For women diagnosed with the localized form of breast cancer, ductal carcinoma in situ (DCIS), a new study in The Lancet Oncology finds that treatment with radiotherapy and tamoxifen after surgery significantly reduces the development of the invasive disease and cuts the likelihood of local cancer resurgence. Survival following standard treatments after breast-conserving surgery (local excision), which include radiotherapy and hormone therapy, is about 98 percent, but there is a higher risk of the local recurrence of a new cancer emerging in the contralateral breast.
In a study of 1,701 women from the U.K., Australia and New Zealand between 1990 and 1998, researchers found that after surgery, radiotherapy reduced the relative risk of new invasive cancer in the same breast by nearly 70 percent during the course of almost 13 years of follow-up. Local radiotherapy also diminished the chance of recurrent DCIS in the same breast by over 60 percent, although no beneficial effect was seen on cancer risk in the opposite breast. In addition, tamoxifen treatment lowered the relative risk of cancer recurrence in the same breast by 30 percent while decreasing the risk of new cancer in the contralateral breast by over 65 percent.
ACSH's Dr. Elizabeth Whelan reminds us that DCIS can also be referred to as stage 0 breast cancer, and it is often considered a risk factor for invasive cancer. Overall, DCIS cases represent about 20 to 25 percent of screen-detected breast cancers.
“Even though surgery is required in patients with DCIS, it is a fairly minor surgery called a lesionectomy, which is less invasive than a lumpectomy,” adds ACSH's Dr. Gilbert Ross.