Klinička vrednost određivanja Ki-67 proliferativnog indeksa u karcinomima dojke sa pozitivnim hormonskim receptorima

Abstract

Uvod: Karcinom dojke je heterogena bolest koju karakterišu različita morfologija, imunohisto-hemijski profil, klinički tok i terapijski odgovor. Ki-67 proliferativni indeks je jedan od markera sa prognostičkim i prediktivnim značajem, čije metodološko određivanje i analiza još uvek nisu standardizovani. Cilj: Utvrditi graničnu (“cut-off”) prognostičku vrednost Ki-67 indeksa, kao i povezanost vrednosti Ki-67 u ranom luminalnom karcinomu dojke sa prognostičkim i prediktivnim parametrima karcinoma dojke, kao što su životna dob bolesnica, veličina tumora, histološki gradus (HG) i nivo tumorske ekspresije receptora estrogena (ER) i progesterona (PR). Takođe, cilj istraživanja je i utvrđivanje značajnosti razlike u vrednosti Ki-67 proliferativnog indeksa u odnosu na pojavu lokalnog recidiva, udaljenih metastaza i dužinu preživljavanja u toku petogodišnjeg perioda praćenja pacijentkinja. Metode: Retrospektivno je analizirano 120 patohistoloških izveštaja bolesnica kojima je u periodu od 01.01.2009. godine do 31.12.2011. godine na Institutu za onkologiju Vojvodine imunohistohemijskom analizom dokazan luminalni karcinom dojke (pozitivan ER i PR, negativan HER2), bez metastaza u aksilarnim limfnim čvorovima. Rezultati: Metodama deskriptivne statistike prosečna starost pacijentkinja je iznosila 57,42±10,17 godina; prosečna veličina tumora 17,98±6,97mm; recidiv je registrovan kod 8 (6,7%) pacijentkinja uz prosečan vremenski period do pojave recidiva od 49±20,23 meseci. Vrednost “cut off” indeksa Ki-67 od prognostičkog značaja za vremenski period bez recidiva je iznosio 20,75%. Nije dokazana signifikantna veza između vrednosti Ki-67 i godina starosti pacijentkinja (p=0,401, odnosno p=0,293), kao i jačine ekspresije ER (p=1,00, p=0,957) i PR (p=0,273, p=0,189). Ustanovljena je signifikantna povezanost Ki-67 postoji sa veličinom (p=0,035, p=0,20) i HG tumora (p=0,041, p=0,20). Prosečan period praćenja bolesnica iznosio je 72,92±8,38 meseci; nije registrovana pojava udaljenih metastaza, kao ni smrtni ishod. U odnosu na pojavu lokalnog recidiva, Kaplan-Majerovom analizom i Koksovom regresionom analizom proliferativni indeks Ki-67 se pokazao kao signifikantan prediktor za procenu ponovnog javljanja bolesti, lokalnog recidiva (Log rank (df = 1) = 2,73; p=0,045). Takođe je ustanovljeno da je statistički značajan prediktor za procenu recidiva bolesti i starosna dob bolesnica (Log rank (df = 1) = 6,885; p=0,009). Intenzitet pozitivnosti ER i PR, veličina tumora i histološki gradus se nisu pokazali kao prediktori za pojavu recidiva luminalnih karcinoma dojke (p > 0,05). Zaključak: Zbog heterogene prirode oboljenja, korišćenjem standardnih histopatoloških faktora i biomarkera teško je predvideti tok i ishod karcinoma dojke. Ki-67 je proliferativni marker, čija visoka vrednost korelira sa faktorima loše prognoze.

Introduction: Breast cancer is a heterogeneous disease characterized by different morphology, immunohistochemical profile, clinical course and response to applied therapy. Ki-67 proliferative index is one of the prognostic and predictive factors, whose methodological determination and analysis are still unstandardized. Objective: Determination of cut-off value for Ki-67 index, its corelation in luminal breast carcinoma with patient's age, tumor size, histological grade (HG) and expression of estrogen (ER) and progesterone (PR). Also, the aim of the study was to determine the significance of the difference in the value of the Ki-67 proliferative index in relation to the occurrence of local relapse, distant metastases and survival rates during the five-year follow-up period of the patient. Methods: Retrospectively, we analysed 120 pathohistological reports of patients who were treated in the period from 01.01.2009 until 31.12.2011 at the Oncology Institute of Vojvodina, and to whom immunohistochemically was proven luminal breast cancer (positive ER and PR, negative HER2), without axillary lymph node metastases. Results: The average patient’s age was 57.42±10.17 years; average tumor size 17.98±6.97mm; recurrence was registered in 8 (6.7%) patients with average recurrence time of 49±20.23 months. "Cut off" Ki-67 value of prognostic significance for period without recurrence was 20.75%. Test didn’t show significant relationship between Ki-67 and patient’s age (p=0.401 and p=0.293), as well as the strength of expression ER (p=1.00, p=0.957) and PR (p=0.273, p=0.189). Significant correlation was present for Ki-67 with size (p=0.035, p=0.20) and tumor’s HG (p=0.041, p=0.20). The average follow-up period for patients was 72.92±8.38 months; there was no registered occurrence of distant metastases or fatal outcome. In relation to the occurrence of local relapse, Kaplan-Meier analysis and Cox regression analysis, the proliferative index Ki-67 proved to be a significant predictor for the assessment of recurrence of the disease, local relapse (Log rank (df = 1) = 2.73; p = 0.045). Also, it was founded that a statistically significant predictor for assessing the recurrence of the disease is the age of the patients (Log rank (df = 1) = 6.885; p = 0.009). The intensity of ER and PR expression, tumor size and histological grade have not been shown to be predictors of the recurrence of luminal breast carcinoma (p> 0.05). Conclusion: Breast carcinoma is heterogeneous disease, so it is difficult to predict its course and outcome using standard histopathological factors and biomarkers. Ki-67 is proliferative marker whose high value correlates with factors of bad prognosis.