The factors that condition the choice of a treatment with hadrontherapy are related mainly to the type of cancer and its natural history, i.e. its evolutionary behavior from the moment it occurs.
The histotype or the histology of the tumor (the type of healthy cell from which a tumor originates) is one of the most important factors that determines the decision for treatment with hadrons. There are certain types of cancers which have a particular capacity for rapid growth and microscopic spread to other organs which may not be visible in normal diagnostic tests. These types of tumors do not benefit from local treatments such as hadrontherapy, but need a systemic or pharmacological treatment that prevents the cancer’s spread.
- Metastasis or the spread of the disease to other organs or tissues is often a criterion used to reject treatment with hadrons. When the disease has affected other organs far from its origin, it means that cancer cells have spread through the blood and/or lymphatic system. In these cases, local treatments such as radiotherapy or surgery must be substituted with systemic treatments that act in a widespread, i.e. diffuse, way.
- Radiosensitive tumors. Tumors that require low doses of radiation to avoid their recurrence and to be “cured” do not need the relatively sophisticated treatment represented by hadrontherapy. In such cases X-ray radiation therapy has proven itself to be both effective and sufficient.