Advances in Breast Cancer Research
Dr. Nicholas Petrelli and Dr. Diana Dickson-Witmer
Photo by Jared Castaldi
The past 20 years of research have yielded some encouraging advances in breast cancer detection and treatment, and the breast cancer mortality rate is dropping dramatically, according to Dr. Nicholas Petrelli, director of Christiana Care’s Helen F. Graham Cancer Center, and Dr. Diana Dickson-Witmer, associate director of its Breast Center. More must be done, however, particularly if we are to achieve the National Breast Cancer Coalition’s goal of ending breast cancer by 2020.
Petrelli and Dickson-Witmer recently discussed some of the advances in breast cancer detection and treatment that have taken place over the past two decades. The treatment of early-stage cancer has been altered dramatically, Petrelli notes, because of clinical trials that proved that breast-conserving surgery combined with radiation and appropriate systemic therapy is as effective as mastectomy.
“We are doing less surgery to accomplish the same chance of cure,” says Dickson-Witmer, who adds that the diagnosis of cancer is now made with a needle biopsy, without a trip to the operating room. In addition, researchers are investigating ways to irradiate the area around the lumpectomy cavity instead of the entire breast, and doing it over five days instead of eight weeks. This would make undergoing radiation much easier for many patients, Dickson-Witmer says.
Treatment of advanced-stage cancer also has improved thanks to clinical trials. “The use of targeted agents such as Herceptin has dramatically improved the survival rate of women with advanced breast cancer,” Petrelli says. In fact, he adds, the drug is so successful that it is now used in early-stage cancer for women who are HER2 positive. Another drug, Tamoxifen, has been shown to cut in half the risk of developing breast cancer. This is particularly beneficial to women at very high risk of developing breast cancer, including women with certain breast cancer susceptibility gene mutations, Petrelli says. It is also used to prevent recurrence in women with estrogen receptor positive breast cancer. The side effects of Tamoxifen, however, limit its use in some women, Dickson-Witmer notes.
The introduction of sentinel lymph node biopsy (SLN) in 1999 allows surgeons to remove fewer lymph nodes in women with no tumor in some representative lymph nodes. The SLNs are identified in the operating room using blue dye injected into the breast. They are the first lymph nodes to which breast cancer spreads. If these nodes are negative, clinical trials have shown that no further nodes need to be removed. Removing fewer lymph nodes cuts in half the risk of lymphedema of the arm, a painful incurable swelling. About 70 percent of the 207,000 women diagnosed with invasive breast cancer have negative sentinel nodes and have benefited from this advance.
Dickson-Witmer adds that in February 2011, results of a clinical trial showed that some patients with one to two positive SLNs may safely be spared removal of additional nodes.
When it comes to detection, Delaware ranked fifth in the country for breast cancer screening. Digital mammography allows doctors to detect tumors even smaller than 1 cm.
“We are screening more women and finding cancers earlier when there is greater chance for a cure,” Dickson-Witmer says.
Despite these advances, she says, we are not moving forward fast enough. “If you had asked me 20 years ago where we would be today, I would have expected that we would have made more progress toward prevention,” she says. “I also would have expected that there would be targeted therapy for every type of breast cancer. We still have work to do, and we won’t reach our goal without greater participation in clinical trials.”