EPIDEMIC OF THYROID NODULES. HOW ARE THEY BEING FOUND?

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1 EPIDEMIC OF THYROID NODULES. HOW ARE THEY BEING FOUND? Jessica K. Levine, BA Robert A. Levine, MD, FACE, ECNU Thyroid Center of New Hampshire Introduction Thyroid nodules are epidemic. Approximately 4% of the population has a thyroid nodule palpable on physical examination. Far more are detectable with ultrasound study. It is estimated that with high-resolution ultrasound approximately 50-60% of the population will have a discernible nodule. Over the past seven years the discovery of thyroid cancer has doubled with an approximately 57,000 cases diagnosed in the US in Paralleling this increase in cancer, the number of biopsies performed in the US has dramatically increased (doubled) to 450,000 per year. We sought to evaluate how thyroid nodules were detected, and whether a correlation exists between the method of detection and rate of malignancy. METHODS The medical records of 200 consecutive patients referred for evaluation of thyroid nodules were reviewed. All consultations were performed by a single physician (Robert A. Levine, MD, FACE, ECNU) at the Thyroid Center of New Hampshire. The mode of discovery of the nodule was determined from the medical record. Major categories included detection at a physical examination by the referring clinician, being found by the patient, and being incidental discovery at another diagnostic study such as CT, MRI, or carotid ultrasound. Additional information reviewed included age and sex of the patient, size and number of nodules, whether a biopsy was performed, and if biopsied, whether benign or malignant. RESULTS Mode of Discovery Of the 200 cases, 67 (33.5%) were found on other imaging studies, including 35 CT scans, 15 MRI studies, and 8 carotid US studies. 75 (37.5%) were found on physical examination. Twenty four (12%) were initially found by the patient. Thirty four (17%) cases were found when a thyroid ultrasound was ordered for other reasons, such as abnormal thyroid function tests. Within the 17% in which the nodule was found for other reasons, in half there was no clear indication for an ultrasound initially being performed. Biopsy was performed in 141 (70%) cases and not performed in 59 cases (30%). In 42 cases biopsy was not performed due to the nodule not meeting current guidelines for biopsy, based on size and lack of suspicious ultrasound features. In 4 cases biopsy was not performed due to age and co-morbidities. Two patients had a benign biopsy prior to consultation. Biopsy was not performed in 9 cases due to the presence of Hashimoto s thyroiditis without significant or suspicious nodules. In two additional cases no nodule was present. Incidence of Cancer Related to Mode of Discovery Twelve of the 141 biopsies (8.5%) were surgically confirmed as cancer. Of these 12 cases seven were initially detected during physical examination, and 3 were detected by the patient. Only one cancer was found in patients referred due to an abnormality detected by another imaging study. One cancer case was detected during ultrasound evaluation of hyperparathyroidism. Thus 9% of the nodules found at physical exam were malignant while only 1.5% of those found incidentally at other imaging were malignant. Within the cancer cases, eight (67%) were lymph node negative and four (33%) had positive lateral lymph nodes. Three cases were T2N1bM0(clin) and one case was T3N1bM1.

2 Discussion Thyroid nodules are extremely common with 4% of the population having a palpable nodule and over 50% having a nodule detectable on high-resolution ultrasound. There has been a dramatic increase in the number of thyroid nodules referred for evaluation over the past two decades. As demonstrated in this study, a significant number of the nodules detected are found incidentally at other imaging studies, including CT, MRI, and carotid ultrasound. Prior studies have demonstrated the incidence of incidental thyroid nodules found at CT to range between 16% and 25%. With approximately 375,000 Chest CT scans performed annually on Medicare patients in the United States, the number of incidental thyroid nodules found in Medicare patients from this modality alone could range between 60,000 and 93,000 cases. This study demonstrated a very low rate of cancer in those nodules detected incidentally at other imaging studies. This is in contrast to several earlier reports. Yoon et al. examined 734 chest CT scans and found thyroid nodules in 16% of the studies. They reported that 9% of these incidentally found nodules were malignant. Liebeskind et al. found a 17% incidence of malignancy in 35 patients with nodules detected on chest CT, but this study was limited by a small sample size and probable pre-selection bias. Shetty et al. reported a 3.9% malignancy rate and a 7.4% potentially malignant (indeterminate biopsy) rate in patients who underwent fine needle aspiration biopsy after a report of incidental thyroid abnormality on CT. In contrast, the current study showed only a 1.5% rate of cancer in those patients with nodules detected incidentally on other imaging studies. The small sample size of this study may account for this discrepancy. In contrast, we found a much higher rate of cancer in those nodules detected by physical examination or reported by the patient. Since hard nodules are more apparent on examination, and nodule stiffness has shown a good correlation with risk of malignancy, it makes sense that those nodules that are easily detected on examination would more likely be malignancy. There are no clear guidelines regarding whether all nodules detected on CT or MRI studies should be evaluated further for malignancy. Recommendations have included that all nodules be reported, and that the decision whether to further evaluate the nodule be left to referring physicians, as they have a better understanding of the patient s medical history and risk factors. NCI guidelines recommend that an US be performed when a thyroid nodule is found on a CT scan. Prior studies have demonstrated a poor correlation between CT and ultrasound characteristics, and ultrasound is considered better able to discriminate between benign and suspicious features of nodules. In an editorial in Radiology published in 2008, Dr. John Cronin discussed the economic impact of evaluating all nonpalpable thyroid nodules. With a conservative estimate that 50% of the US population has a thyroid nodule, there is a potential reservoir of 150 million Americans awaiting ultrasound interrogation in order to determine whether to perform a biopsy. If 10% of those assessed have thyroid cancer, he estimated that it would cost $30 billion for biopsy and surgery alone in these patients. This is clearly an excessive cost for a disease with a mortality rate of 1500 patients per year. With 450,000 biopsies being performed to detect the 57,000 cases of thyroid cancer a year, (with 40% of cancers measuring less than 1 cm), there is clearly a need to decrease the number of patients being evaluated with small, incidentally found, low suspicion nodules. The American Thyroid Association is revising the current guidelines regarding which nodules need biopsy and which nodules can be observed without biopsy. Guidelines for determining which nodules incidentally found on other imaging studies should be further evaluated are also needed.

3 Direction for Future Study We plan to repeat this study in a similar thyroid center in Sarasota, Florida and in a university-based medical center thyroid clinic. We will evaluate whether the low rate of cancer in incidentally found lesions is confirmed with a larger patient population, as well as explore the differences in the mode of discovery of the nodules in different geographic regions and in centers with different referral patterns. Conclusion Of 200 consecutive referrals for thyroid nodules, 37.5% were found on physical examination, and 33.5 % were found incidentally on other imaging studies. While prior studies have suggested that incidentally detected nodules have a similar rate of malignancy to those found clinically, this study found a much higher rate of cancer in cases found by physical examination (9%) compared to those detected incidentally on other imaging studies (1.5%). References Ahmed S, Johnson PT, Horton KM et al. Prevalence of unsuspected thyroid nodules in adults on contrast enhanced 16-and 64-MDC of the chest. World J Radiol 2012;4(7): Shetty SK, Maher MM, Hahn PF, et al. Significance of Incidental Thyroid Lesions Detected on CT: Correlation among CT, Sonography, and Pathology. Am J Roentgenol 2006;187(5): Yoon DY, Chang SK, Choi CS, et al. The prevalence and significance of incidental thyroid nodules identified on computed tomography. J Comput Assist Tomogr 2008; 32(5): Liebeskind A, Sikora AG, Komisa A, et al. rates for malignancy in incidentally discovered thyroid nodules evaluated with sonography and fine needle aspiration. Journal of Ultrasound in Medicine 2005;24(5) Li H, Robinson KA, Anton B et al. Cost-effectiveness of a novel molecular test for psychologically indeterminate thyroid nodules. J Clin Endocrinol Metab 2011;96 (11)E Cronin JJ. Thyroid nodules: Is it time to turn off the US machines. Radiology 2008; 247(3) Levine RA. Current guidelines for the management of thyroid nodules. Endocrine Practice 2012; 18 (4) Ahmed S, Horton KM, Brooke Jeffrey R, et al. Incidental thyroid nodules on chest CT: Review of the literature and management suggestions. AJR 2010;195:

4 1 Epidemic of thyroid Nodules How are they being found? Jessica K. Levine, BA Robert A. Levine, MD, FACE, ECNU Thyroid Center of New Hampshire Geisel School of Medicine, Dartmouth College (RAL) College of Special Studies, Tufts University (JKL) 2 Introduction Thyroid nodules are epidemic 4% of population has a palpable nodule 50-60% of population has nodule detectable on high resolution ultrasound 450,000 Thyroid biopsies performed yearly in US cases of thyroid cancer diagnosed per year (2012) The number of biopsies and the number of cancers diagnosed have doubled over past 7 years The number of deaths from thyroid cancer has remained stable at approximately 1500 per year over several decades. Questions How are nodules being detected? Does the mode of detection impact on the rate of cancer? 3 Study Design 4 Patient demographics 200 consecutive referrals for thyroid nodules Thyroid specialty private practice in New Hampshire Retrospective chart review Data Extracted from Medical record Age Sex Mode of Discovery Ultrasound Characteristics Single vs. Multiple nodules Whether biopsy was performed and why/not Outcome of biopsy and surgical correlation in malignant or suspicious samples Female : Male 167:33 (5:1) Mean age years (range 19-92) Single versus MNG 87 single (43.5%), 102 MNG (51%), (11 no nodule) Biopsy performed in 70% 5 Results 6 Method of nodule discovery for all patients in the study 67/200 found by other imaging 35 CT 16 MRI 8 carotid US 2 PET 75 found at physical exam by physician or NP 24 found by patient 34 Other reasons Abnormal labs Abnormal TFTs hyperparathyroid Neck symptoms 12 Misc 67/ % 34/200 17% 24/200 12% 75/ % Physical Exam Found by pt Other imaging Other

5 7 Breakdown of other category 8 8 Decision for/against biopsy Appropriate indication Dysphagia 6 History of nodule 2 Neck discomfort 5 Cervical adenopathy 1 Jaw Lump 1 Hyperparathyroidism 1 16/34 appropriate Questionable indication Abnormal TFTs / hypothyroidism 14 Sinusitis/URI 3 Fatigue 1 18/34 questionable than Biopsy performed in 141 patients(70%) Biopsy not performed in 59 patients (30%) 42 (71%) Did not meet guidelines for biopsy < 1 cm and no suspicious features (calcifications, infiltrative margins, taller wide, hypoechoic) 4 (7%) due to age and co-morbidities 9 (15%) Hashimoto s without discrete nodule 2 (3%) prior benign biopsy 2 (3%) no nodule found 8.5% male in the biopsy group v 20% in the 9 Cancer Cases 10 Malignancy rate by method of discovery 12 of 200 (6%) of cases were diagnosed with cancer 12 of 141 (8.5%)biopsies diagnosed with cancer 7 (58%) nodule found at physical examination 3 (33%)nodule found by patient 1 detected by other imaging study 1 detected by other (US for hyperparathyroidism) 7/75 (9%) of nodules found at PE were malignant 1/67 (1.5%) of nodules found incidentally at other imaging malignant PE pt other imaging other cancer total 7/75 = 9% 3/24 = 12.5% 1/67 = 1.5% 1/34 = 3% 11 Cancer Cases 12 Discussion cases T1-3 N0 M0 clin 3 cases T2N1bM0 1 case T2N1bM 33% of cancer cases had positive lymph nodes detected on pre-operative US Thyroid nodules are extremely common Palpable nodules in 4% and demonstrable by ultrasound in 50-60% Vast majority are benign with only 57,000 cases of cancer diagnosed per year and only 1500 deaths per year. Incidental thyroid nodules are found in 16 25% of all chest CT scans 375,000 chest CT scans performed on Medicare patients each year 60,000 90,000 nodules detected on chest CT of Medicare patients alone.

6 13 Discussion Discussion - 3 This study demonstrated a very low rate of malignancy (1.5%) in nodules detected incidentally at other imaging studies. Prior studies have shown a higher rate of malignancy in incidental nodules The malignancy rate will be impacted by the process by which nodules found incidentally at other imaging studies are reported and evaluated. 450,000 thyroid biopsies are performed annually. It is essential for cost containment to improve the process by which detected nodules are selected for biopsy Better guidelines are needed to determine which nodules can be observed without biopsy Guidelines are needed to decrease the number of biopsies performed on nodules detected incidentally at other imaging studies. Dissemination of guidelines regarding proper utilization of thyroid ultrasound to primary care providers is needed 15 Conclusions In this study of 200 consecutive patients referred for thyroid nodules 75 (37.5%) were found at Physical examination 7 cancers - 9% malignancy rate if found at PE 24 (12%) were found by patient 3 cancers 12.5% malignancy rate if found by patient 67 (33.5%) were found by other imaging (CT MRI Carotid US) 1 cancer - 1.5% malignancy rate if found by other imaging 34 were found when an US was performed for other reasons 1 cancer - 3% in a patient being evaluated for hyperparathyroidism No cancers found in the 18 cases where there was no accepted indication for the thyroid ultrasound. 16 Plans for additional investigation 1. Repeat the study in a similar thyroid referral practice in Sarasota, Florida 2. Repeat the study at a University-based Medical Center thyroid clinic. Assess whether the low rate of malignancy in incidentally found nodules is confirmed in other sites Assess whether the patterns of discovery are same with different geographic locations and referral patterns. Please scan for digital handout Or go to: