DNA heterogeneity in metastasizing squamous cell head and neck cancer.

This study was carried out to determine whether analysis of DNA content of tumour cells (expressed as DNA-index: DI) from patients with head and neck squamous cell cancer (HNSCC) and lung squamous cell cancer (LSCC) could be helpful in distinguishing HNSCC patients with LSCC as a second primary from those in which LSCC represents a distant metastasis. Based on the assumption that metastasizing tumours retain their original DNA content, the same DI at both locations would suggest LSCC to be a distant metastasis from HNSCC, whereas a difference in DI at both tumour locations makes LSCC to be a second primary more likely. The study comprised 21 cases with HNSCC as well as LSCC. However, the basic assumption that the identity of a tumour can be inferred from its DI proved to be false as 7 of the 21 cases were characterized by more than one DI signifying several tumour cell populations. This DNA heterogeneity was further substantiated by differences in DI between the primary tumour and cervical lymph node metastasis in a second series composed of 16 HNSCC patients. These data indicate that due to variation in DI within one and the same tumour, DNA-analysis does not offer reliable information when trying to differentiate between lung cancer as a second primary or a distant metastasis in HNSCC patients.

DNA ploidy analysis of squamous cell head and neck cancer to identify distant metastasis from second primary.

We conducted an investigation by flow cytometry to determine whether lung cancer in eight patients with oral cancer represented a metastasis or a second primary. One patient had the same aneuploid cell population at both sites which indicated the lung lesion to be a metastasis. Two patients had a diploid lesion at both sites. In these patients, a second primary could not be distinguished from a distant metastasis because (notwithstanding both lesions being diploid) the tumors may have a different DNA content but at a level too low for flow cytometric detection. Five cases had differing DNA indices, which could represent a second primary as well as the emergence of a new clone during tumor progression and metastasis. It appears that DNA flow cytometry can identify tumors that are the same if both have the same aneuploid pattern, but it cannot prove that they are different.

The relationship between radiosensitivity and cell kinetic effects after low- and high-dose-rate irradiation in five human tumors in nude mice.

Radiation-induced synchronization of cells in the radiosensitive G2 phase can, theoretically, be applied to individual tailoring of fractionation schemes, possibly rendering radiotherapy more effective. For that purpose, cell cycle perturbations were studied in five xenografts by flow cytometry. A dose-dependent increase of cells in G2 phase was noticed in all five tumor cell lines after high-dose-rate irradiation, and in four tumor cell lines after low-dose-rate irradiation. The timing of maximum accumulation was not related to dose, but coincided with the cell cycle time of the respective tumors. Furthermore, the increase in the number of cells in G2 phase correlated with the radiosensitivity of the tumors as assessed by measurements of regrowth delays. The observed synchronization provides a basis for further investigations on the relevance of radiation-induced cell cycle synchrony to the effectiveness of fractionated radiotherapy.

The relevance of the DNA index and proliferation rate in the grading of benign and malignant soft tissue tumors.

The relevance of the DNA index (DI) to malignancy grading and the relationships between mitotic score, Ki-67 score, and the proportion of cells in the G1-phase (G1PF) of the cell cycle, as proliferative indicators, were investigated in benign (n = 8) and malignant (n = 46) soft tissue sarcomas. Although DI was not found to be related to the histology of the sarcomas, it was associated with malignancy grade, i.e., 14%, 25%, 42%, and 86% of benign, Grade 1, Grade 2, and Grade 3, respectively had a DI greater than 1. The relevance of aneuploidy in benign tumors is discussed and the literature reviewed. A subgroup of the malignant tumors (n = 13) had both a low mitotic score and a low Ki-67 value. However, a distinct correlation between Ki-67 and the mitotic score could not be shown. For malignant tumours G1PF was related to DI, i.e., low G1PF occurred in tumors with diploid DNA content. Low Ki-67 scores were observed in 59% of diploid tumors and in 20% of aneuploid tumors. However, it appeared that G1PF and Ki-67 were not correlated. In conclusion, (1) benign and Grade 1 tumors were predominantly diploid with high G1PF and low Ki-67 values, (2) most of Grade 3 tumors were aneuploid (86%) with low G1PF and high Ki-67 values, and (3) the group of Grade 2 tumors could be divided into two subgroups either with the characteristics displayed by benign and Grade 1 tumors (DI = 1, low Ki-67 scores, and high G1PF) or with the characteristics exhibited by Grade 3 tumors (DI greater than 1, high Ki-67 scores, and low G1PF). Hence, supplementary to the grading of soft tissue tumors, DI, G1PF, and Ki-67 score could be useful as prognostic parameters in soft tissue tumors.

Relationship between cell kinetics and radiation-induced arrest of proliferating cells in G2: relevance to efficacy of radiotherapy.

Monitoring the radiation-induced G2-arrest with flow cytometry disclosed the relationship between the pattern of accumulation in G2 and the cell kinetics (Tc), as assessed with semi-continuous labelling. A close relationship between these two parameters was observed in a murine mammary tumour after high dose-rate irradiation and in human cervix tumours (xenografted and in patients) after low dose-rate irradiation. In inoperable tumours of the oral cavity, a G2-arrest, observed in the first two weeks of fractionated therapy, was found to predict a local cure. Consequently, it was concluded that the cells accumulated in G2 were not doomed cells. This process of radiation-induced synchronization might be exploited in fractionation schemes of which treatment intervals are adjusted to the Tc-related timing of the radiation-induced G2-arrest.

DNA flow cytometry, histological grade, stage, and age as prognostic factors in human epithelial ovarian carcinomas.

The prognostic value of parameters as determined by DNA flow cytometry, in combination with other parameters, was assessed in 75 patients with ovarian carcinomas (20% in stage I and II). DNA- index of the tumours appeared to predict mainly the degree of differentiation, since the DNA-index only tended to affect prognosis and low grade tumours were mainly diploid. However, with ascites a non-diploid DNA-index was associated with a significantly lower survival in short-term follow-up. Subgroups with a favourable prognosis were defined by an age of patients less than or equal to 40 years, grade 1 tumours, and tumours in stage I or II. Particularly favourable was the combination of a grade 1 tumour, or a tumour in stage I or II, with percentage of cells in G1 greater than 85%. Prognostically poor subgroups were defined by an age greater than 60 years, by grade 2 or 3 tumours and by a clinically advanced stage. The combination of grade 2 or 3, or a clinically advanced stage, with G1-phase fraction less than or equal to 85% identified subgroups with a particularly poor prognosis.