Negative margins are a good thing although according to a study not always as good as you think.
The report linked below says that if tumour cells are within 0.01mm of the margin, called a close margin in the study, then it is classed as negative but the outcome is measurably worse than negative.
You might think 0.01mm is very small and thought a margin would be more than that but the margin is the edge of the prostate sample removed.
This report says that in their sample, 6 years after the op a negative margin has a recurrence (at psa 0.2) of about 14%. A close margin about 25%. A positive margin about 36%. It says T3a, high Gleason and high psa are also more prevalent in the recurrences. The writer suggests adjuvant treatment should be offered for close margins.
Although do they normally measure to that degree. 0.01mm is very small and you’d think it could be classed as positive. (I'd emphasise that the above is from one study and might not be the official figures for recurrence).
You might also think recurrence would be more likely for a close margin near the bladder or other adjoining cells. You could also say a recurrence is sometimes declared at less than psa 0.2, e.g. 3 consecutive rises above 0.1. As always there are a lot of what ifs.
The report was written in 2015 using approx. 1600 samples from RPs done between 1998 and 2011 and had about 200 recurrences. 19% were positive, 15% were close. I can't say I’ve read it in depth especially the statistical information.
Here's the link to it:
In my own case I was told there is some good news your margins are negative. I asked how big the margin is but was told it’s not like other cancers where they cut out say 4mm clear around the tumour cells. Although I could perhaps have been told how far from the margin the cells are having been earlier told from the MRI it was near the margin. Not sure if others would like to know or are aware of such information. I'm not sure I want to know but probably would as I'm suspicious of what close to the edge meant in mine. Any thoughts positive or negative?