Are some therapies compatible?

Dear Dr. Roach: I was diagnosed with stage 1 bladder cancer in April. My urologist advised me to have BCG therapy for it. I completed six weeks of the therapy.

I also have macular degeneration in both eyes and have had Avastin injections in my left eye for almost two years. I have had a couple of injections into my right eye, too.

Neither my urologist nor my retina doctor could answer my question about having injections and BCG therapy done at the same time — whether they are compatible and would continue to benefit me. I understand that BCG therapy reduces the recurrence of returning tumors. The Avastin eye injections may keep me from going blind. — S.P.

I don’t have a definitive answer for you, but I’ll share what I know and found out.

Avastin is an antibody drug that prevents the formation of new blood vessels by blocking vascular endothelial growth factor. This drug has proven to be useful in some cancers, which cannot grow without adequate blood supply, and in wet age-related macular degeneration, where new blood vessels in the retina are the problem. It is effective at slowing progression of AMD, but not effective at returning sight. You shouldn’t go without it.

Avastin is injected directly into the eye, and while some will enter the blood, the amount injected into the eye is approximately 0.1% of the amount that would be injected into the blood to treat colon cancer, for example.

BCG (Bacille CalmetteGuerin) is a vaccine strain of bacteria used to enhance the immune system in people with bladder cancer. BCG treatment of superficial bladder cancer is about 70% effective at giving a complete response. It is instilled directly into the bladder. I don’t think BCG would be any danger to your eyes.

Genentech, had no information about interaction.