Iodine content and distribution in extratumoral and tumor thyroid tissue analyzed with X-ray fluorescence and time-of-flight secondary ion mass spectrometry.
BACKGROUND
The thyroid's ability to enrich and store iodine has implications for thyroid cancer genesis, progression, and treatment. The study objective was to investigate thyroid iodine content (TIC) in tumoral and extratumoral tissue in patients with papillary thyroid cancer (PTC) as opposed to thyroid healthy controls using two different techniques: X-ray fluorescence (XRF) and time-of-flight secondary ion mass spectrometry (TOF-SIMS).


METHODS
Tissue samples from 10 patients with normal thyroids and 7 patients with PTC were collected. TIC was quantified with XRF, and the iodine stores were located on a histological level with TOF-SIMS.


RESULTS
Mean TIC in controls was 0.6 mg/mL (range 0.3-1.2 mg/mL). For the cancer patients, the mean TIC was 0.8 mg/mL (range 0.2-2.3 mg/mL) in extratumoral thyroid tissue, but no iodine was detected in the tumors. TOF-SIMS investigation of the PTC patients showed significantly higher TIC in extratumoral tissue than in tumoral tissue. Iodine in the extratumoral tissue was predominantly located in the follicle lumen with a variation in concentration among follicles.


CONCLUSIONS
XRF and TOF-SIMS are two complementary methods for obtaining insight into content and localization of iodine in the thyroid. XRF can be used in vitro or in vivo on a large number of samples or patients, respectively. TOF-SIMS on the other hand provides detailed images of the iodine location. The combined information from the two methods is of value for further studies on iodine metabolism in thyroid malignancy.
Hansson
Marie
M
Department of Radiation Physics, Göteborg University, Göteborg, Sweden. marie.hansson@radfys.gu.se
Grunditz
Torsten
T
Isaksson
Mats
M
Jansson
Svante
S
Lausmaa
Jukka
J
Mölne
Johan
J
Berg
Gertrud
G
D000328:Adult; D000368:Aged; D000369:Aged, 80 and over; D002291:Carcinoma, Papillary / Q000378:metabolism; D016022:Case-Control Studies; D005260:Female; D006801:Humans; D007455:Iodine / Q000032:analysis* / Q000378:metabolism*; D008297:Male; D008875:Middle Aged; D018629:Spectrometry, Mass, Secondary Ion / Q000379:methods*; D013052:Spectrometry, X-Ray Emission / Q000379:methods*; D013961:Thyroid Gland / Q000378:metabolism*; D013964:Thyroid Neoplasms / Q000378:metabolism*; D014018:Tissue Distribution; D055815:Young Adult
D007455:Iodine