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Patterns of chromosomal imbalances defines subgroups of breast cancer with distinct clinical features and prognosis. A study of 305 tumors by comparative genomic hybridization.

2003; National Institutes of Health; Volume: 63; Issue: 24 Linguagem: Inglês

Karin Rennstam, Minna Ahlstedt-Soini, Bo Baldetorp, Pär-Ola Bendahl, Åke Borg, Ritva Karhu, Minna Tanner, Mika Tirkkonen, Jorma Isola,

Genetic factors in colorectal cancer

Chromosomal copy number aberrations (CNAs) are common in breast cancer and involve genomic regions in a frequency and combination, suggesting distinct routes of tumor development. We studied chromosomal gains (+) and losses (-) by comparative genomic hybridization from a series of 305 unselected primary invasive breast cancers. CNAs were observed in >90% of the tumors and involved all chromosomal arms in various frequencies, the most common being +1q (55%), +8q (41%), +16p (40%), +17q (28%), -13q (27%), -16q (22%), +20q (19%), -8p (18%), and +11q (16%). Eighteen pairs of CNAs were revealed as significantly associated using Fisher's exact test with Bonferroni correction, the most common pairs being -8p/+8q, +17q/+20q, and -4q/-13q. To study more complex relationships between individual CNAs, principal component analysis and distance-based tree modeling were performed independently. Three distinct patterns of CNAs were observed. Group A was defined by +1q, +16p, and -16q, group B by +11q, +20q, +17q, and -13q, and group C by -8p and +8q. Group A was correlated to positive estrogen receptor and progesterone receptor (PgR) status (P < 0.001 and P < 0.05, respectively). Groups B and C were correlated to DNA nondiploidy (P < 0.001 and P < 0.05), high histological grade and lymph node positivity (P < 0.05), and group B also to high proliferation rate, large primary tumor size (P < 0.001), and negative PgR status (P < 0.05). Patients with aberrations in group A only had a significantly higher breast cancer survival rate than all other patients. The worst survival was seen for patients with aberrations in group C only along with the patients displaying aberrations from all CNA pattern groups (ABC). The 5-year survival rates vary from 96% in group A to 56% in group C. These correlations were independent of node status, tumor size, and PgR status in a multivariate analysis. We conclude that patterns of copy number gains and losses define breast tumors with distinct clinicopathological features and patient prognosis.