Yttrium-90 (90Y)-resin microspheres are prescribed using activity. We evaluated overall survival (OS) and radiographic tumor response after selective internal radiation therapy (SIRT) with resin microspheres in patients with liver metastases from colorectal cancer.
We retrospectively reviewed 60 metastatic colorectal cancer patients treated at our institution with SIRT using 90Y-resin microspheres. Each patient underwent pre-SIRT MRI or computed tomography imaging of the liver with intravenous contrast. Patients underwent post-treatment imaging at 2–3-month intervals with response assessed according to unidimensional Response Evaluation Criteria in Solid Tumors (RECIST) criteria as well as published three-dimensional volumetric criteria. We then related the prescribed activity established by the body surface area method and the corresponding prescribed dose to radiographic treatment response and OS.
The median follow-up after the first SIRT treatment was 8.9 months. The mean prescribed activity and the prescribed dose were 26.6 mCi and 52.8 Gy, respectively. OS was not significantly associated with either prescribed activity or prescribed dose. Prescribed dose was also not related to response. However, a significant relationship was found between a higher prescribed activity and an improved radiographic response by RECIST (P=0.04) at the second follow-up.
The prescribed activity of 90Y-resin microspheres may be correlated with radiographic response by RECIST criteria at 4–6 months post-treatment. For a more accurate prediction of response, a valid dose calculation model based on post-90Y PET dosimetry is likely needed given the heterogeneous dose delivery seen in SIRT.
Departments of aRadiation Oncology
bDiagnostic Radiology and Nuclear Medicine
cDivision of Medical Oncology, University of Maryland School of Medicine, Baltimore, Maryland
dUPMC Pinnacle Health Radiation Oncology, Harrisburg
eDepartment of Radiation Oncology, Penn State Health, Milton S. Hershey Medical Center, Hershey, Pennsylvania
fMiami Cancer Institute at Baptist Health South Florida, Miami, Florida, USA
Data were presented previously at the ASTRO annual meeting and published as an abstract in Int J Radiat Oncol Biol Phys 2014; 1:s381.
Correspondence to Byong Y. Yi, PhD, Department of Radiation Oncology, University of Maryland Medical Center, 22 South Greene Street, Baltimore, MD 21201, USA Tel: +1 410 328 6080; fax: +1 410 328 5279; e-mail: firstname.lastname@example.org
Received March 23, 2018
Received in revised form June 29, 2018
Accepted July 6, 2018