Final answer:
The next step in monitoring for residual or metastatic thyroid cancer post-resection is to employ diagnostic imaging with radioactive iodine and to check serum thyroglobulin levels. Additional imaging techniques like CT scans and MRIs, as well as biopsies of suspicious lesions, are also utilized as part of the comprehensive surveillance strategy.
Step-by-step explanation:
When monitoring a patient for residual or metastatic thyroid cancer after a thyroidectomy, the next step typically involves the use of radiopharmaceuticals for diagnostic imaging. Thyroid cells, including cancerous ones, actively absorb iodine which is why radioactive iodine, especially I-131, is used in both diagnosis and treatment of thyroid cancer. For postoperative monitoring, a patient may undergo a whole-body scan using radioactive iodine to detect any remaining or newly developed cancer cells. Furthermore, regularly checking the patient's serum thyroglobulin level can be an indicator of thyroid cancer recurrence since the level should be very low or undetectable after complete thyroidectomy and successful ablation.
Additional tests such as ultrasonography, computed tomography (CT) scans, or magnetic resonance imaging (MRI) can be employed to provide more detailed images of any suspicious areas. It's not uncommon to combine these methods with fine-needle aspiration biopsy of any suspicious lesions to confirm the diagnosis. Monitoring of cancer survivors after treatment is fundamental, including the use of biomarkers, such as elevated AFP in patients previously treated for tumors like teratoma, to suggest relapse.