Neuroendocrine differentiation in prostate cancer: is it detectable and treatable?

Does small-cell phenotype predict the natural history of prostate cancer? A case study in disease behavior

BACKGROUND

A 52-year-old man presented to his urologist with hematuria and symptoms of frequency and incomplete voiding. The patient received antibiotics without symptom resolution. His prostate-specific antigen (PSA) level was 6.6 ng/ml and digital rectal examination revealed a normal-sized firm prostate gland. Biopsy obtained by transurethral resection revealed poorly differentiated Gleason 9 adenocarcinoma of the prostate with small-cell/neuroendocrine features. Pure small-cell cancer or poorly differentiated prostate cancer may secrete little or no PSA. One should be alerted to this phenotype in a patient with large volume disease on biopsy or examination and a low PSA or PSA not in proportion to tumor burden.

INVESTIGATIONS

Digital rectal examination, laboratory tests, cystoscopy, prostatic chips obtained from transurethral resection, prostate biopsy, bone scan, CT scan of the chest, abdomen and pelvis.

DIAGNOSIS

Poorly differentiated Gleason 9 adenocarcinoma of the prostate with small-cell/neuroendocrine features.

MANAGEMENT

Transurethral resection, androgen blockade with a gonadotropin-releasing hormone analog and antiandrogen flutamide, oral bicalutamide, docetaxel and oral estramustine. Total pelvic exenteration with ileal conduit urinary diversion and permanent end-colostomy formation, percutaneous nephrostomy placement, cisplatin combined with etoposide.

Neuroendocrine differentiation in prostate cancer: a sheep in wolf's clothing?

Neuroendocrine differentiation of the prostate is often associated with a dismal prognosis. Whilst it is relatively rare compared with other forms of prostate cancer, it nevertheless remains difficult to treat these cancers effectively and to maintain a durable response. Research aimed at understanding the complexity of neuroendocrine differentiation of the prostate has been conducted for some time. The cells involved in this process secrete a variety of factors that can influence growth patterns and regulatory pathways. Many of these factors can be monitored serologically, but the relationship between the biology of the tumor and clinical response is often discordant. This review outlines the difficulties in treating this disease, both at the time of diagnosis and in the metastatic setting, and focuses on an area of research that remains challenging to both the researcher and clinician.