In January 2016, the American Thyroid Association (ATA) guidelines stated that very low-risk thyroid cancer (eg, papillary carcinoma, no larger than 1 cm in diameter, no metastases or local invasion; no other invasive tumors detected by pathology) may not require surgery for now, and that aggressive periodic follow-up reviews are sufficient.
A US study published in October 2017 “loosened the reins” on this criterion. The researchers followed 291 patients with papillary carcinoma for an average of 25 months and showed that papillary carcinoma with a tumor diameter of no more than 1.5 cm on ultrasound is low risk; only 10% to 15% will grow more than 3 mm within 5 years of first detection. This new US study also echoes a previous landmark study from Japan.
This Japanese study showed that the “safe line of growth” for papillary cancer is 3 mm in diameter. This means that if the tumor grows less than 3 mm in diameter between 2 exams (the first review 6 months after the first tumor is found and then 1 review per year), the tumor is considered “safe” and does not need surgery for now and can be followed up; but above this threshold, surgery is recommended.
To summarize, for smaller (less than 1.5 cm), lower-risk papillary cancers, this new study favors follow-up and close monitoring of disease progression rather than resection at the first sign. This group of patients is expected to be spared the trauma of surgery and medications that may last a lifetime.
Of course, this remains to be confirmed by more studies.