email, “There are almost certainly women with primary DCIS who can avoid radiotherapy without significantly increasing their risk of recurrence; unfortunately we do not yet know how to identify these women.”
“For many physicians and patients, decisions regarding breast conservation and radiation for primary DCIS can be difficult,” he said. “Patients are told that their DCIS is not cancer and that it will not affect their lives and yet they are recommended a four to six week course of daily radiation following breast conservation surgery. This can be confusing to many patients, and that is understandable.”
“Patients should be counseled prior to surgery by their surgeons and radiation oncologists,” Dr. VanderWalde advised. “Ultimately the decision for or against radiation needs to be a decision made by the patient (with the help of their multidisciplinary team) weighing the potential risks of radiation versus the potential risks of invasive or in situ recurrence of their DCIS.”
J Clin Oncol 2014.