Cryoablation of breast tumors, which destroys lesions by exposing them to extremely low temperatures, shows promise as an alternative to surgery in carefully selected women with early-stage disease, according to a study presented at the American Society of Breast Surgeons Annual Meeting in Las Vegas. In the multicenter phase II ACOSOG (Alliance) Z1072 trial of 99 patients with early-stage invasive ductal carcinoma, cryoablation resulted in complete ablation of tumor in 69% of patients overall, but in 94% of patients with tumors < 1 cm, according to Rache Simmons, MD, Professor and Chief of Breast Surgery at Weill Cornell Breast Center, New York.
“A handful of studies have looked at cryoablation of breast tumors, but this is the first multicenter [National Institutes of Health]-sponsored national trial,” Dr. Simmons said in a press briefing.
Cryoablation is an established technique for the treatment of fibroadenomas. The modality involves the percutaneous insertion under ultrasound guidance of a cryoprobe, which destroys the lesion by means of a freeze-thaw-freeze cycle lasting about 20 minutes. Pilot studies have suggested it could also be an effective treatment for breast cancer.
Study Details
In the Z1072 study, patients underwent cryoablation, then had their tumor resected so that the surgical specimen could be examined for residual disease. Patients also underwent postablation magnetic resonance imaging (MRI) to evaluate its negative predictive value in predicting residual disease.
A total of 99 patients from 19 centers were enrolled in the trial; of these, 86 patients (87 tumors) were evaluable for data analysis. Eligible patients included those with unifocal invasive ductal breast cancer ≤ 2 cm, with < 25% intraductal component and with tumor enhancement on MRI.
Successful tumor ablation was defined two ways: no remaining invasive cancer present on the pathologic examination of the targeted lesion, and no residual invasive ductal breast cancer or ductal carcinoma in situ present on the specimen.
Dr. Simmons reported that by the first definition (no residual invasive disease), the success rate was 80.5%, and by the second definition (no residual invasive ductal carcinoma or ductal carcinoma in situ), 69% of patients achieved complete ablation.
Smaller Tumors, Greater Success Rate
“When we broke this down by tumor size, we showed something quite important,” Dr. Simmons added. “Tumor size was a strong predictor of
success.”
For tumors ≥ 1 cm, the success rate was 63%, but in those < 1 cm, it rose to 94%, “which we consider quite a success,” she said. Only one patient had some residual disease, but this was successfully revealed by MRI.
“Therefore, 100% of all 16 tumors less than 1 cm had either complete ablation or residual invasive ductal breast cancer/ductal carcinoma in situ predicted by MRI,” she said.
For the whole group, MRI following the procedure predicted the disease status of 75% of patients with negative reports for both invasive ductal carcinoma or ductal carcinoma in situ and 85.9% of patients with negative pathology reports for invasive residual
disease.
The findings indicated that MRI has an important role in evaluation of the results after cryoablation, and could potentially be used in future trials as a surrogate for pathologic examination of the tissue, Dr. Simmons suggested.
In fibroadenoma patients (from other studies), pre- and post-treatment mammography has indicated a lack of distortion, calcification, and fat necrosis, and a complete disappearance of the lesion. Anecdotally, this mirrors what has been seen in some cancer patients off-study who refused resection after cryoablation, she added. “We may see the same with breast cancer, but we don’t have data yet,” she said.
Looking Ahead
Dr. Simmons indicated this treatment might be applicable to a growing population of patients—in particular, those with small tumors.
“We have lots of patients with tumors less than 1 cm. They probably constitute 25% to 30% of our patients at Cornell. This number will be increasing as our imaging becomes more sophisticated,” she said.
Future studies are needed, but the next step will not be a randomized phase III trial, she said. “The numbers would have to be enormous to compare patients with cancers smaller than 1 cm and follow them for recurrence. Equally important, it would be very difficult to get patients to agree to be randomized,” she noted.
Along with the type of trial—or perhaps, registry—it is also unclear whether these patients should undergo radiotherapy, and if so, what type. Issues of third-party reimbursement are also unsettled. These and other factors are under discussion, she said. ■
Disclosure: Dr. Simmons reported no potential conflicts of interest.
Reference
1. Simmons R, Ballman K, Cox C, et al: A phase II trial exploring the success of cryoablation therapy in the treatment of invasive breast carcinoma: Results from ACOSOG (Alliance) Z1072. American Society of Breast Surgeons Annual Meeting. Presented April 30, 2014.
