Features & Stories
Diagnosis Cancer
When thinking of a pathologist, most people conjure up an image of a white-coated doctor stooped over a body carrying out a post-mortem.
In fact, this is only a very small component of the work done by these highly trained medics and biomedical scientists.
The vast majority of their time is spent in their department studying tissue to make a diagnosis.
Cancer
Pathologists play a part in the diagnosis of 80% of all cancers, the only exceptions being where the tissue is too deep or otherwise difficult to biopsy (e.g. cancer of the pancreas). They take cells and samples of tissue and by microscopic examination diagnose whether they are cancerous.
They also grade tumours, giving an indication of whether the cancer is high or low grade. This gives doctors some idea of how the cancer might behave. High grade cancers – which look least like normal cells – may be faster growing or more likely to spread. This is highly significant; for many types of cancer, the treatment may be different depending on whether the tumour is high or low grade.
Screening
Pathologists too are involved in the national screening programmes that regularly screen patients for specific cancers including breast, cervical and colorectal cancer.
Playing such a critical role, we asked Dr Bob Nairn (pictured), Consultant Pathologist at Crosshouse Hospital, how his field is contributing to the fight against cancer. As he explained, the news on this front is very encouraging.
“Pathology is a subjective science. There are no black or white answers. When my colleagues or I look down a microscope and make a diagnosis or grade a tumour, this is based on individual interpretation through observation. Within the past five years, there have been a number of very exciting developments in pathology which are enhancing these skills to help us achieve consistently more accurate diagnoses.”
Multi-disciplinary
The first development has been to take the pathologists out of their laboratories and into regular multi-disciplinary team meetings to discuss individual cases.
At these meetings, Dr Nairn will join the surgeon, nurse specialist, junior doctors, radiologist and oncologist to consider each patient before agreeing on a treatment plan. “This is hugely beneficial for patients”, explained Dr Nairn. “In these meetings, the details of the clinical examination, radiological findings and pathological diagnosis are drawn together to create a very clear picture of the type and stage of cancer present. The entire team can then be involved in the decision about diagnosis and treatment.
“We’ve also become better organised in other ways. Pathology sub-groups have been set up within the Managed Clinical Networks in the West of Scotland so that pathologists with an interest in specific cancer types can meet to exchange ideas and improve consistency both of diagnosis and of tumour grading. These meetings are helping to create a more consistent and accurate approach to diagnosis and treatment across the West of Scotland.”
New Techniques
Whilst Dr Nairn is enthusiastic about these developments, his real pride lies in the development of the ‘exciting new techniques’ that have become available to aid the diagnosis of cancer in recent years.
One such technique is Immunohistochemistry, or IHC, a process that has been developed to confirm specific cancer types.
Dr Nairn explained: “Cells have a number of internal and external proteins. We can develop antibodies to these proteins and label the antibodies with different markers.
“Research has now enabled us to identify particular antibodies that are specific to certain tumour types. These are known as tumour markers.
“By testing the tissue or cell with these specific tumour markers, pathologists are able to demonstrate the presence of a particular antigen and therefore confirm the presence of a particular cancer.
“The technology is also helpful in confirming whether the disease is primary cancer or if it is metastatic disease when the cancer cells have spread to other parts of the body. For example, a biopsy from the liver can be tested to determine whether it is primary cancer or another type such as thyroid cancer that has spread to the liver.
“Using the same technology, it is also possible to test for the presence of oncogenes – these are modified genes that influence the malignancy of a tumour cell. For certain cancers, such as chronic lymphatic leukaemia, this distinguishes aggressive disease from non-aggressive disease which, in turn, will determine the form of treatment given. These can be used as prognostic markers.”
FISH
The other exciting new laboratory technique that aids diagnosis bears a familiar name. FISH (or fluorescent in situ hybridization) is a complex test. Dr Nairn explained: “FISH can be used to demonstrate mutations in chromosomes by coloured dyes. In some cancers, such as particular brain tumours, these abnormalities provide clinically valuable information that can help us to predict behaviour and aggression of the disease. Once this is known, doctors can tailor treatments to target individual cancers.”
Looking to the future, Dr Nairn is equally optimistic. “These advances – exciting as they may be - are only the beginning. In the next few years, we will learn more and more about the genetics of tumours and be able to identify more tumour makers – and equally importantly – more prognostic markers.
Research using tissue from tumours, such as those donated to the Glasgow Biobank, is vital in this area and this will lead not only to quicker, more accurate diagnosis, but also better tailored, more effective treatments.”
