Significance of surgical margins in prostate cancer prognosis

This study evaluated the potential of surgical margins in predicting biochemical recurrence in patients with localized prostate cancer.

Patients with localized (confined) prostate cancer often undergo radical prostatectomy (surgical removal of all or part of the prostate gland). After undergoing radical prostatectomy, disease progression and survival of patients depend on a number of factors, which include prostate specific antigen (PSA) levels, grade (cell appearance under microscope), stage (extent to which cancer has developed and spread), and the status of surgical margins.

A surgical margin is the edge or border of normal tissue removed with a tumor during surgery. If cancer cells are present at this margin, the margin is described as positive and shows incomplete removal of the cancer. The influence of positive surgical margins in determination of biochemical recurrence (a post-treatment increase in prostate-specific antigen level, indicating that prostate cancer has come back or spread following radical prostatectomy) has not yet been evaluated. This study evaluated the use of surgical margins as a prognostic tool (identifying the likely course or outcome of the disease) in prostate cancer. 

This study involved 863 localized prostate cancer patients treated with radical prostatectomy. No patients received any treatments before or after surgery.

Overall, 40% of the patients had positive surgical margins. When the tumor was confined within the prostate the positive surgical margin rate was 24.7%. When the tumor extended beyond the prostate the rate increased to as high as 58.2%. Those patients with positive surgical margins were more likely to have higher levels of prostate-specific antigen prior to prostatectomy. Positive surgical margins were associated with a higher tumor volume (space taken up by the tumor).

Biochemical recurrence was more likely in patients with positive surgical margins compared to those with negative surgical margins. The rate of biochemical recurrence was 26% in patients with positive surgical margins compared to 13.9% in patients with negative margins. Surgical margin could significantly distinguish the likelihood of biochemical recurrence in cancer that was confined to the prostate.

The rate of biochemical recurrence found between those with prostate gland-confined cancer and a positive surgical margin versus those with prostate cancer that extended beyond the prostate gland and low prostate-specific antigen levels was similar. However, when these two groups of patients were stratified according to tumor grade, high-grade tumors were 2.21 times more likely to experience biochemical recurrence than those with a medium- or low-grade. 

In summary, this study concluded that positive surgical margins in localized prostate cancer are associated with an increased  risk of biochemical recurrence. Inclusion of surgical margins in cancer staging may improve prognostic stratification of prostate cancer patients. 

The analysis was from a single institution, and therefore should be repeated in further populations to validate the results.