Soft Tissue Locations
Since this is such a widespread category, our prior large soft tissue cryoablation series progresses into the following categories:
- Retroperitoneal (i.e. back of the abdomen)
- Intraperitoneal (i.e. inside the abdomen)
- Bone (see also MOTION trial noted below)
- Head and neck tumors
These location groupings may be associated with different tumor types, yet all seem to have excellent outcomes assuming good cryo-technique (i.e., 1-3 rule). Technically, breast cryoablation may be considered a part of soft tissue ablations due to the close proximity of overlying skin, but it has numerous other clinical considerations that will be considered separately.
Cryoablation is almost exclusively used in this category since it offers much greater flexibility for underlying structures, as well as the much closer overlying skin than the prior organ-based ablations. See also Protective Measures below
These are nearly all metastatic tumors that have spread from other primary cancers (i.e., from cancers that arose in the colon, kidney, breast, etc.). However, two unique benign tumors deserve special mention; desmoids which involve the abdominal/chest wall or extremities and osteoid osteoma of bone within pediatric patients.
- Desmoid tumors: rare, predominantly locally aggressive tumors that have a high rate of recurrence (e.g., 50%) by either surgery or aggressive targeted radiation, and do not respond well to systemic treatments. We have treated several desmoid tumors without apparent local recurrence, likely due to excellent tumor margin of visualization by ultrasound in combination with CT for guidance, frequently using MRI as a “roadmap” of its local extent.
- Osteoid osteomas are rare bone tumors usually seen within bones of the extremities that cause significant pain, particularly at night. Pain is notably relieved by anti-inflammatories since the central portion of the tumor, or nidus, produces inflammatory cytokines. Osteoid osteomas have been classically treated by small radiofrequency probes with short active zones, but we have also treated several by cryoablation, using short segment freeze zone cryoprobes.
Soft tissue ablations usually involve solitary tumors, but depending on the size, several tumors may be treated in the same or multiple sessions.
Approximately <6 cm without evidence of extensive local spread into adjacent crucial structures, or multiple metastases to adjacent nodes or elsewhere in the body. The concept of multiple cryoprobes “sculpting” the ice ablation zone beyond all apparent tumor margins is again crucial to our low reported recurrence rates.
As noted above, a broad range of locations are possible for cryoablation due to its excellent healing characteristics, likely due to preservation of underlying collagenous architecture.
- Hydrodissection: Liberal injection of fluid immediately beneath the skin is often used in combination with warm saline bags rubbed on the overlying skin to prevent full thickness skin necrosis. Aggressive diligence with this technique allows impressive treatment to within a millimeter of the dermis. The following tip is suggested for evaluating masses close to the skin:
- Knuckle skin test: As long as the skin overlying the tumor is mobile, similar to moving your skin over a loosely bent knuckle, the tumor has likely NOT invaded the dermis. Subcutaneous fluid can likely be injected in sufficient volume, in conjunction with warming from rubbed overlying saline bags, for safe skin protection.
Multicenter Study of Cryoablation for Palliation of Painful Bone Metastases – for treatment of painful bone metastases:
- For patients with metastatic lesions involving bone who have failed, are not candidates for, or not experiencing adequate pain relief from current pain therapies (EG, radiation, analgesics).
- Pivotal, multicenter, prospective, single arm study with patient serving as their own control, with goal to treat 60 subjects from 10 international centers.
- Basic eligibility requirements include confirmed metastatic disease involving bone, causing the “worst pain” in the last 24 hours of >4 on a scale of 0-10, Karnofsky Performance Status (KPS score >60 and life expectancy >3 months.