Suspected ECE on endorectal coil MRI had neither protective effect nor increased risk for PSMs, which means that, whereas this variable may help with surgical planning, its capacity to decrease PSM rates remains to be prospectively investigated. Although increasing BMI may impact PSMs [17], we did not find such an association, possibly because individuals with high BMI were underrepresented. Of the 407 patients, 79 had a BMI between 30 to 35, and only 10 had a BMI >35.
It is well established that tumour volume is associated with higher PSM rates [1], [12] and prostate biopsy data may help to predict tumour volume and risk of a PSM. Although overall percentage of cancer in the biopsy specimen (total millimeters of cancer in the biopsy specimen divided by total millimeters of biopsy tissue) is a more accurate predictor of cancer volume, we used the maximum percentage of cancer in any core of the specific side because not all prostate biopsies were done at our institution. Of interest, 201 (28%) of the 728 prostate sides that harboured cancer had a negative ipsilateral preoperative biopsy. A PSM was identified in 4% of them, compared with an 8% PSM rate among the 527 prostate sides with a positive biopsy. In other words, surgeons should not become overconfident about dissecting the NVB extremely close to the prostate side where the biopsy was negative.
This was an excellent paper that made several observations that I have seen as well:
Smaller prostates tend to have a higher level of positive margins.
Positive margins often happen on sides where there is no cancer on biopsy.
I do not personally order preoperative MRIs, but this showed it did not make a statistical difference in positive margin rates. I would be curious to see how many of the patients with preoperatively suspicious MRIs for extracapsular extension actually had it at the time of surgery.