(90)Y radioembolization is a promising therapy for patients with primary and secondary liver malignancies. Pretherapeutic assessment consists of hepatic angiography and (99m)Tc-macroaggregated albumin ((99m)Tc-MAA) perfusion scintigraphy to estimate the liver-to-lung shunt and exclude extrahepatic (99m)Tc-MAA deposition. However, the predictive value of intratumoral (99m)Tc-MAA uptake remains unclear.
Methods: One hundred four patients with chemotherapy-refractory liver-dominant metastatic colorectal cancer were treated with (90)Y radioembolization between December 2006 and December 2010. All of the patients underwent angiographic assessment and perfusion scintigraphy with (99m)Tc-MAA before lobar (90)Y radioembolization. For inclusion, patients must have undergone pretherapeutic and follow-up MR imaging (6 wk and 3 mo after radioembolization, respectively). The degree of intratumoral (99m)Tc-MAA uptake was rated, and liver metastases were classified according to changes in tumor diameter on both an individual and a patient basis using Response Evaluation Criteria in Solid Tumors (RECIST) 1.1. Response at both time points, MAA uptake, and catheter position were then statistically analyzed in a linear and generalized linear mixed model at a significance level of 0.05 (P value).
Results: Sixty-six patients with a total of 435 colorectal liver metastases (mean number of lesions ± SD, 6.6 ± 2.8; mean lesion size ± SD, 33.8 ± 21.2 mm; lesion size range, 10-154 mm) were included in this analysis. According to the patient-based analysis, 3 patients had partial response, 49 stable disease, and 6 progressive disease after 6 wk. After 3 mo, 5 patients showed partial response, 26 stable disease, and 17 progressive disease. There was no association of patient-based tumor response with overall (99m)Tc-MAA uptake (P = 0.172) or with catheter position (P = 0.6456). Furthermore, an interaction effect of (99m)Tc-MAA uptake and catheter position in relation to tumor response was not found (P = 0.512). Moreover, in lesion-based analysis according to RECIST 1.1 there was no association of tumor response with degree of (99m)Tc-MAA uptake, catheter position, or interaction of (99m)Tc-MAA uptake and catheter position (P = 0.339, 0.593, and 0.658, respectively).
Conclusion: Response to (90)Y radioembolization was found to be independent of the degree of (99m)Tc-MAA uptake. Therefore, therapy should not be withheld from patients with colorectal liver metastases lacking intratumoral (99m)Tc-MAA accumulation.