Hierarchy of treatment variables affecting outcome of 131I therapy in thyroid cancer patients with lung metastases.
OBJECTIVE
To assess the correlations between the first 131I activity value, time interval between the courses of radioiodine treatment and the overall number of courses required for total destruction of lung metastases in patients with differentiated thyroid cancer with metastatic lesions in lungs.


METHODS
27 patients with differentiated thyroid cancer with metastases in lungs have been treated with radioiodine after surgical intervention. Activities administered amounted from 1600 to 7980 MBq. The number of radioiodine courses before total ablation of all metastatic lesions amounted from 1 to 10. Time interval between the 1st and the 2nd courses amounted from 3.5 to 11.5 months (6 months in average). The regression analysis of the data has been made.


RESULTS
The exponential model fits the actual number of courses as a function of the first-second activity value and time interval between the courses. The first activity has a decisive influence on the number of courses required for total metastases ablation. The greater was the first activity value, the lesser was the overall number of courses. Increasing time interval between 1st and 2nd courses to 10 months seems to result in reducing the number of courses. Nevertheless even in the case of high activities the probability to undergone less then 3 courses is low. According to the proposed model in thyroid cancer patients with metastases in lungs the first activity should be not lesser than 6000 MBq, time interval between treatments--approximately 10 months.


CONCLUSIONS
The results of our study suggest that individual factors such as histology, the number and the size of metastases in lymph nodes could not contribute more to the final outcome than the treatment variables, namely the first-second activity and time interval, nor could they affect the hierarchy of the effects revealed for the treatment variables.
Department of Nuclear Medicine, Institute of Oncology, Kiev 03022, Ukraine. oko@mail.ru
Oksana V
OV
Kozak
Georgiy G
GG
Sukach
Oksana I
OI
Korchinskaya
Alexander M
AM
Trembach
Viktoria L
VL
Turicina
Natalia U
NU
Voit
D000328:Adult; D017677:Age Distribution; D002454:Cell Differentiation; D005260:Female; D006801:Humans; D007457:Iodine Radioisotopes / Q000493:pharmacokinetics / Q000627:therapeutic use*; D008175:Lung Neoplasms / Q000378:metabolism / Q000532:radiotherapy* / Q000556:secondary*; D008297:Male; D011379:Prognosis; D019275:Radiopharmaceuticals / Q000493:pharmacokinetics / Q000627:therapeutic use*; D015996:Survival Rate; D013964:Thyroid Neoplasms / Q000378:metabolism / Q000473:pathology* / Q000532:radiotherapy*; D013997:Time Factors; D016896:Treatment Outcome
D007457:Iodine Radioisotopes; D019275:Radiopharmaceuticals