Clinical outcomes for unresectable anaplastic thyroid cancer treated with radiation: Impacts of radiation intent and the percentage of life spent receiving treatment.

INTRODUCTION

Patients with unresectable anaplastic thyroid cancer have poor prognosis and treatment usually includes radiation therapy. Due to the long radiation courses, many patients may spend a significant portion of their remaining lives receiving radiation.

METHODS

The National Cancer Database (NCDB) was queried to identify patients with unresectable anaplastic thyroid cancer who received radiation. The Percent Remaining Life Spent Receiving Radiation Therapy (PRLSRT) was calculated for each patient. Treatment intent was determined by total dose and dose per fraction actually received by patient. Randomly assigned test and validation cohorts were used to develop and test the Anaplastic Prognosis Score.

RESULTS

Overall 859 patients received radiation with 69 % being treated definitively. Completion rates were low at 43 % and 49 % for definitive vs palliative intents. Patients receiving definitive RT had longer median survival (3.6 m vs 1.3 m), and had a higher PRLSRT. Patients treated with definitive hypofractionated radiation had similar survival, but lower PRLSRT. Anaplastic Prognostic Score (APS) significantly predicted for OS in both the test and validation cohorts. Overall, the median OS of 5.1 m, 2.7 m, and 1.3 m for group 1, 2, and 3, respectively (p < 0.001). The mean and median PRLSRT and the > 50 % PRLSRT all increased with APS score.

CONCLUSIONS

Many patients treated with definitive intent spent a significant portion of their remaining lives receiving radiation therapy. Anaplastic prognostic score (APS) could accurately discriminate prognosis and may help guide treatment intent. Due to the high PRSPRT and high incompletion rates, definitive hypofractionated radiation could be considered and warrants further study.