BOSTON ( TheStreet) -- On Friday, May 20 from 11 a.m.to noon ET, I invite everyone to participate in the first Biotech Stock Mailbag live chat. This will be an opportunity to spend an hour discussing all things biotech and biotech investing with me.

The Biotech Stock Mailbag live chat will follow the same format as my well-received FDA advisory panel live blogs, except the focus will be on your biotech stock questions and comments. If this first live chat goes well, I'll schedule one each month.

Reminders of the May 20 biotech live chat will be posted later but for now mark your calendars and start thinking of some biotech stock topics you want to chat about.

Now onto your emails and questions:

Henry O. emails, "I recall a few months back you were going to write about Neoprobe (NEOP) but since then I haven't seen anything written by you. What do you think about the Lymphoseek results put out by the company this week? Is this a reason for you to get interested in Neoprobe now?"

Neoprobe says the phase III data released this week make a convincing case for the superiority of Lymphoseek over vital blue dye as a diagnostic tracing agent used for detecting the spread of cancer to lymph nodes. The study achieved all primary and secondary endpoints with statistical significance, and on most measures, Lymphoseek even performed better than it did in a previous phase III study.

But I'm a skeptic, everyone knows that, so I also went looking for the bear story. Is there something the Lymphoseek data are not telling us? Could Neoprobe's claim of Lymphoseek superiority over vital blue dye possibly crumble under regulatory review? It's always a good idea to know the long and short thesis of any stock you're considering buying, and, indeed, I found the short thesis on Neoprobe. More on this side of the story below.

Lymphoseek is a proprietary radioactive tracing agent designed for use during a surgical procedure known as intraoperative lymphatic mapping (ILM) or sentinel lymph node biopsy (SLNB). ILM is performed on patients during cancer surgery to determine if cancer has metastasized, or spread, from the primary tumor site into the lymph nodes. Once cancer gets into the lymphatic system, it can spread more easily to the rest of the body.

To prevent cancer from spreading, doctors perform an ILM procedure to identify which lymph nodes are closest to the tumor. Once these lymph nodes are found, doctors can remove them and test to see if they're cancerous. Most ILMs performed in the U.S. today rely on a combination of vital blue dye and an off-label radioactive tracing agent to map out lymph nodes.

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