Medical dictionary – Masson

• a substance fixed to a molecule or cell that can be identified in small quantities (radioactive, fluorescent substances, etc.) and used for functional investigations. The term tracer is also used;
• a substance indicating a specific disease.

Cancer markers

Substances present abnormally or in excessive rates in the serum, indicating cancer.

Genetic and molecular markers

A DNA sequence, variable according to the individual, whose localisation is perfectly known.

This DNA sequence can be identified specifically. Markers are used in genetic mapping to "signpost" the genome.

The Public Health Code (article L.5111-1) defines a medicinal drug as a “substance or compound presented as possessing properties that can cure or prevent diseases in humans and animals, and as any substance or compound that can be used in humans and animals or that can be administered to them, in view to formulating a medical diagnosis or restoring, correcting or modifying their physiological functions through pharmacological, immunological or metabolic action”.

Drugs used to combat cancer mainly comprise cytostatics (chemotherapy) that destroy cells that divide rapidly, such as tumour cells, antihormones (hormonotherapy) which inhibit the hormones favouring certain cancers, and immunotherapy drugs that help the immune system to eliminate cancer cells. Drugs stemming from recent so-called targeted therapies combat the development of tumours, by acting specifically on certain proteins that participate in the multiplication of cancer cells and the formation of blood vessels that nourish them.

A melanoma is a cancerous tumour that develops from skin cells called melanocytes that synthesise skin pigment. 11,000 new cases are diagnosed every year in France. Prolonged exposure to UV rays and the accumulation of the mutations that it causes are the main avoidable risk factor of this cancer. A melanoma can become serious if it propagates in the body. Targeted therapies and immunotherapy have recently demonstrated significant benefits in the treatment of this difficult cancer.

Certain cells in a malignant tumour can detach from it and migrate in the body via the blood or lymph circulation systems. They fix to and develop on one or several organs at a distance from the initial (or primary) tumour. The liver, bones, lungs and brain are affected preferentially by these “secondary” tumours called metastases.

In biological research, this term can apply to in vitro, in vivo and in silico experiments.

• In vitro models are cell cultures used to isolate a biological phenomenon or explain a specific action mechanism.
• In vivo experiments use living models. These can be unicellular, such as bacteria. However, to study a complete organism with all its cellular interactions, development and metabolism, as well as human diseases and the effects of candidate drugs, researchers use animals adapted to each case, such as fruit flies, mice, rats and zebra fish.
• As for computer models (in silico), they use mathematical calculations to simulate a biological phenomenon or define the configuration of a molecule active on certain proteins and cells.

In oncology, it has been shown that antibodies specifically recognise cancerous cells. Monoclonal antibodies are synthesised artificially by genetic engineering from a single strain of lymphocytes. This synthesis makes it possible to target certain specific elements (antigens) in cancerous cells. They were initially used to treat leukaemia and lymphomas, used alone or in association with other treatments (chemotherapy).

Since the number of antibodies that can be synthesised is potentially infinite, the scope of therapeutic application widens every year: it is extending to other cancers and other noncancerous diseases.  Monoclonal antibodies can be developed to treat a disease directly or for the targeted delivery of other curative substances.

Motility : the capacity to move spontaneously or by reaction to stimuli.

Motility is the capacity of the cell to perform movements. The different movements of the cytoskeleton, especially those of actin filaments, give the cell its capacity to change its shape, divide and move. Motility is a complex phenomenon influenced by many factors such as hormones, growth factors, chemical attractors, etc.

All cells move at some moment in their lives. At embryonic stage the cells undergo numerous migrations during the differentiation and installation of different tissues: this process is called organogenesis.
Nonetheless, cells such as spermatozoa are more specialised in movement. These cells are endowed with specific organs called flagella.

As with all its creations, nature has built the apparatus of our motility in a way so ingenious and so simple that the result is an admirable harmony

Balzac, Théor. démarche,1833, p.631

A multicentre clinical trial is performed at the same time in several hospitals or clinics, in different departments and with different investigators (sometimes in different countries), but with the same protocol. It can also include a larger number of patients as well as patients with different social, geographical and ethnic origins, which increases the quality of the trial, especially the precision and “generalisability” of the data collected.

In genetics, a mutation is an abnormal and irreversible alteration of genetic material (DNA or RNA).

This modification can occur either spontaneously during cellular division, or under the influence of external agents called mutagens (physical, chemical or biological agents affecting the structure or number of genes or chromosomes). A gene modified in this way is transmitted to daughter cells. Certain mutations have no consequence on the cell. Others constitute the first step in a long process of carcinogenesis. Thus cancer is considered as a genetic disease since it starts at the scale of a gene inside a cell. Nonetheless, cancer is not a hereditary disease.

Called by its more precise name of “multiple myeloma” or Kahler’s disease, this cancer forms in the bone marrow where the blood cells are produced. Certain cells of the white blood cell family (B lymphocytes) whose role is to produce antibodies, called plasma cells, become abnormal and proliferate in the bone marrow. The production of healthy red and white blood cells decreases, and the bones become painful and fragile. The term “multiple” stems from the fact that this cancer often affects several bones. Nearly 4,900 people were diagnosed with multiple myeloma in France in 2012.