The genetic portrait of a tumor

Imagine that you or someone around you has cancer. Until now, both for diagnosis and treatment, a fragment of malignant tissue was extracted and observed under a microscope, which was supplemented by other tests depending on the type of ailment. This whole process was used to name a tumor, see how it could be addressed and how to proceed with treatment. 

A new medical phase has begun. Through a sample, specialists can now perform genome sequencing, a technique that allows obtaining the complete information of cellular DNA and, therefore, a much more detailed account of the disease. Thanks to this test, alterations in the tumor can be detected, which makes it possible to treat the patient with precision oncological therapies.

As various studies are showing, these techniques are more effective and produce fewer side effects in patients than conventional ones.

Basically, this is how the test works: after extracting the patient’s sample, it is prepared with the help of different machines in a laboratory of the American company, Foundation Medicine, the only one that performs next generation sequencing (NGS).

The tumor tissue fragment is then integrated into a special plate, which is then inserted into a computer that has specialized software, capable of analysing the genes in detail.

This intervention provides detailed information on the molecular alterations contained in the tumor and the extent to which each is expressed; identifying these variations is key to knowing how cancer cells grow and proliferate. In addition, the sample is also conventionally examined with a microscope, so that specialists can visualize the morphology and tumour alterations.

The objective of genome sequencing tests

Genome sequencing tests have a dual objective. The first is to know if a patient is prone to develop a certain type of cancer; and secondly, it is to know, once the diagnosis is made, what type of condition we are facing.

In addition, the first application is particularly useful for detecting the disease at an early stage: if a theoretically healthy person is genetically sequenced, specialists will be able to analyze the sample to detect the genes that predispose the disease. When any of these leads are found, physicians will schedule regular consultations with the patient to monitor whether or not the cancer develops.

Minimally invasive tests, such as a liquid biopsy, which is done by taking a blood sample, can help experts to reveal the presence of malignant cells. In the event of a positive diagnosis, genome sequencing would be applied directly to the cancerous tissue. In this way, it is possible to identify if there are one or more predominant alterations within the tumor, and thus choose the most appropriate therapy.

Carcinoma of unknown primary (CUP)

These tests are useful in many tumors, but there is a modality in which they are especially beneficial. These are referred to CUP, which presents a major difference with the rest: it is unknown where the body generates the cellular process by which the cancer is triggered, although it invades one or several parts of the organism. Only with more complex complementary explorations can this origin be determined at times. The advantage of precision oncology is that it does not take into account the location, but the alterations present in the tumor. Therefore, genome sequencing would make it possible to treat this type of disease without further testing.

Another crucial issue in precision oncology is data records: the more information about a particular type of cancer, the more experience it has accumulated so that it can be applied to the treatment of new cases. There is a factor to be taken into account here: data protection.

In this regard, experts from the Foundation Medicine stress two fundamental aspects. Firstly, the patient’s express consent must be obtained to include the details of his or her sequencing in a database; and secondly, it is necessary to preserve anonymity and to harmonise all this information in order to store it and to simplify its interpretation where necessary. Both the medical community and the entities that carry out these analyses are calling for the development of a regulation that will help to protect patients and, in the same way, allow these data to be collected and stored with a regulation as a basis.