Back pain plus fear of recurrence is a common complaint here. Lower back pain is of course a possible symptom of TC metastasis, but it must be seen in the context of the full clinical picture. In order to cause serious pain, a tumor has to grow to a certain size, often at least 10 cm or so. But sometimes smaller tumors pop up in strategic locations and cause some pain. A 1 cm lymph node, however, will most probably not have such an effect. In your case, then, it's very unlikely that something big enough has grown. Your tumor expresses markers, so at the last blood draw, there can't have been much in the way of metastasis. A large growth since then is so unlikely that I'd stop worrying about it now (it also depends on your initial pathology: seminoma grows slowly, non-seminoma can have a faster rate of growth; but probably still not that fast).I know, though, how difficult getting your mind off the fear is. I have had lots of back pain since my I/O, and it always gets worse before surveillance appointments. The mind-body connection just works like that.