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Cryoablation may be viable alternative to surgery for some early breast cancers
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Cryoablation appeared to be a safe and effective alternative to surgery for women with early-stage small breast cancers, according to results of the phase 2 American College of Surgeons Oncology Group Z1072 trial.
Researchers now are calling for additional studies to further assess the role of cryoablation as a nonsurgical treatment option for patients with early-stage disease.
Cryoablation is an effective technique for noncancerous fibroadenomas of the breast, as well as liver, lung and kidney cancers. However, the technique has not been widely used for treating early-stage small breast cancers.
The Z1072 study included 86 women with unifocal, invasive, ductal breast cancers with tumors less than 2 cm. At least 25% of patients had intraductal component and tumor enhancement on MRI.
The rate of complete tumor ablation, defined as no remaining invasive breast cancer or ductal carcinoma in situ (DCIS) upon examination, served as the primary outcome. Secondary outcomes included residual invasive disease and DCIS.
Results showed successful ablation in 75.9% (90% CI, 67.1-83.2) of breast cancers, regardless of residual invasive disease or DCIS. The negative predictive value of MRI was 81.2% (90% CI, 71.4-88.8). The study also demonstrated the success of cryoablation in 92% of treated cancer when multifocal disease, outside of the targeted cryoablation zone, was not defined as an ablation failure.
HemOnc Today spoke with investigator Deanna Attai, MD, assistant clinical professor of surgery at David Geffen School of Medicine at University of California at Los Angeles, about the potential of this approach for treating breast cancer and what she hopes subsequent research on cryoablation in this patient population will entail.
Question: Can you describe how the technique works?
Answer: Cryoablation uses the principal of freezing cells, which we know kills cells. For breast lesions, the technique is usually done in the office, with local anesthesia. The tumor is identified with ultrasound, a 3-mm cut is made in the skin and the probe passes under ultrasound guidance into the center of the tumor. The probe is hollow on the inside, but it is closed at the end. Liquid nitrogen flows through the probe, and this cools it down to -160 degrees Celsius. Cells cannot survive this degree of cold, so the cells of the tumor are destroyed. We are able to monitor the size of the ice ball, or the freeze zone that develops around the tumor, via ultrasound. The duration of cryoablation depends on the size of the tumor. For example, one would treat a larger lesion for a longer period of time than a smaller lesion. Depending upon the size of the tumor, the procedure can be anywhere from 10 to 20 minutes duration. The patient is able to go home after the procedure.
Q: What is the potential of the technique?
A: I think the potential is huge. The study was designed to address whether this procedure would kill cancer cells and is it safe. These questions have both been answered. The potential now is, with more study, we can envision not operating on certain patients with small favorable breast cancers — the population of patients who met inclusion criteria in our study. Being able to treat breast cancer nonoperatively in an office setting, under local anesthesia, is a significant advantage for these patients.
Q: What led you and colleagues to conduct this study?
A: Smaller studies have suggested that cryoabalation can be effective in treating some breast cancers. These preliminary studies led Rache Simmons, MD, the ACOSOG Z1072 principal investigator, and colleagues to propose the study design.
Q: Can you describe the study’s primary findings?
A: The ablation rate was very good in patients with small cancers. This was somewhat dependent on the size of the tumor and how you really look at the data, but overall our data showed positive results with cryoablation. When looking at any residual invasive or DCIS in the targeted area, cryoablation was 75.9% successful. If we discounted those patients with disease outside of the cryoablation zone, the success rate increased to 92%. This study reinforces the fact that there will always be situations in which there are cancer cells outside of the primary focus — cells that may not be picked up on preoperative imaging studies. We have to recognize that this is a limitation of our preoperative imaging.
Q : Is there a certain patient population that may benefit most from this technique?
A: Patients enrolled in the study had invasive ductal carcinomas, less than 2 cm in size, with less than 25% DCIS on core biopsy. All tumors were visible under ultrasound. We do not have information on larger tumors, invasive lobular tumors or cancers with a larger proportion of DCIS.
Q: What might future research entail?
A: The next step would be nonoperative studies — treat patients with cryoablation and then observe and monitor for recurrence. There are still unanswered questions, such as: Can we treat larger cancers and noninvasive cancers? If we successfully ablate the cancer, do we have to do radiation therapy or can radiation potentially be avoided in some patients? What is the ideal duration of hormonal therapy in patients who undergo ablation? Does the cryoablation procedure stimulate the immune system, as has been suggested in animal models? I am hopeful that future studies will help answer some of these additional questions. – by Jennifer Southall
Reference:
Simmons RM, et al. Ann Surg Oncol. 2016; doi:10.1245/s10434-016-5275-3.
For more information:
Deanna Attai, MD, can be reached at UCLA Health Burbank Breast Care, 191 S. Buena Vista St., #415, Burbank, CA 91505; email: dattai@mednet.ucla.edu.
Disclosure: Attai reports no relevant financial disclosures.