Active surveillance—careful monitoring instead of immediate surgery—is a safe and effective strategy for managing micropapillary thyroid carcinoma (a small thyroid cancer measuring less than 1 centimeter), according to this comprehensive clinical review by experts from Memorial Sloan Kettering Cancer Center. The review examines data from major international studies involving thousands of patients, showing that fewer than 10% of tumors grow during observation, only 2–3% develop lymph node metastasis, and no patients under active surveillance have died from thyroid cancer. The authors provide detailed guidance on identifying ideal candidates for this approach, monitoring strategies, and when surgery becomes necessary.
The rapid rise in thyroid cancer incidence is well documented worldwide. In the United States, the incidence of thyroid cancer has risen almost four times over the last quarter century, while in South Korea it has risen approximately 15 times. This dramatic increase is primarily related to incidentally detected micropapillary carcinomas—tiny thyroid cancers found during routine ultrasound evaluations of the thyroid, often for unrelated reasons.
This surge has resulted in what experts call overdiagnosis and overtreatment. Interestingly, likely due to growing appreciation of this problem, thyroid cancer rates have actually fallen in Korea and stabilized in the United States in recent years. The medical community has generated considerable debate about the impact of diagnosing and treating these tiny cancers on patient outcomes and healthcare costs.
Historically, the standard of care for any thyroid cancer diagnosis was an appropriate thyroidectomy (surgical removal of the thyroid gland). However, the old dictum of routinely using radioactive iodine has been essentially abandoned in patients with micropapillary carcinoma. Today, treatment choices include:
Clearly, it would be almost impossible to operate on every micropapillary carcinoma diagnosed as an incidental finding. Autopsy studies frequently identify incidental, asymptomatic micropapillary carcinoma—meaning many people live with these tiny cancers without ever knowing. As the authors put it: "People live with it, they grow with it, and most of them will die with it and not of it."
There are, of course, legitimate concerns about thyroid surgery, including neck scarring, complications and side effects of surgery, the need for lifetime thyroid medication, and lifelong follow-up. Even though most patients do well with thyroid replacement therapy, there are quality-of-life concerns after thyroidectomy that deserve careful consideration.
The concept of active surveillance for micropapillary thyroid carcinoma was first proposed in 1993 by Dr. Miyauchi from Kobe, Japan, after careful consideration of the natural history of these tumors. He and his team conducted a landmark study involving approximately 2,153 patients with microcarcinoma—55% of whom were on active surveillance while 45% underwent immediate surgery. This number continues to grow as more patients agree to active surveillance.
The results were striking. The disease remained stable in more than 92% of patients. Approximately 5% of patients eventually went to surgery, either because of an increase in tumor size or the patient's unwillingness to continue monitoring. New appearance of lymph node metastasis was noted in less than 1%, and an increase in the size of the primary tumor occurred in only 3% of patients.
From all active surveillance studies combined, the data consistently show that less than 10% of tumors will grow and approximately 2–3% will develop nodal metastasis over 5–10 years of observation—none of which has a major impact on long-term outcomes. Critically, no patients under active surveillance have died of thyroid cancer or developed major cancer-related problems in any of the published studies.
In 2017, Tuttle and colleagues from Memorial Sloan Kettering Cancer Center (MSK) published their large series of approximately 291 patients—the first study of its kind in the United States. Continued surveillance was maintained in 96% of patients. Approximately 4% underwent surgery due to an increase in tumor size or concerns of the patient and family. None of the patients died of thyroid cancer.
With active surveillance, immediate surgery is avoided in favor of continuous monitoring. This approach is known by several names: active monitoring, expectant management, vigilant observation, watchful masterly inactivity, or deferred intervention. The key principle is that this is not inferior treatment—it is a deliberate, evidence-based choice for appropriately selected patients.
One of the challenges revolves around the nomenclature used by pathologists—the word "cancer." As the "C" word is unsettling for most patients, who understandably worry about tumor growth, family responsibilities, or even death, some practitioners have proposed changing the name to papillary microtumor or IDLE (Indolent Lesion of Epithelial Origin). The authors believe most patients will understand the philosophy of observation if we use the analogy of prostate cancer and continuous monitoring, which has become widely accepted in urology.
It is important to train primary care physicians, who are often the first to meet with patients, about the benefits of active surveillance. There should also be more publicly available information and education about this approach. Active surveillance is not inappropriate management—it may be considered as deferred intervention in properly selected patients.
Physicians sometimes worry about medicolegal issues, but expansion of public knowledge will help address these concerns. It is crucial to develop well-defined selection criteria and standardized follow-up protocols to offer patients. Patients can change their mind at any time and opt for surgery. The success of an active surveillance program requires multidisciplinary involvement with surgeons, endocrinologists, radiologists, and other physicians working together as a disease management team.
The principles behind active surveillance become clearer when considering real patient scenarios. The authors present two contrasting cases:
Case 1: An 85-year-old man undergoes a routine carotid ultrasound and the sonographer finds a 5-mm nodule in the right lobe of the thyroid. The family insists he undergo a fine-needle aspiration biopsy of this tiny nodule, which is reported to be papillary carcinoma. What now? The authors note that very few surgeons or endocrinologists would mandate immediate surgical intervention in this scenario. It is quite likely this nodule has been there for a while and can be easily monitored.
Case 2: A 25-year-old female medical student undergoes a routine ultrasound of the neck during a radiology rotation and is found to have a 7-mm nodule on the right side and a 5-mm nodule on the left side. At the insistence of the radiologist, she undergoes a biopsy on both sides, and both show papillary carcinoma. What should be done?
Obviously, the optimal treatment with a diagnosis of carcinoma on both sides would be total thyroidectomy. However, in a 25-year-old woman with a long life ahead, credible academic responsibilities, and proposed family responsibilities, active surveillance is a very reasonable option based on the patient's preferences, values, and risk tolerance. Total thyroidectomy may represent excessive therapy in this patient, requiring lifetime supplementation of thyroid medication. Even in the best of hands, there is a 2% risk of complications related to nerve injury or temporary or permanent hypoparathyroidism (underactive parathyroid glands). Adjusting these patients to thyroid medication may be easy in principle but more difficult in practice—patients often complain that "I just don't feel the same." Quality of life in these individuals needs to be better studied.
In conjunction with Professor Miyauchi, Tuttle and his group from MSK defined three interrelated domains for patient selection: tumor and ultrasound characteristics, medical team characteristics, and patient characteristics. Based on these decision-making domains, a clinical framework was developed to classify patients as ideal, appropriate, or inappropriate for active surveillance.
Many patients may have another concurrent malignancy (a different cancer), which—unlike micropapillary carcinoma—is a major decision maker and should be the focus of initial disease management.
Tumors with irregular margins should be carefully evaluated, as there is a likely higher incidence of both extrathyroidal extension and nodal metastasis. Patients classified as inappropriate for active surveillance include those with:
Even though BRAF (a genetic mutation) has been included in some fine-needle aspiration biopsies, the authors would not consider that a major decision-maker unless the tumor itself shows aggressive clinical features.
Age has always been a concern, but there is good data from Miyauchi's group showing that even young patients can be enrolled into active surveillance, with the understanding that approximately 40–50% may require surgery eventually. However, surgery may be deferred until an opportune time in their life or until there is a distinct increase in tumor size. Interestingly, older patients do very well with active surveillance, with very little tumor growth over time.
Several factors go into the decision-making process for observation. Generally, patients will require serial ultrasounds (repeated ultrasound examinations over time). Initially, the authors prefer to obtain ultrasounds of the thyroid and cervical lymph node chains every 6 months to give confidence to the patient about the stability of the thyroid nodule.
Thyroid hormone therapy is recommended if needed to keep the thyroid stimulating hormone (TSH) in the normal range and less than about 3 mIU/L. Once thyroid function is known to be satisfactory, ultrasounds are usually repeated every year.
For the patient who is a minimalist (prefers less intervention), the follow-up strategy includes ultrasound every 6 months for the first 1 or 2 years, and then every year after that. If there is a substantial change in tumor volume or nodal metastasis, surgery should be considered—which happens in less than 10% of patients according to many studies.
The indications for surgical intervention under observation include:
It should be recognized that active surveillance requires complete understanding in a triangular fashion involving the surgeon, the endocrinologist, and the patient (as well as family members). The strategy of active surveillance will result in approximately 10% migrating from active surveillance to surgery—5% due to an increase in the size of the thyroid nodule or new lymph nodes, and 5% mainly because of patient and family wishes. However, in all reported series, there were no adverse findings either at the time of surgery or in outcomes. Long-term follow-up has been quite satisfactory, with no adverse or deleterious effect on long-term outcome or mortality.
Once again, decision-making rests on the patient, the surgeon, and the endocrinologist who will monitor and follow the patient. It is very important to ensure the patient understands the reason behind active surveillance. The idea is not to defer treatment or offer inferior treatment but to continuously monitor a tumor that the patient may live with for a long time.
Whether a patient will need surgery in the near or distant future is difficult to determine; however, most patients can be monitored very well based on international studies. Several international studies and meta-analyses have shown that the overall risk of an increase in the size of the thyroid nodule is about 3–5%, and new nodal metastasis is noted in less than 2% of people.
The patients who generally switch to surgery are those with considerable anxiety or family members pushing them toward surgery. In this aspect, it is very important to understand the difference between maximalist and minimalist approaches. Pamela Hartzband and Jerome Groopman have published on the subject of medical decision making, including how to decide what is right for you in terms of these approaches.
There must be a good discussion between the patient and the treating physician. It is also important that the surgeon works with an endocrinologist who shares the same philosophy. The decision about surgery versus observation will depend upon a dedicated, high-quality ultrasound to ensure there are no adverse imaging features that would push the patient toward surgery.
There are always cost concerns; however, the whole idea is to try to avoid surgery in these incidentalomas (tumors found incidentally). In principle, a significant number of the general population—approximately 10%—may be harboring microscopic papillary carcinoma, and we do not need to push every one of them toward surgery when the diagnosis is made incidentally. Needless to say, if the tumor is palpable (can be felt) or the patient is symptomatic, they will definitely need surgery.
The philosophy of the maximalist is generally "Why wait? More is better." While minimalists take a "Less is more" approach and feel that any unintended consequences of surgery outweigh potential benefits. This is where the philosophy of believers and doubters, and the idea of technology orientation versus naturalistic orientation, comes in. Patients and their families must understand the philosophy behind observation. The surgeon and the endocrinologist need to explain that this is what they would also recommend for their own family members and that there is no rush to operate, especially in young people who may have concerns about surgical complications.
Although thyroidectomy surgery is generally quite safe, complications do occur in the range of 1–3%, including nerve injury and parathyroid problems. However, it is important to note that complication rates may be significantly higher when thyroid surgery is done outside of major medical centers. Some patients may need thyroid medication, and getting adjusted to thyroid medication and maintaining quality of life are important concerns. The old philosophy "let the punishment fit the crime" is critical in the management of these patients.
It is also important to make the patient and their family aware that the thyroid cancer diagnosis was totally incidental, the tumor is a microcarcinoma, and it is quite likely it may have been there for many years. Patients need reassurance that this particular cancer is not detrimental to their health and will not lead to a major catastrophe in the future. The benefit of monitoring to see if there is any change and deferring surgery until then should be emphasized.
Certain thyroid tumor features are considered adverse and would argue against active surveillance:
Multicentric tumor (tumors in multiple locations within the thyroid) is always a debatable question; however, generally the combination of all multicentricity below 1 cm does not have any major adverse features. Location of the tumor is also important—for example, the disease management team needs to assess whether the tumor is against the posterior wall of the trachea (windpipe) or in other high-risk locations.
The decision-making about active surveillance rests on several factors: tumor volume, tumor location, rate of change of the tumor (doubling time), and the follow-up strategy that can be maintained.
This review has significant implications for patients diagnosed with micropapillary thyroid carcinoma. The key takeaway is that immediate surgery is not always necessary for these tiny cancers. The evidence from multiple international studies involving thousands of patients consistently shows that:
For patients, this means the diagnosis of micropapillary thyroid carcinoma should not automatically trigger anxiety about needing immediate surgery. Instead, patients should have an informed discussion with their medical team about whether active surveillance is appropriate for their specific situation. The decision should consider tumor characteristics (size, location, margins), patient characteristics (age, comorbidities, preferences), and the expertise of the medical team.
The authors emphasize that the decision is more important than the incision—meaning the thoughtful choice of management strategy matters more than the surgical procedure itself. The biology of micropapillary carcinoma is much different from other aggressive human cancers, and treatment should reflect this understanding.
While the evidence strongly supports active surveillance, the authors acknowledge several limitations and uncertainties:
Based on this clinical review, here are actionable recommendations for patients diagnosed with micropapillary thyroid carcinoma:
Based on existing literature and clinical experience, the authors conclude that active surveillance is an appropriate strategy for monitoring micropapillary carcinoma. The key is proper patient selection, a committed multidisciplinary team, and a clear understanding between patients and their physicians about the goals and methods of this approach.
Active surveillance is a strategy of careful monitoring instead of immediate surgery for small thyroid cancers less than 1 centimeter. It involves regular ultrasounds to watch for any changes. This approach is a deliberate, evidence-based choice for appropriately selected patients, not inferior treatment.
Ideal candidates are typically over 60 years old, have a single intrathyroidal nodule with well-defined borders, no extrathyroidal extension, and no lymph node metastasis. They must be willing to comply with regular follow-up and understand that surgery may be needed later. Other health conditions may take priority.
You will have serial ultrasounds of the thyroid and neck lymph nodes. Initially, ultrasounds are done every 6 months for the first 1-2 years, then annually. Thyroid hormone therapy may be given to keep TSH in the normal range. If there is significant tumor growth or new lymph nodes, surgery is considered.
The main risk is that the tumor may grow or spread to lymph nodes, but this happens in a minority of patients. In studies, fewer than 10% of tumors grow, and only 2-3% develop lymph node metastasis. No patients under active surveillance have died from thyroid cancer in published studies.
Surgery is recommended if the tumor increases in size by more than 3 mm or more than 100%, if new lymph node metastasis appears, or if there is direct invasion of surrounding tissues. Patient preference or anxiety can also lead to surgery. About 10% of patients eventually switch to surgery.
Yes, but they have a higher likelihood of eventually needing surgery, approximately 40-50%. However, surgery can often be deferred to an opportune time in their life. The decision should be based on patient preferences, values, and risk tolerance, with a full discussion with the medical team.
Active surveillance avoids the risks of surgery, such as neck scarring, nerve injury, parathyroid problems, and the need for lifelong thyroid medication. It also avoids potential quality-of-life issues after thyroidectomy. Most patients under surveillance never need surgery, and no deaths from thyroid cancer have been reported.
Original Article Title: Active surveillance for micropapillary thyroid carcinoma- a clinical review Tuttle
DOI: 10.21037/gs-22-558
Authors: Ashok R. Shaha, MD, FACS (Head and Neck Service, Department of Surgery, Memorial Sloan Kettering Cancer Center, New York, NY) and R. Michael Tuttle, MD (Endocrinology Service, Department of Medicine, Memorial Sloan Kettering Cancer Center, New York, NY)
Publication: Gland Surgery, Vol 13, No 1, January 2024, pages 100-107
DOI: 10.21037/gs-22-558
Submitted: September 26, 2022 | Accepted: May 8, 2023 | Published online: May 29, 2023
This patient-friendly article is based on peer-reviewed research. It is intended for educational purposes and should not replace professional medical advice. Always consult with your healthcare provider about your specific medical situation.
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