In the United States, cryoablation or freezing tissue to death is a primary treatment option for a variety of cancers, including those originating in or spread to the bone, cervix, eye, kidney, liver, lung, pancreas, and prostate.
Cryoablation for prostate cancer, one of the most common cancers in men, was first approved in the 1990s.
But unlike in Europe, this nonsurgical approach is not approved for breast cancer in the US, one of the most common cancers in women.
So why is this approach still experimental for breast cancer?
“I don’t know,” answered cryoablation researcher Richard Fine, MD, West Cancer Center in Germantown, Tennessee, when asked by Medscape Medical News.
“It’s very interesting how slow the FDA is in approving devices for breast cancer [when compared with] other cancers,” he said.
New Clinical Data
Perhaps new clinical data will eventually lead to approval of this laparoscopic technique for use in low-risk breast cancer. However, the related trial had a controversial design that might discourage uptake by practitioners if it is approved, commented an expert not involved in the study.
Nevertheless, the new data show that cryoablation can be an effective treatment for small, low-risk, early-stage breast cancers in older patients.
The findings come from ICE-3, a multicenter single-arm study of cryoablation in 194 such patients with mean follow-up of roughly 3 years.
It used liquid nitrogen-based cryoablation technology from IceCure Medical Ltd, an Israeli company and the study sponsor.
The results show that 2.06% (n = 4) of patients had a recurrence in the same breast, which is “basically the same” as lumpectomy, the surgical standard for this patient group, said Fine, who is the lead investigator on the trial.
These are interim data, Fine noted, when presenting the findings recently at the American Society of Breast Surgeons annual meeting, held virtually because of the pandemic.
The primary outcome is the 5-year recurrence rate, and this is the first-ever cryoablation trial that does not involve follow-up surgery, he said.
Cryoablation, which delivers a gas to a tumor via a thin needle-like probe that is guided by ultrasound, has multiple advantages over surgery, Fine commented.
“The noninvasive procedure is fast, painless, and can be delivered under local anesthesia in a doctor’s office. Recovery time is minimal and cosmetic outcomes are excellent with little loss of breast tissue and no scarring,” he said in a meeting press statement.
The potential market for cryoablation in breast cancer is large, as it is intended for tumors ≤1.5 cm, which comprise approximately 60%-70% of stage 1 breast cancers that are hormone receptor-positive (HR+), and HER2-negative (HER2–), Fine told Medscape Medical News.
Cryoablation is part of a logical, de-escalation of breast cancer care, he added. “We have moved from radical mastectomy to modified mastectomy to lumpectomy — so the next step in that evolution is ablative technology, which is ‘nonsurgical.’ ”
There are other experimental ablative treatments for breast cancer including high-frequency ultrasound and laser, but cryoablation is the furthest along in development.
Cryoablation as a primary cancer treatment was first approved for coverage by the US Centers for Medicare & Medicaid Services for localized prostate cancer in 1999.
But the concept extends back to 1845, when English physician James Arnott first used iced salt solutions (about –20 °C or – 4 °F) to induce tissue necrosis, reducing tumor size and ameliorating pain. Because the crude cryogen needed to be applied topically, the pioneering technique was limited to breast and cervical cancers because of their accessibility.
Not Likely to Show Superiority
The new study’s population was comprised 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 above.
The liquid nitrogen-based cryoablation consisted of 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 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, and 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 Attai, MD, a breast surgeon at UCLA in Los Angeles and past president of the ASBrS, 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 Medscape Medical News.
“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,” Attai summarized.
The Surgical Mindset and Breast Cancer
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 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,” 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…sometimes the innovation for male diseases and procedures sometimes surpasses that of women’s diseases,” she commented.
But the UCLA breast surgeon 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.
There’s not a lot of vital structures inside the breast.
The disparity between the development of cryoablation for breast and prostate cancer is a mystery when you contemplate the potential side effects, 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 ASBrS 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 Fine.
Currently, cryoablation for breast cancer is only allowed in a clinical trial, so a registry would expand usage considerably, he said.
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 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.
Fine was an investigator in the ICE3 trial, which is funded by IceCure Medical. Attai has disclosed no relevant financial relationships.
American Society of Breast Surgeons 2021 Annual Meeting: Scientific Session Oral Presentation. Presented April 30, 2021.
Nick Mulcahy is an award-winning senior journalist for Medscape, focusing on oncology, and can be reached at email@example.com and on Twitter: @MulcahyNick
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This post originally appeared on Medscape Medical News Headlines