Lack of correlation between Ki-67 labelling index and tumor size of anterior pituitary adenomas

BMC Cancer. 2001;1:12. doi: 10.1186/1471-2407-1-12. Epub 2001 Aug 21.

Abstract

Aims and background: The Ki-67 is a nuclear antigen detected by the monoclonal antibody MIB-1 and its Labeling Index (LI) is considered a marker of normal and abnormal cell proliferation. Pituitary adenomas are generally well differentiated neoplasms, even if in about one third of cases they are invasive of surrounding tissues. The aim of this study is to evaluate the correlation between Ki-67 labelling index and tumor size of pituitary adenomas extimated by means CT and MRI and confirmed at operation.

Methods: Using the monoclonal antibody MIB-1, we evaluated the expression of Ki-67 in 121 anterior pituitary adenomas consecutively operated on in a 48-month period.

Results: In relation to neuroradiological (CT and MRI) and surgically verified tumor size, we identified 24 microadenomas, 27 intrasellar macroadenomas, 34 intra-suprasellar macroadenomas, and 36 intra-supra-parasellar macroadenomas. The adenomas were non-infiltrating (76 cases) and infiltrating (45 cases) adenomas. The wall of the cavernous sinus (CS) was infiltrated in 18 cases. Forty-eight adenomas were non-functioning and 73 functioning. The overall mean +/- SD Ki-67 LI was 2.72 +/- 2.49% (median 1.6). It was 2.59 +/- 1.81 in microadenomas, 2.63 +/- 3.45 in intrasellar macroadenomas, 1.91 +/- 2.11 in intra-suprasellar macroadenomas, and 3.29 +/- 5.45 in intra-supra-parasellar macroadenomas (p = 0.27). It was 3.73 +/- 5.13% in infiltrating and 2.03 +/- 2.41% in non-infiltrating adenomas (p = 0.02), and 5.61 +/- 7.19% in CS-infiltrating versus 2.09 +/- 2.37% in CS-non-infiltrating adenomas (p = 0.0005).

Conclusions: Our preliminary results seem to exclude significative correlations between Ki-67 LI and tumor size of anterior pituitary adenomas, even if this index can be considered a useful marker in the determination of the infiltrative behaviour of these tumors.

MeSH terms

  • Adenoma / metabolism
  • Adenoma / pathology*
  • Adolescent
  • Adult
  • Aged
  • Biomarkers, Tumor / metabolism*
  • Female
  • Humans
  • Ki-67 Antigen / metabolism*
  • Male
  • Middle Aged
  • Pituitary Gland, Anterior / metabolism
  • Pituitary Gland, Anterior / pathology*
  • Pituitary Neoplasms / metabolism
  • Pituitary Neoplasms / pathology*
  • Predictive Value of Tests
  • Prognosis
  • Severity of Illness Index
  • Staining and Labeling* / methods

Substances

  • Biomarkers, Tumor
  • Ki-67 Antigen