The prevalence of thyroid nodules in the United States is 4-7% of adults with palpable thyroid nodules, but fortunately only about 5% of thyroid nodules are malignant. In fact, with the help of ultrasonography, etc., the rate of thyroid nodules in the population is as high as 19-67%, while autopsies (over 60 years of age) also confirm the high incidence of thyroid nodules, about 50%.
Thyroid nodules, in our country, are difficult to have good, definitive information on diagnosis and treatment. And the test data from our hospital in recent years undoubtedly show a high incidence and some unacceptable rates.
In this article, we try to review the latest and authoritative medical information and focus on some practical and critical issues.
How to deal with thyroid nodules, how to deal with nodules less than 1 cm found by ultrasound, what is the prognosis of thyroid cancer, and the most authoritative international information on thyroid guidelines.
I. General information about thyroid nodules
The most common thyroid nodules are colloid nodules, cysts, thyroiditis (about 80% of the above three); benign follicular neoplasms (benign follicular tumors) are about 10-15%. Thyroid cancer is about 5%. In reality, the incidence of thyroid cancer is probably much higher than this percentage. The incidence of thyroid cancer at autopsy may be 0.01% in the United States, 11.3-28.4% in some parts of Japan, but may be as high as 35.6% in Finland [ 3].
The high incidence of thyroid cancer and some specific factors of prognosis determine some inconsistencies in its diagnosis and treatment from the usual thinking.
II. Prognosis of thyroid cancer
To know the prognosis of thyroid cancer, it is necessary to know some classifications of thyroid cancer. The detailed classification is very complicated and there are special guidelines abroad.
There are 4 common pathological classifications.
①Papillary adenocarcinoma, which accounts for 60% to 80%;
Follicular adenocarcinoma, accounting for 10% to 28% (there is another category of eosinophilic adenocarcinoma in foreign countries, which is not classified in China and is classified as follicular adenocarcinoma), both of which originate from the follicular epithelium of the thyroid gland and have good prognosis after treatment;
Medullary carcinoma, which originates from parafollicular cells or c-cells of thyroid gland, accounts for 3% to 10%; ④ undifferentiated carcinoma, which accounts for 3% to 8%. Among thyroid cancer, more than 90% of them are differentiated thyroid cancer.
Undifferentiated carcinoma develops quickly and grows rapidly after the appearance of neck swelling, which can be fixed within 1-2 weeks, with hoarseness and difficulty in breathing. Most patients are diagnosed late and lose the opportunity for radical or palliative surgical treatment. The prognosis is poor in most cases, with most dying within 1 year and a 5-year survival rate of only 5%-15%.
And from the feeling of a physician who has been in medicine for many years, though not an oncologist or general surgeon, I have never seen a case of death from thyroid cancer. In contrast, the projected number of new cases and deaths of thyroid cancer in the United States in 2009 was 37,200 and 1630, respectively [6], with a death rate of about 4.38%. Considering the proportion of undifferentiated cancers, it is likely that the vast majority of these deaths are undifferentiated cancers.
(By the way, the 2009 Chinese Journal of Otolaryngology-Head and Neck Surgery published “Diagnosis and treatment of thyroid cancer” reported that there are about 17,000 new cases per year in the United States, based on the data from 1998-2000 in the United States, so it is important to check the foreign literature for the latest information)
Most thyroid cancers are differentiated and have a good prognosis, but the AMES (age, metastasis, extrathyroidal invasion and size) staging is based on age, presence of distant metastases, gender, presence or absence of extraperitoneal invasion, and tumor size, and patients are divided into low-risk and high-risk groups. The recurrence rate was 5%; the 20-year survival rate in the high-risk group was 54% and the recurrence rate was 55%¨.
And even for patients with neck lymph node metastasis (for which information is available, which is relatively common), the 5-year and lO-year survival rates were 84.3% and 80.4%, respectively, and the 5-year and lO-year survival rates for patients who developed neck lymphatic metastasis after clinical neck-negative surgery and then underwent neck clearance were 91.4% and 82.2%, respectively.
Treatment of thyroid cancer
The high incidence and prognosis of thyroid cancer determines some special aspects of its treatment. Up to 35.6% in Finland and 11.3-28.4% in some parts of Japan, but in Finland and Japan, we see 10-40% of people undergoing thyroid surgery? For thyroid nodules over 1 cm, the treatment and guidelines have clearer treatment steps and recommendations, as detailed in the guidelines. In contrast, the management of nodules below 1 cm is somewhat avoided in China, intentionally or not, but this is actually very important in the clinic with the application of physical examination. An important issue has also been identified in foreign information, the National Guideline Clearinghouse.