Carcinoid is not like other cancers. It is generally slow growing but being in the intestines can cause uncomfortable symptoms. Google for carcinoid and/or neuroendocrine cancer organizations. You need to find a specialist who is familiar with this kind of cancer. There are also several groups on FACEBOOK that share a lot of info. You might want to check them out.
Generally, colon cancer starts as a colon polyp which then becomes cancerous over a period of 5-10 years. From there, that's when it starts to "spread" however, it's got quite a bit of muscle and tissue to work through to get outside the colon/intestine. I underwrite people for life insurance so I read medical records about EVERYTHING you can imagine. Fortunately, there are a lot of treatment options available for colon cancer and, now that they've found it, can screen him more closely and anyone else in your family!
(I was the first in my family to have breast cancer, at age 30 no less, so I said I was "taking one for the team" and now everyone has to be aggressively screened as a result. In a sick way, it makes me feel my family is safer).