Combination Therapy Outperforms Lumpectomy
By Krista Conger
Vol. 12 No. 4 P. 33
Women with localized ductal carcinoma in situ (DCIS) breast cancer fared better when they received radiation therapy or tamoxifen chemotherapy after lumpectomy surgery, according to research from the National Surgical Adjuvant Breast and Bowel Project (NSABP), a National Cancer Institute-sponsored cooperative oncology group headquartered in Pittsburgh that’s known for conducting large clinical trials comparing treatments for breast and colorectal cancers.
Either form of combination therapy after breast-conserving surgery reduced women’s recurrence rate, according to the study. The findings are the final conclusions of a pair of NSABP studies that began in the mid-1980s and early 1990s to compare the effectiveness of breast-conserving surgery alone with surgery plus additional cancer-fighting treatments. They confirm the idea that additional treatments can be a safe, effective way to combat some types of breast cancer.
“Now we can see the natural history of this disease in a large patient population over a period of up to two decades,” says Irene Wapnir, MD, chief of breast surgery at Stanford University’s Stanford Cancer Center and lead author of the research, published online in the Journal of the National Cancer Institute. “These are landmark trials with mature data.”
Long-term survival statistics for any study by definition take years to compile. During the intervening time, the standard of care can change dramatically. In this case, lumpectomy, which removes only a portion of the breast, has continued to be favored as a way to treat the cancer within the breast while preserving a woman’s appearance.
DCIS involves cancerous cells inside the lining of the milk ducts of the breast. Because the cells are confined to the duct and have not spread to other breast tissue, the condition rarely causes a palpable lump. It is primarily diagnosed through mammography and accounts for about 25% of all newly diagnosed breast cancers. Women with DCIS have an increased risk of invasive breast cancer.
One of the two studies included in Wapnir’s recent analysis is the NSABP B-17 trial, which enrolled 813 women with DCIS between October 1985 and the end of 1990 to randomly receive either a lumpectomy alone or a lumpectomy followed by radiation therapy. Five-year outcomes (first reported in 1993) demonstrated that women who received radiation therapy had a 60% lower risk of experiencing tumor recurrence in the same breast within that time period.
The B-24 trial enrolled approximately 1,800 women between May 1991 and April 1994 to investigate whether the addition of the cancer-fighting drug tamoxifen to the lumpectomy and radiation treatment would be beneficial. The study found that women who received tamoxifen experienced a 31% reduction in the risk of tumor recurrence compared with those who received lumpectomy and radiation alone.
The current study looked at the trial participants approximately 15 years after their initial diagnosis to determine the long-term risk of invasive cancer in the same breast. It found that 19% of the women who received a lumpectomy alone went on to develop invasive breast cancer, but only 8.5% of the women who also received radiation therapy plus tamoxifen did so.
Although women with subsequent invasive cancers did have a higher mortality rate than those who did not develop the cancers, the overall risk of death from breast cancer during the 15-year period was relatively low: 4.7% or less across all treatment arms.
“Critics will point out that the majority of patients with lumpectomy alone didn’t have a recurrence. We were not able to identify a group that did not benefit from either radiation or radiation plus tamoxifen,” says Wapnir. “I tell my patients when discussing treatment options that I don’t know how to identify which patients will be in that category.”
Wapnir points out that the women enrolled in the two studies had relatively small DCIS tumors and that the study findings may not apply to a woman diagnosed today with a larger tumor or with other complicating factors.
“A mastectomy may still be indicated in a woman with a very large DCIS,” says Wapnir, who points out that ongoing studies testing specific molecular markers in DCIS or investigating the efficacy of partial breast radiation may define new treatment strategies in the near future. “In the end, we want to treat each patient in such a way as to minimize the chance of that woman developing a subsequent invasive cancer.”
— Krista Conger is a writer with the Stanford University Office of Communication and Public Affairs.