This study demonstrates the feasibility, efficacy, and safety of fiducial-based MRI navigated cryosurgery for EDTs. Imaging-based preoperative planning with the use of skin fiducial markers, intraoperative MRI-computed navigation, and imaging-based confirmation of cryo‐needle placement are precise steps that can improve the overall efficacy of cryosurgery. Our results show a perfect correlation between preoperative modeling and intraoperative execution of needle placement and number. Significant reductions in both Total Tumor Volume (TTV) and Viable Tumor Volume (VTV) were achieved while maintaining a low post-operative complication rate. SF36 scores demonstrated significant improvements in both mental and physical health scores.
Desmoid tumors are associated with high rates of morbidity and local recurrence [23]. Complete removal is the preferred outcome for most tumor surgeries, in the case of desmoids however, the end goal of any treatment should aim to arrest or reduce tumor progression and alleviate symptoms to mitigate morbidity. Once a period of watchful-waiting has failed, the current guidelines set forth by the National Comprehensive Cancer Network call for chemotherapy, radiotherapy, and en‐bloc surgical resection as primary therapy [24]. A recent multicentral multinational study found that among patients treated by surgical resection, 36.6% had local recurrence and 63.4% showed stable disease. Alternatively, patients treated with chemotherapy, radiotherapy or hormonotherapy had 40.2% experienced recurrence and 59.8% had a stable disease (defined as no evidence of disease or stable disease) [4]. Furthermore, in a review of 22 articles, Nuyttens et al. [25], reported extensively on complications. They described combined rates for mild and moderate complications in 27% and 45% of cases for surgery and radiation, respectively. It was further noted that in the surgically treated cohort, severe complications such as amputation or major disability were reported in up to 4% of cases.
Cryosurgery as an alternative treatment option has gained immense popularity in the last decade as a relatively effective and safe alternative to the current guidelines. A recent systematic review and meta-analysis found that out of the proportion of non-progressive disease rates (85.8%), major and minor complications rate ranged from 2.4–14.2% and 4.8–23.3%, respectively, for all procedures [26]. The success rate of percutaneous cryosurgery directly correlates with the accuracy and precision of the ablation process [27][28]. MRI is the imaging modality of choice for optimal visualization of EDTs at preoperative planning and post-operative follow up [29]. Therefore, MRI-computed navigation should simplify and improve cryosurgery once accurate image registration is achieved. Several findings from this study clearly demonstrate the feasibility and advantages of this ablation MRI-navigated cryosurgery protocol.
Firstly, the perfect correlation between needle placement and number during the surgery compared with the preoperative 3D model indicates that the preoperative plan can be feasibly implemented using this navigation protocol. This finding could be attributed to the fact that the preoperative and intraoperative images are both MRI-based scans of the same fiducially marked location and are therefore identical to one another. Additionally, obtaining a necessary scan that includes the fiducial marker placement requires preoperative MRI scanning one day before the procedure allows the surgeon to assess the tumor for any changes in size or composition. The surgeon can then plan any adjustments to the preoperative plan.
The second indication of feasibility is the significant reduction observed in the TTV and VTV in all but one patient. This cohort demonstrated a reduction of 53.7% ± 33.8% and 31% ± 16.1% for TTV and VTV, respectively. This study reinforces findings from previous studies that similarly demonstrated significant reductions in both total and viable tumor volume after percutaneous cryosurgery [30][27][11][4]. Notably, one patient showed a reduction in VTV but not TTV. This patient was offered a revision cryosurgery but sought alternative treatment options instead. Four patients experienced local recurrence and subsequently underwent revision cryosurgeries which, importantly demonstrates that CRA could be performed repeatedly with low morbidity.
A total of 15 cryosurgeries were performed in 11 patients using the current navigation precision protocol. Only one participant (9%) experienced a post-operative complication of skin necrosis classified as a mild complication (grade 1) according to SIR adverse event guidelines [22]. This cohort had significantly lower complication rates compared to cryosurgery and both other modalities. A similar study by Auloge et al. [31] reported a complication rate of 36.6%, consisting mostly of mild complications. Furthermore, Tremblay et al. [28] reported complication rates of 6.7% and 13.3% for major and minor complications, respectively. In this study, the preoperative plan and intraoperative execution successfully achieved a low rate of postoperative complications. These outcomes further validate the effectiveness of the current navigation precision protocol.
SF-36 questionnaires were used to evaluate the individual functional status of each patient by comparing their 12 months follow-up score to their baseline pre-operative values. Significant increases in physical and mental statuses were found in our cohort. Overall, eight participants showed improved physical and mental status, while one participant had an increased mental status but decreased physical status, and two participants had increased physical but decreased mental status. Overall, this data further reinforces the promising clinical results by demonstrating subjective patient satisfaction.
In totality, the data generated in the presented study strongly suggests that cryosurgery should be considered as a valid treatment option for EDT. Advanced imaging-based guidance is fundamental for cryosurgery success.
Application of this study extends beyond merely establishing a new CRA technique. Although MRI navigation has proven to be a valuable tool for precision surgery, its application to soft tissue tumors of the trunk and extremities has been limited by difficulties in the registration process. In a previous study, Eccles et al. [17] successfully achieved margin-free resection with remarkable accuracy while using skin fiducial marker-based MRI navigation to resect soft tissue tumors from cadavers. However, to the best of our knowledge, the current study represents the first attempt to apply this navigation technique in vivo. This study’s success indicates the potential to use this technique for future cryosurgery as well other surgical approaches. Introducing a new surgical technique should follow a specific, stepwise process including: (1) concept/theory formation, (2) procedure development and exploration, (3) procedure assessment, and (4) long-term, ideally evidence-based studies [32]. We believe this study contributes significantly to the second stage.
This study was not without limitations. Importantly, it was a retrospective study based on a small study population. The rare incidence of this tumor makes it difficult to aggregate a large volume of patients. We recognize the need to expand this study and test this procedure on a larger sample size. A long-term follow-up is necessary to validate this procedure.