Residual activity after radioembolization of liver tumours with 90Y resin microspheres

A descriptive analysis of remnant activity during (90)Y resin microspheres radioembolization of hepatic tumors: technical factors and dosimetric implications

OBJECTIVE

Activity planning for (90)Y radioembolization aims to maximize the effect of the treatment while keeping toxicity acceptably low. Our aim was to describe the amount of residual activity in post-treatment v-vials and tubing and analyze the possible factors affecting it (total activity administered, number of split activity injection(s), previous treatments, administration artery and microcatheter size), as these may influence dosimetric planning and treatment.

METHODS

This was a retrospective review using case records of patients who received (90)Y-radioembolization for hepatic tumors at a single tertiary center. From August 2013 to September 2015, seventy-seven out of one hundred and fifty patients who received radioembolization with (90)Y resin microspheres due to inoperable Hepatocellular Carcinoma (HCC) or liver metastases were included. The rest were mainly excluded due to incomplete data sets. The number of split activities (injections) for the radioembolization could be: one single injection, two or three. The remnant activity in post-treatment v-vials and tubing were measured for every patient. The administration arteries evaluated were: proper hepatic artery (PHA), right hepatic artery (RHA), middle hepatic artery (MHA), left hepatic artery (LHA) and small caliber branch arteries. The sizes of the microcatheters (2.2 or 2.7 Fr) used to administer the dose were also evaluated.

RESULTS

In total, 77 out of 150 patients were included in the final analysis. There were 59 men of median age 64.0 years old. The total median dose loss was 0.10 GBq. The total dose loss increased 0.244 GBq [95 % CI = (0.169, 0.318)] when three split activities were given compared to single activity injection. Activity loss for each injection increased 0.0297 GBq [95 % CI = (0.0151, 0.0443)] for every 1.0 GBq increase of split activity injection. There were no significant statistical differences in the rest of patient characteristics.

CONCLUSIONS

There is significant loss of activity observed during radioembolization, which can have a major dosimetric impact. The total administered activity and the number of split injections during radioembolization are the main influencing factors. Further prospective studies as well as measures of clinical outcome are warranted.

Evaluation of the delivered activity of yttrium-90 resin microspheres using sterile water and 5 % glucose during administration

BACKGROUND

The purpose of this study is to evaluate the impact of switching from sterile water to 5 % glucose (G5W) for the administration of yttrium-90 ((90)Y)-resin microspheres on the total activity of (90)Y administered (expressed as a proportion of the prescribed/calculated activity), as well as the number of cases of stasis and the reported incidence of discomfort during the selective internal radiation therapy (SIRT) procedure.

METHODS

In December 2013, we switched from sterile water to G5W for the administration of SIRT using (90)Y resin microspheres in all patients. This retrospective observational single-center case series describes our experience in the months preceding and after the switch. Apart from the change in administration medium, the protocol for SIRT was otherwise identical.

RESULTS

One hundred and four SIRT procedures were performed on 78 patients (45 male, mean age: 63 years, range: 31-87 years) with either unresectable hepatocellular carcinoma, cholangiocarcinoma, or chemorefractory liver-dominant metastatic cancer. Compared with sterile water, the whole prescribed activity was administered in significantly more procedures with G5W: 85 vs. 22 %; p < 0.0001. A significantly higher proportion of the calculated activity was administered with G5W: 96.1 ± 11.0 % vs. 77.4 ± 24.3 % (p < 0.0001). G5W procedures were also associated with a significantly lower incidence of stasis (28 vs. 11 % procedures; p = 0.02) and mild-to-moderate upper abdominal pain during the procedure (1.8 vs. 44 % procedures; p < 0.0001).

CONCLUSIONS

Replacing sterile water with isotonic G5W during administration favorably impacts on the safety of SIRT, eliminates and/or minimizes flow reductions and stasis/reflux during administration of (90)Y resin microspheres, improves percentage activity delivered, and reduces peri-procedural pain.

Survival in patients with hepatocellular carcinoma treated with 90Y-microsphere radioembolization. Prediction by 18F-FDG PET

AIM

This retrospective study aims to evaluate the predictive value of FDG PET/CT in patients with unresectable hepatocellular carcinoma (HCC) undergoing radioembolization with yttrium-90 labeled microspheres (RE).

PATIENTS, METHODS

The study cohort comprised 33 patients who were treated with RE at our institution and underwent FDG PET/CT at baseline and four weeks after radioembolization. According to the baseline FDG metabolic status of the HCC lesions, patients were divided into two groups: FDG-negative (n = 12) and FDG-positive (n = 21) HCC. FDG-positive patients were further divided into early metabolic responders and non-responders according to the relative change in SUVmax of the treated lesions. Survival analyses were performed with the Kaplan-Meier method (log-rank test, p < 0.05). Multivariate analysis was performed to assess the influence of prognostic factors on overall survival (OS).

RESULTS

FDG-negative patients had a significantly longer OS (13 months, 95%CI 7-19) than FDG-positive patients (9 months, 95%CI 7-11; p = 0.010). Among FDG-positive patients, metabolic responders survived significantly longer than metabolic non-responders (10 months, 95%CI 8-12 vs. 5 months, 95%CI 4-6; p = 0.003). From the other baseline factors (including performance status, hepatic tumour burden, presence of extra-hepatic disease, administered activity) only the BCLC stage had a significant impact on OS (p = 0.028).

CONCLUSION

Pre- and post-therapeutic FDG PET independently predicts overall survival in patients with HCC undergoing radioembolization. Interestingly, early metabolic response seems to be assessable as early as four weeks post-treatment.