My wife has had full body scans every 3 months for the past 3 years. She currently has multiple active sites of bone mets, from the spine to shoulders and hips. A single scan is much more convenient and keeps the oncologist up to date with the state of her cancer.

In our experience sometimes a new cancer site isn't diagnosed quickly, especially if it's asymptomatic and slow growing. Having past scans and reviewing them overtime has found multiple tumors so far.

Seems the radiographers err on the side of caution when feeding back to the Oncologist. Her last cancer in her neck (c2) had been tracked over 3 scans (because it was small and slow growing), before it was reported back to us and subsequently treated with cyberknife.