Greater Prognostic Value of Ki67 Index vs Cytology and Growth Pattern in Mantle Cell Lymphoma
Hoster et al found that Ki67 index had greater prognostic value than cytology or growth pattern in mantle cell lymphoma, based on data from European Mantle Cell Lymphoma Network randomized trials reported in the Journal of Clinical Oncology. A modified combination of Ki67 index and Mantle Cell Lymphoma International Prognostic Index (MIPI) identified distinct risk groups.
Study Details
The study sought to determine whether adding cytology and growth pattern could improve risk stratification with the Ki67 index and MIPI. Cox regression models were used to assess the prognostic value of Ki67 index, cytology, and growth pattern with or without MIPI.
Prognostic Power
Blastoid cytology was associated with inferior overall survival independently of MIPI (hazard ratio [HR] = 1.91, P < .001) but not independently of Ki67 index (HR = 1.44, P = .11). Growth pattern was not independently prognostic in a model including MIPI or a model including Ki67 index.
In a model including Ki67 index, cytology, and growth pattern but not MIPI, hazard ratios were 1.26 (P < .001) per 10% increase in Ki67 index, 1.13 (P = .64) for blastoid cytology, and 1.21 (P = .31) for diffuse growth pattern. In a model including MIPI, hazard ratios were 1.15 (P = .003) per 10% increase in Ki67 index, 1.20 (P = .48) for blastoid cytology, and 0.97 (P = .89) for diffuse growth pattern.
Combined Ki67 Index and MIPI
A modified combination of Ki67 index and MIPI defined four groups, with 5-year overall survival (P < .001) of 85% (32% of patients), 72% (34% of patients; HR = 2.3, 95% confidence interval [CI] = 1.4–3.7, vs first group), 43% (23% of patients; HR = 2.2, 95% CI = 1.6–3.2, vs second group), and 17% (11% of patients; HR = 2.2, 95% CI = 1.5–3.3, vs third group).
The modified combination consists of the following: low risk = MIPI low risk plus Ki67 index < 30%; low-intermediate risk = MIPI low risk plus Ki67 index ≥ 30% or MIPI intermediate risk plus Ki67 index < 30%; high-intermediate risk = MIPI intermediate risk plus Ki67 index ≥ 30% or MIPI high risk plus Ki67 index < 30%; and high risk = MIPI high risk plus Ki67 index ≥ 30%.
The investigators concluded: “Using the Ki-67 index is superior to using cytology and growth pattern as prognostic factors in [mantle cell lymphoma]. The modified combination of the Ki-67 index and MIPI showed a refined risk stratification, reflecting their strong complementary prognostic effects while integrating the most relevant prognostic factors available in clinical routine.”
The study was supported by Roche, the European Commission, the Lymphoma Research Foundation, and the Institut National du Cancer.
Eva Hoster, PhD, of the University Hospital Munich, is the corresponding author of the Journal of Clinical Oncology article.
The content in this post has not been reviewed by the American Society of Clinical Oncology, Inc. (ASCO®) and does not necessarily reflect the ideas and opinions of ASCO®.
