82nd Annual Meeting of the American Thyroid Association:

Selective Use of RAI in Papillary Thyroid Cancer Patients

Radioactive iodine (RAI) has been used in the treatment of papillary thyroid cancer since the 1940s.  However, it is not for everyone, and so risk stratification is necessary to determine patient selection.

The American Thyroid Association (ATA) guidelines for well-differentiated thyroid cancer are based on TNM classification, and the recommend the use of RAI in patients with T3 or greater primary tumors.  They recommend selective use of RAI in patients with:

  • Intrathyroidial disease < 1 cm, or
  • Evidence of nodal metastases.

The ATA guidelines recognize that there is insufficient data to make sure recommendations for most patients on the use of RAI, and so significant inter-hospital variability has developed, as well as an increase in the use of RAI.

The researchers of a study presented at the 82nd Annual Meeting of the American Thyroid Association wanted to look at who they were treating—and not treating—with RAI.  This was done at Memorial Sloan Kettering Cancer Center.

A retrospective review of 1,129 patients was undertaken; they had been treated at Sloan Kettering between 1986 and 2005.  The median age was 46 years (range: 11-91 years).  The male-to-female ratio was 1:2.8.

Every patient reviewed had undergone a total thryoidectomy; following surgery, there was no evidence of macroscopic residual disease.  The breakdown of TNM was:

  • pT1/T2N0:  490
  • pT1/T2N1:  193
  • pT3/T4:  444

Using the GAMES risk stratification model, the patients were assessed to see if they should receive RAI, and therefore, not all patients did receive it.

Using the Kaplan-Meier method, details on disease recurrence and disease-specific survival were recorded and compared using the log-rank test.

There was a median follow-up of 63 months (range 1-282 months).

For patients with early primary disease (pT1/T2) and low-volume metastatic disease in the neck (pT1/T2 N1), some were managed without RAI, and they did well.

For patients with advanced local disease (pT3/T4), certain patients with pT3 did not have RAI, and they did well.

The following chart shows the 5-year DSS and RFS rates.

 

pT2/T2 N0

pT1/T2 N1

pT3/T4

DSS

100%

100%

98%

RFS

92%

92%

87%

The results of this study from Sloan-Kettering “justify the selective use of RAI following initial surgical treatment using a risk group stratification method.”  This further proves that RAI is not to be used in all patients with well-differentiated thyroid cancer and that deciding to recommend RAI must be done on a case-by-case basis.

Next Summary:
What Is the Optimal L-T3 to L-T4 Ratio and Administration Plan for Thyroid Cancer Patients Undergoing Withdrawal?
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