Help me understand "negative margins"

I guess I still don't really understand what "negative margins" exactly means. I was under the impression that with negative margins (there is no cancer cells detected on the outer skin of the prostate) that the chance of recurrence are very slim, which would make sense to me.

However, there seems (maybe a disproportionate number) a number of cases here where the sig line post op path report indicates negative margins but a recurrence. What exactly happens? My thinking is either the pathologist incorrectly inspected the margins, or there is another conduit where cancer cells can escape or there still isn't an true understanding on the recurrence process.

Anyone care to expand on this?

Casey gives a fine and understandable explanation. It is important to note that the finding of negative margins does not mean that the cancer cells have been completely contained in the resected specimen. It is always possible that a few (or more) cells may have found their way out without leaving a detectable tumor at the margin. It is all too common in ALL cancers that surgery leaves an apparent complete removal of tumor but recurrence follows. Negative margins make the recurrence less likely, but one can never say that every tumor cell has been eradicated. Psa is the proof for prostate cancer.

In addtion the the explainations above, the gleason grade is also very important in determining reoccurrances. A negative margin for a G6 tumor has very littley likely hood of reoccurring whereas a negative margin for a G10 still has a very high risk of reoccurrance. Higher Gleason grades are more aggressive and stray cells can set up elsewhere in the body. The less aggressive gleason grades find it hard to survive outside the prostate enviornment. It is highly recommended that in high risk cases a course of hormone therapy be given along with the primary treatment in order to kill any stray cells that may be wandering around.
JT

Prostate cancer cells are very blood borne and can also travel along the nerve paths and lymphatic system. When he was diagnosed, Dr. Snuffy Myers had blood drawn from his arm and the sample had cancer cells in the blood. He contends that 50% of men age 50 will show PCa cells in their blood. My urologist agrees with him.

As John T says, most of the cells will have a very hard time finding a place to grow and thrive, however the higher grade cells may do so.

Thus, negative margins in no way indicate that all the cancer was removed because there is always a likliehood that cancer cells have been outside the surgical area for sometime.

Hi everyone.
I'm sorry I wasn't able to respond earlier. Thank you all for your help in me understanding the path reports on negative margins.

I guess I still don't understand why a higher GS with a path report of negative margins has higher probability of spreading vs a lower GS. My analogy was like a water balloon, if there is no wetness on the exterior surface side of the balloon, that would indicate there are no leaks. Just as if there are no cancer cells detected on the surface of the prostate it would seem to me that would indicate the cancer is confined to the prostate which has been removed, even if the cells are aggressive.

Ozbob,
For all high risk cancers the PCRI recommends a combination treatment which includes hormone treatment along with the primary treatment. The length of time on HT varies, with some doctors recommending two years and others 13 months. Adding HT to a primary treatment has shown no benefit to overall survival, but has shown a benefit to PC specific survival. You would be advised to see an oncologist specializing in PC for a consult even if you have to travel for the first visit (you can be treated locally). I just think it is a good idea for high risk guys to have a good oncologist on their team as most Uros or ROs are not well experienced in treating high risk cases.
JT

Tony,
Of course individual differences matter, and I think that all high risk guys should seen an oncologist before making any decisions on treatments. There has been some new research just released that show a significant increase in effectiveness of radiation for G7 guys when combined with a short, 6 month, course of HT.
When I first got into this PC thing I wondered why combination treatments were rarely used. When my wife had BC 7 years ago I had some long discussions with her Onco, one of the best Breast Oncos around. He only used combo treatments and she had a combination of two chemo drugs, then surgery, then radiation, then another course of a different chemo drug. His practice specialized in reoccurrances, most all from other doctor's failed treatments. He was also the one who told me to see Scholz after I had already made a decision on surgery, so I have a lot to thank him for.
You are one of the few patients I have seen to take the aggressive combo treatment route and I think that many doctors and patients should at least consider it for the highest risk cases. It's not for everyone, but after seeing how well it works in BC and other cancers I don't know why it is not used more.
JT