Breast cancer is the most common cancer in women, accounting for more than a third of all new cases of female cancer [1]. In Europe, its incidence and mortality are nevertheless decreasing thanks to new therapeutic approaches [2]. Indeed, breast cancer patients can benefit from many therapeutic options: surgery, radiotherapy, hormone therapy, chemotherapy, and targeted therapies. The choice of treatments is personalized and adapted to each patient’s setting. Recently, new minimally invasive therapeutic approaches for tumour ablation have been developed in patients at risk of surgery or in patients refusing surgery. The purpose of my lecture at CIRSE 2023 will be to show the place of ablative treatments in breast cancer (in particular cryotherapy), explain how a procedure is carried out, and discuss the results available to date.
Percutaneous ablation of breast cancer
The standard treatment for breast cancer remains surgery. However, in elderly patients, there are more comorbidities, more contraindications to general anaesthesia, more complications of surgery, and more refusals of intervention from patients. Before any treatment decision, a benefit-risk evaluation based on a treatment’s potential benefits outweighing the potential risks must be made, after careful geriatric assessment [3]. The indication for ablative treatment must always be validated at a tumour board. Various ablative techniques have been used in the breast so far: radiofrequency, microwave, laser, IRE, and cryoablation [4]. While studies on treatment efficacy in patients with breast cancer are limited, cryoablation and RFA have been extensively studied and have shown promising results compared to other minimally invasive methods.
Cryotherapy has several important advantages vis-à-vis other heat-based tumour ablation techniques and is increasingly being used. First, the intrinsic anaesthetic properties of cold make cryoablation feasible under local anaesthesia. In a study of 40 patients treated with cryotherapy or radiofrequency for breast cancer, the authors found comparable efficacy and cosmetic effect, but preferred cryotherapy because of its less painful nature [5]. Second, cryoablation better preserves the collagenic matrix of tissues and causes less retraction in the fatty tissues, which represents a real advantage for superficial organs such as breasts. Finally, cryotherapy can stimulate the immune response and a combination with an anti-CTLA4 has shown promising results [6].
In a meta-analysis published in 2021 reviewing 17 studies involving 399 patients with breast tumour smaller than 2 cm treated with RFA, Xia et al showed that most ablations were done using straight needles and under general anaesthesia [7]. Regarding the success rate, it varies strongly among studies, ranging from 50 to 100%, as shown in another large meta-analysis [8].
Best indications and technique
Most of the lesions eligible for ablation are infiltrating ductal carcinomas without in-situ component, measuring less than 25 mm in diameter, whose margins are clearly visible with ultrasound. To carry out a percutaneous ablation in the breast, an approach using ultrasound guidance is preferred. In general, needles run parallel to the skin surface, the patient being placed in supine position. For cryoablation, the positioning of the needles and the treatment itself can be carried out under local anaesthesia. Ideally, with a multi-needle technique, the spacing between the needles should be between 10 and 15 mm, the number of needles depending on the size of the tumour. As a rule, we use 2 or 3 cryoprobes. For radiofrequency ablation, a straight needle is placed at the centre of the lesion. Although ultrasound is the technique of choice for placing the needles, it has limitations to monitor the ablation itself. For cryoablation, visualisation of the entire ice-ball is not possible because of a strong posterior acoustic shadowing. For RFA, gas forming obscures the ablated area. Only a cross-sectional imaging technique such as CT or MRI at the end of the procedure allows to visualize the extent of the ablation area.
The key issue in the breast is to protect the skin, whatever ablation technique is used. The preferred technique is hydrodissection, which consists of injecting fluid between the tumour and the skin using a spinal needle to increase the distance separating them. It is also very useful to perform a massage of the skin to ensure that it remains permanently mobile, without blister, which warrants that the skin remains vascularized and at a distance from the ablated area. Finally, it is possible to apply a glove filled with warm or cold water onto the skin, depending on the ablation technique used.
After treatment, there is in all cases an induration of the ablation zone, which is maximal at three months, then disappears after one year. For cryoablation, about 70% of patients present with redness of the skin next to the cryolesion which resolves spontaneously in the days following the ablation. For RFA, the most common complication is the occurrence of skin lesions (mostly skin burns), which occur in up to 3% of patients, followed by muscle burns [7,8]. The follow-up of these elderly patients over the long term is deliberately spaced to make it acceptable for the patient.
The treatment objectives for small breast cancer in the elderly are a significant reduction in tumour volume, and whenever possible, ablation or R0 resection adjusted to life expectancy, but above all obtaining the best quality of life. In this perspective, ablation is a good alternative to surgery. The efficacy of breast ablation in the literature is around 75% [7–11]. The published data and the experience we have now makes it possible to better select candidate lesions for ablation. Ablation should be avoided for in situ ductal carcinomas and invasive lobular carcinomas, which are generally not very visible with ultrasound.
