Hi there. I'm so sorry about your Dad's recurrence. I suspect that the NCCN guidelines for post-treatment surveillance of head/neck cancer patients didn't even exist in 2006, when your Dad's first round of treatment concluded. The routine use of surveillance scans is controversial. Today, many institutions order one scan 2-6 months post-treatment and that is all many insurance companies cover. Beyond that, it's highly unlikely that your Dad would have been scanned routinely during the last 8 years unless he had symptoms pointing to a possible recurrence. That's not odd at all.