Improving Your Outcome in Papillary Thyroid Cancer

Do You Need a Total Thyroidectomy? What About Radioiodine (RAI) ?

A look the impact that surgery and RAI have on papillary thyroid microcarcinoma outcomes.
A look the impact that surgery and RAI have on papillary thyroid microcarcinoma outcomes. clipart.com

Papillary microcarcinoma is a form of papillary thyroid cancer that is extremely small in size. These small cancers -- microcarcinomas -- make up about half of all the thyroid cancers diagnosed in the United States and Europe in the past three decades.

How Small Is a Papillary Microcarcinoma?

How small is small? Guidelines say that a papillary cancer is a "microcarcinoma" if it is smaller than .4 inches (1 centimeter) in size.

Incidence and Detection

The incidence of microcarcinoma is increasing, primarily due to better detection. These small, asymptomatic tumors tend to be found during ultrasounds and X-rays of the head and neck areas.

Treatment Controversies for Papillary Microcarcinoma

Papillary microcarcinoma is considered to have a very low risk for mortality. However, it's fairly common for it to recur, or persist, so surgery is usually recommended.

Researchers at the 10th European Congress of Endocrinology (ECE) reported on a long-term follow-up study that looked at the results of Mayo Clinic patients with papillary thyroid microcarcinoma. That study found that:

  • Among almost 900 patients who had tumors surgically removed, none had any spread of the cancers in 20 years of followup
  • 20-year and 40-year recurrence rates for thyroid tumors were 6% and 9%.
  • Among the entire study population, less only 3 patients (0.3%) died of papillary thyroid microcarcinoma
  • Survival and mortality rates for the study group did not differ significantly from the control population

The researchers concluded that their findings confirm the following:

  • Papillary thyroid microcarcinoma has an excellent prognosis if the primary tumor is completely removed during surgery.
  • More than 99% of patients with papillary thyroid microcarcinoma are at no risk of a distant spread of the cancer or of dying of thyroid cancer.
  • Postoperative radioiodine remnant ablation did not improve the risk of recurrence or death from papillary thyroid cancer over a 40-year period.

The American Thyroid Association guidelines suggest total thyroidectomy for papillary microcarcinoma that is diagnosed before surgery, and for tumors that are metastatic or invasive, to help ensure that the tumor is completely removed.

The European Thyroid Association (ETA) and the British Thyroid Association (BTA), however, recommend partial thyroidectomy and lobectomy respectively in low-risk patients who don't have any history of radiation exposure. And the American Association of Clinical Endocrinologists suggest that lobectomy (removal of half the thyroid gland) plus isthmectomy (removing the isthmus that connects the lobes) is recommended for low-risk papillary microcarcinoma patients.

Even more controversial is whether radioactive iodine (RAI) -- also known as radioiodine -- treatment is also needed post-surgery to provide the best possible outcome.

While the Mayo study found no benefit, it is generally agreed on that it is recommended for higher-risk papillary microcarcinoma patients, i.e., those who are having a recurrence, have multiple tumors, positive lymph nodes, and/or or any other evidence of spread.

A 2009 study published in the journal Thyroid had surprising results that contradicted the Mayo Clinic study. The 2009 study found that 43% of the papillary microcarcinoma patients studied had spread of their cancer to the lymph nodes within 3 years of surgery, and that less aggressive approaches that don't include radioactive iodine may not be appropriate.

A 2012 article in the Journal of Oncology, however, found that radioiodine treatment is not necessary and does not improve the outcomes/prognosis for papillary microcarcinoma in general -- and was only a benefit in higher-risk patients with larger tumors, where RAI did reduce recurrence rates.

Implications for Patients

The majority of patients who have a partial thyroidectomy still end up requiring thyroid hormone replacement medication. So it may make sense, if you are going to have surgery, and require medication afterwards anyway, to discuss the pros and cons of a total versus partial thyroidectomy with your doctor.

As far as RAI, you should discuss the possible benefits if you have any risk factors, including family history, radiation exposure, previous thyroid cancer, or other concerns. And make sure that your physician is aware of the latest guidelines, so that he/she can assess your risk factors, and make the best possible recommendation regarding postoperative RAI.

Sources:

Arora, N et. al. "Papillary thyroid carcinoma and microcarcinoma: is there a need to distinguish the two? Thyroid 2009;19:473–77 PDF

Carballo, Marilee et. al. "To Treat or Not to Treat: The Role of Adjuvant Radioiodine Therapy in Thyroid Cancer Patients," Journal of Oncology. September 2012, Online

Hay, Ian et. al. "Neither total thyroidectomy nor radioiodine remnant ablation improved long-term outcome in 900 patients with papillary thyroid microcarcinoma treated during 1945 through 2004," Endocrine Abstracts,(2008) 16 P685 Online

Noguchi, S. et. al. "Papillary microcarcinoma." World Journal of Surgery, Volume 32, Issue 5, pages 747-53. May 2008, Abstract

Pearce, E. and Braverman, L. "Papillary Thyroid Microcarcinoma Outcomes and Implications for Treatment," Journal of Clinical Endocrinology & Metabolism, July 02, 2013 Online

Roti, Elio (2008) Thyroid papillary microcarcinoma: a descriptive and meta-analysis study. European Journal of Endocrinology, (2008) 159 659–673

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