Murphy, I'm saddened to read this.
Please get another treatment opinion from a top Comprehensive Cancer Centre. Your life may just depend on it.
By the way, I would do the neck dissection, most definitely . Last times has no relevance to this time. This new tumour may well have seeded to the nodes. And it does not mean its curtains.
Get another opinion first. But do get the neck dissection.
Tammy