The spread of cancer, seeding, via a FNAB is rare. In rarity, it's occurrence were with larger core needle biopsy in the breast, and have read some in the thyroid, but it's widely used, and considered safe, and an alternative to a surgical biopsy, which has its risk too. Some say, doctors that is, that a PET/CT is 90% accurate at 6-8 weeks, earlier has more false positives, 3 months or 12 weeks is when most have a scan is more accurate, 4 months is more accurate, and at 12 months, it's 100%. The is no general consensus when any period scanning should be done post treatment, in absence of any suspicion, and is only recommended for certain T3, T4 disease only, per NCCN guidelines in the oropharynx, larynx, etc. none in oral cancer, but each doctor, hospital may have different procedures.

My sister went ahead and had the needle biopsy because the lump was still on her neck though it had shrunk some. The cancer Dr. told her to wait because it was still shrinking and it could go away on it's own. The Surgeon told her that she should get it taken out asap so she chose to do the surgery. She had it done April 10 (on her birthday) and she was able to go home the next day. They didn't put a drain in her neck and they told her that her arm would be sore but it isn't. She has some numbness in her tongue and lip and the welling is all under her chin. She doesn't get the results of the biopsy until April 28.

Glad she followed through... Better safe than sorry hopefully - she will get the results before then..