Journal articles this month include a look at RFA for prostate cancer, factors that influence thermal lesion sizes, and the incidence of postablation syndrome.

New techniques

Pilot study of radiofrequency interstitial tumor ablation for the treatment of radio-recurrent prostate cancer

Prostate 2005;65(3):260-267

This study from the Baylor Prostate Center and The Methodist Hospital in Texas evaluates radiofrequency interstitial tumor ablation for the focal treatment of patients with local prostate cancer recurrence. Eleven patients were studied. Eight had failed prior radiation therapy, and three were not candidates for curative primary therapy. All were treated with RF interstitial tumor ablation in an office setting, under intravenous sedation, and were discharged after the procedure. Complications from the procedure included transient macrohematuria, bladder spasms, and dysuria. Serum PSA levels decreased after RF interstitial tumor ablation by more than 50% in 90% of patients, and by more than 80% in 46% of patients. At 12 months after RF interstitial tumor ablation, half of the patients with sufficient follow-up had no residual cancer on repeat systematic 12-core biopsies, and 67% were cancer-free in biopsy cores sampled from the RF interstitial tumor ablation-treated areas. The authors conclude that focal ablation with RF interstitial tumor ablation results in effective local disease control in patients with nonmetastatic prostate cancer recurrence, and they recommend further clinical study.

Kidney treatment

Percutaneous thermal ablation for recurrent hepatocellular carcinoma after hepatectomy

Br J Surg 2005;92(11):1393-1398

A team from Guangzhou, China, evaluates long-term outcomes after percutaneous thermal ablation for recurrent HCC following liver resection. They used RFA or microwave ablation to treat a total of 124 tumor nodules in 72 patients with recurrent HCC. They achieved complete ablation of 96% of tumors, with a major complication rate of 4%. Local recurrence developed in 13.6% of cases. With repeated ablation for both local and distant recurrence, the one-, three-, and five-year overall survival rates after initial ablation were 75%, 43%, and 18%, respectively. Patients with a serum alpha-fetoprotein level greater than 200 ng/mL before treatment had significantly poorer survival than those with a lower level, and multivariate analysis identified preablation AFP level as an independent prognostic factor.

Evaluating RFA

Patient factors affecting thermal lesion size with an impedance-based radiofrequency ablation system

J Vasc Interventl Rad 2005;16:1341-1348

A study from the Mallinckrodt Institute of Radiology evaluates factors that affect the size of the thermal lesion created from RFA with an impedance-based system. The researchers looked at 32 nonresectable liver tumors treated in 29 patients. Twenty-eight of the 32 tumors were durably ablated in a single session. Mean tumor diameter and resulting thermal lesion size were similar for HCC and metastatic lesions, but a significant difference was observed when comparing the thermal lesion/electrode ratios of HCC with metastases. Nine of 20 HCC ablations resulted in a ratio >1, whereas 11 of 12 metastatic ablations attained a ratio >1. Thermal lesion size did not correlate with time to impedance roll-off for the entire group or by tumor type. The study concluded that thermal lesion size and the ability to obtain a margin of normal tissue are significantly affected by the presence of cirrhosis. The majority of small hepatic neoplasms can still be successfully treated with RFA.

Complications

Image-guided percutaneous radiofrequency ablation and incidence of post-radiofrequency ablation syndrome: prospective survey

Radiology 2005;237:1097-1102

The Boston-based study prospectively evaluates the incidence of post-RFA syndrome and its impact on the quality of life in the 10 days after percutaneous RFA. Thirty-six patients underwent RFA for 26 liver tumors and 17 renal tumors. Twenty control patients underwent biopsy of focal liver lesions or renal lesions. After RFA, 33% of patients had complete post-RFA syndrome, 42% developed low-grade fever, and 81% had flulike symptoms. Four patients were asymptomatic. Symptoms peaked on day three and mainly resolved by day 10. Flulike symptoms were more prolonged when they were accompanied with fever, peaked on day five, and resolved more quickly for patients with renal lesions than they did for patients with liver lesions. No control patients developed both fever and flulike symptoms. Post-RFA patients with symptoms experienced significantly greater pain and interference with general and work activities, which peaked on day one, than did control patients. The team concluded that post-RFA syndrome occurs in approximately one-third of patients but is self-limiting within 10 days after the procedure. They further concluded that persistent or late-onset fever may indicate concurrent infection elsewhere or possible abscess formation.