Long-time fans of "General Hospital" were happy when Tristan Rogers joined the cast of "General Hospital: Night Shift," SOAPnet's primetime spin-off of the daytime drama. After all, Tristan's character, super spy Robert Scorpio, was a favorite.

But the fans aren't as happy now that their hero has been diagnosed with colon cancer -- and on Tuesday's show, he will start to lose his hair. Tristan agreed to have his head shaved. A lot of times actors opt to wear a bald cap instead of shaving their head, but Tristan chose to take the more real route -- and his reasons for doing so are personal: he lost his father to colon cancer.

"In my dad's case, he was never diagnosed. Ever," the Aussie actor tells ET. "Nobody ever gave him a colonoscopy. Nobody ever asked about it. I have been going through it ever since I was told that guys over 45 should look into this. In retrospect, I look back at what happened to my dad [and think], if they had given him a check up, he would have gone another 10 years."

Even though Tristan volunteered to go completely bald, storyline needs dictated otherwise. He explains: "There was a problem going completely bald. No one had taken into account that there has to be an appliance put on the back of my head to look like a cut with staples in it, so we couldn't actually shave my head as we had originally thought. I have less than a quarter inch of hair which is close to bald."

[Note: The need for the appliance was storyline dictated because prior to the colon cancer diagnosis, Scorpio had a brain tumor removed. It was then that the doctors realized that the tumor was symptomatic of a larger problem.]

In addition to "General Hospital: Night Shift," Tristan is bringing attention to colon cancer, by filming a public service announcement for the National Colorectal Cancer Research Alliance and appearing on the upcoming "Stand Up to Cancer" special," airing on ABC, NBC and CBS on Sunday, Sept. 5.

"General Hospital: Night Shift" airs Tuesday nights at 11 p.m. on SOAPnet.