Commentary

Yttrium-90 Radioembolization for Breast Cancer Liver Metastases

Radionuclide therapy is based on the systemic or locoregional administration of a radiolabelled agent that is specifically distributed according to its pharmacokinetics and metabolism. Starting from the treatment of thyroid cancer with the administration of I131 many decades ago, the radionuclide therapy has achieved nowadays a central role in many oncological applications such as peptide radiotherapy, radioimmunotherapy, radioembolization and many others. Different radionuclide and radiopharmaceuticals are used and most of them or of their surrogates are suitable and used for theranostics and dosimetry. Dosimetry, performed before (provisional) or during therapy (verification) calculates the absorbed dose in organs at risk and target issues with the aim to maximize the efficacy of the treatment and to control its potential toxicity.

SPECT and SPECT/CT technologies, compared to planar imaging, improve the accuracy of activity distribution evaluation and, consequently, of dosimetry. Accurate and quantitative SPECT/CT images are obtained thanks to the inclusion in the tomographic reconstruction process of attenuation, scatter, dead time, and collimator response corrections.

This chapter evaluates the principal application of SPECT and SPECT/CT in dosimetry for radionuclide therapy. Specific paragraphs are dedicated to radioiodine treatment of metastatic thyroid cancer, radioimmunotherapy, 131I-MIBG treatment in patients affected by neuroblastoma, radioembolization of primary and metastatic liver cancer, radiopeptide therapy of neuroendocrine and other tumors overexpressing somatostatin receptors, radiometabolic treatment of skeletal metastases.

To determine predictors of survival after transarterial radioembolization of hepatic metastases from breast cancer.

Twenty-four patients with chemotherapy-refractory hepatic metastases from breast cancer who underwent radioembolization from 2013 to 2018 were evaluated based on various demographic and clinical factors before and after treatment. Overall survival (OS) was estimated by Kaplan–Meier method. Log-rank analysis was performed to determine predictors of prolonged OS from the time of first radioembolization and first hepatic metastasis diagnosis.

Median OS times were 35.4 and 48.6 months from first radioembolization and time of hepatic metastasis diagnosis, respectively. Radioembolization within 6 months of hepatic metastasis diagnosis was a positive predictor of survival from first radioembolization, with median OS of 38.9 months vs 22.1 months for others (P = .033). Estrogen receptor (ER)–positive status predicted prolonged survival (38.6 months for ER⁺ vs 5.4 months for ER⁻; P = .005). The presence of abdominal pain predicted poor median OS: 12.8 months vs 38.6 months for others (P < .001). The presence of ascites was also a negative predictor of OS (1.7 months vs 35.4 months for others; P = .037), as was treatment-related grade ≥ 2 toxicity at 3 months (5.4 months vs 38.6 months for others; P = .017).

In patients with metastatic breast cancer, radioembolization within 6 months of hepatic metastasis diagnosis and ER⁺ status appear to be positive predictors of prolonged survival. Conversely, baseline abdominal pain, baseline ascites, and treatment-related grade ≥ 2 toxicity at 3 months after treatment appear to be negative predictors of OS.

Liver metastases are an important cause of cancer-related death. Whereas treatment options previously consisted mainly of systemic chemotherapy and in some cases surgical resection, interventional radiological techniques offer alternatives for effecting disease control or even cure. In this chapter, the techniques of radioembolization and chemoembolization are reviewed. In addition, the role of chemoembolization and radioembolization is discussed in the management of liver metastases, focusing on the strongest evidence base in the areas of colorectal cancer and neuroendocrine tumors. Transcatheter embolization of liver metastases in other diseases such as uveal melanoma and breast cancer is also outlined.

Curative options for the treatment of primary or secondary hepatic malignancies are transplant and surgical resection. Transplant and surgical resection offers the best clinical outcome; however, it is only available to a limited number of patients who present with early-stage disease. For patients beyond curative resection or outside transplant criteria, locoregional therapies remain an excellent treatment option. Yttrium-90 (⁹⁰Y) radioembolization is a transarterial catheter–based technique that is increasingly being used in the management of primary and secondary liver malignancies. The focus of this article is to discuss the use of ⁹⁰Y radioembolization for the treatment of unresectable hepatic malignancies along with a review of the relevant literature.