Bilan

Personalised medicine’s impact: far beyond the person

At the beginning of this century, thanks to an impressive international effort, scientists working on the complete sequence of the human genome were able to describe some three billion pairs of nucleobases that build up our DNA. This decoding of the human genome was a great advance in our knowledge and led to the possibility of a number of innovative medical applications, including personalised or genomic medicine. This medicine uses new methods of molecular analysis to better manage a patient’s disease or their predisposition towards a particular disease. Oncology on the starting-blocks

Ten years after the sequencing of our genetic heritage, advances in biotechnology are now suggesting huge opportunities for genomic medicine. Recent research focuses on the identification of genetic variations that affect a gene’s activity in very specific populations. The results of this research will have significant implications for understanding susceptibility to rare as well as to common diseases.

The medicine that has benefited the most from those advances in genetics is oncology, the study and treatment of cancer. Molecular biomarkers are regularly used as diagnostic and prognostic tests. The genetic characteristics of a tumour or a particular physiology – for instance, modifying the metabolism of anti-tumour drugs – are used to determine the most appropriate treatment for each patient, and so the most effective and least likely to cause side effects. And another field of research has grown up: predictive oncology. This allows the risk of developing certain types of cancer to be specified with a genetic blood test. It is estimated that 5 to 10% of all patients diagnosed with cancer are people with high genetic predispositions to the disease.

Since 1995, the oncogenetic and cancer prevention unit of the University Hospitals of Geneva has been offering a specialist consultation to people with an individual medical or family history of cancer. This consultation sets out to determine the probability of the existence of a genetic predisposition to some types of cancers, with the aim of adjusting the follow-up and prevention of acknowledged risks. Being a carrier of a genetic susceptibility doesn’t necessarily mean you will develop a cancer, but it does mean that your risk is significantly greater than that of other individuals from the general population.

People who use this consultation service are likely to have various motivations. One could be afraid of developing the disease because of their family history. Another may want to know the risk of developing another tumour after one bout of illness. Finally, someone else could be afraid of transmitting the disease to their offspring.

Some individuals only ask for genetic screening in order to get to know their own risk. The information gained may then be used to start a follow-up or prevention programme. In other cases, the genetic investigation and its results may be useful for other family members. But some subconscious aspects may also play an important role in the patient’s request. Patients may want to know the real ties within their family and could, with the new information, adopt a new family history. Indeed, the “individual” and “family” dimensions often intersect. Sent to the oncogenetic consultation by a treating physician or specialist, patients may clarify their request during the various consultations provided.Family stories

At the first consultation, the medical history of family members for at least three generations is taken. This information is put down onto the family tree and will help in assessing whether a mutation conferring a cancer predisposition is present in the person or another family member and accordingly whether to propose, when appropriate, genetic screening.

The public is generally aware that the presence of several cases of malignant tumour in the same family branch might mean that it could be passed from one generation to another. Yet an individual patient using the consulting service might not know that genetic testing will often have implications for other family members.

When medical information about various members of the family is gathered at the first consultation, the stories often mention scenarios that go beyond the strictly biological or medical. They are often re-adapted according to the subjective experience of the person who tells them. Evoking words like “cancer”, “history” or “death” may bring back painful, conflictual, repressed memories. Depending on how the history is taken or who is interpreting it, and depending on the patient, what is passed on from one generation to another may also concern personality, habits and beliefs.

If the patient has never had cancer, genetic testing may be offered to another member of their family who has developed a tumour at some point. That person’s genetic predisposition could then be considered as the trigger. Once identified, this mutation may then be sought in other relatives. So the results of a genetic analysis contain important information for the entire family, and may be used to set up a follow-up and prevention programme. Disclosing these results may have some serious family implications, and the members concerned may not necessarily be prepared to take in the information. Difficulties may arise when the bonds within the family are broken or a family member has kept their disease secret.Conflicting dimensions

Importantly, those cancer predisposing mutations are specific to a given family. This situation, as well as the fact that the person is confronted with genetics, can assume a symbolic role within the family. This sense of affiliation could bring out mixed feelings. First, the patient could want to reject their relationship to their family. They could also think they are the ones who passed on the mutation and therefore feel guilty – or be angry about inheriting it. Humans can identify themselves as unique individuals on a biological level, but also feel affiliated to a family or even a group. These conflicting dimensions also appear during the consultations, revealing the need for several sessions in order to deal with the complexity of the issues.

One purpose of predictive medicine is to be able to offer follow-up and prevention adapted to the risk, together with the most effective medical treatments, as part of a “personalised” medicine. New discoveries in genetics are helping doctors to target the therapy more effectively.

The prospects for genomic or personalised medicine are indeed remarkable, but genetics cannot entirely solve the complexity of living organisms and their related diseases. Environmental, behavioural and biological characteristics such as age and gender should always be taken into account. And growing access to genetic information, especially outside a strict specific medical environment – DNA tests are already available on the Internet – could lead to major dilemmas regarding the interpretation of these tests as well as their impact, particularly on a socio-psychological level.

By Marta

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