Research ArticleCLINICAL INVESTIGATIONS

The Dental Safety Profile of High-Dose Radioiodine Therapy for Thyroid Cancer: Long-Term Results of a Longitudinal Cohort Study

Martin A. Walter, Christian P. Turtschi, Christian Schindler, Peter Minnig, Jan Müller-Brand and Beat Müller
Journal of Nuclear Medicine October 2007, 48 (10) 1620-1625; DOI: https://doi.org/10.2967/jnumed.107.042192

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  • TABLE 1

    Participants' Baseline Criteria (n = 176)

    CharacteristicFindingValue
    SexFemale126 (71.6%)
    Male50 (28.4%)
    Age at radioiodine treatment (y)Median48.4
    Range17.6–86.3
    Thyroid cancer entityPapillary110 (62.5%)
    Follicular65 (36.9%)
    Unspecified*1 (0.6%)
    TNM stageT1, T2, T3, T422 (12.5%), 89 (50.6%), 24 (13.6%), 21 (11.9%)
    Tx20 (11.4%)
    N0, N1, N270 (39.8%), 29 (16.5%), 3 (1.7%)
    Nx74 (42.0%)
    M0, M151 (29.0%), 3 (1.7%)
    Mx122 (69.3%)
    Number of radioiodine treatment cycles1, 2, 3, 4, 5, 633, 125, 11†, 5†, 0, 2†
    Median2
    Range1–6
    Cumulative 131I activity (GBq)‡≤3.7, 3.8–7.4, >7.428, 90, 58
    Median7.4
    Range1.9–35.0
    131I score0, 1, 2, 3, 4128 (72.7%), 1 (0.6%), 7 (4.0%), 0 (0%), 17 (9.7%)
    No scan23 (13.1%)
    Follow-up (y)Median6.6
    Range1.0–32.6
    Observed period (patient-years)Before radioiodine8,472
    After radioiodine1,421
    Frequency of tooth brushing (per day)1, 2, 3, 410 (5.7%), 93 (52.8%), 49 (27.8%), 7 (4.0%)
    >42 (1.1%)
    No information15 (8.5%)
    Additional dental care tools§0, 1, 2, 326 (14.8%), 72 (40.9%), 46 (26.1%), 13 (7.4%)
    >31 (0.6%)
    No information18 (10.2%)
    Additional caries prevention‖No, yes136 (77.3%), 19 (10.8%)
    No information21 (11.9%)
    Xerostomia before radioiodine therapyNo, yes138 (78.4%), 2 (1.1%)
    No information36 (20.5%)
    Caries before radioiodine therapyNo, yes18 (10.2%), 69 (39.2)
    No information89 (50.6%)
    Tooth extractions before radioiodineNo, yes100 (56.8%), 21 (11.9%)
    No information55 (31.3%)

    • ↵* One patient had received thyroidectomy in South Africa and pathologic files were unavailable.

    • ↵† Multiple treatment cycles (>2) were administered for reablation (6 cases) or metastatic disease (12 cases).

    • ↵‡ GBq = gigabequerels (convert values from gigabequerel to curies by dividing by 37).

    • ↵§ Dental floss, tooth picks, mouth rinsing.

    • ↵‖ Fluoride rail, fluoride gel, fluoridated tooth paste.

    • ↵ After written and oral invitation, the respective dentists were not willing or able to provide data.

  • TABLE 2

    Risk Factors for Early (n = 176) and Late (n = 121) Endpoints

    EndpointRisk factor*Odds ratio unadjustedP valueOdds ratio adjusted†P value
    Sialadenitis‡Age0.997 (0.98–1.02)0.790.99 (0.97–1.02)0.59
    Male0.67 (0.32–1.39)0.280.59 (0.26–1.37)0.22
    Iodine activity1.03 (0.96–1.10)0.401.03 (0.94–1.13)0.53
    Iodine score1.28 (1.04–1.58)0.0201.31 (1.05–1.63)0.015
    Xerostomia‡Age0.99 (0.97–1.02)0.551.00 (0.98–1.03)0.76
    Male1.66 (0.74–3.75)0.221.79 (0.92–3.48)0.09
    Iodine activity1.11 (0.98–1.25)0.0881.15 (1.04–1.29)0.010
    Iodine score1.52 (1.09–2.11)0.0141.58 (1.16–2.16)0.004
    Sialadenitis2.37 (1.28–4.41)0.0062.88 (1.64–5.07)0.001
    % increase unadjusted% increase adjusted†
    Caries§Age1.5 (−0.1 to 3.2)0.071.4 (−0.3 to 3.2)0.12
    Male−13.1 (−51.2 to 54.8)0.63−11.0 (−32.7 to 82.8)0.68
    Iodine activity−2.0 (−9.6 to 6.3)0.63−3.2 (−9.5 to 3.4)0.33
    Iodine score−3.1 (−27.5 to 29.7)0.83−14.7 (−33.9 to 10.1)0.22
    Sialadenitis35.9 (−7.5 to 99.9)0.12−15.6 (−41.9 to 22.5)0.37
    Xerostomia82.0 (10.9 to 199)0.01898.8 (26.5 to 212)0.003
    Prior caries39.3 (18.6 to 63.7)0.00132.2 (12.0 to 56.1)0.001
    Tooth brushing10.6 (−18.3 to 49.7)0.52−10.4 (−37.5 to 28.5)0.55
    Tooth extraction§‖Age−1.32 (−4.40,1.85)0.41−0.72 (−4.27, 2.97)0.70
    Male−26.4 (−75.0–116.5)0.58−45.1 (−85.4,106)0.37
    Iodine activity6.91 (0.74–13.5)0.038.14 (1.07, 15.7)0.02
    Iodine score−7.5 (−43.8–52.4)0.76−1.19 (−41.6, 67.2)0.96
    Sialadenitis16.3 (−33.9, 105)0.60−10.6 (−56.2, 82.3)0.76
    Xerostomia2.24 (−58.9, 154)0.96−25.7 (−73.1, 105)0.57
    Prior caries1.14 (−30.6, 47.3)0.957.50 (−29.6, 64.1)0.74
    Date of radioiodine therapy−5.46 (10.3,-0.42)0.03−5.11 (−10.9, 1.02)0.10
    Tooth brushing−28.7 (−64.0, 41.3)0.33−39.6 (−72.1, 30.7)0.20

    • ↵* The respective units are as follows: age, per year; male, vs. female; iodine activity, per GBq; iodine score, per gland; sialadenitis, per gland affected; prior caries, per site; tooth brushing, times per day.

    • ↵† Adjusted for all other covariates in the list.

    • ↵‡ Estimates were obtained from binomial regression models and refer to individual sites.

    • ↵§ Estimates were obtained from Poisson regression models and refer to individual sites.

    • ↵‖ Number of tooth extractions after radioiodine therapy in patients without prior extractions.

    • Corresponding 95% confidence intervals are in parentheses. Boldface type indicates statistical significance of the respective covariate.

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