Heterogeneity of immunostaining for tumour markers in non-small cell lung carcinoma

Ki-67 is a strong prognostic marker of non-small cell lung cancer when tissue heterogeneity is considered

Background

Ki-67 expression is a well-established prognostic marker in various cancers. However, Ki-67 expression is also known as being heterogeneous. We investigated the prognostic significance of Ki-67 from the view of staining heterogeneity by the technique of Spiral Array.

Methods

100 cases of resected lung cancer from Toyama university hospital archive were collected. Spiral Array blocks were generated out of 100 cases using 100 μm thick paraffin sections. Four μm thick sections of the Array block were stained for Ki-67. Staining results in each reel were scored for areas with lowest (LS), highest (HS), and average (AS) expression, exclusively in the cancer cells. Heterogeneity score (HeS) was designed as the difference between HS and LS. The scores were divided into four grades (0–3). Clinical information was collected, and the prognostic significance of Ki-67 was analyzed.

Results

Pathological stage was available for 91 patients (43 stage IA, 22 stage IB, 2 stage IIA, 9 stage IIB, 13 stage IIIA, 1 stage IIIB, and 1 stage IV). The HS of Ki-67 score in non-small cell lung cancer was 3 in 17 cases, 2 in 27 cases, 1 in 28 cases, 0 in 21 cases, and 4 reels were lost. 78 cases had clinical follow up. 74 cases had all the information available and were analyzed for correlation between Ki-67 expression and survival. Cases with score 2 and 3 of HS and HeS showed significant poorer prognosis (both P < 0.001), whereas LS or AS did not show significance. The results were identical when analyzing adenocarcinoma and squamous cell carcinoma, separately. Cox multivariate analysis of Ki-67 showed that HS was an independent risk factor affecting overall survival.

Conclusions

Ki-67 is a strong prognostic marker for non-small cell lung cancer when the degree of highest staining frequency or heterogeneity is considered.

Clinical impact of ki-67 labeling index in non-small cell lung cancer

The ki-67 index is a marker of proliferation in malignant tumors. Studies from the period 2000 to 2012 on the prognostic and predictive value of ki-67 labeling index (LI) in non-small cell cancer (NSCLC) are reviewed. Twenty-eight studies reported on the prognostic value of ki-67 index with various endpoints. No consensus on the prognostic value of ki-67 LI was found among the published studies neither according to disease stage nor histological subtype. Comparison of studies is hampered by differences in patient populations, methodologies and cut-off values. Five studies explored the predictive value of ki-67 to chemotherapy and none revealed significant influence. Ki-67 index seems to be of prognostic influence in NSCLC although largely variable cut-off levels have been used in the various studies and standardization of methodology is required. The relative importance of ki-67 compared to newer biomarkers has not been explored. It is likely that a signature of several biomarkers in combination may be necessary to more sufficiently stratify patients to various treatment options than is currently possible, especially when it comes to the question of the optimal use of classical chemotherapy. A predictive impact of ki-67 to treatment in NSCLC remains unclear.

Prognostic impact of Deoxyribonucleic acid (DNA) image analysis cytometry and immunohistochemical expression of Ki67 in surgically resected non-small cell lung cancers

BACKGROUND

The aim of the present study was to evaluate the prognostic significance of DNA ploidy and Ki67 expression in non-small cell lung carcinoma (NSCLC).

METHODS

This prospective study included 96 patients with stages I-IIIA NSCLC who underwent surgical excision. DNA image analysis cytometry was applied on imprints. Calculation of the DNA index (DI) and the 5c exceeding rate (5cER) was performed and the histograms were classified as peridiploid, peritetraploid, and x-ploid-multiploid. The Ki67 immunoreactivity was determined according to the avidin-biotin complex immunoperoxidase method.

RESULTS

DNA histogram classification disclosed 30 peridiploid cases, 15 peritetraploid and 51 x-ploid-multiploid. Forty-eight cases (50%) had 5cER > 5%. The Ki67 immunoreactivity was below 25% in 53 tumors (62.4%) and above 25% in 32 (32.6%). Our results revealed the existence of a statistically significant relationship of DNA ploidy with nodal status (p = 0.042) and grade (p = 0.005). Adenocarcinomas and large cell carcinomas were more frequently encountered in x-ploid-multiploid tumors as compared to squamous cell carcinomas, which were more frequently peridiploid (p = 0.003). 5cER showed statistically significant association with nodal status (p = 0.037). Univariate analysis with respect to survival revealed significant association with stage (p < 0.001), nodal status (p < 0.001), tumor status (p < 0.001), DNA ploidy (p = 0.008) and 5cER (p = 0.0124). Multivariate analysis revealed stage and ploidy status as independent factors: peridiploid tumors were associated with better survival as compared to x-ploid-multiploid tumors (p = 0.022).

CONCLUSION

Our results suggest that DNA ploidy, as determined by image analysis, provides an independent prognostic parameter for patients with NSCLC and thus, could be used to identify a subset of patients with more aggressive tumors.