Radiation After DCIS Surgery Reduces Recurrence

N. Bijker and others

San Antonio Breast Cancer Symposium, December 8, 2005, Abstract 7

Is this for me? If you have been diagnosed with DCIS and are considering radiation treatment after surgery, you might want to read this article.

Background and importance of the study: Mammography screening detects many breast cancers in their earliest stage, known as ductal carcinoma in situ (DCIS). DCIS is an uncontrolled growth of breast cells that stay on the inside of the milk duct. The cells have not started to break through the wall of the duct into the normal surrounding breast tissue. Because DCIS hasn't learned how to spread into nearby normal breast tissue, it can't spread to other parts of the body. You may have heard other names for this kind of cancer, including non-invasive, pre-cancer, and Stage 0 (zero).

Although DCIS itself isn't life-threatening because it hasn't started to spread, doctors still take it seriously because it is associated with an increased risk of developing an invasive cancer in the future. Reducing the risk of ever getting an invasive cancer is the main reason to treat non-invasive breast cancer carefully.

Studies of women with small invasive breast cancers have shown that radiation after lumpectomy (breast-conserving surgery) can lower the risk of the cancer coming back by about two thirds, or 66%. But these results cannot be automatically applied to DCIS, which is non-invasive. Other research suggests that radiation after lumpectomy for DCIS also can lower the risk of the cancer coming back in the same breast.

The study reported here is different. It specifically looked at whether radiation treatment after surgery to remove DCIS reduced the risk of recurrence (the DCIS coming back) or of the risk of developing invasive cancer.

Study design: The study included 1,010 European women younger than 70 who had been diagnosed with DCIS. The women all had lumpectomy to remove the DCIS (all were less than five centimeters). After surgery, about half the women received radiation therapy for five weeks and the other half received no additional treatment. The women were followed for about 10 years.

The study is known as the European Organization for Research and Treatment of Cancer (EORTC) Trial 10853.

Results: After 10 years of follow-up, 85% of the women treated with radiation therapy had no recurrence of DCIS, compared to 75% of women who had no radiation after lumpectomy. This difference was significant, meaning it was likely due to the radiation and not just to chance.

The risk of recurrence of DCIS or of developing invasive cancer was significantly reduced by 42% in women who had radiation therapy, compared to women who did not receive radiation.

The risk of being diagnosed with breast cancer in the OTHER breast was similar in both groups. Overall survival (how long the women lived) was also the same in both groups.

Conclusions: The researchers concluded that radiation after breast-conserving surgery to remove DCIS reduced the risk of DCIS or invasive breast cancer coming back in the same breast by nearly half.

Take-home message: This large, long-term, study confirms what earlier research has suggested: Lumpectomy plus radiation is more effective than lumpectomy alone for women with DCIS.

Although DCIS hasn't started to invade normal tissue, it is associated with an increased risk of developing invasive cancer in the future, so careful treatment is important.

This study adds more support to the current recommendation that all women who have lumpectomy for non-invasive or invasive breast cancer should seriously consider radiation treatment to reduce their risk of recurrence.

The February 2006 Research News section was made possible by an unrestricted educational grant from Genentech BioOncology.