I think some anal cancers are labeled recurrent, when in fact they are residual.
I completed treatment at the end of March 2013, and PET scans in June and September 2013 showed continued improvement. There really was no cause for alarm.
However, I was fortunate to have a surgeon that decided to do a sigmoidoscopy in October 2013 to take a closer look at the anal canal. She had virtually completed the exam, finding nothing. But as she was withdrawing the scope, she noticed a tiny area that was slightly raised - no color differentiation from the surrounding tissues, and not palpable digitally. She repeatedly assured me that she was certain it was nothing of concern, but that she wanted to biopsy the area.
Result: positive for squamous cell anal cancer.
I'm certain that mine was residual, rather than recurrent. And I'm sure there are many other similar cases.
Face it: We don't have the benefit of all the means used to diagnose and monitor other cancers. Tumor markers, for example, have proven unreliable with anal cancer. Yet you can speak with breast, ovarian, uterine, pancreatic and lung cancer survivors - to just name a few - who refer to their "numbers" being great.