Follow-up Tests - Is PET scan only sufficient?

For all you melanoma survivors out there, I have a question. What scans/tests do y'all receive for follow-up care, and how often do you receive them? Do you feel it is sufficient?

I'm still in my first year of treatment. I had a cutaneous melanoma removed from my back shoulder region in 1992, then nothing more for 17 years. Then this past July a lymph node under my right arm suddenly "popped" up seemingly overnight. (When I asked the radiologist who did the ultrasound & core-needle biopsy, she told me it was about the size of a plum!) I got a lecture about doing self-breast exams, since a lump this big would have been hard to miss, but I do them! Breast cancer runs in my family, plus I'd already had one run-in with skin cancer - I know to watch for swollen lymph nodes. (And honestly, I thoroughly wash, then shave that area every morning, it's not like I would have missed a mass that large!) That THING came out of nowhere. I went to bed one night feeling fine, and when I woke up the next morning, it hurt to lower my arm, and there was this big mass that hadn't been there before. Best we can figure is it had "hidden" behind the muscles in that area until it was just too large to hide anymore. That's why it seemed to appear overnight - it DID "appear" overnight. (It's also why that area was so sore the next morning.)

We have never found a primary skin cancer this time around, so the oncologist (who does NOT specialize in melanoma, but is head of research at the local cancer center, and has been in contact with a melanoma specialist in a nearby city asking about clinical trials, etc. in case I qualified) is assuming it is a skin cancer cell left over from 17 years ago that has been sitting dormant since then and something triggered it. Of minor concern to him is that my skin cancer was on the LEFT back/shoulder, while the lymph node affected is under the RIGHT arm. Then I explained to him just how WIDE an excision the surgeon had to take in order to get a clean margin because he apparently found some cutaneous metastases. This seemed to "prove" his theory to him.

My oncologist seems to find me a curiosity - the 17 years between initial onset and metastases to the lymph is a rarity apparently. One which we both hope happens again! He's "Dr Positive", so he won't tell me the true likelihood of that happening, however. He wouldn't even stage my disease - said he doesn't like to put a number on things like that. We had to explicitly ask him, and even then he didn't answer definitively. He said depending on criteria used, he could stage it either stage III or stage IV. Going strictly by the treatment protocol I'm receiving, however (surgery + interferon), I'm a stage III. I just don't know what level of stage III.

According to the oncologist, since the core-needle biopsy confirmed melanoma, SLNB was necessary. A complete lymph node dissection was done by default, and I am now about half way thru my year of interferon treatments. So far, I've had three PET scans. Other than the first one (done pre-operatively to look for other metastases), they have all been clear, and I am currently NED (thank God). I have some issue with my oncologist's office as to the schedule being used for my PET scans, as they have been inconsistent and I can't actually pin down a schedule. The "standard" I have been able to find is every 3 months the first year. And it looked like that was what they were going to follow, as my 2nd scan was 3 months after the 1st. However, when it was time for my next scan, and I asked about it, my oncologist replied that "since your last scan was so beautiful", he felt we could postpone my next scan for "awhile". I was so shocked, I didn't even think to ask how long "awhile" was! I was still trying to puzzle out how a "beautiful" scan justified delaying my next scan! So scan #3 ended up being 5 months after scan #2 (I ended up asking the nurse practioner, who seemed a little upset that it was 5 months since my last scan). When I finally get to see the oncologist again, I'll be asking him about follow-up care, including the PET scan schedule. Especially since the cancer treatment is undergoing a massive amount of cost-cutting initiatives (you would think something that generates revenue wouldn't be affected, but who knows - it could be the insurance companies directing some of the cuts).

I've read so many things about how scans aren't necessary, and that some cancer centers actually don't do them at all. Then I've read scans ARE necessary, but that PET scans alone aren't enough because they aren't sensitive enough to detect brain and/or lung metastases. That you also need MRI and/or CT scans of the brain and lung.

Personally, I'm on the side of doing the scans/tests. In my opinion, melanoma is too sneaky and often too aggressive once it gets a foot-hold not to be vigilant. We have so few drugs that truly work, and they don't even work on everybody. We all deserve all the time available to find the drug combinations that work for us! I don't want to die, and I want every minute of every day to fight for my life!

So, back to my question (sorry for the wordiness - it's a problem of mine!): What scans/tests do all y'all get, how often, and do you feel it's enough?