I had thyroid cancer for...I don't know how many years - probably at least 5, looking back at old photos - with no symptoms at all. I hadn't even noticed the lump until a doctor pointed it out.

If it's any consolation, I will add my cancer was stage 1 and I wasn't sick after diagnosis either, except for a couple of days after the operation because of the anaesthetic. I will add I also had a very large tumour. The full cyst was 10.5cm. (Apparently, most thyroid cysts are under 1cm.)

You will read and hear a lot of stuff and much of it won't be relevant to your dad's situation. I know this reply probably isn't very helpful as whatever is causing the lump, it's almost certainly not thyroid cancer. 

I hope you get an answer soon and it turns out to be something completely harmless.

Hi MargaretMary,

Thankyou so much for taking the time to read and post a reply, I really appreciate it. I had ideas that a lump is found and pretty much straight away someone might feel unwell or the body might tell you somethings wrong but perhaps not so. We are now waiting for what seems like forever for a scan or something that might confirm what it is. We are just left with the GP's opinion that it is C. He has also just recently found another lump which raises our urgency within a system that doesn't feel urgent enough. 
It's an emotional time isn't it. 
I do hope you are feeling ok in yourself, thankyou once again for sharing your thoughts and experiences. Wishing you the very best, take care x

My wife sometimes uses these forums, and she would tell you herself that for the year before she was diagnosed, and up until she received treatment, she felt the best she had in years.

A lot of cancers can be symptomless. It's why some people get diagnosed late and some cancers are more deadly than others. Cancers near the surface tend to get picked up quicker and earlier because people have more chance of just randomly finding them or actually seeing them. Take pancratic cancer, one of the worst cancers around because it tends to only be symptomatic once it has become advanced.

Pain wise, cancer tends to only cause pain once it presses on nerves or causes a blockage. It's why a lot of cancers, when running through symptom descriptions, usually have painless lumps as one of the first symptoms. Painful lumps tend to be infections.