Cell kinetics and in vitro clonogenicity of primary colorectal cancer: clinicopathological relationships and the implications for chemotherapy

Colorectal cell kinetics

The assessment of cell proliferation in colorectal tissue may provide information with both prognostic and therapeutic implications. A variety of methods are available, including flow cytometric estimations of S phase fraction, immunohistochemical and autoradiographic visualization of exogenous and endogenous proliferation proteins, and morphological and stathmokinetic techniques. There is some correlation between Dukes stage and proliferation state features, and there is increased proliferative activity throughout the adenoma-carcinoma sequence. Data on cell proliferation rates are difficult to obtain. When correctly applied, the metaphase arrest technique remains the 'gold standard' of measuring proliferation, but its usefulness in clinical practice is limited. Recent studies have employed dual measurement flow cytometry and double labelling techniques to produce rate data.

Lack of association between in vitro clonogenic growth of human cervical carcinoma and tumour stage, differentiation, patient age, host cell infiltration or patient survival

Biopsies from 117 patients with cervical carcinoma were studied using a clonogenic assay to assess in vitro growth. Successful colony growth was achieved in 84 tumours (72%) with a mean colony-forming efficiency (CFE), based on total viable nucleated cell counts, of 0.18 +/- 0.49% (+/- 1 standard deviation). There was a wide range of values, from 0.003-4.28%, with a coefficient of variation of 272%. The relationship between clinical features of cervical carcinoma and in vitro colony formation was investigated. No significant association was demonstrated between in vitro growth and either clinical stage (r = 0.02), tumour differentiation (r = -0.08) or patient age (r = -0.12). There was no significant difference in tumour grade between the group of tumours which failed to grow in culture and those which grew well (p = 0.70). In addition, there was no correlation between CFE and the degree of macrophage (r = 0.001), lymphocyte (r = 0.12), or granulocyte (r = 0.08) infiltration. There was no significant difference between CFEs of tumours from patients who had died and from those who were alive and well after a minimum of 2 years' follow-up after radiotherapy (p = 0.51). Ability to form colonies in agar was not associated with a worse prognosis (p = 0.49). Although CFE is an independent biological parameter, our results suggest that, for cervical carcinoma, it is not useful as a univariate prognostic factor.

Assessment of cell proliferation in colorectal carcinomas using the monoclonal antibody Ki-67. Correlation with pathohistologic criteria and influence of irradiation

Cell proliferation was measured by a three-step immunoperoxidase technique on cryostat sections of 61 resected colorectal adenocarcinomas using the monoclonal antibody Ki-67 that is directed against a proliferation-associated nuclear antigen. The percentage of Ki-67-positive cells was quantified with the point-counting method. The frequency distribution of the percentage of Ki-67-positive tumor cells in 52 unirradiated carcinomas was gaussian with a mean of 38.7% (range, 7.7% to 75.3%). Analysis of the unirradiated tumors showed no relation between Ki-67 staining and various clinicopathologic features including age, sex, tumor volume, tumor differentiation, location, and tumor stage. Although some tumors demonstrated intratumor heterogeneity of immunoreactivity, there was no significant difference in proliferative activity among peripheral, intermediate, and central tumor areas. Whereas the Ki-67 index increased to 47.1% in recurrent carcinomas, it decreased significantly to 24.7% in rectal carcinomas given radiotherapy before surgery. Therefore, Ki-67 immunostaining might be used as a tool to select and monitor patients with colorectal cancers who might benefit from radiotherapy. The marked differences of Ki-67 expression among different tumors may relate to heterogeneity in growth kinetics and may therefore carry prognostic implications.