The ecancer 'Choosing Wisely' conference was held for the first time in Latin America in Santa Cruz, Bolivia. The event had more than 150 registered attendees in addition to 22 speakers from different countries and different specialities in the field of oncology, who presented topics on prevention, oncological surgery, clinical oncology and palliative care, in order to demonstrate the current evidence of how to approach a patient in daily clinical practice based on the human resources, materials and drugs available, trying to offer the maximum benefit to the patient based on current scientific evidence. In addition to addressing issues of vital importance in breast cancer, during the 2 days of the event, updated information generated in recent years was presented, the results of which will change clinical practice. All the experts were in favour of developing strategies and methods that help us to properly select treatments to optimise resources and reduce the economic toxicity of the most modern and current treatments. This conference was an event of vital importance because it was the first face-to-face event for ecancer and the physicians after difficult years due to COVID-19.

Recent advances in cancer treatment such as PD-1/PD-L1 checkpoint inhibitors have prompted multiple research studies to determine all of the factors that influence response or failure to these new treatments. One of those identified factors is myeloid-derived suppressor cells (MDSCs). These cells were identified and described for the first time in 2007 in laboratory mice and cancer patients. Previous studies showed that a greater number of MDSCs was directly related to a greater tumour volume. There are two clearly identified subpopulations: Mononuclear-type myeloid-derived suppressor cells (M-MDSCs) and polymorphonuclear (PMN-MDSCs). These cell population subtypes play a very important role, depending on the type of cancer, since they have the particularity of expressing PD-L1, which interacts with PD-1, inhibiting the expansion of cytotoxic T lymphocytes, promoting resistance to these treatments.