Treatment choice affects recurrence rates for ductal carcinoma in situ patients

The study examined the recurrence rates and disease-free survival times associated with different treatments used for ductal carcinoma in situ.

In women with ductal carcinoma in situ, an early form of breast cancer, cancer cells are found only in the milk ducts of the breast. The increased use of screening mammograms has led to an increase in the diagnosis of ductal carcinoma in situ, which can be considered a precursor to more invasive breast cancers. However, studies have shown that fewer than 2% of ductal carcinoma in situ patients die from breast cancer within 10 years, and less than 5% after 28 years.

This high survival rate is partially due to treatments such as breast conserving surgery (surgery to remove only the tumor) combined with radiation therapy and tamoxifen (Nolvadex), which blocks the estrogen tumors often need for growth. However, recurrence rates were even lower for women who underwent mastectomy, or full removal of the breast, rather than breast conserving surgery. The current study examined the recurrence risks and disease-free survival times associated with different treatments for ductal carcinoma in situ.

In this study, 1676 women diagnosed with ductal carcinoma in situ were followed for an average of 7.1 years. Of these, 36.8% used tamoxifen. Tamoxifen was used more often by women who underwent breast conserving surgery, and use increased over time: in the mid-1990s, 13.2% of patients diagnosed with ductal carcinoma in situ used tamoxifen, compared to 46.5% diagnosed between 2004 and 2006.

143 second breast cancers were reported. In women who had a mastectomy, recurrence was more likely to be seen in the breast not removed, while following breast conserving surgery recurrences were more common in the same breast. No recurrences were noted in patients who had a full mastectomy, or both breasts removed.

87% of patients who underwent breast conserving surgery were still disease-free by the end of the study, compared to 95% of patients who underwent breast conserving surgery with additional radiation therapy, and 100% following full mastectomy. Women who were treated with breast conserving surgery and radiation had a 60% higher risk of recurrence than did women who underwent mastectomy. Tamoxifen use did not change the risks of recurrence. Patients who had a partial mastectomy (only the affected breast removed) had recurrence risks similar to those of breast conserving surgery patients who also underwent radiation and tamoxifen therapy. 

This study concluded that breast conserving surgery combined with radiation therapy and tamoxifen can be as effective a treatment as partial mastectomy for women with ductal carcinoma in situ. However, full mastectomy offered the lowest risk of recurrence.