Prognostic significance of positive surgical margins post-surgery
Posted Sep 29 2008 4:46pm
Scardino and his colleages at Memorial Sloan-Ketting Cancer Center (MSKCC) have now published data that appear to finally confirm the prognostic significance of positive surgical margins (PSM) after radical prostatectomy. They conclude their report by stating that a PSM has a significant adverse impact on prognosis for biochemical progression-free survival after radical prostatectomy, and that “surgeons should continue to strive to reduce the rate of positive surgical margins to improve cancer control outcomes.”
The precise clinical significance of positive surgical margins in radical prostatectomy specimens has been unclear for some time. While most studies have concluded that a PSM is an independent adverse prognostic factor for disease progression, others have reported that surgical margin status didn’t appear to affect prognosis. Reasons for these different conclusions potentially include variation in the numbers of patients with a PSM who receive adjuvant therapy of some type and the differing statistical methods used to account for the effects of the time course of adjuvant treatment on recurrence. Swindle et al. have used the MSKCC data to evaluate the prognostic significance of PSMs using multiple methods of analysis while taking account of patients who received adjuvant therapy.
They analyzed data from 1,389 consecutive patients with clinical stage T1-3 prostate cancer who received radical prostatectomies from two surgeons between 1983 and 2000. Of these 1,389 patients, 179 (12.9 percent) had a PSM, and of those 179 patients, 29 received adjuvant radiation therapy and 8 received adjuvant hormonal therapy. The post surgical data also showed that PSMs occurred in 6.8 percent of 847 patients with pathological T2 and 23 percent of 522 patients with pathological T3 disease.
The data were analyzed using five different statistical strategies in a sophisticated attempt to account for the fact that adjuvant therapy can affect the outcome of the analysis. It was shown that PSM was a statistically very significant predictor of cancer recurrence when the patient data was analyzed using four of the five statistical strategies. Only if adjuvant therapy status was completely ignored was PSM not a statistically significant predictor of disease recurrence. Furthermore, one of the analyses clearly demonstrated that a PSM was an independent predictor of 10-year probability of progression-free survival, along with Gleason score, extracapsular extension, seminal vesicle invasion, positive lymph nodes, and preoperative serum prostate specific antigen. Using this analysis the 10-year progression-free prognosis was 58 + 12 percent for patients with a PSM and 81 + 3 percent for patients without a PSM, respectively.