| Abstract: |
RT is a common and effective treatment for head and neck cancer but it is also associated with significant acute and chronic complications. These adverse effects are closely tied to the duration and dosage of RT. Acute side effects, such as inflammation and mucositis, can often be managed by adjusting the treatment schedule, but chronic complications are more difficult to control, as they stem from cumulative radiation damage. The most widely accepted theory explaining the longterm effects of RT involves increased fibrosis and reduced vascularity, leading to tissue hypoxia, necrosis, and a heightened risk of infection. These complications often manifest long after treatment, affecting salivary glands, connective tissues, vascular systems, and endocrine or immune functions. These chronic issues represent lifelong challenges for patients, requiring ongoing care to manage symptoms and maintain quality of life. One long-term effect of RT in HNC patients is vascular injury, which can lead to vasculitis, atherosclerosis, and increased risk of stroke. The complexity of the head and neck anatomy and the tumor's proximity to key vascular structures makes it difficult to avoid collateral damage during RT. Ionizing radiation damages endothelial cells, triggering inflammation, oxidative stress, and the formation of atherosclerotic plaques. FDG-PET imaging has emerged as a valuable tool for monitoring vascular inflammation and atherosclerosis after RT. Studies have demonstrated its ability to track glucose uptake in inflamed tissues, providing a noninvasive method to detect vasculitis early. Additionally, the use of NaF-PET offers promising insights into atherosclerotic plaque formation by identifying areas of microcalcification, a key marker of cardiovascular risk. Early detection and monitoring are critical in preventing severe outcomes such as strokes in these patients. Central nervous system (CNS) complications from RT, such as PNS and radiation necrosis, are also significant concerns in HNC patients. PNS, where cancer spreads along nerve pathways, is associated with a poor prognosis. Early detection and optimal RT target volume delineation are crucial for improving outcomes, and FDG-PET has shown excellent sensitivity in identifying PNS, outperforming MRI, which can struggle to detect these changes due to inflammation caused by radiation. FDG-PET is also valuable in differentiating between radiation necrosis and tumor recurrence, a critical distinction that influences treatment decisions. Although the precise mechanisms of radiation necrosis are still debated, PET imaging has shown promise in identifying necrotic tissue, aiding in early diagnosis and management. In conclusion, while radiation therapy is an essential component of HNC treatment, its longterm effects on vascular, connective, and nervous tissues demand careful monitoring. Imaging techniques like FDG-PET and NaF-PET play a pivotal role in detecting and managing radiation-induced complications, helping clinicians make informed decisions about patient care. |
