Clinical and pathological assessment of high-risk ductal and lobular breast lesions: What surgeons must know.

Terminology in pathology is sometimes over-complicated and may be misinterpreted by clinicians facing patients and having difficulty answering questions posed by them. This may especially be true for some breast lesions with an increased risk of malignant transformation, the complex terminology of which reflects attempts to stratify them according to potential risk. On the basis of morphological and molecular features, both ductal and lobular proliferations have been classified and named in different ways by pathologists, and this often makes it difficult for the treating physicians and the patients to fully understand the nature of the lesions and their associated risks. In order to clarify pathology reports, unambiguous and simple terms are needed.

Angiosarcoma and atypical vascular lesions of the breast: diagnostic and prognostic role of MYC gene amplification and protein expression.

MYC amplification has been reported as a prominent feature of secondary angiosarcomas (SAS). The differential diagnosis between atypical vascular lesion (AVL) and low-grade angiosarcoma (AS) can be occasionally very difficult or even impossible, and MYC amplification status has been pointed as an important diagnostic tool to distinguish cutaneous vascular lesions of the breast. We assessed MYC amplification and protein expression status by fluorescent in situ hybridization (FISH) and immunohistochemistry (IHC), respectively, in 49 patients diagnosed with breast AS, and 30 patients diagnosed with post-radiation AVL of the breast. Clinical and pathological features, and follow-up data were collected, and survival analyses were performed. Among 37 patients with SAS, twenty patients had tumors with high-level MYC amplification and protein overexpression (54 %). None of primary angiosarcomas (PAS) or AVL cases showed MYC amplification or protein expression. Concordance between MYC amplification (FISH) and protein expression (IHC) was 100 % in AVL, PAS, and SAS. Survival analysis of the SAS patients demonstrates that those with MYC amplification had a significantly worse overall survival compared to cases without MYC amplification (P = 0.035). There was a non-significant trend toward a poor disease-free survival between cases with and without MYC amplification (P = 0.155). Our findings show that MYC amplification is a highly specific but poorly sensitive marker for SAS and, therefore, a negative result does not exclude the diagnosis of angiosarcoma. MYC amplification was associated with adverse prognosis, suggesting a prognostic role of MYC amplification status on SAS of the breast.

Changes in PgR and Ki-67 in residual tumour and outcome of breast cancer patients treated with neoadjuvant chemotherapy.

BACKGROUND: Limited data are available on the prognostic value of changes in the biological features of residual tumours following neoadjuvant therapies in breast cancer patients. PATIENTS AND METHODS: We collected information through the institutional clinical database on all consecutive breast cancer patients treated with neoadjuvant chemotherapy at the European Institute of Oncology (IEO), Milan, Italy, between 1999 and 2011. We selected patients who did not achieve pathological complete response at final surgery. All patients had a pathological evaluation, including ER, PgR, HER2 protein and Ki-67 expression carried out at the IEO both at diagnostic core biopsy and at final surgery. RESULTS: We identified a total of 904 patients. The 5% of patients who were ER positive at diagnostic biopsy had ER-negative residual tumour at final surgery. For PgR expression, 67% of the patients, whose tumours had a PgR >20% at diagnostic biopsy had a PgR <20% at final surgery. The Ki-67 expression changed from >20% to <20% in 40% of the patients. At the multivariate analysis, the decrease of PgR-immunoreactive cells correlated with improved outcome in terms of disease-free survival (DFS) [hazard ratio (HR) 0.73; 95% confidence interval (CI) 0.54-1.00, P 0.046]. In addition, the decrease of Ki-67 expression to <20% of the cells at final surgery was found to be associated with better outcome both in terms of DFS (HR 0.52; 95% CI 0.40-0.68 P < 0.0001) and overall survival (HR 0.45; 95% CI 0.32-0.64, P < 0.0001). CONCLUSION: The decrease of PgR and Ki-67 expression after preoperative chemotherapy has a prognostic role in breast cancer patients with residual disease.

Clinicopathological and immunohistochemical study of 30 cases of post-radiation atypical vascular lesion of the breast.

Atypical vascular lesions (AVL) that occur in the field of prior radiation therapy for breast carcinoma are placed within the differential diagnosis with low grade angiosarcoma and other benign vascular lesions. Although considered a benign entity, the exact biological behavior of AVLs is not fully established because of the small number of cases reported in the literature. We aim to further characterize these lesions clinically and histopathologically, and to study their behavior. We report a series of 30 patients with AVL of the breast occurring after radiation exposure, diagnosed and treated at the European Institute of Oncology, Italy. Immunohistochemical study was performed in all cases, using CD31, D2-40, CD105, and Ki-67 antibodies. Twenty-seven patients were treated with standard doses of conventional adjuvant radiation therapy for the prior breast carcinoma. Three patients were treated with intraoperative radiotherapy with electrons. The post-radiation latency interval from breast carcinoma to AVL was 48.5 months (ranged from 1 to 146 months). Most of the lesions were classified as lymphatic type (78.6 %) based on D2-40 positivity. No extension into subcutaneous tissue or significant atypia was noted in all cases. Despite the fact that the AVL of our series have shown benign behavior in 93.3 %, one patient developed local recurrence of AVL, and two cases progressed to angiosarcoma at the previous AVL site. Further studies should be conducted to better understand the clinical behavior and to propose additional histopathologic diagnostic criteria to distinguish AVL from low grade angiosarcoma and those AVL with increased risk for malignant progression. Concerning current treatments of AVL, we recommend complete excision with free surgical margins and close follow up.

High Ki67 predicts unfavourable outcomes in early breast cancer patients with a clinically clear axilla who do not receive axillary dissection or axillary radiotherapy.

AIM: Axillary dissection is increasingly forgone in early breast cancer patients with a clinically negative axilla. The GRISO 053 randomised trial recruited 435 patients of age over 45 years, tumour ≤1.4 cm and clinically negative axilla, to assess the importance of axillary radiotherapy versus no axillary radiotherapy in patients not given axillary dissection. In the present study on a subgroup GRISO cases our aim was to assess the prognostic importance of tumour biological factors after more than 10 years of follow-up. METHODS: We retrospectively assessed biological factors in a subgroup of 285 GRISO cases (145 given axillary radiotherapy; 140 not given axillary radiotherapy) with complete biologic, therapeutic and follow-up information, using multivariable Cox proportional hazards regression modelling. RESULTS: Only 10-year cumulative incidence of distant metastasis was lower in the axillary radiotherapy (1%) than no axillary radiotherapy arm (7%) (p=0.037). Irrespective of study arm, hormone receptor positivity had significantly favourable effects on 10-year disease-free survival (DFS) and overall survival. human epidermal growth factor receptor 2 (HER2)-positive and triple-negative subtypes were associated with lower 10-year DFS (60% and 76%, respectively) than luminal A (96%) and B (91%) (p=0.001). Ten-year DFS for high (≥14%) Ki67 cancers was lower than for low Ki67 cancers (p=0.027); however, this effect was mainly confined to the no axillary radiotherapy arm. CONCLUDING STATEMENT: For patients with clinically node-negative small breast cancer not given axillary dissection, 10-year DFS is worsened by HER2 positivity, triple-negative phenotype and high Ki67. Axillary radiotherapy counteracts the negative prognostic effect of high Ki67 in patients not receiving axillary dissection.

Progesterone receptor loss identifies Luminal B breast cancer subgroups at higher risk of relapse.

BACKGROUND: The immunohistochemical (IHC) evaluation of estrogen receptor (ER), progesterone receptor (PgR), Ki-67 and HER2 is considered a surrogate means for identifying the molecular subtypes of breast cancer with different prognosis. PATIENTS AND METHODS: We explored patterns of recurrence in 4837 women with breast cancer defined as Luminal B (ER-positive and/or PgR-positive, HER2 positive and/or Ki-67≥14%) by IHC classification. We evaluated four subgroups within the Luminal B subtype according to HER2 expression and PgR status. RESULTS: Patients within the ER+/PgR+/HER2- subgroup presented a 5-year breast cancer-related survival (BCS) of 97% (95% confidence interval (CI), 96-97) and overall survival (OS) of 95% [95% CI, 95-96], the best survivals of the Luminal B subgroups. In the multivariate analysis, the ER+/PgR-/HER2- subgroup was associated with a reduced BCS (HR 1.71; 95%CI, 1.25-2.35) and OS (HR 1.47; 95%CI, 1.10-1.96) when compared with the ER+/PgR+/HER2- subgroup. Also patients within the ER+/PgR-/HER2+ subgroup had a reduced BCS (HR 1.93; 95%CI, 1.32-2.83) and OS (HR 1.62; 95%CI, 1.14-2.30) when compared with ER+/PgR+/HER2- subgroup. On the other hand, no statistically significant differences were found with regard to BCS and OS among patients with ER+/PgR+/HER2+ and patients with ER+/PgR+/HER2- disease. CONCLUSIONS: PgR loss identifies Luminal B breast cancer subgroups at higher risk of relapse and death, both with HER-2-positive and HER-2-negative disease.

Breast cancer subtypes and outcome after local and regional relapse.

BACKGROUND: To evaluate the outcome of breast cancer patients after locoregional recurrence (LRR) according to tumor biological features evaluated at first diagnosis and at the time of recurrence. PATIENTS AND METHODS: We collected information on all consecutive breast cancer patients operated at the European Institute of Oncology between 1994 and 2005. The tumor characteristics and subsequent outcome of patients who experienced LRR were analyzed. RESULTS: Two hundred and seventy nine patients with LRR were identified, 197 and 82 patients with local and regional recurrence respectively. The overall discordance rate between primary cancer and LRR was 9% for estrogen receptor expression, 22% for progesterone receptor and 4% for human epidermal growth factor receptor 2. For patients with regional recurrence, the risk of distant metastasis was significantly higher compared with local relapse in case of late recurrence (hazard ratio [HR] = 2.76; 95% CI 1.31-5.85). Patients with triple-negative breast cancer at LRR experienced a higher risk of subsequent relapse (HR 2.87 [1.67-4.91]) and death (HR 2.00 [1.25-3.19]). CONCLUSION: LRR correlates with a high risk of subsequent events and death in particular in patients with triple-negative subtype.

Outcome of special types of luminal breast cancer.

BACKGROUND: The identification of special types of breast cancer might be of value in assessing prognosis and predicting response to therapy. METHODS: A total of 7372 consecutive patients with immunohistochemically defined luminal invasive breast cancer operated at the European Institute of Oncology between 1997 and 2005 were included. We then explored patterns of recurrence by histological type. Median follow-up was 5.8 years. RESULTS: Tumors from 5707 patients were classified as invasive ductal cancer (IDC) not otherwise specified (NOS), 851 lobular, 338 mixed ductal and lobular, 250 cribriform, 143 mucinous and 83 tubular carcinomas. Compared with IDC NOS disease-free survival (DFS) was significantly longer in patients with cribriform tumors [5-year DFS 97.9% versus 87.4%; hazard ratio (HR) = 0.48; P = 0.015) and in pooled cribriform plus tubular carcinomas (5-year DFS 98.7% versus 87.4%; HR = 0.45; P = 0.005). Mucinous tumors presented similar DFS if compared with IDC (5-year DFS 93 % versus 87.4%; HR = 1.03; P = 0.91). Conversely, DFS was poorer for patients with lobular carcinoma (5-year DFS 86.8% versus 87.4%; HR = 1.27; P = 0.01). CONCLUSIONS: The diagnosis of tubular, cribriform and lobular carcinomas carry distinct prognostic implications. The identification of these special types has a significant utility in luminal breast cancer and should be considered in therapeutic algorithms.

Prognosis in women with small (T1mic,T1a,T1b) node-negative operable breast cancer by immunohistochemically selected subtypes.

Knowledge is limited about prognostic significance of breast cancer subtypes among women with small invasive node-negative breast tumours. We explored patterns of recurrence in 1691 women with pT1mic/T1a/T1b, pN0 and M0 breast cancer according to four immunohistochemically defined tumour subtypes: (i) Luminal A (ER-positive, PgR-positive, HER2-negative and Ki-67 < 14%); (ii) Luminal B (ER-positive and/or PgR-positive, HER2-positive and/or Ki-67 ≥ 14%); (iii) HER2-positive, both endocrine receptors absent; and (iv) Triple Negative. At multivariate analysis, women with the Triple Negative breast cancer subtype had an increased risk of loco-regional relapse (LRR) (Hazards Ratio (HR) 3.58; 95%CI: 1.40-9.13) and breast cancer related events (HR 2.18; 95%CI: 1.04-4.57). Overall, Luminal B subtype was not associated with a statistically significant increased risk of recurrence compared with Luminal A, while patients with Luminal B subtype tumours overexpressing HER2 had a 2 fold risk of reduced breast cancer related survival (BCS), but not an increased risk of LRR and distant metastases. Women with HER2 breast cancer subtype had a statistically significant increased risk of LRR (HR 4.53; 95%CI: 1.56-13.1), distant metastases and reduced BCS (HR 3.22; 95%CI: 1.44-7.18) and overall survival (HR 2.87; 95%CI: 1.05-7.89) when compared with the Luminal A subtype, at multivariate analysis. In conclusion, women with small size, node-negative, breast cancer are at higher risk of relapse if with HER2-positive endocrine receptor absent or Triple Negative disease.

Which patients benefit most from adjuvant aromatase inhibitors? Results using a composite measure of prognostic risk in the BIG 1-98 randomized trial.

BACKGROUND: On average, aromatase inhibitors are better than tamoxifen when used as initial or sequential therapy for postmenopausal women with endocrine-responsive early breast cancer. Because there may be contraindications to their use based on side-effects or cost, we investigated subgroups in which aromatase inhibitors may be more or less important. PATIENTS AND METHODS: Breast International Group 1-98 trial randomized 6182 women among four groups comparing letrozole and tamoxifen with sequences of each agent; 5177 (84%) had centrally confirmed estrogen receptor (ER) positivity. We assessed whether centrally determined ER, progesterone receptor (PgR), human epidermal growth factor receptor 2, and Ki-67 labeling index, alone or in combination with other prognostic features, predicted the magnitude of letrozole effectiveness compared with either sequence or tamoxifen monotherapy. RESULTS: Individually, none of the markers significantly predicted differential treatment effects. Subpopulation treatment effect pattern plot analysis of a composite measure of prognostic risk revealed three patterns. Estimated 5-year disease-free survival for letrozole monotherapy, letrozole→tamoxifen, tamoxifen→letrozole, and tamoxifen monotherapy were 96%, 94%, 93%, and 94%, respectively, for patients at lowest risk; 90%, 91%, 93%, and 86%, respectively, for patients at intermediate risk; and 80%, 76%, 74%, and 69%, respectively, for patients at highest risk. CONCLUSION: A composite measure of risk informs treatment selection better than individual biomarkers and supports the choice of 5 years of letrozole for patients at highest risk for recurrence.

What can the pathologist offer for optimal treatment choice?

The choice of the most appropriate systemic treatment of patients with metastatic breast carcinoma is a multifaceted decision-making process. The role for the pathologist is to provide a definite diagnosis of metastatic breast carcinoma, whenever needed, and especially to assess the biological parameters with prognostic and predictive value. Although the vast majority of breast carcinomas maintain the same biological features both in the primary and in the metastases, some undergo changes that may indicate that a targeted systemic treatment should be stopped or started, be it endocrine or anti-HER2. Unfortunately these tumours cannot be easily identified clinically, and it may be useful to biopsy the metastatic sites for reassessment of the biological characteristic of the tumours. Intra-tumoural heterogeneity and clonal selection due to the therapy could explain changes in biological features during tumour progression, but it should also be taken into account that the available assays for evaluating hormone receptor and HER2 status are not 100% accurate, even in the hands of expert pathologists. To minimize the risk of inducing inappropriate changes in systemic treatments due to false-positive or false-negative results, the pathologists should make all efforts to improve accuracy and reproducibility of the assay procedures.

Prognosis and adjuvant treatment effects in selected breast cancer subtypes of very young women (<35 years) with operable breast cancer.

BACKGROUND: There is limited knowledge about prognosis of selected breast cancer subtypes among very young women. PATIENTS AND METHODS: We explored patterns of recurrence by age according to four immunohistochemically defined tumor subtypes: Luminal A and Luminal B (estrogen receptor positive and/or progesterone receptor positive and either human epidermal growth factor receptor 2 (HER2) positive and/or high Ki-67), HER2-positive (and) endocrine receptor absent and Triple Negative, in 2970 premenopausal patients with pT1-3, pN0-3 and M0 breast cancer. RESULTS: Patients <35 years of age (315, 11%) presented a significantly increased risk of recurrence and death [hazards ratio (HR) = 1.65, 95% confidence interval (CI) 1.30-2.10 and HR = 1.78, 95% CI 1.12-2.85, respectively] when compared with older patients (2655, 89%) with similar characteristics of disease. This was true considering patients with Luminal B [HR = 1.62, 95% CI 1.21-2.18 for disease-free survival (DFS) and HR = 2.09, 95% CI 0.96-4.53 for overall survival (OS)] and with Triple Negative (HR = 2.04, 95% CI 1.11-3.72 for DFS and HR = 2.20, 95% CI 1.10-4.41 for OS) breast cancer, observing the highest risk of recurrence in the younger patients with HER2-positive breast cancer (HR = 2.37, 95% CI 1.12-5.02) when compared with older patients. CONCLUSIONS: Very young patients with Triple Negative, Luminal B or HER2-positive breast cancer have a worse prognosis when compared with older patients with similar characteristics of disease.

Adverse prognostic value of peritumoral vascular invasion: is it abrogated by adequate endocrine adjuvant therapy? Results from two International Breast Cancer Study Group randomized trials of chemoendocrine adjuvant therapy for early breast cancer.

BACKGROUND: Peritumoral vascular invasion (PVI) may assist in assigning optimal adjuvant systemic therapy for women with early breast cancer. PATIENTS AND METHODS: Patients participated in two International Breast Cancer Study Group randomized trials testing chemoendocrine adjuvant therapies in premenopausal (trial VIII) or postmenopausal (trial IX) node-negative breast cancer. PVI was assessed by institutional pathologists and/or central review on hematoxylin-eosin-stained slides in 99% of patients (analysis cohort 2754 patients, median follow-up >9 years). RESULTS: PVI, present in 23% of the tumors, was associated with higher grade tumors and larger tumor size (trial IX only). Presence of PVI increased locoregional and distant recurrence and was significantly associated with poorer disease-free survival. The adverse prognostic impact of PVI in trial VIII was limited to premenopausal patients with endocrine-responsive tumors randomized to therapies not containing goserelin, and conversely the beneficial effect of goserelin was limited to patients whose tumors showed PVI. In trial IX, all patients received tamoxifen: the adverse prognostic impact of PVI was limited to patients with receptor-negative tumors regardless of chemotherapy. CONCLUSION: Adequate endocrine adjuvant therapy appears to abrogate the adverse impact of PVI in node-negative disease, while PVI may identify patients who will benefit particularly from adjuvant therapy.

p27 and Skp2 immunoreactivity and its clinical significance with endocrine and chemo-endocrine treatments in node-negative early breast cancer.

BACKGROUND: Low p27 and high Skp2 immunoreactivity are associated with a poor prognosis and other poor prognostic features including resistant phenotypes and antiestrogen drug resistance. We investigated these proteins in two International Breast Cancer Study Group trials studying node-negative early breast cancer. PATIENTS AND METHODS: Trial VIII compared chemotherapy followed by goserelin with either modality alone in premenopausal patients. Trial IX compared chemotherapy followed by tamoxifen with tamoxifen alone in postmenopausal patients. Central Pathology Office assessed p27 and Skp2 expression in the primary tumor by immunohistochemistry among 1631 (60%) trial patients. RESULTS: p27 and Skp2 were inversely related; 13% of tumors expressed low p27 and high Skp2. Low p27 and high Skp2 were associated with unfavorable prognostic factors including larger size and higher grade tumors, absence of estrogen receptor and progesterone receptor, human epidermal growth factor receptor 2 overexpression and high Ki-67 (each P < 0.05). Low p27 and high Skp2 were not associated with disease-free survival (P = 0.42 and P = 0.48, respectively). The relative effects of chemo-endocrine versus endocrine therapy were similar regardless of p27 or Skp2. CONCLUSIONS: We confirm the association of low p27 and high Skp2 with other poor prognostic features, but found no predictive or prognostic value, and therefore do not recommend routine determination of p27 and Skp2 for node-negative breast cancer.

[The stereotaxic core breast biopsy using the Mammotome: an alternative to intraoperative examination]. / La core-biopsy mammaria stereotassica con Mammotome: un'alternativa all'esame intraoperatorio.

The aim of this work was to evaluate the accuracy of vacuum-assisted biopsy by comparing it with frozen biopsy. 141 stereotaxic biopsies were performed by Mammotome (Ethicon Endo-Surgery, Hamburg) from January 2000 to March 2001. Biopsies were performed for microcalcifications (n = 105, 74.5%), irregular opacities (n = 20, 14.2%), regular opacities (n = 6, 4.2%), stellate lesions (n = 10, 7.1%). Histological analysis showed 85 (60.3%) benign lesions, 46 (32.6%) malignant lesions including (21 cases of carcinoma in situ and 25 invasive carcinomas) and 10 (7.1%) atypical lesions. All malignant lesions were subjected to surgery. In three cases (1 in situ and 2 invasive), core biopsy was excisional and no residual lesion was observed. Two of the carcinomas in situ revealed invasive features on the surgical biopsy. One of the atypical lesions was underestimated and the final diagnosis was "well differentiated carcinoma in situ." Only three of benign lesions underwent surgery after Mammotome biopsy. Among the 55 frozen-section biopsies of mammographically detected breast lesions performed in the same period, were one false-positive and 3 false-negative cases, while in 4 cases the diagnosis was deferred after paraffin embedding. Our results confirmed Mammotome biopsy as an effective alternative and a more reliable method than frozen-section examination.

[A new technique for foetal brain fixation and extraction]. / Una nuova procedura per la fissazione ed estrazione dell'encefalo fetale.

We performed a new technique for foetal brain fixation and extraction that offers a remarkable reduction in sampling time facilitates specimen handling while conserving high quality. With the new fixation method, it is possible to obtain samples adequate for macroscopic and microscopic observations and immunohistochemical analysis. The technique involves the creation of an ex vacuo phenomenon in the subarachnoideal space prior to injecting the fixative solution. In this manner, the solution is homogenously distributed. Ease, reproducibility and the possibility of standardizing the procedure are the principal advantages. Low costs, reduced wording time and less need for human resources are other advantages. Histologically, we obtained, quickly, high quality slides with routine and immunohistochemical stains. Disadvantages of the technique derive from the use of formaldehyde and glacial acetic acid, rather than water to wash the samples; thus one must work in a well ventilated area, with gloves, protective glasses and an adequate lab coat to avoid skin and respiratory tract damage.

[Argyrophilic nucleolar organizer regions (AgNORs) as malignancy biomarkers in colorectal neoplasms]. / Studio delle regioni organizzatrici argirofile del nucleolo (AgNORs) nelle neoformazioni colo-rettali quale indice di malignità biologica.

The high incidence of intestinal cancer has aroused strong interest in researching and trying to discover its morphologic precursors. In this contest the study of nucleolar organizing regions could be interesting as prognostic factor for bowel neoplasm and useful for differential diagnosis of intestinal diseases. The Authors report on the results of their study performed on 30 selected samples from 6 different bowel lesions.

Regulation of mRNA and protein levels of beta1 integrin variants in human prostate carcinoma.

Alterations of integrin expression levels in cancer cells correlate with changes in invasiveness, tumor progression, and metastatic potential. The beta1C integrin, an alternatively spliced form of the human beta1 integrin, has been shown to inhibit prostate cell proliferation. Furthermore, beta1C protein levels were found to be abundant in normal prostate glandular epithelium and down-regulated in prostatic adenocarcinoma. To gain further insights into the molecular mechanisms underlying abnormal cancer cell proliferation, we have studied beta1C and beta1 integrin expression at both mRNA and protein levels by Northern and immunoblotting analysis using freshly isolated neoplastic and normal human prostate tissue specimens. Steady-state mRNA levels were evaluated in 38 specimens: 33 prostatic adenocarcinomas exhibiting different Gleason's grade and five normal tissue specimens that did not show any histological manifestation of benign prostatic hypertrophy. Our results demonstrate that beta1C mRNA is expressed in normal prostate and is significantly down-regulated in neoplastic prostate specimens. In addition, using a probe that hybridizes with all beta1 variants, mRNA levels of beta1 are found reduced in neoplastic versus normal prostate tissues. We demonstrate that beta1C mRNA down-regulation does not correlate with either tumor grade or differentiation according to Gleason's grade and TNM system evaluation, and that beta1C mRNA levels are not affected by hormonal therapy. In parallel, beta1C protein levels were analyzed. As expected, beta1C is found to be expressed in normal prostate and dramatically reduced in neoplastic prostate tissues; in contrast, using an antibody to beta1 that recognizes all beta1 variants, the levels of beta1 are comparable in normal and neoplastic prostate, thus indicating a selective down-regulation of the beta1C protein in prostate carcinoma. These results demonstrate for the first time that beta1C and beta1 mRNA expression is down-regulated in prostate carcinoma, whereas only beta1C protein levels are reduced. Our data highlight a selective pressure to reduce the expression levels of beta1C, a very efficient inhibitor of cell proliferation, in prostate malignant transformation.