Does persistent thoracic spine pain worse at night in a cancer patient in remission with normal cancer marker & esr still need urgent imaging workup?

Maybe.: The imaging would be useful to help explain the cause of the pain. It doesn't have to be cancer.

Some work-up: Check with your oncologist. There are certain metastatic tumors that can metastasize to the spine. Certainly, if there are neurological signs like weakness or numbness, this would warrant an urgent evaluation. Metastatic disease to the spine when detected early is much easier to treat than when found late.