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From the Department of Surgical Oncology, University of Texas M. D. Anderson Cancer Center, Houston, Texas.
Correspondence: Address correspondence to: S. Eva Singletary, MD, University of Texas M. D. Anderson Cancer Center, Department of Surgical Oncology, 1515 Holcombe Blvd., Box 444, Houston, TX 77030-4095; Fax: 713-792-2225; E-mail: esinglet{at}mdanderson.org
In this issue, Gardner and colleagues present a pilot study of an intriguing new technology using focused microwave phased array thermotherapy for the treatment of primary breast cancer.1 Their study involved 10 patients with breast carcinomas ranging from 1–8 cm in maximum clinical size. After focused microwave phased array treatment, all patients underwent mastectomy. They achieved a significant tumor response in 80% of patients, with 30% of patients developing full-thickness, limited-flap necrosis following mastectomy. These interesting preliminary results should provide needed background information for the implementation of a well-designed clinical trial to definitively test the usefulness of this new approach.
The concept behind this study, that it is both possible and desirable to remove the primary tumor without surgery, is increasingly attracting the interest of researchers around the world. This represents the next step in an evolution that began over 100 years ago with radical surgery and has more recently involved the adoption of breast conservation therapy and sentinel lymph node biopsy as treatment standards for early-stage breast cancer.
A variety of minimally invasive ablation techniques exist that are candidates for nonsurgical removal or destruction of breast tumors. Such techniques are designed to either cool the tumor (cryosurgery) or to heat the tumor (radiofrequency ablation, laser interstitial therapy, or focused ultrasound) sufficiently to result in complete cell death. Currently, however, the majority of experiences in treating breast tumors with in situ ablation has been with the techniques that heat tumor cells.
Radiofrequency ablation (RFA) destroys tumor cells through the generation of frictional heat by intracellular ions moving in response to a high frequency alternating current. An electrode is inserted into the tumor under ultrasound guidance, and a larger electrode pad is placed against the patient’s skin, usually on the anterior thigh. The electrode placed in the tumor contains secondary electrodes that are deployed in the tumor into a star-like array. This multiprong electrode can generate an ablation zone of 3–6 cm in diameter.
At the University of Texas M. D. Anderson Cancer Center, we are in the final stages of a multicenter clinical trial exploring the use of RFA for the treatment of invasive breast tumors 
2 cm in size.2 After RFA, the probe was retracted and the surgeon proceeded with the resection (mastectomy or lumpectomy). Histological staining using standard hematoxylin and eosin and nicotinamide adenine dinucleotide-diaphorase was carried out to assess the extent of coagulative necrosis. To date, 28 patients have been registered on the study, and 25 have received RFA. The majority of cases receiving RFA demonstrated 100% ablation of the primary tumor with virtually no side effects from the procedure. Further studies are needed to determine if RFA alone for the treatment of primary breast cancer will result in local recurrence and survival rates equivalent to those seen with breast conservation therapy. A study is currently in preparation at the M. D. Anderson Cancer Center to answer these questions. After RFA treatment in this study, patients will receive multiple core biopsies at 2–4 weeks after the procedure to assess local tumor control. If the core biopsies are negative, the patient will then receive radiation therapy to the breast, including a radiation boost to the primary tumor site and systemic therapy as indicated by the initial size of the primary tumor. She will undergo imaging studies and quality of life evaluations at appropriate intervals over the next 5 years.
Laser interstitial therapy destroys tumor cells with laser energy delivered through a fiberoptic probe inserted into the tumor under imaging guidance. Dowlatshahi and colleagues used this technique to treat 36 patients with mammographically detected tumors 2 cm in diameter.3 They found total tumor ablation with negative margins and insignificant side effects when tumors were treated to a temperature of 60°C. A similar study underway at the University of Arkansas for Medical Sciences is using laser interstitial therapy in combination with high-contrast, high-resolution magnetic resonance imaging (MRI) to treat breast lesions. Preliminary results indicate complete tumor ablation and accurate assessment of the ablation field by MRI (S. Harms, personal communication, October 2000).
MRI-guided focused ultrasound focuses waves through the intact skin resulting in intratumoral temperatures as high as 70°C. MRI is able to localize the hot spot in the tumor and also to measure the increase in temperature during treatment. This technique has been used in a pilot study to treat patients with inoperable breast cancer.4
As systemic therapy (chemotherapy, hormonal therapy, or both) is increasingly used even for the treatment of small tumors, the possibility of managing breast cancer as a chronic long-term disease is becoming more real. With the development of these innovative ablation techniques, the treatment paradigm for breast cancer will continue to evolve into one that uses minimally invasive local therapy to eradicate small primary tumors or any residual tumor that persists after the completion of systemic therapy. This will be assisted by the development of new technologies to precisely define the location and size of tumors. Nonetheless, as surgical excision with negative margins now offers excellent results, surgeons should be cautious in adopting these new technologies outside the arena of clinical trials.
Received for publication February 25, 2002. Accepted for publication March 8, 2002.
REFERENCES
This article has been cited by other articles:
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  M. S. Sabel, C. S. Kaufman, P. Whitworth, H. Chang, L. H. Stocks, R. Simmons, and M. Schultz Cryoablation of Early-Stage Breast Cancer: Work-in-Progress Report of a Multi-Institutional Trial Ann. Surg. Oncol., May 1, 2004; 11(5): 542 - 549. [Abstract] [Full Text] [PDF]
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H. I. Vargas, W. C. Dooley, R. A. Gardner, K. D. Gonzalez, R. Venegas, S. H. Heywang-Kobrunner, and A. J. Fenn Focused Microwave Phased Array Thermotherapy for Ablation of Early-Stage Breast Cancer: Results of Thermal Dose Escalation Ann. Surg. Oncol., February 1, 2004; 11(2): 139 - 146. [Abstract] [Full Text] [PDF]
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