[Lani]

Have you had a brain biopsy of any of your brain mets? If so, you might want to send some of the specimen for testing for Na/I symporter, a marker which theoretically makes treatment with radioactive iodine possible (simple treatment, small molecules so should cross the blood-brain barrier, already FDA approved for treatment of thyroid disorders). The other variable which decides whether one is a candidate for this treatment from what I understand is knowing how much radiation the brain has already had, so it sounds like it is something worth looking into BEFORE deciding for WBR.

Might help you "not burn any bridges"

J Neurooncol. 2009 Jul 19. [Epub ahead of print]

Breast cancer brain metastases express the sodium iodide symporter.

Renier C, Vogel H, Offor O, Yao C, Wapnir I.
Department of Surgery, Stanford University School of Medicine, 300 Pasteur Drive H 3625, Stanford, 94305-5655, CA, USA.
Breast cancer brain metastases are on the rise and their treatment is hampered by the limited entry and efficacy of anticancer drugs in this sanctuary. The sodium iodidesymporter, NIS, actively transports iodide across the plasma membrane and is exploited clinically to deliver radioactive iodide into cells. As in thyroid cancers, NIS is expressed in many breast cancers including primary and metastatic tumors. In this study NIS expression was analyzed for the first time in 28 cases of breast cancer brain metastases using a polyclonal anti-NIS antibody directed against the terminal C-peptide of human NIS gene and immunohistochemical methods. Twenty-five tumors (84%) in this retrospective series were estrogen/progesterone receptor-negative and 15 (53.6%) were HER2+. Overall 21 (75%) cases and 80% of HER2 positive metastases were NIS positive. While the predominant pattern of NIS immunoreactivity is intracellular, plasma membrane immunopositivity was detected at least focally in 23.8% of NIS-positive samples. Altogether, these findings indicate that NIS expression is prevalent in breast cancer brain metastases and could have a therapeutic role via the delivery of radioactive iodide and selective ablation of tumor cells.
PMID: 19618116

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Mol Imaging. 2006 Apr-Jun;5(2):76-84. Links
Bioluminescent Monitoring of NIS-mediated 131I Ablative Effects in MCF-7 Xenografts.

Ghosh M,
Gambhir SS,
De A,
Nowels K,
Goris M,
Wapnir I.
Stanford University School of Medicine.
AbstractOptical imaging has made it possible to monitor response to anticancer therapies in tumor xenografts. The concept of treating breast cancers with 131I is predicated on the expression of the Na+/I- symporter (NIS) in many tumors and uptake of I- in some. The pattern of 131I radioablative effects were investigated in an MCF-7 xenograft model dually transfected with firefly luciferase and NIS genes. On Day 16 after tumor cell implantation, 3 mCi of 131I was injected. Bioluminescent imaging using d-luciferin and a cooled charge-coupled device camera was carried out on Days 1, 2, 3, 7, 10, 16, 22, 29, and 35. Tumor bioluminescence decreased in 131I-treated tumors after Day 3 and reached a nadir on Day 22. Conversely, bioluminescence steadily increased in controls and was 3.85-fold higher than in treated tumors on Day 22. Bioluminescence in 131I-treated tumors increased after Day 22, corresponding to tumor regrowth. By Day 35, treated tumors were smaller and accumulated 33% less 99mTcO4- than untreated tumors. NIS immunoreactivity was present in <50% of 131I-treated cells compared to 85-90% of controls. In summary, a pattern of tumor regression occurring over the first three weeks after 131I administration was observed in NIS-expressing breast cancer xenografts.
PMID: 16954021
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