Ductal carcinoma in situ of the breast: histological classification and genetic alterations

ASPN and GJB2 Are Implicated in the Mechanisms of Invasion of Ductal Breast Carcinomas

The mechanism of progression from ductal carcinoma in situ (DCIS) to invasive ductal carcinoma (IDC) remains largely unknown. We compared gene expression in tumors with simultaneous DCIS and IDC to decipher how diverse proteins participate in the local invasive process.

Twenty frozen tumor specimens with concurrent, but separated, DCIS and IDC were microdissected and evaluated. Total RNA was extracted and microarray analysis was performed using Affymetrix GeneChip® Human Gene 1.0 ST Arrays. Microarray data were validated by quantitative real time reverse transcription-PCR (qRT-PCR) and immunohistochemistry. Controls included seven pure in situ carcinomas, eight fragments from normal breast tissue, and a series of mouse breast carcinomas (MMTV-PyMT).

Fifty-six genes were differentially expressed between DCIS and IDC samples. The genes upregulated in IDC samples, and probably associated with invasion, were related to the epithelial-mesenchymal transition (ASPN, THBS2, FN1, SPARC, and COL11A1), cellular adhesion (GJB2), cell motility and progression (PLAUR, PLAU, BGN, ADAMTS16, and ENPP2), extracellular matrix degradation (MMP11, MMP13, and MMP14), and growth/proliferation (ST6GAL2). qRT-PCR confirmed the expression patterns of ASPN, GJB2, ENPP2, ST6GAL2, and TMBS10. Expression of the ASPN and GJB2 gene products was detected by immunohistochemistry in invasive carcinoma foci. The association of GJB2 protein expression with invasion was confirmed by qRT-PCR in mouse tumors (P < 0.05).

Conclusions: The upregulation of ASPN and GJB2 may play important roles in local invasion of breast ductal carcinomas.

Mechanisms of progression of ductal carcinoma in situ of the breast to invasive cancer. A hypothesis

Ductal carcinoma in situ (DCIS), a known precursor lesion of invasive cancer of the female breast, is surrounded by a thick basement membrane and a layer of myoepithelial cells. For DCIS to become invasive, both these barriers must be breached by cancer cells. It has been repeatedly suggested that proteolytic enzymes are somehow involved in this process but a direct proof of this event has never been provided. It is our hypothesis that invasion of the DCIS by capillary vessels derived from the periductal necklace of vessels is the most likely mechanism of breaching the basement membrane, providing an escape hatch for cancer cells. This hypothesis was initially tested on ten randomly selected cases of DCIS, with or without invasion. Capillary vessels were visualized by staining histologic sections with an antibody to CD 34 and, in three cases, by combined stain for CD 34 and collagen IV. In five of the 10 cases of DCIS, the presence of discrete capillary vessels invading DCIS could be documented. In two of these five cases, the vessels subdivided the cancerous ducts into territories of unequal sizes. Vascular invasion of DCIS is a plausible mechanism of breaching the basement membrane in DCIS as a prelude to invasion. This hypothesis must be further tested on a much larger number of cases. The hypothesis, if confirmed, may suggest that invasive cancer derived from DCIS may be prevented by antiangiogenic therapy.

Breast-conserving therapy for ductal carcinoma in situ of the breast: the French Cancer Centers' experience

PURPOSE

To assess the long-term outcome for women with ductal carcinoma in situ of the breast treated in current clinical practice by conservative surgery with or without definitive breast irradiation.

METHODS AND MATERIALS

We analyzed 705 cases of ductal carcinoma in situ treated between 1985 and 1995 in nine French regional cancer centers; 515 underwent conservative surgery and radiotherapy (CS+RT) and 190 CS alone. The median follow-up was 7 years.

RESULTS

The 7-year crude local recurrence (LR) rate was 12.6% (95% confidence interval [CI] 9.4-15.8) and 32.4% (95% CI 25-39.7) for the CS+RT and CS groups, respectively (p <0.0001). The respective 10-year results were 18.2% (95% CI 13.3-23) and 43.8% (95% CI 30-57.7). A total of 125 LRs occurred, 66 and 59 in the CS+RT and CS groups, respectively. Invasive or microinvasive LRs occurred in 60.6% and 52% of the cases in the same respective groups. The median time to LR development was 55 and 41 months. Nine (1.7%) and 6 (3.1%) nodal recurrences occurred in the CS+RT and CS groups, respectively. Distant metastases occurred in 1.4% and 3% of the respective groups. Patient age and excision quality (final margin status) were both significantly associated with LR risk in the CS+RT group: the LR rate was 29%, 13%, and 8% among women aged < or =40, 41-60, and > or =61 years (p <0.001). Even in the case of complete excision, we observed a 24% rate of LR (6 of 25) in women <40 years. Patients with negative, positive, or uncertain margins had a 7-year crude LR rate of 9.7%, 25.2%, and 12.2%, respectively (p = 0.008). RT reduced the LR rate in all subgroups, especially in those with comedocarcinoma (17% vs. 59% in the CS+RT and CS groups, respectively, p <0.0001) and mixed cribriform/papillary tumors (9% vs. 31%, p <0.0001). In the multivariate Cox regression model, young age and positive margins remained significant in the CS+RT group (p = 0.00012 and p = 0.016). Finally, the relative LR risk in the CS+RT group compared with the CS group was 0.35 (95% CI 0.25-0.51, p = 0.0001). Subsequent contralateral breast cancer occurred in 7.1% and 7.5% of the patients in the CS+RT and CS groups, respectively.

CONCLUSION

Despite the absence of randomization, our results are extremely consistent with the updated National Surgical Adjuvant Breast Project B17 and European Organization for Research and Treatment of Cancer 10853 trials. We also noted that the LR risk was very high in women <40 years and/or in the case of incomplete excision.

Ductal carcinoma in situ of the breast results of conservative and radical treatments in 716 patients

Until now, less than 5% of the patients with breast ductal carcinoma in situ (DCIS) have been enrolled in clinical trials. Consequently, we have analysed the results of "current practice" among 716 women treated in eight French Cancer Centres from 1985 to 1992: 441 cases (61.6%) corresponded to impalpable lesions, 92 had a clinical size of less than or equal to 2 cm and 70 from 2 to 5 cm; in 113 cases, the size was unspecified. Median age was 53.2 years (range: 21-87 years). 145 patients underwent mastectomy (RS) and 571 conservative surgery (CS) without (136) or with (435) radiotherapy (CS+RT). The mean histological tumour sizes in these three groups were 25.6, 8.2, 14.8 mm, respectively (P<0.0001). After a 91-month median follow-up, local recurrence (LR) rates were 2.1, 30.1 and 13.8% in the RS, CS and CS +RT groups, respectively (P=0.001); LR were invasive in 59 and 60% in the CS and CS+RT groups, respectively. In these groups, the 8-year LR rates were 31.3 and 13.9%, respectively (P=0.0001). Nodal recurrence occurred in 3.7 and 1.8% in the CS and CS+RT groups. Metastases rates were 1.4, 4.4 and 1.4% in the RS, CS and CS+RT groups. Among the 60 cases of invasive LR, in CS and CS+RT groups 19% developed metastases. After multivariate analysis, we did not identify any significant LR risk factor in the CS group, whereas young age (<40 years) and incomplete excision were significant in the CS+RT group (P=0.012 and P=0.02, respectively).

Amplification of growth regulatory genes in intraductal breast cancer is associated with higher nuclear grade but not with the progression to invasiveness

Ductal carcinoma in situ (DCIS), as an identifiable progenitor lesion of invasive breast cancer, represents a morphologically, biologically, and prognostically heterogeneous disease. It is not clear which molecular mechanisms are involved in progression to infiltrative growth. In this study, 83 DCIS classified according to the Van Nuys grading scheme were examined for amplification of growth regulatory genes that have been found to be amplified in invasive breast cancer (c-erbB2, topoisomerase IIalpha, c-myc, and cyclinD1 genes). Exact quantification of gene amplification was enabled by a combination of laser microdissection of paraffin-embedded tissue with real-time PCR. In DCIS, gene amplifications of all tested genes were found. The most frequently amplified gene was c-erbB2 found in 21 of 83 (25%) cases. Amplification of the other genes under investigation was observed in 4% to 6% of cases, high-grade DCIS being predominantly affected. High-grade DCIS differed significantly from low- and intermediate-grade DCIS in frequency and level of c-erbB2 amplification. In addition, high-grade DCIS revealed an accumulation of genetic aberrations. Amplification status in pure in situ lesions did not differ from intraductal carcinoma with an infiltrative component, indicating that although associated with a higher nuclear grade gene amplification might not represent an independent prognostic marker of disease progression.