Predicting SIR-Spheres® microspheres Treatment Outcome for Metastatic Colorectal
Pre-treatment laboratory tests may play a key role in predicting patient outcomes prior to selective internal radiation therapy for metastatic colorectal cancer, while a new modeling technology for enhancing delivery of treatment could improve treatment success, according to two studies presented at the American Society of Clinical Oncology’s 2014 Gastrointestinal Cancers Symposium.
Selective Internal Radiation Therapy (SIRT), also known as radioembolization, delivers doses of radiation directly to the site of tumors—and is used to treat inoperable liver cancer. During the minimally invasive treatment, millions of radioactive SIR-Spheres microspheres are infused via a catheter into the liver where they selectively target liver tumors with a dose of internal radiation up to 40 times higher than conventional radiotherapy, while sparing healthy tissue.
Once a patient with metastatic colorectal cancer has failed multiple lines of chemotherapy, there is no standard of care to treat the disease. Clinical studies have confirmed that patients with metastatic colorectal cancer treated with SIR-Spheres microspheres have response rates higher than with other forms of treatment, resulting in increased life expectancy, greater periods without tumor activity and improved quality of life. SIRT has been found to shrink liver tumors more than chemotherapy alone.
The MORE study (__M__etastatic colorectal cancer liver metastases __O__utcomes after __R__adio __E__mbolization) was one of the largest radioembolization studies and included data from 606 patients with metastatic colorectal cancer. The retrospective review included values for the following parameters 10 days prior to treatment: hemoglobin, albumin, alkaline phosphatase, AST, ALT, total bilirubin and creatinine.
After a median follow-up of 8.5 months after SIRT, fewer than 11 percent of patients were treated outside recommended guidelines, with grade 2 albumin being the most common at time of SIRT. Abnormal parameters were associated with statistically significantly decreased median survivals. The researchers concluded that review of pre-SIRT laboratory parameters could help improve median survivals if abnormal values can be addressed prior to radiation delivery in order to optimize treatment response.
In another study, researchers used complex modeling of the hepatic arterial route and the tumor microvascular bed in which the 90Y-microsphere radioactive particles will become permanently embedded. This shows promise to more accurately outline the path microspheres take to the tumor arteriole end which may improve treatment success. The researchers concluded that predictive modeling may now be possible for microspheres exiting from a catheter into the hepatic artery to its final position in a tumor end arteriole, or for systemic therapies.
Both studies aimed to improve SIRT patient outcomes—and provide insight for enhancing the degree of precision for delivering SIRT.
Have a question about treatment for metastatic colorectal cancer? Sarah Cannon Radiation Oncology Physician-in-Chief Andrew Kennedy, MD, will discuss metastatic colorectal cancer and answer participants’ questions during a live Web chat on April 2, 2014 at 6:00 p.m. EST. Clickhereto pre-register for the Web Chat and submit a metastatic colorectal cancer question for Dr. Kennedy to answer during the live Web Chat (time permitting).
 Kennedy AS, Ball D, Cohen SJ, et al: Pre-90Y hepatic radiotherapy hemoglobin and liver functions predict overall survival in unresectable chemotherapy refractory metastatic colorectal cancer. ASCO Gastrointestinal Cancers Symposium 2014; Abstract 292.
 Kennedy A, Clipp R, Christensen D. First in man fractal methodology to model both the hepatic arterial tree and tumor microvasculature for 90y-microsphere brachytherapy. ASCO Gastrointestinal Cancers Symposium 2014; Abstract 248.
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