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Radiation Therapy Greatly Reduces Risk of Local Recurrence, Does Not Affect Overall Survival After Ductal Carcinoma in Situ: Presented at SABCS

By Cameron Johnston

SAN ANTONIO, TX -- December 9, 2005 -- Two European studies involving more than 7000 women found significant differences in the rate of local recurrence between women with ductal carcinoma in situ and early breast cancer who undergo radiation therapy after tumor excision and those who do not have radiation.

The studies also showed that the invasive recurrence rates were not different between groups but also that there was no difference in overall survival.

Conducted in the Netherlands, the studies recruited 1010 women, of whom 507 had radiation therapy after a complete local excision of their DCIS. The remaining women received no further treatment. The women were matched for age and other demographic and tumor characteristics.

Nina Bijker, MD, oncologist, Netherlands Cancer Institute, Amsterdam, the Netherlands, presented the results of the first study here on December 8^th at the 28^th Annual San Antonio Breast Cancer Symposium (SABCS) on the behalf of the European Organisation for Research and Treatment of Cancer's Breast Cancer and Radiotherapy Group.

In her study, 75% of women who did not have radiation therapy were recurrence-free after a mean of 9.5 years of follow-up compared with 85% of those who had radiation therapy.

Of those who had radiation therapy, 92% did not have invasive recurrence compared with 87% of those who had no radiation. This corresponds to an overall reduction in the risk of recurrence of 42%, Dr. Bijker said.

There were no differences between groups in distant metastases or overall survival and, although more women who did not have radiation therapy were likely to develop a further cancer in the contralateral breast, this difference was not significant.

Younger women were more likely to have a recurrence, Dr. Bijker said. Also, she said, the clarity of tumor margins were predictive -- patients who had clear margins were less likely to relapse, while those whose margins were indeterminate or poorly differentiated where much more likely to have a local recurrence.

The tumor architecture -- whether it was solid/comedoform or cribriform -- was also a significant predictor of recurrence. Tumors that were symptomatic (i.e., those that could have been detected through a breast self-examination) were significantly more likely to recur as compared with those that were detected on x-ray alone.

The second study presented at the SABCS was an analysis of 2 Austrian studies with 5921 women who had early breast cancer and either received radiation therapy or simple observation. These women all had node-negative, hormone receptor-positive disease, with tumors of less than 3 cm diameter.

Michel Gnant, MD, professor of experimental surgical oncology, Medical Universities of Vienna, Graz, Salzburg, and Innsbruck, Vienna, Austria, presented the findings on behalf of the Austrian Breast and Colorectal Cancer Study Group.

At the end of 5 years of follow-up, Dr. Gnant said the local relapse rate in 1 of the studies was almost 11-fold greater among patients who had not had radiotherapy compared with those who had radiotherapy (5.2% vs 0.4%). In the second study, which allowed women to choose whether or not to have radiation therapy, the 10-year relapse rates were 3.5% in those who did not have it and 3.3% in those who did.

Dr. Gnant said these data show that although radiation therapy is the standard of care for women with DCIS, breast conservation can still be carried out with a reasonable degree of safety if the women choose not to have radiation therapy. Moreover, since the risk of relapse is relatively low, and overall survival is not affected in any case, radiation therapy might be avoided safely in women over the age of 70 years because the risk of local relapse is so low over a 10-year period.


[Presentation title: Radiotherapy in Breast-Conserving Treatment for Ductal Carcinoma in Situ (DCIS): Ten-Year Results of European Organization for Research and Treatment of Cancer (EORTC) Randomized Trial 10853. Abstract 7. Breast Conservation Without Radiotherapy in Low Risk Breast Cancer Patients - Results of 2 Prospective Clinical Trials of the Austrian Breast and Colorectal Cancer Study Group Involving 1,518 Postmenopausal Patients With Endocrine Responsive Breast Cancer. Abstract 8]

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