Promoter hypermethylation of p16, BRCA1 and RASSF1A genes in triple-negative breast cancer patients from Serbia.

PURPOSE: In order to investigate if aberrant promoter methylation of p16, BRCA1 and RASSF1A genes contributes to biological behavior of triple-negative breast cancer (TNBC), marked as the most aggressive phenotype of breast cancer, we compared the hypermethylation pattern between TNBC and ER+PR+Her2- breast cancer. METHODS: 131 patients with histologically confirmed breast cancers were included - 61 TNBC and 70 ER+PR+Her2- cases. The patients were followed up for 1-87 months (median 78). DNA from tumor tissues was isolated by the salting out procedure. The methylation status was assessed by nested methylation-specific PCR after bisulfite modification of DNA. RESULTS: The frequency of p16 hypermethylated breast cancer cases was significantly higher in TNBC than in ER+PR+Her2- group (33; 54.1% vs. 20; 28.6%, p=0.00298). Co-methylated p16 and RASSF1A genes were more frequent in the TNBC than in ER+PR+Her2- group (20; 32.8% vs. 10; 14.3%, p=0.0225). The same result was observed when hypermethylated BRCA1 gene was added in the analysis: 12; 19.7% vs. 3; 4.3%, p=0.00791. Although there was significant difference in disease-free survival (DFS) and overall survival (OS) between TNBC and ER+PR+Her2- group, further analysis of co-methylation of p16 and RASSF1A (p16+RASSF1A+) showed that DFS was significantly shorter in the patients with both genes co-methylated in TNBC than in ER+PR+Her-2- group (8/20; 40% vs. 2/10; 20%, p=0.03272). CONCLUSIONS: The obtained data indicate that hypermethylated p16 and RASSF1A cell-cycle inhibitor genes might be considered as biomarkers for bad prognosis in breast cancer. Hypermethylation of these genes may influence the clinical disease course, distinguishing a particular group of TNBC patients with even more aggressive phenotype.

Difference between Luminal A and Luminal B Subtypes According to Ki-67, Tumor Size, and Progesterone Receptor Negativity Providing Prognostic Information.

BACKGROUND: The St. Gallen International Expert Consensus of 2011 proposes a new classification system for breast cancer based on its division into five subgroups. The criteria to identify these subtypes were recently refined at the 2013 Conference. In this respect, the authors of this paper have conducted a retrospective analysis of breast cancer subtypes, related to Ki-67 and involvement of the axillary lymph nodes (ALNs). The analysis was performed only in the cases of invasive breast cancer in the pT2 stages. The research and results of the paper have shown that investigating the value of these parameters could be of great benefit in future treatment strategies of invasive breast cancer. METHODS: A retrospective analysis of breast cancer subtypes, tumor nodal metastatic staging, and histopathological grading of 108 cases has been performed according to the methods recommended and provided by the St. Gallen International Expert Consensus Report, 2011. The estrogen receptor (ER), progesterone receptor (PR), human epidermal growth factor receptor-2 (HER2), and Ki-67 of 108 tumor samples were all investigated by immunohistochemistry according to the methods used to classify breast cancer subtypes as proposed in the St. Gallen Consensus Report, 2011. Invasive breast cancers (n = 108) were immunohistochemically classified as follows: 28 (25.92%) as Luminal A, 51 (47.22%) as Luminal B (HER2 negative), 21 (19.44%) as Luminal B-like (HER2 negative), 2 (1.85%) as HER2 positive, and 6 (5.55%) as being a triple-negative subtype. RESULTS: The conclusion was made that when Ki-67 was found to be higher, patients also showed a higher involvement in their ALNs. The chi-square test shows the difference to be significant (chi-square = 4.757; P = 0.029). Luminal B subtypes had the highest percentage (54.9%) of involvement of lymph nodes when compared to the other four subtypes. The Luminal B subtype had a higher percentage (51.4%) of involvement of lymph nodes than did Luminal A (10.7%). The chi-square test also shows the difference to be significant (P < 0.05). CONCLUSION: A combination of the Ki-67 index, HER negative tumors, PR negativity, and a low value that can be used to segregate ER positive pT2 tumors into prognostically significantly different clinical outcomes may be utilized clinically to guide patient management in accordance with these tumor characteristics.