Colorless.

There are things that have no color, but we assign color to. Love for instance is often represented with red while getting motion sick is often associated with being green. I have been motion sick, but my face didn't turn green. Still, being all throwy uppy somehow associates a person with the color green. Driving really fast is often associated with the color orange because that is the same color as a box of tide. Well, maybe I make that association myself, but I am sure everyone sees where I am coming from.

I looked at the sites for the American Cancer Society, National Cancer Institute as well as a few sites all about cancer and cancer related topics. I didn't notice a thematic color associated with cancer. Maybe for the same reason I associate speeding with orange, I associate cancer with yellow. I don't know why I am even thinking about it, but from now on, anything yellow means cancer.