When I was diagnosed by biopsy two years ago, my ENT doctor ordred PET scan to see if it has spread to other areas. However, the PET scan was all clean - even the primary cancer was not shown.

The explanation from ENT is that PET is not very accurate for head and neck cancer, 15% false negative.

Following his suggestion, I did radical neck dissection, he took out 74 lymph nodes and 4 of them confirmed positive of cancer.

Since PET is not working on me, he never ordered PET scan for follow-up.