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Differences between adjuvant and neoadjuvant treatment

Updated: Apr 17, 2023

There are four cancer stages (I and II localized, III locally advanced and IV metastatic, also called advanced or disseminated).

We call the intention of the treatment adjuvant, neoadjuvant or palliative depending on the moment in which it is carried out:

  • Adjuvant therapy is the treatment that is performed AFTER surgery.

  • Neoadjuvant treatment is the treatment that is performed PRIOR to surgery.

  • Palliative care is focused on providing relief from the symptoms and stress of the illness, with the goal to improve quality of life.

The general objective in adjuvant and neoadjuvant treatment is the same: avoid the appearance of metastases or at least delay them; technically we call it increasing overall survival or increasing relapse-free survival.

When is adjuvant or neoadjuvant therapy used in cancer treatment?

Traditionally, neoadjuvant treatment has been used in cases in which the tumor cannot be operated on, either because it is very large or because it is in contact with important structures that cannot be removed (large blood vessels, some muscles, etc).

In breast cancer, it has also been used to try to preserve the breast in patients who need a mastectomy (remove the entire breast) but who want conservative surgery (remove only the portion affected by the tumor).

For a few years now, neoadjuvant therapy has also been used in cases in which patients can benefit from subsequent treatment if there is residual tumor after the operation. That is, a patient receives neoadjuvant treatment, undergoes surgery, and tumor cells are still seen in the microscopic analysis.

This means that the tumor is resistant to the drugs used in neoadjuvant treatment and that it is therefore more likely to relapse. In these cases, other different drugs can be administered when the patient recovers to try to reverse this increased risk of relapse.

This is the case with certain types of breast cancer, such as triple negative and HER2 positive. It has recently been shown in two clinical trials that capecitabine, in triple negative, and T-DM1, in HER2 positive, increases survival in patients with residual tumors after neoadjuvant chemotherapy.

In this way, we select patients with a poor prognosis and can offer them post-surgery treatment. In adjuvant chemotherapy, in the vast majority of cases, we cannot select patients for drug sensitivity or resistance.

What treatments are used in adjuvant and neoadjuvant?

To date, we use chemotherapy, radiotherapy, and hormone therapy. In recent conferences and publications, positive data have also been presented with other drugs:

  • Immunotherapy, such as the NADIM study in stage IIIA lung cancer

  • Cyclin inhibitors, such as the CORALEEN study in breast cancer

  • Tyrosine kinase inhibitors, such as the ADAURA study, also in lung cancer

What role does neoadjuvant therapy have in research?

Also in recent years, a large number of drugs used in neoadjuvant treatment have been developed in research. Since patients still have the tumor in their body, we can know if these drugs are effective or not by taking measurements and analyzing them. This is done after these drugs have shown activity in animals, and the vast majority also in the metastatic setting.

In adjuvant therapy, as the tumor has already been resected, we cannot know exactly if the drugs are effective at that precise moment. We only know with the passage of time, if the disease reappears or not. This requires a very long follow-up time and delays the appearance of meaningful data in a clinical trial.

If you have more questions about neoadjuvant and adjuvant therapy, please feel free to reach out, we are here to answer your questions and guide you through your care.

Article written by:

Anna Lopez, Doctor in medicine. Medical Oncologist at the León University Assistance Complex , Breast Unit. Resident Tutor. Head of the Clinical Trials Unit.



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