One of the priorities in oncology is to carry out early detection and diagnosis. Because the earlier cancer is treated, the better the chances of recovery .
When cancer is suspected, following a clinical examination by the doctor or screening, various examinations are carried out to establish a diagnosis. The examinations performed depend on the location of the tumor mass.
The diagnosis is based on interdisciplinary collaboration. It makes it possible to find the location of the initial (primary) tumor and to measure its extension (stage), to identify as precisely as possible the type of cancer and its genetic particularities, to establish whether the tumor can be removed surgically . The therapeutic strategy is established on all of these results. By going as close as possible to the characteristics of the tumor today , the diagnosis makes it possible to move towards personalized treatments.
Don’t ignore the warning signs
First of all, you should consult before any unusual phenomenon that persists: cough, pain, size, blemish on the skin, digestive problems, urinary tract, wound, bleeding, unexplained weight loss, etc. The first clinical examination is done by the doctor.
A blood test assesses the general state of health and the functioning of the main organs. The presence of particular blood markers can be sought. These are usually proteins produced abnormally high by cancer cells. Their presence is simply a clue for the diagnosis, as it can also sign non-malignant pathologies.
- PSA (prostate specific antigen) in the case of prostate cancer;
- CEA ( carcinoembryonic antigen ) mainly for colon cancer and also for other cancers (breast, lung, pancreas…)
- CA125 for cancer of the ovaries, cervix, lungs…
The first diagnosis is often made via imaging. Considerable progress has been made in recent years in this area. Many techniques coexist; each has its indications, its specificities and its limits.
- Radiography: based on X-rays, it is mainly used as a first approach to detect lung and breast cancers (mammography).
- Scanner (also called computed tomography, or CT): type of radiography which, by taking a succession of images, allows a 3D reconstruction of the organs.
- Endoscopy (or fibroscopy): examination consisting in introducing a camera inside an organ. Depending on the organ, it can be a colonoscopy (colon), gastroscopy (stomach), cystoscopy (bladder), etc.
- Magnetic resonance imaging (MRI): advanced technique based on the use of a magnetic field which provides very precise images of soft tissue.
- Positron emission tomography (PET or PET-Scan): sophisticated technique allowing the detection of rapidly multiplying cells, characteristic of tumors and metastases, using a weakly radioactive tracer. The radioactive substance, a sugar derivative, is absorbed by cancer cells and detected by a special camera.
- Scintigraphy: it reflects the functioning of an organ. It is based on the injection of a weakly radioactive tracer which is specifically fixed on the organ to be studied, in more or less large quantity depending on its structure and activity. The distribution of the tracer, represented by the accumulation of scintillating points, is examined using a camera and computer image processing. This distribution is homogeneous for a healthy organ .
- Tomoscintigraphy: the capture of several images using a mobile camera makes it possible to reconstruct a 3D image of the organ studied.
It consists in taking a sample of tissue in the suspect region to examine it under a microscope (anatomopathological examination) in order to confirm the cancerous nature of the lesion and to determine its characteristics and stage. It is also used to identify genetic alterations present in the tumor (see below).
Genetic and molecular analysis of tumors
It is now possible to list some of them by analyzing the genome (all of the genes) of the tumor. With a dozen genetic anomalies, called markers, it is now possible to stratify a type of cancer (breast cancer for example) into several subtypes that share the same anomalies, therefore similar development mechanisms.
- Offer targeted therapy to counter these mechanisms, if it exists.
- Predict the appearance of resistance to treatment and avoid unnecessary treatments.
- Assess the risk of metastasis.
This recent discipline is interested in cancers that occur in a context of genetic predisposition (5 % of cases). Indeed, certain genetic mutations, greatly increasing the risk of developing certain cancers, are transmitted from generation to generation. In the same family, several people will then develop the same cancer. Thanks to genetic tests, oncogenetics aims to identify patients and their relatives carrying such a mutation to offer them suitable monitoring. In France, a hundred consultations are offered via the national oncogenetics system.
It should be noted that the diagnostic techniques indicated (in particular the assay of biomarkers, medical imaging, genetic and molecular analysis) are also used for monitoring the response to treatments and after remission.