Background: Bevacizumab (Avastin®) is a monoclonal antibody against vascular endothelial growth factor. Addition of Avastin to chemotherapy has shown to improve survival and response rates in patients with metastatic colorectal cancer (CRC). Percutaneous radiofrequency ablation (RFA) of liver and lung lesions offer an alternative organ-directed therapy in patients with metastatic CRC who are considered unresectable. The safety of RFA after Avastin-based chemotherapy is currently unknown.

Methods: We retrospectively reviewed our cohort of CRC patients who have had RFA. The chemotherapy data was obtained from pharmacy records. Those who have not received Avastin prior to RFA are the internal control group. Peri-procedure complications and complications within first 4 weeks were reviewed. Between 12/2002 and 12/2006, 56 lesions were treated in 28 sessions (n= 17 patients, 3 patients crossed over). The median time between RFA from the last dose of Avastin was 45 days, and Avastin was resumed in 6 patients after RFA, after a median duration of 21 days.

	Avastin prior to RFA	No Avastin prior to RFA
Patients (n)	10	10
RFA Treatments (n)	13	15
Lesions treated (n)	36	20
Organs targeted	3 lung, 33 liver	1 lung, 19 liver

Results: There was no significant difference in complications between the two groups. Small asymptomatic hematoma, not requiring treatment, was noted in 3 patients in each arm. One patient with prior Avastin exposure was re-admitted, for pain management and blood product transfusion for a hematoma. The median hospital stay after RFA in both arms is less than 2 days. Overall, no unexpected complications were seen in either group.

		Avastin Prior to RFA	No Avastin Prior to RFA
Clinical Complications	Immediate	3 x pneumothorax	2 x pneumothorax
		n = 3	n = 2
	4 weeks	1 x hematoma n = 1	No major complications n = 0
Radiological Complications During Procedure		3 x hematoma	1 x portal vein thrombus
(Not clinically signifcant)			3 x hematoma
			1 x biloma
		n = 3	n = 5
Days of Hospitalization per treatment		mean = 1.4 days	mean= 1.1 days
Patients requiring blood transfusions		n = 1	n = 0

Conclusions: In our experience, exposure to Avastin does not increase the expected complications from percutaneous RFA, and there were no unexpected complications noted. The majority of the complications noted in both arms are radiological findings not requiring treatment. Prospective studies of integrating percutaneous RFA to Avastin-based treatment for unresectable metastatic CRC are warranted.