Lateral differences in Ki‑67 in breast cancer
- Alexey Petrovich Dmitrenko
Published online on: April 4, 2016
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Morphological features of right‑ and left‑sided breast cancer (BC) have been rarely studied. Ki‑67 is an independent predictive marker for a local relapse, and for overall and disease‑free survival. In previous literature, lateral differences in Ki‑67 in BC have not been reported. Using immunohistochemical analysis, the biopsy material of 500 patients was investigated. Four BC parameters were investigated: The expression levels of the estrogen receptor (ER), progesterone receptor (PR), Ki‑67 and Her‑2‑neu. A comparative analysis of Ki‑67 in groups with right‑ and left‑sided BC was performed. Lateral differences in Ki‑67 in three age groups, ≤49, 50‑59 and ≥60 years, were assessed. A higher expression of Ki‑67 corresponded with right‑sided BC (r=‑0.08; P=0.046). Correlation of Ki‑67 with the age of the patient was characteristic only for right‑sided BC (r=‑0.28; P<0.001). The comparative analysis revealed that tumors from patients with right‑sided BC aged ≥60 years exhibited a lower Ki‑67 index compared with tumors from patients aged ≤49 (P=0.003) and 50‑59 years (P=0.000013). In left‑sided BC, the Ki‑67 in the different age intervals revealed no significant difference. On performing an assessment of lateral differences for the different age intervals, it was established that the Ki‑67 index of right‑sided BC was significantly higher compared with the left‑sided BC in two of the age groups, ≤49 (P=0.038) and 50‑59 years (P=0.047). In the ≥60 years group, lateral differences in Ki‑67 were not revealed (P=0.4). The analysis of lateral differences in Ki‑67 in tumors of various receptor profiles revealed significant differences in Ki‑67 of the right‑ and left‑sided BC under ER+ PR‑ (P=0.007) and ER‑ PR‑ (P=0.016) conditions. The reasons behind lateral and age differences of Ki-67 are discussed.