What is the role of nuclear medicine in thyroid cancer treatment?

Verified by Dr. Anand Zade, Sr. Consultant & Head Nuclear Medicine, Apollo Cancer Centres, Navi Mumbai.

Thyroid cancer can pose a significant threat to one’s health. Fortunately, advancements in medical technology have equipped us with powerful tools for diagnosis and treatment, including nuclear medicine. Let us understand the crucial role nuclear medicine plays in the management of thyroid cancer, exploring its applications in diagnosis, therapy, and follow-up care.

Diagnosis with precision

• Thyroid cancers usually present as nodules or lumps in the neck region. The majority of the lumps or nodules in thyroid are benign or non-cancerous. Thyroid scans are done in a specific clinical setting where Blood TSH level is low. It helps to assess the probability of having cancer and avoid further additional tests.  
• Tc-99m pertechnetate is a dye similar to iodine which is taken up by the thyroid tissue. Cancer cells have a lower ability to concentrate and hence appear as areas of low uptake (cold spot) on a scan. Thus, high uptake (seen as a hot spot) on scan virtually rules out the possibility of cancer and no additional tests are required.  However, a cold nodule can be due to various non-cancerous causes also such as simple cyst, colloid nodule, adenoma etc. Hence it needs to be evaluated further with ultrasound neck and FNAC where a small sample of the nodule is aspirated with the help of a needle. It is examined under a microscope by the pathologist who determines the true nature of the nodule.  

Targeted Therapy

• Treatment of thyroid cancer is primarily surgery. Small amount of thyroid tissue which remains in neck after surgery could harbor cancer cells and may cause disease recurrence in future. To destroy these cells and decrease the chances of recurrence, radio-iodine ablation treatment is given. 
• Thyroid cells and thyroid cancer cells both have the ability to concentrate iodine. This property of cancer cells is exploited to kill the cells remaining after surgery. Radioactive iodine (I-131) emits beta radiation which is internalized by thyroid cells. It then kills the cell due to radiation effects from within. 
• To maximize efficacy and success rate of treatment the patient is not on any levothyroxine medications for 4 weeks. A Sr TSH > 30 µIU/ml is desirable. 
• Also, the patient is asked to follow an iodine restricted diet for 2 weeks prior to therapy. This helps to decrease the iodine pool in the body which in turn ensures the majority of the iodine concentrated by the thyroid cells is radioactive iodine.  
• A low dose whole body radioiodine scan is done prior to therapy which helps us to know the regions in body which are concentrating radioiodine.  
• The radioactive iodine therapy is carried out in Nuclear Medicine Department approved by the Competent Authority (AERB in India). Radioactive iodine is administered as an oral solution. The dose administered depends on the extent of spread of disease. The patient might need admission to a dedicated isolation room in Nuclear Medicine department for 1-2 days depending upon the dose administered. After discharge the patient is asked to follow radiation protection measures. There are no major side effects. Some patients may experience nausea, vomiting, dryness of mouth and altered sensation. These are non-serious and self-resolving side effects. 
• Radioiodine therapy is a simple and very effective way of treating thyroid cancer.

Follow-up

• Even after successful thyroid cancer treatment, monitoring for recurrence is crucial in thyroid cancer management. The patients are followed up with sonography of neck and blood tests like serum thyroglobulin and anti-thyroid antibody. In case any residual or recurrent disease is suspected a low-dose radio-iodine scan is done. Depending upon the scan findings, radio-iodine therapy may be performed. 
• Nuclear medicine helps in the monitoring of disease with its sensitive imaging techniques.  

Nuclear medicine has revolutionized the landscape of thyroid cancer management. From precise diagnosis to targeted therapy and vigilant follow-up, its applications offer a comprehensive and effective approach to combatting this disease. As research continues to refine these techniques and explore new possibilities, nuclear medicine promises to play an even greater role in securing a brighter future for patients with thyroid cancer.

Consult our expert, Dr. Anand Zade, Sr. Consultant & Head Nuclear Medicine, Apollo Cancer Centres, Navi Mumbai for nuclear medicine and therapy.

Call 022 6280 6280 for an appointment.