- Nodule shrinkage not removal. Unlike surgery, RFA shrinks but doesn’t entirely remove a nodule. This has important implications that patients should consider:
- Nodules can regrow. Some untreated tissue will remain after RFA which has the potential to regrow in the future. If sufficient regrowth occurs this could result in symptoms returning and possibly the need for repeat treatment. Nodule regrowth is normally seen in about 10 to 15% of cases and could be seen as early as 2 to 3 years after treatment in some cases. Regrowth is generally not an issue with surgery where the entire nodule or gland is excised.
- Some benign non-cancerous nodules can contain cancer. We know from studies that after surgical removal of thyroid nodules anywhere between 3% – 10% of nodules are found to contain small cancers within them (this could be within the nodule for which treatment was mainly being performed or another nodule in the removed gland) . These are mainly low risk cancers which are unlikely to have caused a problem in the future. Equally these cancers would not have been identified if patients had undergone RFA. To mitigate this risk, patients who undergo thyroid RFA have a clinical assessment, ultrasound scan and fine needle sampling of the nodule before RFA and patients are followed up with ultrasound scans afterwards. There still however remains a small risk of an undiagnosed thyroid cancer.
- Gradual shrinkage. Unlike with surgical removal of a nodule, RFA does not achieve an immediately noticeable shrinkage. The largest proportion of shrinkage normally occurs over 1 to 3 months and thereafter more modest shrinkage occurs up to a year and some times beyond.
- Poor shrinkage. A proportion of nodules may shrink poorly. This is more likely to be an issue with larger nodules. This means that patients may require more than one treatment if their symptoms or cosmetic issues remain unresolved. Poor shrinkage could also mean patients end up having surgery. Large nodule size as well as multiple nodules is a limiting factor in RFA treatment.
- Longer term follow-up. After RFA the nodule and patients symptoms should be monitored, normally with an initial scan at 1 to 3 months after treatment and then at 1 year if there is satisfactory progress. Most guidelines also recommend longer term follow up of RFA treated thyroid nodules. This is both to assess nodule shrinkage (which can occur not only over several weeks and months but also beyond a year) and to monitor for possible nodule regrowth which can occur much later. A shorter follow up might be acceptable for much smaller nodules if there has been very significant shrinkage. Routine follow up is not necessary for surgically treated patients.
