I am a male aged 64 years who has been a heavy smoker for 50 years. I was diagnosed with Medullary Thyroid Cancer 15 months ago and had a total thyroidectomy and levels 2,3 and 4 neck dissection. CEA levels dropped from 20 pre operation to 10.3 on 8/14/2015 and rose again slightly to 11.6 on 2/24/2016. As at 02/24/16 the calcitonin levels remain at <0.6 pmol/L. A recent CT scan identified a 5mm nodule in one lung and a 6mm nodule in the other lung. Given my age and history should I have a biopsy of the nodules or await the results of another CT scan in three months?