A common theme on melanoma discussion forums is frustration with the length of time between scans when when patients are on the “watch and wait” regimen after being told there is no evidence of disease. It’s been bugging me lately – probably because I needed to have something to stew about to ward off scanxiety as we approach Robert’s six-month scans in early June.

So, I asked Robert's melanoma doctor about this when we went in for the four-month check-up last week. Robert quipped that I want him to glow in the dark so I wouldn’t need a flashlight to get to the bathroom at night, but Dr. Lipson answered thoughtfully with a discussion of how much radiation is too much. Here’s the gist of what he said.

U.S. guidelines for the frequency of radiological scans to look for any suspicious growths in the body that might be melanoma are set by the National Comprehensive Cancer Network. For patients whose disease is staged from IIB to IV the guidelines call for chest xray, CT, and/or PET scans every three to 12 months for five years and annual MRIs of the brain. (The guidelines are discussed in an article published in the Journal of Clinical and Aesthetic Dermatology in September 2013.)

So, within that range, how do you decide how often to scan? You look at the extremes. The most frequent extreme would call for scans every week or two, but this would be too much because the change you see from one week to the next would be negligible. That means it would be too much exposure to radiation. One month doesn’t give enough time for something to change either. Could you do it every two months? Again, probably not; eight weeks isn’t that much time unless you’re looking at something very specific and want to know whether this particular spot has changed.

At the other extreme, is a year too long? Probably so, because if something is starting to grow you want to know about it sooner. Even nine months, he said, is “probably an uncomfortable period of time.” In our case, four to six months is the range Dr. Lipson is comfortable with.

Another factor is how closely the patient is being followed with skin and physical exams. Since Robert sees the dermatologist every three months for a thorough skin exam, including destruction and removal of suspicious spots and biopsies when appropriate, and sees Dr. Lipson every four months for physical exams, including lymph node palpation, a six-month schedule seems reasonable to him.

Then, the clinch factor is considered (at least by this doctor) – the patient’s comfort level. Since the national guidelines leave it pretty open, he said, “if … you’re really not comfortable with six months, then let’s do it every four months – that’s certainly within the guidelines. It’s an extra exposure to radiation every year, that’s all.”

Robert’s next scans are early in June – about five months since the last set were done at Johns Hopkins. He will also have scans and a brain MRI in December for his next yearly follow-up after the GVAX vaccine trial. Assuming all goes well between now and then, I’ll have to become comfortable with the six-month schedule – to prove to Robert that I don’t want him to glow in the dark!

One more wrinkle in learning to live with melanoma …