In a process called cryoablation, surgeons freeze the tumors to kill the cells. The technique is already used as a non-surgical treatment for benign breast disease. Results of the study, published in the May issue of the Annals of Surgical Oncology, found cryoablation is effective at killing cancerous cells in small tumors.
Although still an experimental treatment for breast cancer, these findings move cryosurgery one step closer to clinical application for early stage disease.
As mammograms and other imaging techniques become more sophisticated, doctors are able to find breast cancer earlier, when tumors are very small. Progress in detection has led to an increased interest in developing alternatives to traditional surgery for early-stage cancer.
"This trial shows that cryoablation is a safe, well-tolerated office-based procedure that holds real promise for treating early stage breast cancer," says Michael Sabel, M.D., a surgical oncologist from the University of Michigan Comprehensive Cancer Center and lead author of the study.
In late 2003, University of Michigan Health System researchers reported findings from a preliminary study, focusing on the UMHS results. The current paper reflects the results of seven trial centers from across the country.
The study followed 27 women with primary invasive breast cancers no larger than 2.0 centimeters in diameter. One to four weeks following ultrasound-guided cryoablation, the women's tumors were removed by lumpectomy and studied to determine whether cryoablation was effective.
Cryoablation is an outpatient procedure requiring only local anesthesia. Directed by ultrasound images, a physician guides a disposable probe through a small breast incision and into the center of the tumor. Super-cold argon gas flows through the probe, forming an iceball that engulfs the tumor and nearby tissue. To complete the procedure, the iceball is allowed to thaw, and another freeze-thaw cycle is repeated. The probe is then removed and the incision closed with a bandage.
Of the 27 procedures performed in the study, cryoablation successfully destroyed all cancers less than 1.0 centimeters in diameter. The procedure was equally effective for tumors between 1.0 and 1.5 centimeters in those women with a type of cancer called invasive ductal carcinoma who did not have significant ductal carcinoma-in-situ, a non-invasive breast cancer, in the surrounding tissue. Cryoablation was not shown effective for tumors larger than 1.5 centimeters in diameter.
"Right now, its application should be limited to patients with invasive ductal carcinomas no larger than 1.5 centimeters. But we're continuing to determine the boundaries of the procedure," Sabel says.
Sabel notes that a follow-up study will begin soon at U-M and other centers to learn more. "But as is the case with this study," he cautions, "patients enrolled in that study will be required to undergo a lumpectomy following the procedure. More data is needed before we'll be able to offer cryosurgery alone as a treatment for breast cancer."
Funding for the study came from Sanarus Medical Inc., who developed the cryoablation probe used in the study.
In addition to Sabel, the other authors of the study included: Cary S. Kaufman, M.D., the University of Washington Bellingham Breast Center; Pat Whitworth, M.D., Nashville Breast Center; Helena Chang, M.D., Ph.D., Revlon UCLA Breast Center, Los Angeles; Lewis Stocks, M.D., Ph.D., Executive Surgical Center, Raleigh, N.C.; Rache Simmons, M.D., Weill Medical College, Cornell University, New York; and Michael Schultz, M.D., Surgery Center of Greater Baltimore, Owings Mills, Md.
Patients wishing to learn more about the procedure or other treatments for breast cancer can contact the U-M Cancer AnswerLine at 1-800-865-1125.