Making Breast Surgery More Effective
An important presentation at the recent Miami Breast Cancer Conference concerned the impact that preoperative endocrine (hormonal) therapy can have on reducing the size of large tumors, possibly sparing many patients the need for a mastectomy.
Hormone-sensitive tumors are partly dependent on the hormone estrogen to grow. By blocking the effect of estrogen or preventing its production, hormonal therapy before surgery starves the tumor of estrogen and causes it to shrink, making surgical removal easier.
Dr. J. Michael Dixon of the Edinburgh Breast Unit in Scotland, presented the results of a study assessing the tumor-reducing impacts of letrozole and tamoxifen in 337 postmenopausal women with hormone-sensitive invasive breast cancers. None of the patients was initially eligible for breast conserving surgery because of the size of their tumors.
Chemotherapy, rather than hormonal therapy, is often the preoperative treatment of choice for shrinking large tumors, Dixon said. But for women with hormone-receptor positive cancers, hormonal therapy can have significant benefits, he strongly suggested.
After 4 months of treatment, the patients given letrozole demonstrated an average 55 percent reduction in tumor volume. Similarly, those in the tamoxifen group demonstrated a 36 percent response rate. These reductions were sufficient enough for breast conserving surgery to be performed in 45 percent of the women receiving letrozole and 35 percent of the women treated with tamoxifen.
"Most of you have probably never considered neoadjuvant endocrine therapy in your patients when trying to avoid mastectomy," Dixon told his audience of medical oncologists, breast surgeons and radiologists. "But I hope now you're aware of it and realize it's powerful."
A similar study was presented by Dixon to attendees at the San Antonio Breast Cancer Symposium in December. At that time, he reported on a Phase II study involved 12 patients with estrogen-sensitive tumors who were given hormonal therapy using exemestane for three months prior to surgery.
Dixon noted that exemestane significantly reduced the size of breast cancer tumors in 11 of the patients, with a median tumor reduction of 85 percent. "These early data show promise in the treatment of women who have large breast tumors," he said. "Treatments that shrink tumors can be important for women who are considering breast conserving surgical options rather than a complete mastectomy," he added.
Dixon had earlier published a study in the journal Clinical Cancer Research on hormonal therapy using anastrozole in the pre-surgical treatment of estrogen receptor-positive tumors. That study included 24 postmenopausal women with hormone-sensitive, locally advanced or large breast tumors (greater than 3 cm). They were treated with anastrozole for 3 months prior to surgery to remove the tumor.
Anastrozole treatment resulted in a median reduction in tumor volume of 75 percent, Dixon wrote. As a result, of the 17 women who were originally scheduled for mastectomy at the start of the study, 15 of them were found to be suitable for breast conserving surgery after being treated with anastrozole.
In a separate presentation at the Miami Breast Cancer Conference, Dr. Michael Baum of University College in London reported on a study of a new device that will enable patients to receive a high dose of radiation during breast cancer surgery. He contended that a single dose of radiation during the surgery may be sufficient to prevent local recurrence in many instances.
Baum and his colleagues are conducting the Targeted Intraoperative Radiotherapy Trial (TARGIT) with an Intrabeam System developed by AstraZeneca. "This is a miniature electron generator that can deliver soft x-rays to the breast in about 20 minutes," Baum explained.
Thirty-seven patients have undergone the procedure at University College London as part of Phase I and II clinical trials, Baum noted. To date, there have been no significant complications, and safety and efficacy have all met expectations, he said. Patients are now being enrolled in more extensive Phase III trials.
SOURCES:
The 18th Annual Miami Breast Cancer Conference, Miami Beach, Florida, March 6, 2001
The 23rd Annual San Antonio Breast Cancer Symposium, San Antonio, Texas, December 7, 2000
Clinical Cancer Research, June 2000; 6:2229-2235
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