Cryoablation 'Quite Successful' for Small Breast Cancers

Nick Mulcahy

April 30, 2014

Freezing breast cancers to death with cryoablation could be a viable option for small lesions, and might allow some women to forgo surgery in the future, according to a multi-institutional phase 2 study.

Of 16 patients with invasive breast cancers smaller than 1 cm, 15 had complete tumor ablation with the technique, reported principal investigator Rache M. Simmons, MD, from Weill Cornell Medical College in New York City.

She spoke at a presscast today at the American Society of Breast Surgeons (ASBS) 15th Annual Meeting in Las Vegas.

The technique had an ablation rate in small tumors of 93.8%. "It was quite successful," Dr. Simmons said in an interview with Medscape Medical News.

The rate of complete tumor ablation was the primary outcome in the open-label single-group study, known as the American College of Surgeons Oncology GroupZ1072 trial.

Of the 99 patients enrolled, 86 women (with a total of 87 breast cancers) were evaluable. All patients had unifocal invasive ductal breast cancer that was 2 cm or smaller, an intraductal component of less than 25%, and no extensive calcifications.

The overall ablation rate was only 69%; the procedure was much less successful in larger breast cancers and in patients who had some measure of ductal carcinoma in situ (DCIS).

Dr. Simmons explained how cryoablation works and why it might not work as well with larger lesions.

The procedure involves a "cryoprobe" — a thin wand-like device that is inserted through the skin to the targeted lesion using ultrasound guidance. Once inside the tumor core, the probe, which is filled with nitrogen gas, is "like a popsicle," said Dr. Simmons. The cold creates a "freeze ball" in the surrounding tumor tissue, destroying it. However, the freeze ball appears to have a limited expanse, rendering it ineffective beyond 1 cm.

Cryoablation should be appreciated in a historic perspective, suggested presscast moderator Deanna Attai, MD, a breast surgeon from Burbank, California.

 
It's amazing.
 

"As a surgeon, it's incredible to think that in my career, I've seen radical mastectomies as the only treatment option and, now, we have the potential to avoid surgery altogether in selected patients with small breast cancers," she told Medscape Medical News. "It's amazing."

Dr. Attai, who is a member of the ASBS communications committee, is also a trial investigator.

"Cryoablation is not going to work for all breast cancers," she cautioned.

In fact, "it's horrible for DCIS," said Dr Simmons. "This is an ultrasound-directed technology and you can't see DCIS with ultrasound."

Notably, the study is the first cryoablation trial in cancer sponsored by the National Institutes of Health and the first-ever multicenter cryoablation trial.

The next step for cryoablation in breast cancer is not clear, but "it will not be a phase 3 randomized trial," Dr. Simmons said. "The numbers would have to be enormous." A registry trial is a possibility, she added.

Trial enrollment could also be an issue, if the current study is an indicator. The trial started enrolling patients in September 2008 at 19 centers, but is only now reporting very short-term outcomes from 99 patients. That is 9 years after results from an earlier phase 1 pilot study were reported by Medscape Medical News.

Another Important Outcome

In this study, all patients underwent imaging to determine the size of their breast cancers. They then underwent ablation using a freeze–thaw–freeze cycle that lasted approximately 6–10–6 minutes or 8–10–8 minutes.

After the procedure, patients underwent MRI to see if any residual disease was visible. The MRI component of the study is important, Dr. Simmons explained. It can serve "as a surrogate for surgical margins."

Finally, study patients underwent surgical resection within 28 days of the completion of cryoablation.

The tissue excised during surgery allowed investigators to do a pathologic examination of the targeted lesion. And that allowed them to assess just how good the MRI was at evaluating disease status after the procedure.

The MRI and the postsurgical pathology matched up for the 1 patient with a lesion smaller than 1 cm who did not have complete ablation. Because success was defined as either full ablation of the cancer or accurate detection of the residual cancer by MRI, the investigators claimed that, for that size of lesions, cryoablation is "100% successful."

Patients who have residual disease on MRI can be treated with surgery.

Overall, the investigators report that MRI after the procedure predicted the disease status of 85.9% of patients with negative pathology reports for invasive cancer, according to meeting press materials.

American Society of Breast Surgeons (ASBS) 15th Annual Meeting. To be presented May 3, 2014.

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