Tuesday, June 8, 2010

Radiosurgical Treatment of Primary Liver Cancer: Baylor Radiosurgery Center Experience

Radiosurgical Treatment of Primary Liver Cancer: Baylor Radiosurgery Center Experience
John O’Connor, M.D., Medical DirectorBaylor Radiosurgery Center, Dallas, TXRobert Goldstein, M.D., Director, Liver and Pancreas Disease CenterBaylor University Medical Center, Dallas, TX

Hepatocellular carcinoma (HCC) is the fifth most common cancer and third leading cause of cancer death, with 626,000 new cases and 598,000 deaths per year.1 Although it is less common in the United States, its incidence has tripled in the past 30 years principally in relation to the spread of hepatitis C infection.2 Survival for patients with hepatocellular cancer remains poor, about 10% at 5 years.3 HCC is potentially curable with hepatic resection or transplantation, but fewer than 30% of patients are eligible for surgery.4,5 Liver transplantation is the primary treatment for patients with cirrhosis and unresectable HCC, with low rates of recurrence and 5-year survival of about 70%.6,7

Stereotactic body radiotherapy (SBRT) has the ability to deliver high, focused doses while limiting irradiation of normal liver tissue. The use of SBRT for both primary and metastatic liver cancer is increasing worldwide at an impressive rate as clinicians are encouraged by favorable safety and efficacy data.8-11 CyberKnife® researchers have been active in the use of SBRT for liver as well.12-14 At the Baylor Radiosurgery Center we have been treating unresectable HCC since April of 2005. In March 2010 we updated our findings at the CyberKnife Scientific Meeting in Dallas.

We presented outcomes of a retrospective review of 24 patients with 27 tumors. All patients were evaluated by a liver transplant surgeon prior to radiosurgery and were deemed unresectable. The median tumor diameter was 4 cm and we have successfully treated liver tumors as large as 11 cm in diameter. Patients were treated with the CyberKnife System using Synchrony® Respiratory Tracking. The median dose was 42 Gy (range 27 - 54 Gy) to the median 66% isodose line (range 50 - 80%), delivered in 3 daily fractions in 22 patients and 5 fractions in four patients. We followed our patients using MRI obtained at 3-month intervals.

To date our outcomes have been encouraging. Grade 1 or 2 toxicity (based on CTCAE 3.0 guidelines) occurred in four patients (17%); a single Grade 3 toxicity was observed. There were no Grade 4-5 toxicities and no occurrence of radiation-induced liver disease. Overall local tumor control in all patients based on RECIST criteria was 87% at a median follow-up of 12 months. One-year Kaplan-Meier survival was 43%, and median survival was 11 months.

An additional eight patients with HCC (and nine tumors) were treated as a “bridge” to liver transplantation, that is, to control the growth of their tumors so that they may remain on the organ waitlist until a liver is available for transplant. We presented our preliminary findings on these patients at the 2009 meeting of the American Society for Radiation Oncology (ASTRO).15 All of these patients proceeded to transplant in a median of 90 days (range 8 – 209 days) after radiosurgery. We assessed the tissue response in the explanted tissue; three of the lesions responded completely, three were reduced in size, and three were stable.

The CyberKnife System has become a valuable component of our treatment program for unresectable HCC. Its ability to track liver tumors as they move with respiration has allowed us to deliver high doses of radiation accurately to achieve excellent rates of local control.

Source: Accuray Newsletter April 2010

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