Freezing of bone tumors: a minimally invasive reli
Radiation therapy, though the “gold standard” in the management of focal (localized) pain in metastatic (spreading) cancers, provides only short-acting pain relief. This is according to study that compared the effectiveness of cryoablation, as pain treatment for cancers that spread to the bone, to existing pain control alternatives.
In the study, 14 patients whose cancers had metastasized to the bone underwent percutaneous cryoablation for 18 months. These patients either did not respond to radiation treatment and chemotherapy or refused such other conventional treatments. Prior to the procedure, they reported a pain scale of 4 or greater out of 10 for the worst pain. Cryoablation decreased their average pain levels from 6.7 to 3.8 of 10 within four weeks after treatment.
The research also measured the effectiveness of cryoablation in the improvement of activities of daily living (ADL) and found that the average interference of pain in ADL was down to 3.2 from 5.5 of 10 after four weeks. All patients who were prescribed narcotics prior to the procedure reported reduction in analgesic medications. No major complications resulted from the procedure.
The results showed 80 percent of the patients experienced a clinically significant reduction in pain. And patients continued to report a drop in pain levels even after six months of the procedure.
“Two key parts of this study are that the reduction in pain lasts and their quality of life improves after receiving the treatment,” says lead researcher Matthew Callstrom, MD, PhD, a resident radiologist at Mayo Clinic.
Aside from having more durable effects than radiation therapy for the treatment of bone pain, cryoablation is more precise and minimally invasive, using image-guided methods to penetrate into the bone lesion. Guided by CT imaging, a probe with a coolant gas is inserted into the tumor and turns it into a ball of ice. The patient is released 24 hours later and typically starts to feel relief within a few days.
Other effective ablative treatments have certain limitations that cryoablation does not have, such as the difficulty of radiofrequency ablation in depicting the ablation margin using CT or the intolerance of normal tissue to repeated radiation therapy for recurring pain. A study found recurrence of pain in 57 percent of patients at about 15 weeks after radiation therapy.
The study concluded that percutaneous cryoablation is a safe and effective method for bone metastasis, which can cause extreme pain. Cryoablation has been used extensively for cancers of the prostate, kidney, liver, lung, breast and uterus.