[The squamous-cell carcinoma of the prostate as an example of metaplasia in a tumor (author's transl)]

Squamous cell carcinoma of the prostate: long-term survival after combined chemo-radiation

Background

Carcinoma of the prostate gland is the most frequent malignant tumour affecting male population. While the large majority of tumours is represented by adenocarcinoma, pure squamous cell carcinoma comprises only 0,5–1% of all prostate neoplastic lesions.

It is characterised by a high degree of malignancy, commonly metastasising to the bone (mainly with osteolytic lesions), liver and lungs with a median survival time of 14 months.

Several therapeutic approaches have been employed in the effort to treat prostate pure squamous cell carcinoma, including radical surgery, radiotherapy, chemotherapy and hormonal therapy. All of them mostly failed to gain a significant survival benefit.

Case report

We herein report on a case of pure squamous cell carcinoma of the prostate approached with combined-modality treatment, with the administration of 3 courses of cisplatin 75 mg/m² on day 1 and continous infusion 5-fluorouracil 750 mg/m² on day 1 to 5 and, subsequently, radiotherapy, with the delivery of a total dose of 46 Gy to the whole pelvis, with additional boost doses of 20 Gy to the prostatic bed and adjunctive 6 Gy to the prostate gland (72 Gy in total). The patient remained free of disease for 5 years, finally experiencing local relapse and, subsequently, dying of acute renal failure due to bilateral uretero-hydro-nephrosis.

In addition, we provide a complete overview of all reported cases available within the medical literature.

Conclusion

Since it remains questionable which should be the most appropriate therapeutic approach towards prostate pure squamous cell carcinoma, our report demonstrates that a prolonged disease control, with a consistent survival time, may be achieved by the combination of an effective local treatment such as radiotherapy with systemic infusion of chemotherapeutic drugs.

Squamous cell carcinoma of the prostate

Squamous cell carcinoma of the prostate is rare, accounting for 0.5-1% of all prostatic cancers. It is highly aggressive and responds poorly to any mode of therapy. We present a case of squamous cell carcinoma of the prostate that developed in a patient with prostatic adenocarcinoma following radiation therapy.

Squamous cell carcinoma of the prostate

Eleven case of squamous cell carcinoma of the prostate have been divided into four groups according to their histological features and natural history: a pure squamous cell carcinoma of the prostate (one case); b common prostatic adenocarcinoma with malignant squamous component after oestrogen treatment (two); c urothelial carcinoma of the prostate with malignant squamous cell metaplasia (four); and d urothelial carcinoma of the urinary bladder with squamous cell metaplasia growing into the prostate (four). The squamous portions may spread to invade the fibromuscular stroma and grow in prostatic ducts. Necrosis of comedo type and inflammatory infiltrates appeared in a number of cases. The survival times of nine patients ranged from 1 to 17 months. Squamous components were shown by immunohistochemistry to contain various keratin types, carcino-embryonic antigen and peanut agglutinin binding sites. Whenever a squamous cell carcinoma in the prostate is diagnosed histologically various possibilities as to its origin should be considered.

[Morphogenesis and significance of epithelial metaplasia in the human prostate gland. An electron-microscopic study (author's transl)]

Electron-microscopic studies were done to point out the morphogenesis of transitional and squamous epithelial metaplasia in the human prostate gland. The basis of epithelial metaplasia is a multi-layered proliferation of the basal cells and subsequent divergent differentiation. Transitional metaplasia can be viewed under the light microscope; the electron microscope on the other hand does not show all structural features of the transitional epithelium, such as: The cover cells of the metaplastic epithelium, which do not reach the basement membrane; the surface cells, which are always mononuclear and show signs of beginning adenoid differentiation. Extreme twisting of the lateral cell membranes as a morphological equivalent of deformability was not observed. Squamous epithelial metaplasia, contrary to transitional epithelial metaplasia, shows the criterions true characteristics of squamous epithelium at both the light and electron microscopic levels: The metaplastic cells have an abundant cytoplasm containing the characteristic structures with numerous tonofibrils and broad desmosomes. Microvilli-like processes of the cytoplasm project into the lacunar interfacial canals. In addition aggregates of glycogen granules and deposits of osmiophilic material can be seen, representing the first step of keratinization. Epithelial metaplasias in the prostate occur not only in the central area near the urethra, but also in the peripheral ducts and glandular acini. An estrogen-androgen imbalance is suggested to be an essential factor in the etiology of prostatic epithelial metaplasia. A reversibility of squamous epithelial metaplasia is unlikely. To our knowledge, the epithelial metaplasias in the prostate do not represent a precancerous lesion.