Not likely to show superiority
The new study’s population was composed of women aged 60 years or older (mean of 75 years) with unifocal invasive ductal cancers measuring ≤1.5 cm or less that were all low-grade, HR+, and HER2–, as noted.
The liquid nitrogen–based cryoablation consisted of a freeze-thaw-freeze cycle that totals 20-40 minutes, with freezing temperatures targeting the tumor area and turning it into an “ice ball.”
That ice ball eventually surrounds the tumor, creating a “lethal zone,” and thus a margin in which no cancer exists, akin to surgery, said Dr. Fine.
There were no significant device-related adverse events or complications reported, say the investigators. Most of the adverse events were minor and included bruising, localized edema, minor skin freeze burn, rash, minor bleeding from needle insertion, minor local hematoma, skin induration, minor infection, and pruritis.
Two of 15 patients who underwent sentinel lymph node biopsies had a positive sentinel node. At the discretion of their treating physician, 27 patients underwent adjuvant radiation, 1 patient received chemotherapy, and 148 began endocrine therapy. More than 95% of the patients and 98% of physicians reported satisfaction from the cosmetic results during follow-up visits.
Because not all patients underwent sentinel lymph node biopsy and adjuvant radiation, there is likely to be controversy about this approach, suggested Deanna J. Attai, MD, a breast surgeon at the University of California, Los Angeles, and past president of the American Society of Breast Surgeons, who was asked for comment.
“We have studies that [indicate that] these treatments don’t add significant benefit [in this patient population] but there still is this hesitation [to forgo them],” she told this news organization.
“The patients in this study were exceedingly low risk,” she emphasized.
“Is 5 years enough to assess recurrence rates? The answer is probably no. Recurrences or distant metastases are more likely to happen 10-20 years later.”
Thus, it will be difficult to show that cryoablation is superior to surgery, she said.
“You can show that cryoablation is not inferior to lumpectomy alone – which allows patients to avoid the operating room,” Dr. Attai summarized.
The surgical mindset and breast cancer
Dr. Attai, who was not involved in the current trial, was an investigator in an earlier single-arm cooperative group study of cryoablation for breast cancer, which had the rate of complete tumor ablation as the primary outcome. The study, known as the American College of Surgeons Oncology Group Z1072 trial, enrolled 99 patients, all of whom underwent ablation followed by surgery. The study reported results in 2014 but was very slow to develop, she observed.
“I did my first training in 2004 and I don’t think the study opened for several years after that. I think there’s been a lot of hesitation to change the mindset that every cancer needs to be removed surgically,” Dr. Attai stated.
“When you put breast cancer in the context of the other organs, we are lagging behind a bit [with cryoablation],” she added.
“I don’t want to go there but … the innovation for male diseases and procedures sometimes surpasses that of women’s diseases,” she said.
But she also defended her fellow practitioners. “There’s been tremendous changes in management over the 27 years I’ve been in practice,” she said, citing the movement from mastectomy to lumpectomy as one of multiple big changes.
The disparity between the development of cryoablation for breast and prostate cancer is a mystery when you contemplate the potential side effects, Dr. Fine observed. “There’s not a lot of vital structures inside the breast, so you don’t have risks that you have with the prostate, including urinary incontinence and impotence.”
As a next move, the American Society of Breast Surgeons is planning to establish a cryoablation registry and aims to enroll 50 sites and 500 patients who are aged 55-85 years; for those aged 65-70, radiation therapy will be required, said Dr. Fine.
Currently, cryoablation for breast cancer is allowed only in a clinical trial, so a registry would expand usage considerably, he said.
However, cryoablation, including from IceCure, has FDA clearance for ablating cancerous tissue in general (but not breast cancer specifically).
Dr. Attai hopes the field is ready for the nonsurgical approach.
“Halsted died in 1922 and the Halsted radical mastectomy really didn’t start to fall out of favor until the 1950s, 1960,” said Dr. Attai, referring to Dr William Halsted, who pioneered the procedure in the 1890s. “I would hope we are better at speeding up our progress. Changing the surgical mindset takes time,” she said.
Dr. Fine was an investigator in the ICE3 trial, which is funded by IceCure Medical. Dr. Attai has disclosed no relevant financial relationships.
A version of this article first appeared on Medscape.com.