by Debbie “The Rat Lady” Ducommun
These articles first appeared in the Rat-a-tat Chat, the newsletter of the non-profit organization Rat Assistance & Teaching Society.
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Tamoxifen for Other Cancers
Whenever rat owners have asked me if tamoxifen can be used to treat tumors other than mammary cancer, I have always said no, because I thought it only worked for estrogen sensitive tumors. However, I recently got an email from rat owner Paul Gregor who is a scientist interested in how different drugs work. His rat has grown some tumors, so he was reading the info I have about tamoxifen on my website. He told me that there is scientific evidence that tamoxifen can help slow the growth of cancers other than mammary tumors. It appears that tamoxifen not only blocks estrogen receptor sites in tumors, but it also helps prevent the growth of new blood vessels, which a tumor must do to grow.
One study found that tamoxifen helped slow the growth of squamous cell carcinoma cells in a culture. This was an in vitro experiment, using cell cultures and not tumors growing in animals, which means that no animals were harmed for this experiment! The cancer cells used in this study were from squamous cell carcinoma tumors on the head and neck of humans, which are apparently very difficult to treat. One of the most common types of cancer in rats is squamous cell carcinoma on the head and face! Although this study showed that treatment of the cancer cells was most successful when tamoxifen was used together with a chemotherapy drug called cisplatin, just the tamoxifen by itself did help slow the grow of the cancer cells. (Cisplatin must be given intravenously, and so is not practical for rat treatment.)
Although in vitro studies are wonderful because they do not use animals, it is also good to know that tamoxifen appeared to slow the growth of malignant fibrosarcoma tumors implanted in rats, since fibrosarcoma is also a fairly common type of cancer in rats. This study found that tamoxifen helped to slow the growth of blood vessels in the tumors, which would presumably slow the growth of tumors. The rats were euthanized only ten days after the tumor cells were implanted in their legs, so this study did not look at long-term effects of the treatment.
So, if your rat has cancer, any kind of cancer, it looks like it might be worth it try treatment with tamoxifen.
Tamoxifen Inhibits Angiogenesis in Estrogen Receptor-negative Animal Models. Clin Cancer Res., Blackwell, K.L. et al. November 2000 6; 4359.
Tamoxifen inhibits the growth of head and neck cancer cells and
sensitizes these cells to cisplatin
induced-apoptosis: role of TGF-β1. Tavassol, M., et al. Carcinogenesis
Possible New Cancer Treatment
Nitroxoline is an antibiotic that has been used to treat
urinary infections in
2011, researchers in
this antibiotic is not available in the
Antibiotic Slows Growth of Bladder, Breast Cancer Cells, JAMA, 2004 Feb 18;291(7):827-35.
J Natl Cancer Inst. 2010 December 15; 102(24): 1855–1873.
For breast cancer, mice were injected with 60-mg/kg nitroxoline in vehicle, intraperitoneally, every other day for 30 days.
For bladder cancer mice were given nitroxoline in vehicle (30 mg/kg/day, n = 6) by oral administration daily for 2 weeks.
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