James Van Der Beek has cancelled his appearance at a Dawson's Creek reunion event. The actor shared on Instagram that he won't be at Monday's event, a reunion featuring Katie Holmes, Joshua Jackson and Michelle Williams staged to raise cash for F Cancer in light of Van Der Beek's stage 3 colorectal cancer diagnosis. "This is the evening I'd been looking forward to MOST since my angel Michelle Williams said she was putting it together, way back in January," he began his post. Ending his post on an upbeat note, Van Der Beek wrote, "Everyone please enjoy all the love in that room. The show will go on at New York City's Richard Rogers Theatre.