Gary, I'm not by anymeans an expert on this but-- perineural invasion doesn't affect your stage at all--which is one reason why just looking at things by stage alone is misleading. It comes from looking at the pathology of the tumor itself--were there any nerves involved--if so, you have perineural invasion.

Since I have it, and it's the main reason why rad. and chemo were recommended to me, I did some reading up on perineural invasion and it is a significant predictor of cancer recurrence. In one study, it was the most significant predictor, stage being distinctly secondary. BUT this too is somewhat misleading (and I'm glad I had enough statistical knwoeldge to know this) because stage and perineural invasion are correlated--its rare to find it at stage I and more common at more advanced stages. So if it's entered as a predictor into a regression equation first, it can look like it's the big predictor but really that's because stage is really in there too.

Anyway, I know that's kind of a technical answer and I know we have to be careful with statisitcs here but I felt they were soemwhat necessary to answer this. I hope I amde it clear they have to be trated with caution as well.

But it's the one reason why I had aggressive treatment even though my nodes were clean.