Increased Expression of MicroRNA-221 in gastric cancer and its clinical significance

OBJECTIVE

MicroRNA-221 (miR-221), which is located on chromosome X, is an oncogenic microRNA that is involved in several human malignancies. This study aimed to characterize the role of miR-221 in the initiation and malignant progression of gastric cancer.

METHODS

The level of miR-221 expression in 92 pairs of primary gastric tumour tissue and adjacent nontumour tissue was quantified by real-time reverse transcription-polymerase chain reaction. The relationship between the miR-221 level and clinicopathological features was explored.

RESULTS

MiR-221 was up-regulated in 88% (81/92) of gastric cancer tissue samples compared with their paired adjacent nontumour tissue samples. High expression of miR-221 showed a significant correlation with advanced tumour-node-metastasis stage, local invasion and lymphatic metastasis. Univariate and multivariate Cox proportional hazard regression analyses revealed that miR-221 overexpression was an unfavourable prognostic factor for overall survival in patients with gastric cancer.

CONCLUSIONS

These findings suggest that miR-221 is a novel prognostic indicator in gastric cancer and may be a potential target for diagnosis and gene therapy.

Concordance among gene expression-based predictors for ER-positive breast cancer treated with adjuvant tamoxifen

BACKGROUND

ER-positive (ER+) breast cancer includes all of the intrinsic molecular subtypes, although the luminal A and B subtypes predominate. In this study, we evaluated the ability of six clinically relevant genomic signatures to predict relapse in patients with ER+ tumors treated with adjuvant tamoxifen only.

METHODS

Four microarray datasets were combined and research-based versions of PAM50 intrinsic subtyping and risk of relapse (PAM50-ROR) score, 21-gene recurrence score (OncotypeDX), Mammaprint, Rotterdam 76 gene, index of sensitivity to endocrine therapy (SET) and an estrogen-induced gene set were evaluated. Distant relapse-free survival (DRFS) was estimated by Kaplan-Meier and log-rank tests, and multivariable analyses were done using Cox regression analysis. Harrell's C-index was also used to estimate performance.

RESULTS

All signatures were prognostic in patients with ER+ node-negative tumors, whereas most were prognostic in ER+ node-positive disease. Among the signatures evaluated, PAM50-ROR, OncotypeDX, Mammaprint and SET were consistently found to be independent predictors of relapse. A combination of all signatures significantly increased the performance prediction. Importantly, low-risk tumors (>90% DRFS at 8.5 years) were identified by the majority of signatures only within node-negative disease, and these tumors were mostly luminal A (78%-100%).

CONCLUSIONS

Most established genomic signatures were successful in outcome predictions in ER+ breast cancer and provided statistically independent information. From a clinical perspective, multiple signatures combined together most accurately predicted outcome, but a common finding was that each signature identified a subset of luminal A patients with node-negative disease who might be considered suitable candidates for adjuvant endocrine therapy alone.

PAM50 assay and the three-gene model for identifying the major and clinically relevant molecular subtypes of breast cancer

It has recently been proposed that a three-gene model (SCMGENE) that measures ESR1, ERBB2, and AURKA identifies the major breast cancer intrinsic subtypes and provides robust discrimination for clinical use in a manner very similar to a 50-gene subtype predictor (PAM50). However, the clinical relevance of both predictors was not fully explored, which is needed given that a ~30 % discordance rate between these two predictors was observed. Using the same datasets and subtype calls provided by Haibe-Kains and colleagues, we compared the SCMGENE assignments and the research-based PAM50 assignments in terms of their ability to (1) predict patient outcome, (2) predict pathological complete response (pCR) after anthracycline/taxane-based chemotherapy, and (3) capture the main biological diversity displayed by all genes from a microarray. In terms of survival predictions, both assays provided independent prognostic information from each other and beyond the data provided by standard clinical–pathological variables; however, the amount of prognostic information was found to be significantly greater with the PAM50 assay than the SCMGENE assay. In terms of chemotherapy response, the PAM50 assay was the only assay to provide independent predictive information of pCR in multivariate models. Finally, compared to the SCMGENE predictor, the PAM50 assay explained a significantly greater amount of gene expression diversity as captured by the two main principal components of the breast cancer microarray data. Our results show that classification of the major and clinically relevant molecular subtypes of breast cancer are best captured using larger gene panels.

Increased expression of microRNA-21and its association with chemotherapeutic response in human colorectal cancer

The expression of microRNA-21 (miR-21) was determined in 42 patients with colorectal cancer (CRC) using real-time reverse transcription-polymerase chain reaction. The level of miR-21 in CRC tumour tissue was compared with paired normal adjacent tissue (NAT) and the relationships of miR-21 levels to clinicopathological characteristics and pathological tumour response to neoadjuvant chemotherapy were investigated. There was a significantly higher level of miR-21 in CRC tumour tissue than in NAT and high expression of miR-21 was significantly correlated with advanced clinical stage and poor cell differentiation. Receiver operating characteristic curve analysis indicated a maximum optimal cut-off cycle threshold value of 10.32 for differentiating pathological responders from non-responders, with a sensitivity of 80.0% and specificity of 88.2%. These data showed that miR-21 was significantly overexpressed in CRC tumour tissue and was associated with advanced CRC, and that miR-21 may be a potential candidate biomarker for predicting pathological tumour response to chemotherapy.

Early levothyroxine treatment on maternal subclinical hypothyroidism improves spatial learning of offspring in rats

Maternal hypothyroidism has adverse effects on neural development in the offspring. The present study aimed to investigate whether maternal subclinical hypothyroidism impairs spatial learning in the offspring, as well as the efficacy and optimal time of levothyroxine (L-T(4)) treatment in pregnancy. Female adult Wistar rats were randomly divided into six groups (n = 10 per group): control, hypothyroid (H), subclinical hypothyroid (SCH) and SCH treated with L-T(4), starting from the tenth, thirteenth and seventeenth gestational day (GD10, GD13 and GD17), respectively, to restore normal thyroid hormone levels. Spatial learning was assessed on progenies by a water maze test, a field excitatory postsynaptic potential (fEPSP) recording, and an long-term potentiation induction assay. Protein levels of early growth response protein 1 (Egr1), activity-regulated cytoskeleton-associated protein (Arc), Ras-proximate-1 (Rap1), p-extracellular signal-regulated kinase (p-ERK) and brain-derived neurotrophic factor (BDNF) were determined by western blotting. Progenies from the SCH and H groups demonstrated significantly longer mean latency in the water maze test and a lower amplification percentage of the amplitude and slope of the fEPSPs compared to offspring of the control group. L-T(4) treatment for the GD10 and GD13 groups significantly shortened mean latency and increased the amplification percentage of the amplitude and slope of the fEPSPs of the progeny of rats with subclinical hypothyroidism. However, L-T(4) treatment for the GD17 group showed only minimal effects on spatial learning in the offspring. Progenies of SCH and H groups had lower levels of Egr1, Arc, p-ERK and BDNF but higher levels of Rap1 compared to those of the controls. L-T(4) treatment ameliorated these protein expression changes in the progeny of rats with subclinical hypothyroidism. Maternal subclinical hypothyroidism impaired spatial learning in the offspring; L-T(4) treatment in early pregnancy recovered this adverse effect, and the optimal time of treatment should start from early pregnancy (GD10 and GD13).

S5-2: PAM50 HER2−Enriched Subtype Enriches for Tumor Response to Neoadjuvant Anthracyclines/Taxane and Trastuzumab/Taxane Containing Regimens in HER2−Positive Breast Cancer

Background: Patients with clinically HER2−positive (clinHer2+) tumors often receive trastuzumab in combination with chemotherapy as their standard of care. This study sought to determine the predictive value of the HER2−enriched (HER2−E) molecular subtype for sensitivity to neoadjuvant anthracycline/taxane containing chemotherapy and a trastuzumab plus taxane-based regimen within clinHer2+ disease.

Materials and methods: Gene expression data on pre-treatment fresh-frozen tumor tissues were collected from a combined cohort of MDACC/I-SPY trial (GSE25055/65), and the XeNA trial (GSE22358). Patients from MDACC/I-SPY were treated with doxorubicin/cyclophosphamide (AC) or 5-fluorouracil/epirubicin or doxorubicin/C (FEC or FAC) sequentially with paclitaxel. All patients from XeNA received capecitabine/docetaxel (and trastuzumab if clinHer2+). Intrinsic subtypes were determined using PAM50. Chisquare test and multivariable logistic regression analysis were used to test significance of association between subtype and pathological complete response (pCR or residual cancer burden [RCB] 0/1) and residual disease (RD or RCB2/3) adjusted with pre-treatment tumor size. Kaplan Meier was used for distant relapse-free survival (DRFS) estimates.

Results: For the MDACC/I-SPY cohort (n=595), pCR rates for intrinsic subtypes were 3% (5/168) for LumA, 16% (14/90) for LumB, 33% (23/69) for HER2−E and 37% (76/208) for Basal-like. Tumors achieving RCB0/1 were significantly associated with better DFRS compared to those tumors with RCB 2/3, even within each intrinsic subtype. The 5-year DFRS for HER2−E with RCB0/1 and RCB2/3 was 100% and 31% (p=0.007), respectively. ClinHer2+ status was also significantly associated with pCR (34% vs. 19%, p=0.016). Strikingly, among the clinHer2+ tumors (n=47), 75% (12/16) of the responders were classified as HER2−E (Table 1A) and those tumors that were clinHer2+/HER2−E had 6 times odds to achieve pCR when compared to clinHer2+/non-HER2−E. In the XeNA trial (n=122), the HER2−E subtype was significantly associated with response, composing 85% (7/8) of the clinHer2+ who achieved a pCR. Finally, clinHer2+/HER2−E tumors were 34 times more likely to achieve pCR than clinHer2+/non-HER2−E tumors (Table1B).

Synthesis, characterization and biocompatibility of poly(2-ethyl-2-oxazoline)-poly(D,L-lactide)-poly(2-ethyl-2-oxazoline) hydrogels

A novel thermoreversible hydrogel based on poly(2-ethyl-2-oxazoline)-derived amphiphilic triblock copolymer, poly(2-ethyl-2-oxazoline)-poly(D,L-lactide)-poly(2-ethyl-2-oxazoline) (PEOz-PLA-PEOz), was developed. The synthesis of PEOz-PLA-PEOz was carried out by coupling monohydroxylated PEOz-PLA diblocks with adipoyl chloride as coupling agent and dimethylamino pyridine as catalyst. The tube inverting and rheological tests showed that triblock copolymers had sol-gel-sol transition behavior with increasing temperature, and the gelation was found to be thermoreversible. The critical gelation concentration, the sol-gel transition temperature at a given concentration depended on the EOz/LA ratio and the molecular weight of PEOz. Scanning electron microscopy observation revealed that the resultant bulky gel exhibited an interconnected porous three-dimensional (3D) microstructure after freeze-drying. In addition, the hydrogels showed good cytocompatibility in vitro. MTT assays revealed that the human skin fibroblast cells encapsulated within the hydrogels were viable and proliferated inside the 3D scaffold. This newly described thermoreversible hydrogel demonstrated attractive properties to serve as cell matrix for a variety of tissue engineering applications or pharmaceutical delivery vehicles.

Pathobiology and prevention of cancer chemotherapy-induced bone growth arrest, bone loss, and osteonecrosis

Cancer chemotherapy has been recognized as one severe risk factor that influences bone growth and bone mass accumulation during childhood and adolescence. This article reviews on the importance of this clinical issue, current understanding of the underlying mechanisms for the skeletal defects and potential preventative strategies. Both clinical and basic studies that appeared from 1990 to 2010 were reviewed for bone defects (growth arrest, bone loss, osteonecrosis, and/or fractures) caused by paediatric cancer chemotherapy. As chemotherapy has become more intensive and achieved greater success in treating paediatric malignancies, skeletal complications such as bone growth arrest, low bone mass, osteonecrosis, and fractures during and/or after chemotherapy have become a problem for some cancer patients and survivors particularly those that have received high dose glucocorticoids and methotrexate. While chemotherapy-induced skeletal defects are likely multi-factorial, recent studies suggest that different chemotherapeutic agents can directly impair the activity of the growth plate and metaphysis (the two major components of the bone growth unit) through different mechanisms, and can alter bone modeling/remodeling processes via their actions on bone formation cells (osteoblasts), bone resorption cells (osteoclasts) and bone "maintenance" cells (osteocytes). Intensive use of multi-agent chemotherapy can cause growth arrest, low bone mass, fractures, and/or osteonecrosis in some paediatric patients. While there are currently no specific strategies for protecting bone growth during childhood cancer chemotherapy, regular BMD monitoring and exercise are have been recommended, and possible adjuvant treatments could include calcium/vitamin D, antioxidants, bisphosphonates, resveratrol, and/or folinic acid.

Abstract PD07-09: Hypoxia (VEGF-S) Signature and CRYAB Predict Response to Neoadjuvant Anthracycline/Taxane Containing Chemotherapy within Triple Negative and Unselected Breast Tumors

Background: Aggressive breast tumors are a clinically challenge to manage. A VEGF-signature (VEGF-s) developed in vivo (Hu et al. BMC Med. 09) and the profile of the anti-apoptotic gene and regulator of tumor angiogenesis, CRYAB (Moyano et al. J Clin Invest 06; Dimberg et al. Blood 08), are both associated with distant metastasis. In this study, we sought to test if these two mechanistically related biomarkers predict pathological complete response(pCR) to anthracyline/taxane-based neoadjuvant chemotherapy.

Methods: Gene expression data of pre-treatment fresh frozen tumors were combined, 149 from the ISPY trial (Agilent 44K) and 225 from MD Anderson Cancer Center(MDACC) (Affymetrix HG U133A). Patients from I-SPY were treated with doxorubicin/cyclophosphamide followed by a taxane. Patients from MDACC were treated with paclitaxel followed by sequential fluorouracil-AC. Tumors were classified into intrinsic subtypes using PAM50(Parker et al. J Clin Oncol 09) and Claudin-low(CL) predictor(Prat et al., Submitted). Odds ratios of biomarkers to pCR were determined using logistic regression. Predictive values of multivariable models were estimated using receiver operating characteristic curve. Results: 319 patients had complete data; the pCR rate was similar between the datasets (ISPY 22%, MDACC 20%). Both the VEGF-s and CRYAB were highly expressed within Basal-like(BL) and CL (P<0.0001); these two biomarkers were positively correlated with each other (r: 0.4, P<0.001). In univariate analysis, both VEGF-s (P<0.001) and CRYAB (P<0.001) were significantly associated with pCR. A multivariable test including tumor size, grade, ER, Her2, intrinsic subtypes, VEGF-s and CRYAB, had an AUC value of 0.86 to predict pCR(Table 1). T stage, Her2, intrinsic subtypes and CRYABwere significant.

82 patients with triple-negative tumors within this combined cohort. In univariate analysis, T stage, grade or classifying tumors into BL vs not did not predict pCR; but VEGF-s (p= 0.04) and CRYAB (p = 0.02) were associated with pCR. Multivariable model, including VEGF-s, CRYAB and the clinical variables, had a predictive value of 0.71 to pCR(Table 1), which identified CRYAB as the most significant factor by likelihood ratio test.

Table 1: Multivariable logistic regression models to predict pCR.

Conclusion: VEGF-s and CRYAB expression are associated with aggressive subtypes and may possibly help to predict response of anthracycline/taxane-based neoadjuvant chemotherapy beyond ER, Her2, and intrinsic subtypes.

PTEN inhibits BMI1 function independently of its phosphatase activity

BACKGROUND

PTEN is the second most mutated tumor suppressor gene other than p53. It suppresses tumorigenesis by dephosphorylating phosphatidylinositol (3,4,5)-triphosphate (PIP3) to phosphatidylinositol (4,5)-biphosphate (PIP2), thereby directly inhibiting phosphatidylinositol 3 kinase (PI3K)-mediated tumorigenic activities. Consistent with this model of action, cytosolic PTEN is recruited to the plasma membrane to dephosphorylate PIP3. While nuclear PTEN has been shown to suppress tumorigenesis by governing genome integrity, additional mechanisms may also contribute to nuclear PTEN-mediated tumor suppression. The nuclear protein BMI1 promotes stem cell self-renewal and tumorigenesis and PTEN inhibits these events, suggesting that PTEN may suppress BMI1 function.

RESULTS

We investigated whether PTEN inhibits BMI1 function during prostate tumorigenesis. PTEN binds to BMI1 exclusively in the nucleus. This interaction does not require PTEN's phosphatase activity, as phosphatase-deficient PTEN mutants, PTEN/C124S (CS), PTEN/G129E (GE), and a C-terminal PTEN fragment (C-PTEN) excluding the catalytic domain, all associate with BMI1. Furthermore, the residues 186-286 of C-PTEN are sufficient for binding to BMI1. This interaction reduces BMI1's function. BMI1 enhances hTERT activity and reduces p16(INK4A) and p14(ARF) expression. These effects were attenuated by PTEN, PTEN(CS), PTEN(GE), and C-PTEN. Furthermore, knockdown of PTEN in DU145 cells increased hTERT promoter activity, which was reversed when BMI1 was concomitantly knocked-down, indicating that PTEN reduces hTERT promoter activity via inhibiting BMI1 function. Conversely, BMI1 reduces PTEN's ability to inhibit AKT activation, which can be attributed to its interaction with PTEN in the nucleus, making PTEN unavailable to dephosphorylate membrane-bound PIP3. Furthermore, BMI1 appears to co-localize with PTEN more frequently in clinical prostate tissue samples from patients diagnosed with PIN (prostatic intraepithelial neoplasia) and carcinoma compared to normal prostate epithelium. While PTEN co-localized with BMI1 in 2.4% of normal prostate epithelial cells, co-localization was observed in 37.6% and 18.5% of cells in PIN and carcinoma, respectively. Collectively, we demonstrate that PTEN inhibits BMI1 function via binding to BMI1 in a phosphatase independent manner.

CONCLUSION

We demonstrate that nuclear PTEN reduces BMI1 function independently of its phosphatase activity. It was recently observed that nuclear PTEN also suppresses tumorigenesis. Our results, therefore, provide a plausible mechanism by which nuclear PTEN prevents tumorigenesis.

Notch-associated expression profiles in basal-like and claudin-low breast cancer molecular subtypes

11017

Background: An attractive candidate target for breast cancer (BC) and BC tumor-initiating cells is the Notch signaling pathway. To better understand the potential dependence of breast cancer upon Notch-signaling, we used a genomic approach to study the activation of this pathway in the different molecular subtypes. Methods: Breast basal-like, luminal and HER2+ cell lines were examined for sensitivity to gamma-secretase inhibition (GSI). Gene expression data from the most sensitive cell line was analyzed during treatment and upon releasing from GSI (4h, 8h and 24h post-treatment). Using an unsupervised analysis, all time points were hierarchically clustered and genes that changed in expression were identified (SAM one-class). This Notch-associated signature identified in vitro was used to classify 2 distinct sporadic breast tumor populations (UNC and NKI, n=495). Each tumor sample was categorized into 6 molecular subtypes (basal-like, claudin-low [submitted], luminal A/B, HER2-enriched and normal-like). Results: In vitro, breast basal-like cell lines SUM102 and SUM149 were more sensitive to GSI (IC50, 0.3 and 1.5μM, respectively) compared to the luminal MCF7 (>10μM) and HER2+ SKBR3 (>5μM) cell lines. Over 340 genes that changed in expression (FDR<0.03%) were identified in SUM102, including known targets of the canonical Notch pathway (Hes1 and Hey2). Selected GO terms overrepresented in this signature were the following (EASE score, p<0.01): Wnt and Hedgehog signaling, embryonic development and cell differentiation. In vivo, 2 distinct gene clusters were evident in both populations, one of which was predictive of poor patient outcome. This Notch-associated poor prognostic signature was highly expressed in >90% of basal-like tumors. The second cluster was highly expressed in the recently identified claudin-low subtype, and was uniquely enriched with genes involved in cell differentiation (Sox7/9, Hey2, Dll1, Fzd5) and cell adhesion. Conclusions: Notch associated expression profiles are associated with basal-like and claudin-low BC subtypes, providing additional biological insight of pathway activation. GSI could represent a novel strategy for both subtypes, which represent the vast majority of the “triple negative” population.

No significant financial relationships to disclose.

Low-temperature heat transport in the low-dimensional quantum magnet NiCl2-4SC(NH2)2

We report a study of the low-temperature thermal conductivity of NiCl2-4SC(NH2)_{2}, which is a spin-1 chain system exhibiting the magnon Bose-Einstein condensation (BEC) in a magnetic field. It is found that the low-T thermal conductivity along the spin-chain direction shows strong anomalies at the lower and upper critical fields of the magnon BEC state. In this state, magnons act mainly as phonon scatterers at relatively high temperature, but change their role to heat carriers upon temperature approaching zero. The result demonstrates a large thermal conductivity in the magnon BEC state and points to a direct analog between the magnon BEC and the conventional one.

Building prognostic and predictive models for cancer patients using expression modules and clinical variables

Abstract #5063

Background: Prognostication for breast cancer patients is improving, in part through the use of genomic predictors. However, most predictors only utilize one data type that is gene expression data, and thus prognostication that simultaneously uses multiple data types may result in even more accurate predictors.&#x2028; Methods: We recently developed a unique risk of relapse predictor based upon a Cox proportional hazards model that contained gene expression (5 intrinsic subtypes) and clinical variables (tumor size and node status)(Parker ASCO 2008 abstract #11008). This model was accurate in predicting 7 year relapse probabilities and out performed the genomic or clinical variables only models. Building upon this combined genomic plus clinical parameters approach, we reasoned that including other expression modules indicative of pathway activation and cell type signatures might further improve our models. Therefore we build a collection of &gt;200 expression modules using 1) unsupervised hierarchical and bi-clustering analysis 600 human tumors, 2) similar cluster analyses of 250 mouse mammary tumors, 3) &gt;50 published breast tumor genomic profiles, and 4) signaling pathway activation modules derived from our own work. Each signature, or module, was then used with LASSO variable selection to determine if prognostic Cox Proportional Hazards models could be built using a local therapy and tamoxifen only treated patient set.&#x2028; Results: These analyses show that highly significant prognostic models could be built for 1) all patients, 2) ER-positive patients, and 3) Luminal patients. Less predictive, yet significant models were created Basal-like patients, and no successful models could be developed for ER-negative patients, or for the expression-defined HER2-enriched subtype. For most significant predictors, the Cox model contained human-derived modules, mouse-derived modules, and pathology variables; for example the predictor for ER-positive patients contained human modules for proliferation, hypoxia, an embryonic stem cell derived signature, three mouse modules with one containing multiple metalloproteinases, tumor size and node status. In addition, the actual modules selected for the different patient subsets varied such that the modules selected for the Basal-like patients did not overlap any module selected for all patients, or for the ER-positive patient subset.&#x2028; Conclusions: These analyses further reinforce the idea that breast cancer is a heterogeneous disease and suggest that prognostic models for each important patient subset should be developed and used. Models that contain treatment variables, in addition to prognostic terms, are also being developed and will be presented. In summary, these analyses argue that the best prognostic algorithms for breast cancer patients contain biological variables coming for humans, from model systems, and from classic pathology.

Citation Information: Cancer Res 2009;69(2 Suppl):Abstract nr 5063.

A five-year follow-up study of goiter and thyroid nodules in three regions with different iodine intakes in China

OBJECTIVE

The association between iodine status and the prevalence of goiter and thyroid nodules has been well established but the extent to which different iodine intake levels influence the incidence of goiter and thyroid nodules is unclear. The aim of the study was to determine the incidence of goiter and thyroid nodules in 3 regions with different iodine intake levels: mildly deficient, more than adequate, and excessive.

DESIGN, PATIENTS AND MEASUREMENTS

Of the 3385 unselected subjects enrolled in 1999 in Panshan, Zhangwu, and Huanghua where median urinary iodine excretion (UIE) was 83.5 microg/l, 242.9 microg/l, and 650.9 microg/l, respectively, 2708 (80.0%) participated in the follow-up study in 2004. The examinations of thyroid ultrasonography, thyroid function, thyroid autoantibodies and UIE were performed at baseline and follow-up.

RESULTS

The cumulative incidence of diffuse goiter was 7.1%, 4.4%, and 6.9%, respectively, higher in Panshan and Huanghua than in Zhangwu (p=0.013 and p=0.015) and that of nodular goiter was 5.0%, 2.4%, and 0.8%, respectively, declining with increasing iodine intake levels (p<0.001). Mild iodine deficiency, chronic iodine excess as well as positive thyroid autoantibodies were associated with the occurrence of goiter [Logistic regression: odds ratio (OR)=1.83 (95% confidence interval (CI) 1.26-2.65), OR=1.46 (95% CI 1.01-2.11) and OR=1.68 (95% CI 1.14-2.48), respectively]. The cumulative incidence of single nodule was 4.0%, 5.7%, and 5.6%, respectively and that of multiple nodules was 0.4%, 1.2%, and 1.0%, respectively.

CONCLUSIONS

The relationship between iodine and the risk for the occurrence of diffuse goiter shows a U-shaped curve. Nodular goiters are more prevalent in iodine-deficient areas.