Effect of Timing of Postop Radioactive Iodine Ablation in PTC

NASHVILLE, Tenn. — The timing of postoperative radioactive iodine ablation (RAI) does not appear to affect overall survival in patients with papillary thyroid cancer and high-risk or metastatic features, according to data presented at the American Association of Clinical Endocrinologists (AACE) 24th Annual Scientific & Clinical Congress.

“We made these decisions in the past, and it was thought that if it is cancer you treat it with big guns. But now, we are seeing that we don’t have to shoot big guns at these cancers to provide good care,” said study investigator Tricia Moo-Young, MD, who is an endocrine surgeon at the University of Chicago NorthShore University HealthSystem in Evanston, Illinois.  

“We looked at a delay in treatment. We were surprised that even in patients who were high-risk that delaying treatment didn’t affect their overall survival.”

Moo-Young and her colleagues conducted a large retrospective analysis based on The National Cancer Data Base (NCDB) and queried for papillary thyroid cancer from 1998 to 2006. Their analysis included all patients treated with near, subtotal or total thyroidectomy and adjuvant RAI ablation.  

For this investigation, the researchers categorized patients as high-risk based on American Thyroid Association (ATA) criteria, including tumor size (>4 cm), cervical lymph node involvement or grossly positive margins. They analyzed patients with distant metastatic disease separately.

Among the 9,727 patients in the high-risk group without metastatic cancer, the median and overall survival were similar regardless of the timing of RAI ablation, the researchers found. In addition, there were not any survival differences at any time point.

Controversy surrounds this issue because one previous study (Higashi et al) showed decreased disease-specific survival in metastatic papillary thyroid cancer patients with delay in RAI ablation beyond 6 months, according to Moo-Young.

“It is important to look at this because we are trying to tailor the therapy to the patient. It is not a one-size-fits-all. We want to personalize the care. We want to better understand whether they need aggressive treatment up front,” said Moo-Young in an interview with Endocrinology Advisor. “This study shows us that if a patient comes in that they don’t have to rush in and get treatment. We can tell patients they can wait.”

This is very good news for patient who may benefit from delaying treatment due to other factors, according to Moo-Young. In addition, she said this is reassuring news for clinics where there are problems with resource allocation. Patients who must wait for an available surgery date may no longer need to worry that a delay will harm their chances for overall survival.

The researchers noted that the ATA guidelines recommend adjuvant RAI ablation in high-risk and metastatic papillary thyroid cancer, and treatment within 3 months was considered important. However, that 3-month period does not seem to hold up.  

“It is not like other cancers, such as pancreatic or head and neck cancer, where we know that any delay in treatment may be detrimental,” said Moo-Young. “Not all patients need aggressive treatment and now it is more about cutting back. The treatments do come with side effects.”


  1. Suman P et al. Abstract #1057. Presented at: American Association of Clinical Endocrinologists (AACE) 24th Annual Scientific & Clinical Congress; May 13-17, 2015; Nashville, Tenn.