How do nano-sized drug delivery micelles ACTUALLY target cancer cells?

I just attended a most excellent presentation on using micelles to deliver anti-cancer drugs, and because the scope of the presentation was mostly focused on the chemistry aspects I was left wondering how a tiny bubble of lipid-like molecules is able to specifically "find" tumor tissue. Why don't the micelles just fuse with everything and totally poison your entire body? I looked it up:

One way is by exploiting the "EPR effect" (which WAS mentioned in the presentation). EPR stands for Enhanced Permeability and Retention, and tumor tissue apparently has these enhanced characteristics. According to the National Cancer Center Research Institute of Japan in 2003, the EPR effect in solid tumor tissue got its name through the following pathophysiological characteristics: (a) hypervasculature; (b) incomplete vascular architecture; (c) several vascular permeability factors stimulating extravasation within the cancer; and (d) little drainage of macromolecules and particulates.

I suppose I trust that.

Another way to ensure that your drug-filled micelle gets to the tumor is to link some tissue-specific molecular marker or "vector" to the outside of the micelle. Some of these vectors include: antibodies, peptides, lectins, saccharides, and hormones. However, antibodies are most common vector used these days.

Nanotechnology!

Thanks to Kate for teaching us about some awesome research.