Small thyroid cancer, most often papillary thyroid microcarcinoma, is common and usually slow growing. While active surveillance is an option for carefully selected patients, expert evaluation and surgery remain the most definitive way to achieve cure and long-term peace of mind.

Understanding Small Thyroid Cancer

Small thyroid cancer, specifically papillary thyroid microcarcinoma, has become one of the most frequent thyroid cancer diagnoses today. Patients often arrive frightened, holding an ultrasound report with the word “carcinoma,” and their instinct is almost always the same: remove it immediately.

For decades, that instinct was correct.

Today, the conversation has evolved. Thanks to long-term data from Japan and validation in the United States, observation is now discussed as an option in select cases. This approach is reflected in the 2025 American Thyroid Association guidelines.

However, this is not a decision to take lightly. Watching a small thyroid cancer requires as much expertise, and often more, than removing it.

What Is Papillary Thyroid Microcarcinoma?

Papillary thyroid microcarcinoma is defined as a papillary thyroid cancer measuring 1 centimeter or less.

These cancers are most often discovered incidentally during imaging performed for other reasons such as carotid ultrasounds, CT scans, or MRI studies. Physical examination rarely detects these tumors.

Key facts about small thyroid cancer:

• Definition: Papillary thyroid cancer ≤ 1.0 cm

• Typical prognosis: Excellent, with survival greater than 99 percent

• Detection: Usually incidental

Modern imaging has dramatically increased detection. The critical question is whether all small thyroid cancers require immediate treatment. Increasingly, the answer is no, but that does not mean they are harmless.

The Japanese Experience and Active Surveillance

The concept of active surveillance originated at Kuma Hospital in Kobe, Japan. In 1993, Dr. Akira Miyauchi and Dr. Yasuhiro Ito proposed monitoring small thyroid cancers instead of removing them immediately.

Their hypothesis was that most small thyroid cancers are biologically indolent. After nearly 30 years of follow-up, the data supported this conclusion.

Key findings from Kuma Hospital:

• Only about 8 percent of tumors grew by 3 mm or more over 10 years

• No patient died of thyroid cancer

• Patients who later required surgery had outcomes equivalent to immediate surgery

Age matters

Younger patients demonstrated higher progression rates than older patients. This finding is counterintuitive but critical.

10-Year Tumor Progression Rate by Age

The American Experience: Confirming the Data

Dr. Michael Tuttle at Memorial Sloan Kettering Cancer Center replicated the Japanese surveillance protocols in the United States.

The results were remarkably consistent.

These data confirm that small thyroid cancer can be safely observed in carefully selected patients under expert supervision.

Who Is a Candidate for Surveillance?

Not every small thyroid cancer is suitable for observation.

At the Clayman Thyroid Center, strict exclusion criteria are applied. Surgery is recommended if any high-risk features are present:

• Tumors adjacent to the recurrent laryngeal nerve or trachea

• Any lymph node involvement

• Extrathyroidal extension

• Significant patient anxiety

Patient anxiety is a medical contraindication. If knowing you have cancer causes ongoing distress, observation is not appropriate.

The Lymph Node Trap in Small Thyroid Cancer

One of the most underestimated risks in small thyroid cancer is occult lymph node metastasis.

Our research, presented at the American Thyroid Association Annual Meeting, demonstrated that:

• 97 percent of standard neck ultrasounds are incomplete

• Metastatic lymph nodes are present in 40 to 60 percent of so-called low-risk patients

• Central neck spread is common even with normal imaging

Observation may monitor the thyroid but miss cancer already present in the lymphatic system.

The Young Patient Reality

The Japanese data itself argues against surveillance in younger patients.

Patients in their 20s demonstrate a lifetime progression risk approaching 50 percent. For these individuals, surveillance often means delaying inevitable treatment rather than avoiding it.

Anatomy of Risk: Why Waiting Can Matter

Small thyroid cancers eventually grow. As they enlarge, they may invade nearby structures:

• Recurrent laryngeal nerve: Permanent voice changes

• Trachea: Airway invasion requiring complex surgery

Even minimal growth in the wrong direction can significantly alter outcomes.

Thermal Ablation for Small Thyroid Cancer

Thermal ablation techniques such as radiofrequency, microwave, and laser ablation are increasingly discussed for small thyroid cancer.

These approaches destroy most of the primary tumor but do not address lymph nodes.

Critical limitations:

• Central neck lymph nodes remain hidden behind the thyroid gland

• Ultrasound surveillance of lymph nodes becomes less reliable

• Microscopic disease may persist

Thermal ablation is not equivalent to curative surgery.

Comparison of Management Options

The Expert Solution: Cure Without Compromise

The argument for surveillance is often rooted in fear of complications. That fear is justified when surgery is performed by inexperienced surgeons.

In expert hands, a thyroid lobectomy is a 30-minute outpatient procedure with near-zero complication risk and high cure rates.

Why live with constant monitoring and uncertainty when cure is achievable?

Quick Facts About Small Thyroid Cancer

• Most small thyroid cancers are papillary microcarcinomas

• Survival exceeds 99 percent

• Lymph node spread is common even in small tumors

• Observation requires expert ultrasound and judgment

• Surgery provides definitive cure and peace of mind

Frequently Asked Questions

Is small thyroid cancer dangerous?
Most small thyroid cancers grow slowly, but some progress and spread to lymph nodes.

Is surgery always necessary?
No, but it remains the most definitive and curative option.

Who should consider active surveillance?
Older patients with centrally located tumors and no lymph node disease.

What is the safest option long-term?
Expert surgery offers cure without ongoing uncertainty.

In Summary

If you have a small thyroid cancer, you have time. The choice is not urgency versus delay, but expertise versus risk. Whether you choose observation or surgery, your outcome depends on the quality of your evaluation and the experience of your care team.

Written by: Dr. Gary Clayman, MD, FACS, FACE, Founder & Medical Director, Clayman Thyroid Center
Chief Medical Officer, Hospital for Endocrine Surgery

Reviewed by: Dr. Jim Norman, MD, FACS, FACE, Founder of the Norman Parathyroid Center at the Hospital for Endocrine Surgery

References

• Miyauchi A, Ito Y, Oda H. Active surveillance for papillary thyroid microcarcinoma: Current evidence and future perspectives. Endocrine Journal. 2018.

• Ito Y, Miyauchi A, Kihara M, Higashiyama T, Kobayashi K, Miya A. Patient age is significantly related to the progression of papillary microcarcinoma of the thyroid under observation. Thyroid. 2014.

• Tuttle RM, Fagin JA, Minkowitz G, et al. Natural history and management of papillary thyroid microcarcinoma. Endocrinology and Metabolism Clinics of North America. 2019.

• American Thyroid Association. Management guidelines for adult patients with thyroid nodules and differentiated thyroid cancer. Updated 2025.

• Clayman Thyroid Center. Small thyroid cancer, papillary thyroid microcarcinoma, and lymph node management educational resources. ThyroidCancer.com.