Return of Serum Prostate Specific Antigen to Undetedtable Level Following Removal of Solitary Lymph Node Metastasis

Historically pelvic lymph node metastasis of prostate cancer has been considered a systemic disease that is incurable by regional therapy, including surgery and radiation. We report a case in which an isolated pelvic lymph node recurrence was removed during low anterior resection of the rectum. The patient had previously undergone radical retropubic prostatectomy and bilateral pelvic lymphadenectomy for adenocarcinoma of the prostate. Serum prostate specific antigen (PSA), which had become detectable 1 year after radical retropubic prostatectomy, returned to an undetectable level following low anterior resection of the rectum. PSA remained undetectable for 18 months postoperatively. CASE REPORT A 67-year-old man with a PSA of 12.1 ng./ml. and clinical stage T2b Gleason grade 3 4 7 adenocarcinoma of the prostate underwent bilateral pelvic lymphadenectomy and radical retropubic prostatectomy. The right neurovascular bundle to the penis was excised widely with the prostate because of palpable tumor in the right lobe of the gland. Final pathological evaluation revealed high volume bilateral Gleason grade 3 4 7 adenocarcinoma of the prostate with perineural and perivascular invasion. In the right lobe there was extensive extraprostatic extension of tumor into the periprostatic and periseminal vesicle tissue. However, all surgical margins, both seminal vesicles and the pelvic lymph nodes were negative for tumor. PSA decreased to less than 0.10 ng./ml. postoperatively and remained undetectable for 1 year. At 1-year followup PSA was 0.12 ng./ml. A repeat test showed a PSA of 0.14 ng./ml. Rectal examination demonstrated no evidence of locally recurrent tumor. However, stool hemoculture was positive, and the patient subsequently underwent colonoscopy, which revealed a large polyp 10 cm. from the anus. Low anterior resection of the rectum was performed with a temporary diverting colostomy. Final pathological evaluation showed well differentiated adenocarcinoma of the rectum with all surgical margins negative. However, 1 of 4 pericolic lymph nodes contained a focus of metastatic adenocarcinoma of the prostate. Three months after rectal surgery PSA was again undetectable. PSA remained undetectable for 18 months postoperatively, and 2.5 years following the original radical retropubic prostatectomy and bilateral pelvic lymphadenectomy. DISCUSSION Pelvic lymph node metastasis of prostate cancer is presumed to be a systemic disease that is incurable surgically. This traditional concept has recently been challenged by Studer et al, who reported that extensive pelvic lymph node dissection may be curative in patients with carcinoma of the prostate and bladder as demonstrated at short-term followup. 1, 2 Our case supports this hypothesis in that delayed removal of a single positive perirectal lymph node 1 year following radical prostatectomy and bilateral pelvic lymphadenectomy resulted in PSA returning to an undetectable level, at which it remained for 18 months of followup. Obviously, it would be impractical to attempt to remove the presacral and pericolic lymph nodes in all patients at high risk who undergo radical prostatectomy. However, it may be worthwhile to perform a meticulous dissection of the hypogastric lymph nodes as well as the external iliac and obturator lymph nodes in an attempt to cure the patient with low volume lymph node metastases. Bader et al found that the hypogastric lymph nodes were positive in 62% of patients with positive lymph nodes who had undergone radical prostatectomy, and these nodes were the only site of metastatic nodal disease in 20% of the patients. 3 In patients with positive lymph nodes undergoing radical cystectomy 5-year survival was 29%. Survivors had positive nodes at any site in the pelvis but, again, these were located predominantly along the hypogastric artery. 2 We would agree that longer followup is needed but at least in our patient a second extensive pelvic lymphadenectomy appears to have had therapeutic benefit in removing minimal residual lymphatic disease.