Active Surveillance and Surgery Outcomes in Low Risk Papillary Thyroid Cancer

This is a prospective, observational multi-center study, building on an initial single-centre study from Toronto, Canada (ClinicalTrials.gov Identifier: NCT03271892). Adult patients with small, low-risk papillary thyroid cancer may choose either active surveillance (close follow-up with the intention of surgery if the disease progresses or if the patient changes their mind and wants surgery) or immediate thyroid surgery (thyroidectomy). Patients who choose active surveillance are clinically followed at the participating study centre and those who choose surgery, receive usual care from their treating surgeon and/or other thyroid cancer specialists.

Thyroid cancer clinical and treatment outcomes are tracked (by medical record review) at least yearly for up to 10 years after enrollment. Patients are also asked to complete study questionnaires (patient reported outcomes) yearly for up to 5 years.

The underlying assumption in the study is that since patients' disease management goals differ for individuals choosing active surveillance and those choosing surgery, 'successful' disease management is defined differently for these patient groups. For patients choosing active surveillance, successful disease management may be defined by avoiding thyroid surgery for thyroid cancer progression (i.e. thyroid cancer that has grown or spread to other tissues). For patients choosing surgery, the ultimate goal is cure of the thyroid cancer (i.e. no thyroid cancer detected at long-term follow-up).

The primary analysis in this study is a description of how often patients' initial disease management goals are not achieved at long-term follow-up. For this study, 'failure' of disease management is defined as follows: a) in active surveillance group - surgery for disease progression, and b) in the immediate surgery group - requiring additional treatment for persistent or recurrent thyroid cancer (i.e. thyroid cancer that is detected and treated in follow-up). Thyroid cancer clinical and treatment outcomes as well as patient questionnaire outcomes will be reported.

Inclusion criteria

• Patients 18 years of age or older.
• Newly diagnosed previously surgically untreated papillary thyroid cancer (PTC) or suspicious for PTC on fine needle aspiration biopsy of the thyroid. PTC must be < 2 cm in maximal diameter on thyroid ultrasound.
• The absence of metastatic cervical lymphadenopathy or gross extrathyroidal extension of PTC, as confirmed on neck ultrasound imaging.
• The absence of other current absolute indication for thyroid or parathyroid surgery (e.g. severe hyperthyroidism that cannot be controlled medically, large goitre with severe compressive symptoms, or primary hyperthyroidism meeting surgical criteria).

Exclusion criteria

• Metastatic thyroid cancer (lymph nodes or distant).
• History of prior thyroid surgery for any indication.
• The primary PTC being on the trachea or immediately adjacent to the recurrent laryngeal nerve, and with progression would be deemed to be at high risk of growth into these critical structures.
• Clinical signs, imaging, or laryngoscopy findings suggestive of locally advanced thyroid cancer (i.e. vocal cord paralysis due to the thyroid cancer or any clinical or radiographic signs of extrathyroidal invasion into adjacent structures such as the strap muscles of the neck, trachea or esophagus).
• Known/suspected poorly differentiated or non-papillary thyroid cancer.
• Medically unfit for surgery due to severe co-morbidity. Severe comorbidity may include another active malignancy with limited life expectancy of < 1 year).
• Pregnancy at the time of study enrollment.
• Unable/unwilling to provide informed consent for the study or comply with study follow-up procedures due to current active physical limitations/medical co-morbidity, cognitive, or psychiatric impairment substance abuse, or other reasons.