In Spain, oncology specialists have conducted a large-scale study on the impact of radiation therapy on the sense of smell in patients with head and neck tumors. In recent years, the number of such diagnoses in the country has been steadily rising, and treatment methods are becoming increasingly precise and personalized. However, despite advances in medicine, the side effects of therapy continue to raise serious concerns among both doctors and patients.
During clinical observations, Spanish researchers set out to answer a key question: at what radiation dose does the risk of losing the sense of smell become truly significant? The answer turned out to be less straightforward than previously thought. The researchers focused on patients undergoing treatment with modern intensity-modulated radiation technologies, which allow for highly targeted tumor treatment while minimizing damage to healthy tissues.
Study details
The study involved 63 people with different forms of head and neck tumors. Most were at advanced stages of the disease, requiring the utmost precision and caution in therapy. Special attention was given to those whose tumors were located near the nasal cavity and paranasal sinuses—areas considered the most vulnerable to radiation exposure.
Doctors monitored changes in olfactory function at various stages of treatment and after it was completed. It turned out that some patients experienced a diminished sense of smell after just the first rounds of radiation therapy; however, some showed partial recovery over time. Nevertheless, a significant proportion of participants suffered long-lasting impairment, negatively impacting their daily life and nutrition.
Critical Dose
A key outcome of the study was determining the threshold dose above which the risk of developing olfactory dysfunction rises sharply. Statistical analysis revealed that when the olfactory bulb receives less than 22 gray, the risk of serious impairment is minimal. But once this level is exceeded, 64% of patients experience problems with their sense of smell.
Multifactor analysis confirmed that an average dose above 22 gray is an independent risk factor. The odds ratio for developing olfactory dysfunction reaches 20.65, highlighting how crucial this parameter is for treatment planning. Doctors can now calculate radiation zones more precisely to reduce the likelihood of unpleasant side effects for patients.
Impact on Quality of Life
Loss of smell is more than just a minor inconvenience. For many patients, it becomes a serious issue, affecting appetite, taste perception, and even psychological well-being. Spanish specialists note that early identification of the risk not only allows for adjustments in treatment, but also helps prepare the patient in advance for possible changes, as well as offering options for rehabilitation.
In recent years, increasing attention in Spain has been focused on the quality of life for cancer patients. New data on the critical radiation dose will help doctors tailor treatment to each case, and help patients better understand what to expect during therapy and recovery.
Outlook and new approaches
Research by Spanish oncologists opens up new opportunities to improve radiotherapy protocols. Now, when planning treatment for head and neck tumors, doctors can consider not only how effectively the tumor is destroyed, but also the potential risks to the olfactory system. This is especially important for patients whose professions or lifestyles are closely connected with their sense of smell.
In the coming years, new technologies are expected to be introduced that will allow for even more precise control over radiation dose distribution. Spanish clinics have already begun to revise their standards to minimize side effects and improve patient satisfaction with treatment outcomes.
Incidentally, Chang Gung University, whose specialists participated in the international study, is considered one of the leading centers for research on head and neck cancers. In Spain, its developments are actively being implemented in clinical practice, and local doctors undergo training and exchange experiences with international colleagues. Thanks to this collaboration, Spanish oncology continues to advance, offering patients increasingly effective and safer treatment methods.
