DNA ploidy

The Institute for Cancer Genetics and Informatics (ICGI) has developed an image cytometry system, consisting of PWS (Ploidy Work Station) Grabber and PWS Classifier for analysing the DNA distribution in a given tumour sample. DNA is stained in situ by Schiff’s reagents by the Feulgen technique. The method results in stained nuclei were the staining intensity is proportional with the DNA content.

ICGI has established DNA ploidy analysis as a method for diagnostic and prognostic assessment in clinical activity within gynaecological cancer and to some extent cancer of the prostate. We now conduct approximately 750 measurements for DNA ploidy analyses for our clinic each year. We also have on-going studies on large retrospective series of several cancer types, such as rectal and colon cancer, where the results are very promising.

DNA ploidy has been shown in multiple studies to be a diagnostic and prognostic marker for patients with different cancer types, and in particular for patients with gynaecological cancers. By performing DNA ploidy analyses on tumour material one can therefore obtain valuable information that can contribute in the process of determining the best treatment scheme for each patient.

The DNA ploidy analyses give an objective measure of large-scale genomic instability which discriminates between specimen with a normal DNA content and nuclei with an abnormal and often unstable DNA content.

Illustration describing the DNA Ploidy project

Experience since 1993

DNA ploidy systems have been developed by our research group since 1993. Our Section for Applied Informatics has developed the software PWS Grabber, that enables fully automated grabbing, segmention and sorting of cell nuclei, and PWS Classifier, that enables analyses of the captured nuclei, and finally a classified DNA histogram.

In simple words, the basic concept is that tumours with abnormal DNA content and/or unstable chromatin structure is in a more advanced stage and is more likely to have micro metastases (spreading of the cancer). This “large scale genomic instability” can be measured on samples from routine biopsy specimens by computerized analysis of images from the microscope.

Texture AnalysisImages captured are collated in galleries according to shape, size, chromatin content and chromatin texture. These are manually checked and a histogram is produced, indicating the DNA ploidy classification of the sample. Further analysis can include heterogeneity, Nucleotyping and detailed texture analysis.

Highlights for DNA Ploidy

• DNA ploidy analyses can give diagnostic and prognostic information that can contribute in the process of determining the best treatment scheme for cancer patients.
• PWS could sort the nuclei into galleries containing different cell types. Visual control of the images ensures that only intact tumor nuclei are analyzed.
• PWS Classifier handles objects grabbed by the PWS Grabber. The software enables manual editing (sorting of objects), it displays DNA ploidy histograms, and performs calculations and statistics.
• PWS Classifier enables manual and automatic DNA ploidy classification that could be used in diagnosis and prognosis of cancer patients.

PWS is commercially available through Room4 Group Limited, England.