Prostatic atrophy: evidence for a possible role of local ischemia in its pathogenesis

Prostate cancer detection and diagnosis: the role of MR and its comparison with other diagnostic modalities--a radiologist's perspective

It is now universally recognized that many prostate cancers are over-diagnosed and over-treated. The European Randomized Study of Screening for Prostate Cancer from 2009 evidenced that, to save one man from death from prostate cancer, over 1400 men need to be screened, and 48 need to undergo treatment. The detection of prostate cancer is traditionally based on digital rectal examination (DRE) and the measurement of serum prostate-specific antigen (PSA), followed by ultrasound-guided biopsy. The primary role of imaging for the detection and diagnosis of prostate cancer has been transrectal ultrasound (TRUS) guidance during biopsy. Traditionally, MRI has been used primarily for the staging of disease in men with biopsy-proven cancer. It has a well-established role in the detection of T3 disease, planning of radiation therapy, especially three-dimensional conformal or intensity-modulated external beam radiation therapy, and planning and guiding of interstitial seed implant or brachytherapy. New advances have now established that prostate MRI can accurately characterize focal lesions within the gland, an ability that has led to new opportunities for improved cancer detection and guidance for biopsy. Two new approaches to prostate biopsy are under investigation. Both use pre-biopsy MRI to define potential targets for sampling, and the biopsy is performed either with direct real-time MR guidance (in-bore) or MR fusion/registration with TRUS images (out-of-bore). In-bore and out-of-bore MRI-guided prostate biopsies have the advantage of using the MR target definition for the accurate localization and sampling of targets or suspicious lesions. The out-of-bore method uses combined MRI/TRUS with fusion software that provides target localization and increases the sampling accuracy of TRUS-guided biopsies by integrating prostate MRI information with TRUS. Newer parameters for each imaging modality, such as sonoelastography or shear wave elastography, contrast-enhanced ultrasound and MRI elastography, show promise to further enrich datasets.

Prostatic atrophy. Clinicopathological significance

Prostatic atrophy is a benign lesion that may mimic adenocarcinoma histologically and on imaging. It is more frequent in the peripheral zone and has gained importance with the increasing use of needle biopsies. Diffuse atrophy occurs secondarily to radiotherapy and/or endocrine therapy. Inflammation and/or chronic local ischemia may cause focal atrophy with an increasing frequency in age. Atrophy may be classified morphologically into diffuse and focal. The latter may be partial, complete or combined. Partial focal atrophy is the most frequent mimicker of adenocarcinoma on needle biopsies. Complete focal atrophy may be subtyped into simple, sclerotic and hyperplastic (or postatrophic hyperplasia). Combined lesions are frequent and partial atrophy may precede complete atrophy. The several morphologic types of focal atrophy may represent a morphologic continuum and the hyperplastic (or postatrophic hyperplasia) subtype seems to be at the extreme end of this continuum. Chronic inflammation associated to focal atrophy (proliferative inflammatory atrophy) has been linked to high-grade prostatic intraepithelial neoplasia and/or carcinoma. This link, however, remains controversial in the literature. The question whether inflammation directly produces tissue damage and atrophy or some other insult induces atrophy directly, with inflammation occurring secondarily, is still unresolved. An intriguing finding that needs further studies is a possible association of extent of atrophy to serum PSA elevation.

State-of-the-art uroradiologic imaging in the diagnosis of prostate cancer

In the diagnostic process of prostate cancer, several radiologic imaging modalities significantly contribute to the detection and localization of the disease. These range from transrectal ultrasound (TRUS) and magnetic resonance imaging (MRI) to positron emission tomography (PET). Within this review, after evaluation of the literature, we will discuss the advantages and disadvantages of these imaging modalities in clarifying the patient's clinical status as to whether he has prostate cancer or not and if so, where it is located, so that therapy appropriate to the patient's disease may be administered. TRUS, specifically with the usage of intravenous contrast agents, provides an excellent way of directing biopsy towards suspicious areas within the prostate in the general (screening) population. MRI using functional imaging techniques allows for highly accurate detection and localization, particularly in patients with prior negative ultrasound guided biopsies. A promising new development is the performance of biopsy within the magnetic resonance scanner. Subsequently, a proposal for optimal use of radiologic imaging is presented and compared with the European and American urological guidelines on prostate cancer.

Increased expression of CCAAT/enhancer-binding protein beta in proliferative inflammatory atrophy of the prostate: relation with the expression of COX-2, the androgen receptor, and presence of focal chronic inflammation

BACKGROUND

Proliferative inflammatory atrophy (PIA) in the prostate has been proposed to be a precursor to prostate cancer. CCAAT/enhancer-binding protein beta (C/EBPbeta) is an important transcription factor involved in cellular proliferation and differentiation. Activation of C/EBPbeta plays a crucial role during the initial stage of cyclo-oxygenase 2 (COX-2) induction by proinflammatory mediators. Overexpression of C/EBPbeta has been reported in several human tumors. Nevertheless, the C/EBPbeta expression and functions in human prostate tissue are basically unknown.

METHODS

C/EBPbeta immunohistochemical staining was performed on 45 benign prostate hyperplasia (BPH) samples. The expression of C/EBPbeta in PIA lesions and normal-appearing acini was analyzed. In addition, by using double-IHC staining, C/EBPbeta expression and the association with chronic inflammatory cell density, co-expression of COX-2 and androgen receptor (AR) were also investigated.

RESULTS

C/EBPbeta was occasionally observed in normal-appearing prostate acini (4.9% +/- 6.7%, Mean +/- SD) but was clearly overexpressed in PIA lesions (81.8% +/- 16.4%) (P < 0.0001). Atrophic glands with T-lymphocyte and macrophage inflammation expressed higher level of C/EBPbeta. Furthermore, C/EBPbeta correlated significantly with COX-2 expression. Downregulation of the AR was common in PIA and was also related to the C/EBPbeta overexpression.

CONCLUSIONS

The data demonstrated that chronic inflammation appeared to play roles in the induction of C/EBPbeta expression in prostate epithelium, which was in turn associated with increased COX-2 expression and AR downregulation. In combining with other molecular alteration in the epithelium of PIA, it is suggested that these cells might be a kind of intermediate cells and involved in the pathogenesis of prostate cancer.

Prostatic atrophy: Immunohistochemical study of hypoxia induced factors

BACKGROUND

There is evidence that chronic local ischemia may be one possible etiology of prostatic atrophy (PA). Our aim was to study the expression of hypoxia induced factors in areas of PA.

DESIGN

The immunohistochemical expression of hypoxia-inducible factor-1 alpha (HIF-1) and vascular endothelial growth factor (VEGF) was studied in atrophic acini of 33 needle prostatic biopsies. Prostatic atrophy was the only diagnosis in these biopsies. For HIF-1alpha, a total of 27,158, 10,060 and 9920 nuclei were counted in atrophic acini, acini with squamous metaplasia, and acini without squamous metaplasia surrounding acute infarct, respectively. For VEGF, a total of 24,966, 9849 and 9918 nuclei were counted for the same acini. A total of 1326 nuclei were counted in acini of the needle biopsy used as negative control. The Student's test for independent samples with significance level at 5% (p<0.05) was used to compare the mean ratio (MR) of positive nuclei over total nuclei for HIF-1 and VEGF.

RESULTS

For HIF-1, 108 (MR=0.004), 6877 (MR=0.68), and 6566 (MR=0.66) nuclei were positive in atrophic acini, acini with squamous metaplasia, and acini without squamous metaplasia surrounding acute infarct, respectively. There was a highly significant difference (p<0.001) between atrophic acini and acini surrounding acute infarct. For VEGF, 139 (MR=0.05), 5926 (MR=0.60), and 4948 (MR=0.50) nuclei were positive in the same acini. The difference was highly significant (p<0.001). All 1326 nuclei counted in the needle biopsy with essentially normal findings were negative for HIF-1 and VEGF.

CONCLUSIONS

This study showed that prostatic atrophic acini are not on acute ischemia. However, local chronic ischemia cannot be ruled out. Experimental data showed that on chronic ischemia, the signal triggering HIF-1alpha accumulation may disappear despite continuous hypoxia suggesting that compensatory mechanisms triggered during prolonged hypoxia may be able to restore normal tissue oxygen levels.