Thyroid cancer: diagnosis and medical treatment

2021-07-27 12:05 AM

Thyroid cancer, which is cancer of the follicular epithelial cells, includes papillary, follicular, poorly differentiated, or parathyroid cells

Thyroid cancer tends to occur in an older population when compared with other differentiated thyroid cancers. Its incidence peaks between 40 and 60 years of age, compared with the incidence of papillary thyroid cancer which peaked earlier, between the ages of 30 and 50 years. In addition, follicular thyroid cancer is about three times more common in women than in men. Iodine may also play a role in the epidemiology of thyroid cancer. In iodine-deficient regions of the world, there is a higher incidence of follicular cancer than in iodine-sufficient regions. With the introduction of iodine, some studies have shown that the incidence of thyroid cancer decreases, while papillary thyroid cancer increases.

Thyroid cancer is a cancer of the follicular epithelial cells (including papillary, follicular, or poorly differentiated) or from parafollicular cells (depending on the type).

Thyroid cancer accounts for only 1% of all cancers, but it is the most common endocrine cancer and the deadliest.

Definite diagnosis

Clinical symptoms

The clinical symptoms of thyroid cancer are very poor. Most patients only have a simple thyroid nodule, in the late stages, some patients have signs of cancer metastasizing to surrounding tissues, causing hoarseness, difficulty swallowing...

Symptoms that suggest a patient is at high risk for thyroid cancer are:

Family history of medullary thyroid cancer or multiple endocrine neoplasias (MEN).

+ The nucleus is solid or hard and adheres to the surrounding organization, less mobile.

+ The patient has paralysis of the vocal cords causing hoarseness.

+ Gland.

+ There are signs of distant metastases in bones, lungs...

Subclinical symptoms

Blood tests: TSH and FT4 levels are normal in most patients. Calcitonin levels are increased in patients with medullary thyroid cancer.

Ultrasound of the thyroid and neck: some signs suggestive of malignant thyroid nodules are hypoechoic nodules, microcalcifications, irregular margins, regular or high rounded nuclei, and intranuclear vascular proliferation, especially evidence of invasion of cervical lymph node or tumor.

Fine needle aspiration of thyroid nuclei is a technique with an accuracy of up to 95%, the most valuable in the preoperative diagnosis of thyroid cancer. Use a 25 or 27 size needle attached to a 10- or 20-ml syringe, usually aspirate 2-4 times, only aspirating when the needle tip is in the nucleus. Success rates are higher if supported by ultrasound, especially with nodules > 4 cm large or small < 1 cm, nodules located posteriorly, mixed nodules (cysts account for more than 50%).

Thyroid scintigraphy (by I 131 , I 131 or 99mTc): thyroid cancer nodules often have decreased radioactivity (cold nodules).

Diagnosis of thyroid cancers

Papillary cancer

Accounts for 70-80% of thyroid cancers. The disease is common in women, aged <40 or 60-70. Papillary cancer often has many foci or metastases to surrounding lymph nodes, less distant metastases.

Prognosis is good due to slow progression of cancer, survival >10 years to 95%.

Follicular cancer

Accounts for about 5-10% of thyroid cancers, common in women, middle age. Follicular cancer often invades blood vessels or metastasizes to the brain, lungs, bones...

The prognosis is relatively good. The 5-year survival rate is about 85% depending on the degree of invasion

Undifferentiated body cancer

Accounts for about 1-3% of thyroid cancers. Seen mainly in women, age > 60. Cancer progresses rapidly, invades, and compresses surrounding tissues such as nerves, blood vessels, larynx, esophagus...

Prognosis is poor because of the malignancy; patients usually die within 1 year of diagnosis.

Medullary cancer

Accounts for 5-10% of thyroid cancers, originating from the parafollicular cells. Seen at all ages, including children, more women than men. In 5-10% of cases, medullary thyroid cancer is familial, in the setting of multiple endocrine neoplasia type 2A (Sippel syndrome) or 2B. Medullary cancer can metastasize to lymph nodes and surrounding tissues, but can also metastasize to the liver, lungs, and bones.

Prognosis depends on the patient's age and metastatic status at the time of diagnosis. The 5-year survival rate is about 50%.

Lymphoid tumor

Usually occurs against the background of Hashimoto's thyroiditis. Tumors often grow rapidly.

Histopathological examination revealed many large lymphocytes, which should be distinguished from small cell lung cancer and undifferentiated thyroid carcinoma.

Differential diagnosis

Benign thyroid nodules

Up to 10 - 30% of normal people in the community have thyroid nodules, but less than 5% of them are malignant.

Differential diagnosis by fine-needle aspiration cytology.

Cancer metastasis to the thyroid gland

Cancer metastases to the thyroid gland are rare, mainly from fibrosarcoma or lymphocytic sarcoma.

Diagnosis is by cytology and primary cancer.

Diagnose the cause

It can be caused by radiation outside the head, face, neck, chest, causing chromosomal breaks, leading to changes and loss of tumor suppressor genes or other causes of mutations in oncogenes and tumor suppressor genes such as RET gene, TRK1, RAS...

Treatment and follow-up

Treatment of differentiated thyroid cancer papillary and follicular cancer

Total thyroidectomy (and cervical lymphadenopathy, if present) is required with the primary aim of removing the tumor, reducing mortality, and also for histopathological diagnosis, stage of the disease, and to help treat I. 131 is favorable.

The treatment I 131 aims to reduce the recurrence rate. After 4-12 weeks of thyroidectomy, when TSH > 50IU/I, patients will be given a whole-body scan with a dose I 131 from 3 to 5mCi to detect residual thyroid tissue or cancer metastasis. Thyroid. If the result is positive, I 131 will be given at a dose of 30 - 50mCi. Whole-body I 131 scans will be repeated every 6 months and stopped if 2 consecutive scans are negative. Patients in the low-risk group (papillary cancer, age 15-45, no history of external radiation, small tumor, no metastases, total thyroidectomy) may not need treatment. radioactive lode.

TSH inhibitor therapy: after 1 - 2 weeks of I 131 treatment, patients will be treated with L-thyroxine to suppress TSH below normal levels to prevent cancer recurrence. The target TSH should be as low as possible without side effects (thus requiring additional monitoring of FT4 levels to avoid overdose). For patients with low-risk thyroid cancer, TSH should be maintained at 0.1 - 0.5IU/I.

Once the target is reached, check FT4 and TSH every 6 months to adjust the dose.

Thyroid cancer recurrence should be followed for life with cervical ultrasound, Tg (thyroglobulin), and anti-Tg tests at the same time as the first whole-body scan (when TSH is elevated) and every 6-1 2 months (must stop L-T4). If Tg < 2ng/ml, treatment with L-T4 can be continued, and if Tg > 5ng/ml, treatment should be resumed with I 131.

Treatment of undifferentiated thyroid cancer

It has poor efficacy because it is often detected late, is no longer suitable for surgery, and also does not respond to treatment with I 131 or chemotherapy. Some patients respond to external radiation.

Treatment of medullary thyroid cancer

Mainly by thyroidectomy. These tumors do not capture iodine, so they cannot be treated with I 131 . External radiation and chemotherapy can be used in some late-stage patients to relieve symptoms. Monitor for recurrence with the calcitonin test.

Thyroid lymphoma treatment

Guidelines for the treatment of other types of lymphoma should be followed. Surgical treatment is not recommended because it can promote metastasis. Can be treated with external radiation.

Prevention

Limiting radiation outside the head and neck area, such as to treat skin hemangiomas...

Patients with goiter should be examined and monitored (including aspiration of thyroid cells) every 6 -1 2 months.