Ki-67 expression in pulmonary tumors

Editor’s note: In the era of personalized medicine, a critical appraisal new developments and controversies are essential in order to derived tailored approaches. In addition to its educative aspect, we expect these discussions to help younger researchers to refine their own research strategies.

Controversies on Lung Cancer: Pros and Cons

Ki-67 expression in pulmonary tumors

Lucian R. Chirieac

Department of Pathology, Brigham and Women’s Hospital, Boston, MA, USA

Correspondence to: Lucian R. Chirieac, MD. Associate Professor of Pathology, Harvard Medical School; Pathologist, Department of Pathology, Brigham and Women’s Hospital, 75 Francis Street, Boston, MA 02115, USA. Email: lchirieac@partners.org

Submitted Sep 13, 2016. Accepted for publication Sep 28, 2016.

doi: 10.21037/tlcr.2016.10.13


Ki-67 as a proliferative marker

Ki-67 was introduced more than two decades ago as a measure of the tumor proliferative fraction, in the need for a useful marker that might help clinicians to guide therapy and predict the prognosis of patients with cancer (1). Although several methods have been used to determine the tumor proliferative fraction in the research setting, the only practical methods used in the pathology laboratory were Ki-67 and mitotic count (2). Mitotic count was long used by surgical pathologists as diagnostic and prognostic criteria in malignant tumors, but is subjective, has poor reproducibility and is dependent on laboratory techniques (3-5).

Alternatively, the Ki-67 proliferative index (PI), determined as the percentage of Ki-67 positive cells by immunohistochemistry (IHC) could be assessed using a commercially available Ki-67 antibody to estimate the growth fraction of a tumor cell population. Ki-67 is a non-histone DNA-binding nuclear protein that is expressed in all phases of the cell cycle in proliferating cells, but not in quiescent (G0) cells (6). In contrast, counting mitotic figures measures only a portion of those cells in the G2 phase and in all M-phase cells. Ki-67 was first developed by Gerdes and colleagues in 1983 and has been used to distinguish growing from non-growing cells (7). In many malignancies the percentage of Ki-67 positive cells is correlated with parameters reflecting tumor aggressiveness or progression (8). These findings demonstrate the potential value of the Ki-67 antigen for the cytopathologic or histopathologic study of tumors, although neither its biochemical structure nor its function have been fully elucidated to date.

Ki-67 PI correlates with other markers of cell proliferation (9,10), but overestimates the proliferative activity of tumors and is therefore not an exact reflection of tumor growth (11). Sarbia et al. (12) found a significant association between Ki-67 PI and the mitotic activity in tumor tissue.

Currently, immunohistochemical staining for Ki-67 is a widely accepted method for evaluating proliferative activity in various tumor types (13-19), but in clinical practice is only incorporated in the diagnostic algorithms of neuroendocrine tumors of gastrointestinal tract.

In lung, reports suggest a key role of Ki-67 in (I) the prognosis of non-small cell lung carcinoma; (II) prediction of brain metastases in patients with lung adenocarcinoma and (III) in the diagnosis, classification and prognosis of pulmonary neuroendocrine tumors.


Ki-67 as a prognostic marker in non-small cell lung cancer (NSCLC)

Metaanalyses of numerous studies performed on early-stage resected NSCLC suggested that high Ki-67 values are correlated with poor prognosis (20), a shorter disease-free survival (DFS) (21,22) and a shorter recurrence-free survival (RFS) after lung tumor resection (23). Similarly, significant correlations between high Ki-67 expression and clinicopathologic characteristics (males, higher tumor stage, and poor differentiation) were found in Asian patients with NSCLC (24). However, the informative value of the vast majority of studies on this issue is limited by the small sample numbers investigated, different Ki-67 clones used in different studies, and the use of various Ki-67 cutoff points for defining a tumor positive or negative (25). Moreover, subgroup analyses of different NSCLC histologies demonstrate that the prognostic impact of Ki-67 PI depends on the NSCLC type (26) and studies of NSCLC cohorts with mixed histologies will not lead to meaningful results. Despite the large number of published analyses exploring the prognostic role in NSCLC, Ki-67 is still not considered an established factor for routine use in clinical practice. A recent study investigated the Ki-67 PI in three large, independent NSCLC cohorts and found the need for use of different cutoff values for each histologic NSCLC type (26). Ki-67 PI was a highly significant and independent predictor for DFS for lung adenocarcinoma and adenosquamous carcinoma, in both the test and validation cohorts, but not for OS and disease-specific survival (DSS) (26). Interestingly, the authors found that in squamous cell carcinoma a high PI was reversely correlated with a better OS (cut-off value of 50%; HR =0.65; P=0.007). A standardized assessment of proliferation by Ki-67 IHC might become a useful biomarker in the daily routine diagnostic setting of NSCLC.


Ki-67 as a predictive marker of brain metastases in NSCLC

It is important to identify patients with NSCLC who are at greater risk of developing brain metastases since they may exist in the absence of neurological symptoms (27). Furthermore, reports show that prophylactic cranial irradiation may be an effective modality for preventing brain metastases in patients with NSCLC treated with adjuvant chemoradiation (28). Despite advances in diagnostic and therapeutic modalities, and sophisticated clinical practice guidelines, it remains unclear whether patients with early stage NSCLC should be screened for brain metastases or not (29-31). The metastatic cascade is rather complex and involves reciprocal interactions between tumor cells and host tissues, including alterations in tumor cell proliferation, adhesion, proteolysis, invasion, and angiogenesis (32).

In a recent study we evaluated patients with NSCLC with and without brain metastasis in a unique series that had tumor material from both the primary lung tumor and matched metachronous brain metastasis (33). We have found that patients with high Ki-67, low caspase-3, high VEGF-C, and low E-cadherin in their primary NSCLC tumors have a higher risk of developing brain metastases when compared with a control group of NSCLC diagnosed during the same period of time. Patients with Ki-67 PI of ≥30% had a 12-times increased risk of developing brain metastases (P<0.001) and a worse prognosis compared to those with lower proliferative activity.

Our study suggests that patients with NSCLC and a specific biomarker expression may benefit from an individualized surveillance regimen and preventive therapeutic intervention designed to prevent or delay the development of brain metastases. These biomarkers are promising for predicting the development of brain metastases, and additional studies on larger series of patients are needed to validate the findings from our study.


Ki-67 in pulmonary neuroendocrine tumors

Pulmonary neuroendocrine tumors include typical carcinoid (TC) tumor, atypical carcinoid (AC) tumor, large-cell neuroendocrine carcinoma (LCNEC) and small cell lung carcinoma (SCLC) (34-36) and represent 20% of lung tumors. An initial accurate diagnosis is essential for patients with pulmonary neuroendocrine tumors because there are dramatic differences in outcome and therapeutic approach (37-42). The distinction between TC, AC, and LCNEC is based on the mitotic count and the presence of necrosis (43). While the mitotic count is an important component of the classification of pulmonary neuroendocrine tumors, it can be difficult to assess in limited biopsies. Mitoses can be difficult to distinguish from apoptotic cells and may be obscured by crush artefact (4,44-46). Also, evaluating mitotic count is time consuming and is subject to interobserver variability (37).

Studies performed using the current classification of pulmonary neuroendocrine tumors have shown an association between the Ki-67 PI and the grade of the neuroendocrine carcinoma (41,45,47-56). Although recent studies have attempted to identify the cutoff points for the Ki-67 proliferative indices for each diagnostic category of pulmonary neuroendocrine tumor (41,48,56), a consensus on how the Ki-67 proliferative index should be integrated into the diagnostic algorithm has not been established in detail (34,57).

While the presence of necrosis had been in Arrigoni’s original definition of AC, the mitotic count he had proposed to define AC was between 5–10 mitoses per high power fields (HPFs) (58). Subsequently it was determined that the optimal cut-off values for mitotic counts are 0–1 mitoses per 10 HPFs for TC, 2–10 mitoses per 10 HPFs for AC, and greater than 10 mitoses per 10 HPFs for LCNEC (38). Based on these criteria the 10-year OS is 87%, 35%, and 9% for patients with TC, AC and LCNEC, respectively. A statistically significant difference in survival was also confirmed in more recent studies (46,59,60). We would suggest performing a Ki-67 IHC on all cases of pulmonary neuroendocrine tumors. For cases that have a Ki-67 proliferative index in the expected range for that diagnostic entity, the Ki-67 stain would support the H&E diagnosis. Ultimately, the final diagnosis, must be based on the H&E findings, and therefore, we recommend that after re-review, if there is no change in interpretation that the histologic evaluation stands regardless of the mitotic count, though a higher than expected Ki-67 proliferative activity could be mentioned in a note with the statement that the prognostic/biologic significance of the increased proliferative index in uncertain. We believe that immunohistochemical staining for Ki-67 is extremely helpful in the diagnosis of pulmonary neuroendocrine tumors and should be integrated as a valuable component in their diagnostic algorithm.


Acknowledgements

None.


Footnote

Conflicts of Interest: The author has no conflicts of interest to declare.

Related to: Kriegsmann M, Warth A. What is better/reliable, mitosis counting or Ki67/MIB1 staining? Transl Lung Cancer Res 2016;5:543-6.
Kriegsmann M, Warth A. Ki-67 expression in pulmonary tumors—reply. Transl Lung Cancer Res 2016;5:552-3.
Chirieac LR. Tumor cell proliferation, proliferative index and mitotic count in lung cancer. Transl Lung Cancer Res 2016;5:554-6.


References

  1. Hitchcock CL. Ki-67 staining as a means to simplify analysis of tumor cell proliferation. Am J Clin Pathol 1991;96:444-6. [Crossref] [PubMed]
  2. Sahin AA, Ro JY, el-Naggar AK, et al. Tumor proliferative fraction in solid malignant neoplasms. A comparative study of Ki-67 immunostaining and flow cytometric determinations. Am J Clin Pathol 1991;96:512-9. [Crossref] [PubMed]
  3. Donhuijsen K, Schmidt U, Hirche H, et al. Changes in mitotic rate and cell cycle fractions caused by delayed fixation. Hum Pathol 1990;21:709-14. [Crossref] [PubMed]
  4. Ellis PS, Whitehead R. Mitosis counting--a need for reappraisal. Hum Pathol 1981;12:3-4. [Crossref] [PubMed]
  5. Sadler DW, Coghill SB. Histopathologists, malignancies, and undefined high-power fields. Lancet 1989;1:785-6. [Crossref] [PubMed]
  6. Seigneurin D, Guillaud P. Ki-67 antigen, a cell cycle and tumor growth marker. Pathol Biol (Paris) 1991;39:1020-8. [PubMed]
  7. Gerdes J, Schwab U, Lemke H, et al. Production of a mouse monoclonal antibody reactive with a human nuclear antigen associated with cell proliferation. Int J Cancer 1983;31:13-20. [Crossref] [PubMed]
  8. Gerdes J. Ki-67 and other proliferation markers useful for immunohistological diagnostic and prognostic evaluations in human malignancies. Semin Cancer Biol 1990;1:199-206. [PubMed]
  9. Wilson MS, Anderson E, Bell JC, et al. An evaluation of five different methods for estimating proliferation in human colorectal adenocarcinomas. Surg Oncol 1994;3:263-73. [Crossref] [PubMed]
  10. Gerdes J, Becker MH, Key G, et al. Immunohistological detection of tumour growth fraction (Ki-67 antigen) in formalin-fixed and routinely processed tissues. J Pathol 1992;168:85-6. [Crossref] [PubMed]
  11. Scott RJ, Hall PA, Haldane JS, et al. A comparison of immunohistochemical markers of cell proliferation with experimentally determined growth fraction. J Pathol 1991;165:173-8. [Crossref] [PubMed]
  12. Sarbia M, Bittinger F, Porschen R, et al. The prognostic significance of tumour cell proliferation in squamous cell carcinomas of the oesophagus. Br J Cancer 1996;74:1012-6. [Crossref] [PubMed]
  13. Reid MD, Bagci P, Ohike N, et al. Calculation of the Ki67 index in pancreatic neuroendocrine tumors: a comparative analysis of four counting methodologies. Mod Pathol 2015;28:686-94. [Crossref] [PubMed]
  14. Johannessen AL, Torp SH. The clinical value of Ki-67/MIB-1 labeling index in human astrocytomas. Pathol Oncol Res 2006;12:143-7. [Crossref] [PubMed]
  15. Mittal K, Demopoulos RI. MIB-1 (Ki-67), p53, estrogen receptor, and progesterone receptor expression in uterine smooth muscle tumors. Hum Pathol 2001;32:984-7. [Crossref] [PubMed]
  16. Trihia H, Murray S, Price K, et al. Ki-67 expression in breast carcinoma: its association with grading systems, clinical parameters, and other prognostic factors--a surrogate marker? Cancer 2003;97:1321-31. [Crossref] [PubMed]
  17. Wiesner FG, Magener A, Fasching PA, et al. Ki-67 as a prognostic molecular marker in routine clinical use in breast cancer patients. Breast 2009;18:135-41. [Crossref] [PubMed]
  18. Zhang K, Prichard JW, Yoder S, et al. Utility of SKP2 and MIB-1 in grading follicular lymphoma using quantitative imaging analysis. Hum Pathol 2007;38:878-82. [Crossref] [PubMed]
  19. Hayashi Y, Fukayama M, Koike M, et al. Cell-cycle analysis detecting endogenous nuclear antigens: comparison with BrdU-in vivo labeling and an application to lung tumors. Acta Pathol Jpn 1993;43:313-9. [PubMed]
  20. Martin B, Paesmans M, Mascaux C, et al. Ki-67 expression and patients survival in lung cancer: systematic review of the literature with meta-analysis. Br J Cancer 2004;91:2018-25. [Crossref] [PubMed]
  21. Yamashita S, Moroga T, Tokuishi K, et al. Ki-67 labeling index is associated with recurrence after segmentectomy under video-assisted thoracoscopic surgery in stage I non-small cell lung cancer. Ann Thorac Cardiovasc Surg 2011;17:341-6. [Crossref] [PubMed]
  22. Poleri C, Morero JL, Nieva B, et al. Risk of recurrence in patients with surgically resected stage I non-small cell lung carcinoma: histopathologic and immunohistochemical analysis. Chest 2003;123:1858-67. [Crossref] [PubMed]
  23. Sofocleous CT, Garg SK, Cohen P, et al. Ki 67 is an independent predictive biomarker of cancer specific and local recurrence-free survival after lung tumor ablation. Ann Surg Oncol 2013;20 Suppl 3:S676-83. [Crossref] [PubMed]
  24. Wen S, Zhou W, Li CM, et al. Ki-67 as a prognostic marker in early-stage non-small cell lung cancer in Asian patients: a meta-analysis of published studies involving 32 studies. BMC Cancer 2015;15:520. [Crossref] [PubMed]
  25. Lee JS, Yoon A, Kalapurakal SK, et al. Expression of p53 oncoprotein in non-small-cell lung cancer: a favorable prognostic factor. J Clin Oncol 1995;13:1893-903. [PubMed]
  26. Warth A, Cortis J, Soltermann A, et al. Tumour cell proliferation (Ki-67) in non-small cell lung cancer: a critical reappraisal of its prognostic role. Br J Cancer. 2014;111:1222-9. [Crossref] [PubMed]
  27. Ferrigno D, Buccheri G. Cranial computed tomography as a part of the initial staging procedures for patients with non-small-cell lung cancer. Chest 1994;106:1025-9. [Crossref] [PubMed]
  28. Pöttgen C, Eberhardt W, Grannass A, et al. Prophylactic cranial irradiation in operable stage IIIA non small-cell lung cancer treated with neoadjuvant chemoradiotherapy: results from a German multicenter randomized trial. J Clin Oncol 2007;25:4987-92. [Crossref] [PubMed]
  29. Shen KR, Meyers BF, Larner JM, et al. Special treatment issues in lung cancer: ACCP evidence-based clinical practice guidelines (2nd edition). Chest 2007;132:290S-305S.
  30. Shi AA, Digumarthy SR, Temel JS, et al. Does initial staging or tumor histology better identify asymptomatic brain metastases in patients with non-small cell lung cancer? J Thorac Oncol 2006;1:205-10. [Crossref] [PubMed]
  31. Ettinger DS, Wood DE, Akerley W, et al. NCCN Guidelines Insights: Non-Small Cell Lung Cancer, Version 4.2016. J Natl Compr Canc Netw 2016;14:255-64. [PubMed]
  32. Palmieri D, Chambers AF, Felding-Habermann B, et al. The biology of metastasis to a sanctuary site. Clin Cancer Res 2007;13:1656-62. [Crossref] [PubMed]
  33. Saad AG, Yeap BY, Thunnissen FB, et al. Immunohistochemical markers associated with brain metastases in patients with nonsmall cell lung carcinoma. Cancer 2008;113:2129-38. [Crossref] [PubMed]
  34. Caplin ME, Baudin E, Ferolla P, et al. Pulmonary neuroendocrine (carcinoid) tumors: European Neuroendocrine Tumor Society expert consensus and recommendations for best practice for typical and atypical pulmonary carcinoids. Ann Oncol 2015;26:1604-20. [Crossref] [PubMed]
  35. Chen LC, Travis WD, Krug LM. Pulmonary neuroendocrine tumors: What (little) do we know? J Natl Compr Canc Netw 2006;4:623-30. [PubMed]
  36. Gustafsson BI, Kidd M, Chan A, et al. Bronchopulmonary neuroendocrine tumors. Cancer 2008;113:5-21. [Crossref] [PubMed]
  37. Tsuta K, Raso MG, Kalhor N, et al. Histologic features of low- and intermediate-grade neuroendocrine carcinoma (typical and atypical carcinoid tumors) of the lung. Lung Cancer 2011;71:34-41. [Crossref] [PubMed]
  38. Travis WD, Rush W, Flieder DB, et al. Survival analysis of 200 pulmonary neuroendocrine tumors with clarification of criteria for atypical carcinoid and its separation from typical carcinoid. Am J Surg Pathol 1998;22:934-44. [Crossref] [PubMed]
  39. Cooper WA, Thourani VH, Gal AA, et al. The surgical spectrum of pulmonary neuroendocrine neoplasms. Chest 2001;119:14-8. [Crossref] [PubMed]
  40. Filosso PL, Rena O, Donati G, et al. Bronchial carcinoid tumors: surgical management and long-term outcome. J Thorac Cardiovasc Surg 2002;123:303-9. [Crossref] [PubMed]
  41. Skov BG, Holm B, Erreboe A, et al. ERCC1 and Ki67 in small cell lung carcinoma and other neuroendocrine tumors of the lung: distribution and impact on survival. J Thorac Oncol 2010;5:453-9. [Crossref] [PubMed]
  42. Han B, Sun JM, Ahn JS, et al. Clinical outcomes of atypical carcinoid tumors of the lung and thymus: 7-year experience of a rare malignancy at single institute. Med Oncol 2013;30:479. [Crossref] [PubMed]
  43. Travis W, Brambilla A, Burke A, et al. Pathology and Genetics of Tumors of the Lung, Pleura, Thymus and Heart. World Health Organization Classification of Tumors. Lyon, France: IARC Press, 2015.
  44. Pelosi G, Rodriguez J, Viale G, et al. Typical and atypical pulmonary carcinoid tumor overdiagnosed as small-cell carcinoma on biopsy specimens: a major pitfall in the management of lung cancer patients. Am J Surg Pathol 2005;29:179-87. [Crossref] [PubMed]
  45. Aslan DL, Gulbahce HE, Pambuccian SE, et al. Ki-67 immunoreactivity in the differential diagnosis of pulmonary neuroendocrine neoplasms in specimens with extensive crush artifact. Am J Clin Pathol 2005;123:874-8. [Crossref] [PubMed]
  46. Skov BG, Krasnik M, Lantuejoul S, et al. Reclassification of neuroendocrine tumors improves the separation of carcinoids and the prediction of survival. J Thorac Oncol 2008;3:1410-5. [Crossref] [PubMed]
  47. Böhm J, Koch S, Gais P, et al. Prognostic value of MIB-1 in neuroendocrine tumours of the lung. J Pathol 1996;178:402-9. [Crossref] [PubMed]
  48. Grimaldi F, Muser D, Beltrami CA, et al. Partitioning of bronchopulmonary carcinoids in two different prognostic categories by ki-67 score. Front Endocrinol (Lausanne) 2011;2:20. [Crossref] [PubMed]
  49. Pelosi G, Papotti M, Rindi G, et al. Unraveling tumor grading and genomic landscape in lung neuroendocrine tumors. Endocr Pathol 2014;25:151-64. [Crossref] [PubMed]
  50. Pelosi G, Rindi G, Travis WD, et al. Ki-67 antigen in lung neuroendocrine tumors: unraveling a role in clinical practice. J Thorac Oncol 2014;9:273-84. [Crossref] [PubMed]
  51. Sayeg Y, Sayeg M, Baum RP, et al. Pulmonary neuroendocrine neoplasms. Pneumologie 2014;68:456-77. [PubMed]
  52. Swarts DR, van Suylen RJ, den Bakker MA, et al. Interobserver variability for the WHO classification of pulmonary carcinoids. Am J Surg Pathol 2014;38:1429-36. [Crossref] [PubMed]
  53. Zahel T, Krysa S, Herpel E, et al. Phenotyping of pulmonary carcinoids and a Ki-67-based grading approach. Virchows Arch 2012;460:299-308. [Crossref] [PubMed]
  54. Arbiser ZK, Arbiser JL, Cohen C, et al. Neuroendocrine lung tumors: grade correlates with proliferation but not angiogenesis. Mod Pathol 2001;14:1195-9. [Crossref] [PubMed]
  55. Rugge M, Fassan M, Clemente R, et al. Bronchopulmonary carcinoid: phenotype and long-term outcome in a single-institution series of Italian patients. Clin Cancer Res 2008;14:149-54. [Crossref] [PubMed]
  56. Rindi G, Klersy C, Inzani F, et al. Grading the neuroendocrine tumors of the lung: an evidence-based proposal. Endocr Relat Cancer 2013;21:1-16. [Crossref] [PubMed]
  57. Walts AE, Ines D, Marchevsky AM. Limited role of Ki-67 proliferative index in predicting overall short-term survival in patients with typical and atypical pulmonary carcinoid tumors. Mod Pathol 2012;25:1258-64. [Crossref] [PubMed]
  58. Arrigoni MG, Woolner LB, Bernatz PE. Atypical carcinoid tumors of the lung. J Thorac Cardiovasc Surg 1972;64:413-21. [PubMed]
  59. Asamura H, Kameya T, Matsuno Y, et al. Neuroendocrine neoplasms of the lung: a prognostic spectrum. J Clin Oncol 2006;24:70-6. [Crossref] [PubMed]
  60. Beasley MB, Thunnissen FB, Brambilla E, et al. Pulmonary atypical carcinoid: predictors of survival in 106 cases. Hum Pathol 2000;31:1255-65. [Crossref] [PubMed]
Cite this article as: Chirieac LR. Ki-67 expression in pulmonary tumors. Transl Lung Cancer Res 2016;5(5):547-551. doi: 10.21037/tlcr.2016.10.13

Refbacks

  • There are currently no refbacks.