Ki67 and cyclin A as prognostic factors in early breast cancer. What are the optimal cut-off values?
OBJECTIVE
To find the optimal cut-off values for cyclin A and Ki67 in early breast cancer tumours and to evaluate their prognostic values.


RESULTS
Tissue microarray (TMA) slides were constructed from 570 T1-4 N0-1 M0 breast cancer tumours. The TMA slides were stained for cyclin A and Ki67 using immunohistochemistry with commercial antibodies. To investigate the optimal cut-off values for cyclin A, Ki67 average and maximum values the material was split into two parts at cut-offs defined by dividing it into deciles. For each cut-off value the relative risk (RR) for metastasis-free survival (MFS) and overall survival (OS) was calculated comparing patients with high versus low cyclin A or Ki67 expression. When using a cut-off value around the seventh decile, cyclin A and Ki67 score correlated with the highest RR ratio for MFS in the chemotherapy-naïve subgroup. Among patients having received adjuvant chemotherapy, no statistically significant differences in MFS or OS were found.


CONCLUSIONS
The optimal cut-off value for cyclin A average is 8% and for cyclin A maximum value 11%; for Ki67 the corresponding values are 15% and 22%. Additional studies are needed to verify these results.
Ahlin
C
C
Department of Oncology, Orebro University Hospital, Orebro, Sweden. ahlins.post@telia.com
Aaltonen
K
K
Amini
R-M
RM
Nevanlinna
H
H
Fjällskog
M-L
ML
Blomqvist
C
C
D014408:Biomarkers, Tumor / Q000378:metabolism; D001943:Breast Neoplasms / Q000378:metabolism* / Q000473:pathology; D019925:Cyclin A / Q000378:metabolism*; D005260:Female; D006801:Humans; D053208:Kaplan-Meier Estimate; D019394:Ki-67 Antigen / Q000378:metabolism*; D046228:Microarray Analysis; D011379:Prognosis; D012307:Risk Factors
D014408:Biomarkers, Tumor; D019925:Cyclin A; D019394:Ki-67 Antigen