The effect of external beam radiotherapy volume on locoregional control in patients with locoregionally advanced or recurrent nonanaplastic thyroid cancer.
OBJECTIVE
We evaluated outcomes of patients treated with external beam radiotherapy (EBRT) for locoregionally advanced or recurrent nonanaplastic thyroid cancer and analyzed the effect of EBRT volume on locoregional control.


METHODS
This study included 23 patients with locoregionally advanced or recurrent nonanaplastic thyroid cancer who were treated with EBRT. Two different EBRT target volumes were executed as follows: 1) limited field (LF, n = 11) included the primary (involved lobe) or recurrent tumor bed and the positive nodal area; 2) elective field (EF, n = 12) included the primary (involved lobe) or recurrent tumor bed and the regional nodal areas in the cervical neck and upper mediastinum. Clinical parameters, such as gender, age, histologic type, recurrence, stage, thyroglobulin level, postoperative residuum, radioiodine treatment, and EBRT volume were analyzed to identify prognostic factors associated with locoregional control.


RESULTS
There were no significant differences in the clinical parameter distributions between the LF and EF groups. In the LF group, six (55%) patients developed locoregional recurrence and three (27%) developed distant metastasis. In the EF group, one (8%) patient developed locoregional recurrence and one (8%) developed a distant metastasis. There was a significant difference in locoregional control rate at 5 years in the LF and EF groups (40% vs. 89%, p = 0.041). There were no significant differences in incidences of acute and late toxicities between two groups (p >0.05).


CONCLUSIONS
EBRT with EF provided significantly better locoregional control than that of LF; however, further larger scaled studies are warranted.
Kim
Tae Hyun
TH
Center for Thyroid Cancer, Research Institute and Hospital, National Cancer Center, Goyang, Korea. k2onco@ncc.re.kr
Chung
Ki-Wook
KW
Lee
You Jin
YJ
Park
Chan Sung
CS
Lee
Eun Kyung
EK
Kim
Tae Sung
TS
Kim
Seok Ki
SK
Jung
Yoo Seok
YS
Ryu
Jun Sun
JS
Kim
Sang Soo
SS
Cho
Kwan Ho
KH
Shin
Kyung Hwan
KH
D000328:Adult; D000368:Aged; D005260:Female; D006801:Humans; D008297:Male; D008875:Middle Aged; D009364:Neoplasm Recurrence, Local / Q000532:radiotherapy*; D009367:Neoplasm Staging; D011379:Prognosis; D011878:Radiotherapy / Q000379:methods*; D012189:Retrospective Studies; D013964:Thyroid Neoplasms / Q000473:pathology / Q000532:radiotherapy*