Adjuvant external beam radiation for medullary thyroid carcinoma.
BACKGROUND
Adjuvant radiation is rarely used to treat medullary thyroid carcinoma (MTC). We hypothesized that external beam radiation therapy (EBRT) would improve overall survival (OS) in MTC patients.


METHODS
The Surveillance, Epidemiology, and End Results (SEER) database identified patients who underwent total thyroidectomy and lymph nodes excision for MTC between 1988 and 2004. The Kaplan-Meier method was used for univariate comparisons of OS. Multivariate Cox proportional hazards models controlled for gender, age, lymph node status, tumor size, extent of disease, and EBRT.


RESULTS
After 12 years, EBRT did not significantly improve OS (log rank, P < 0.14). In node-positive patients, univariate analysis demonstrated an OS benefit with EBRT (log rank, P < 0.05). In a multivariate model of node-positive patients, only increasing age (P < 0.001) and tumor size (P < 0.001) significantly influenced OS.


CONCLUSIONS
The OS benefit attributed to EBRT in node-positive patients by univariate analysis could not be duplicated when controlling for known prognostic factors.
Martinez
Steve R
SR
Division of Surgical Oncology, Department of Surgery, UC Davis Cancer Center, University of California at Davis, Sacramento, California 95817, USA. steve.martinez@ucdmc.ucdavis.edu
Beal
Shannon H
SH
Chen
Allen
A
Chen
Steven L
SL
Schneider
Philip D
PD
D000367:Age Factors; D018276:Carcinoma, Medullary / Q000401:mortality* / Q000473:pathology / Q000532:radiotherapy* / Q000601:surgery; D005260:Female; D006801:Humans; D008197:Lymph Node Excision; D008297:Male; D008875:Middle Aged; D016016:Proportional Hazards Models; D018714:Radiotherapy, Adjuvant; D018426:SEER Program; D013964:Thyroid Neoplasms / Q000401:mortality* / Q000473:pathology / Q000532:radiotherapy* / Q000601:surgery; D013965:Thyroidectomy