Chemotherapy

The purpose of chemotherapy is to kill the cancerous cells. It may be prescribed:

• As an adjuvant treatment once the tumour has been removed, to ensure that no cancerous cells remain.
• As a neo-adjuvant treatment, to reduce the size of the tumour before surgery: this helps to limit potential after-effects linked to the surgery.
• In the case of metastatic disease, to treat the whole organism.

There are many types of chemotherapy, which are used according to the characteristics of the cancer.

Chemotherapy is frequently administered intravenously. It is usually performed in the form of sessions lasting from a few minutes to several hours, in a day hospital. The sessions are repeated every two to three weeks.

Chemotherapy can also be administered orally in the form of a tablet, which can be taken at home.

Chemotherapies have one major drawback: they are unable to make a distinction between cancerous cells and healthy cells. They therefore destroy a large part of the rapidly renewed cells of the organism. This explains the many possible side effects, such as loss of hair, problems with the nails or skin, and nausea. Oftentimes, chemotherapy also causes a temporary decrease in the immune defences, so patients must therefore be given advice on how to react in case of infection.

Hormone Therapy

Some cancers, in particular various breast and prostate cancers are sensitive to sex hormones, and the latter stimulate the growth of cancerous cells. By blocking the hormone receptor on these cancerous cells, they are prevented from proliferating.

Some side effects may arise, such as vaginal dryness or a drop in libido, but these are totally reversible when treatment has ended. Hormone therapy is usually very effective, in particular for the treatment of hormone-dependent breast cancers (almost three-quarters of all such cancers), for which it is often prescribed in addition to chemotherapy. It has caused a drop in mortality linked to breast cancer.

Immunotherapy

Immunotherapy involves using the immune system to eliminate cancer cells, just as it works to attack bacteria and viruses. Rather than targeting the cancer cells directly, this treatment teaches the immune system to recognize and destroy them. This type of treatment can target various cells involved in the immune response.
Immunotherapy covers several therapeutic approaches and has been very successful in recent years. Some immunotherapy treatments are already authorized and others are still being assessed.

• Therapeutic vaccines against cancer: Traditional vaccines specifically activate the immune system so that it can defend itself against bacteria or viruses. Vaccines against cancer teach the immune system to attack cancer cells. This teaching process involves presenting the immune system with a protein located on the tumors. The only approved vaccine to date treats advanced forms of prostate cancer. Others are still being studied.
• Unlocking the immune system to enable it to attack cancer cells: This is the strategy that has been the most highly developed in recent years. Everything started from a simple observation that cancer cells are able to bypass the immune system by activating immune response inhibitors known as immune checkpoints. There are already several treatments using antibodies capable of blocking the action of the immune checkpoints and thus “unlocking” the immune system to enable it to reject tumors. These treatments have already proven effective in several tumor locations, among others in lung cancer, melanoma and kidney cancer. Today, the majority of patients unfortunately don’t respond to these treatments and research must continue to increase the number of people that can benefit from immunotherapy. Some options are already promising, and a number of trials are underway to expand the list of cancers than can be cured using immunotherapy.

Targeted Therapy

Targeted therapies have revolutionised anti-cancer treatment. They consist of targeting a particular part of the cancerous cell and blocking that target, which is involved in the information chain responsible for cell proliferation. The cancerous cell can thus no longer replicate itself. These therapies are therefore based on the molecular profile of the tumour and no longer on its location: the same therapy can function for cancers on different organs if they carry the same molecular particularity. To find out, it is necessary to analyse the DNA of the cancerous cell and go in search of anomalies for which a targeted therapy may serve. They are often prescribed in addition to chemotherapy.

Today, some 30 targeted therapies exist, divided into several families: the antibodies, which attack a specific target at the surface of the cell; the inhibitors, which instead enter the cell to block a reproduction phase; and in 2013 another type, based on immune checkpoint inhibitors, underwent rapid development. The researchers realised that the cancerous cells sometimes had the power to lower the immune defences that could have flushed them from the organism. Some therapies now make it possible to block the lymphocyte receptors sensitive to cancerous attacks: they are not eliminated, and can continue to exterminate the cancerous cells. The treatment thus helps the organism to defend itself against cancer. These techniques are now producing promising results in the treatment of cancers which usually have a poor prognosis, such as some lung and bladder cancers.