The early accurate identification of residual or recurrent disease, distant metastases, and de-differentiation from posttreatment changes is vital in posttreatment imaging and evaluation in order to determine the need for salvage therapy for improved survival. The incidence of recurrent disease following therapy has been reported to range from 6% to 16% with around half of recurrences occurring in the first 2 years [142,143]. The presence of recurrence is associated with increased risk for distant metastatic disease, reported at 30%, with distant metastatic disease the most common cause of death after treatment in NPC [142]. Direct visualization with flexible endoscopy is considered the most sensitive method for detecting mucosal recurrence. However, submucosal and deep-seated recurrences are best identified by imaging, preferably cross- sectional imaging such as MRI or functional imaging with FDG-PET/CT. Additionally, imaging in the setting of treated NPC may be geared toward detecting complications secondary to therapy, which include but are not limited to osteoradionecrosis of the skull base, brain parenchymal radiation necrosis, and infection, among others. The Assessment of Head and Neck Cancer appropriate imaging modality to evaluate each potential suspected complication will depend on the clinical scenario and is beyond the scope of this document. Radiography Chest CXR is not considered the imaging modality of choice for the evaluation of pulmonary metastatic disease in treated nasopharynx cancer or EBV-associated unknown primary of the head and neck. Chest CT is far more sensitive in detecting pulmonary metastatic disease compared to radiography [15], with the sensitivity of CXR to detect pulmonary metastatic disease reported as low as 28% compared to chest CT [11]. The low sensitivity may in part be due to the small size of pulmonary nodules at presentation or peripheral location, in which CXR tends to be less reliable [11].
Staging and Post Therapy Assessment of Head and Neck Cancer. The early accurate identification of residual or recurrent disease, distant metastases, and de-differentiation from posttreatment changes is vital in posttreatment imaging and evaluation in order to determine the need for salvage therapy for improved survival. The incidence of recurrent disease following therapy has been reported to range from 6% to 16% with around half of recurrences occurring in the first 2 years [142,143]. The presence of recurrence is associated with increased risk for distant metastatic disease, reported at 30%, with distant metastatic disease the most common cause of death after treatment in NPC [142]. Direct visualization with flexible endoscopy is considered the most sensitive method for detecting mucosal recurrence. However, submucosal and deep-seated recurrences are best identified by imaging, preferably cross- sectional imaging such as MRI or functional imaging with FDG-PET/CT. Additionally, imaging in the setting of treated NPC may be geared toward detecting complications secondary to therapy, which include but are not limited to osteoradionecrosis of the skull base, brain parenchymal radiation necrosis, and infection, among others. The Assessment of Head and Neck Cancer appropriate imaging modality to evaluate each potential suspected complication will depend on the clinical scenario and is beyond the scope of this document. Radiography Chest CXR is not considered the imaging modality of choice for the evaluation of pulmonary metastatic disease in treated nasopharynx cancer or EBV-associated unknown primary of the head and neck. Chest CT is far more sensitive in detecting pulmonary metastatic disease compared to radiography [15], with the sensitivity of CXR to detect pulmonary metastatic disease reported as low as 28% compared to chest CT [11]. The low sensitivity may in part be due to the small size of pulmonary nodules at presentation or peripheral location, in which CXR tends to be less reliable [11].