I. Papillary Thyroid Cancer
Overview.
Papillary carcinoma is the most common type of malignant tumor of the thyroid gland. It accounts for 50%-70% of the cases. In papillary carcinoma foci, 1/3-1/2 of patients have lymphocytic infiltration. There is usually no lymphocytic infiltration in the normal thyroid tissue outside the lesion. Microscopic foci of dissemination are often seen in resected specimens of papillary carcinoma quite distant from the primary focus or even in the contralateral glandular lobe, and have been reported in 90% of specimens on close examination, making it difficult to distinguish between intra-glandular lymphatic tract dissemination and multicentric focal tumors.
Papillary carcinoma has a marked tendency to infiltrate regional lymph nodes. Regional lymph node metastases are evident in approximately 50% or more of cases at the time of surgery. The rate of metastasis in the cervical lymph nodes can be as high as 90% with careful examination of the excised specimen. Distant metastases from papillary carcinoma usually occur in the lungs, skull, and soft tissues. Regardless of the structure of papillary carcinoma distant metastases are often a mixture of papillary and follicular or predominantly follicular form.
Diagnosis.
Papillary carcinoma often presents clinically as an isolated nodule in the thyroid region, mostly over 1 cm in diameter. The masses are hard, with unclear borders, and have little up and down mobility with swallowing movements, and are not easily pushed, with poor basal activity. On ultrasound, most of the nodules are solid, and a few are cystic or cystic solid. Nuclear examination is mostly cold nodules, and a few are cool or cold nodules. Occult papillary carcinoma is also not uncommon, and many cases have been reported in recent years both at home and abroad.
However, 20 years ago. It is still mainly limited to autopsy. Occult carcinoma refers to carcinoma with a diameter of 1 cm, which cannot be detected through physical examination or other examinations; it is often diagnosed only through pathological examination in specimens surgically removed from other diseases; or occult carcinoma has metastasis in cervical lymph nodes and can be diagnosed only through cervical lymph node biopsy. Enlarged cervical lymph nodes are often the only clinical manifestation of occult papillary carcinoma with lymph node metastasis. It has been reported that up to 57% of occult carcinoma with cervical lymph node metastasis and its 10-year postoperative survival rate is much lower than that of those found by surgery for other thyroid diseases. Therefore, for those with swollen lymph nodes in the neck, especially those with swollen lymph nodes in the internal jugular vein. It is important to be alert to the possibility of occult thyroid cancer.
Occasionally, such patients present with pulmonary or bone metastases at the outset. The metastatic carcinoma is later confirmed to be an atypical papillary or follicular thyroid weave, indicating that the metastatic carcinoma is of thyroid origin. An occult primary focus is present in the thyroid gland. Those thyroid cancers detected by physical examination or other tests (excluding pathological examination), even if the tumor is about 1 cm in size, cannot be called occult cancer. It is more appropriate to call this type of cancer as microscopic cancer.
Treatment.
Papillary carcinoma is mainly treated by surgery, supplemented by postoperative thyroid hormone and I131 therapy. The surgical method should be determined by tumor stage, but there are many controversies. The main controversies are twofold.
1. what should be the extent of thyroid gland resection;
2. whether to perform cervical lymphatic contouring.
The European and American literature emphasizes that surgical treatment is not necessary to perform cervical lymphatic dissection, and total thyroidectomy is the principle of treatment. The reasons are;
1. high incidence of multicentricity of papillary carcinoma;
2, postoperative recurrence is mainly due to intra-glandular metastasis spared by the initial surgery;
3. There is no significant difference in the 10-year survival rate of patients with or without cervical lymphatic contouring;
4.It can avoid the transformation of residual cancer in the gland into undifferentiated cancer;
5.It can facilitate postoperative I131 detection and treatment. However, most scholars in China and Japan advocate subtotal or near-total thyroidectomy and cervical lymphatic contouring. This can reduce the occurrence of complications (hypothyroidism and laryngeal nerve injury) and avoid reoperation of cervical lymph node recurrence.
Therefore. In the process of thyroid cancer development, both intrathyroidal metastasis and lymph node metastasis should be taken seriously, and the selection of the surgical approach should be based on the pathology of the tumor, i.e. the stage of the tumor, as appropriate. Intraoperative frozen sections are generally instructive for surgical selection.
Clinical staging and treatment.
Stage I cancer (occult or microscopic cancer).
Small nodules in the thyroid gland, especially in adolescent patients, or isolated nodules found soon after, must be removed immediately. If there is no suspicion of cancer by visual observation and no palpable cervical lymph nodes, only a subtotal excision of the ipsilateral thyroid gland is usually required. The envelope behind the thyroid gland is preserved or only a small amount of thyroid tissue is preserved. Once the cancer is confirmed by postoperative paraffin section, reoperation may not be necessary. However, if the cancer is clinically suspected or confirmed by needle aspiration biopsy, total excision of the thyroid lobe on the sick side should be performed. Lymph nodes in the paratracheal sulcus should also be removed. This is more effective than subtotal thyroidectomy. Although cervical lymph node metastasis is more common in occult and microscopic carcinoma, it is not necessary to perform prophylactic cervical lymph node dissection if it is not accompanied by enlarged lymph nodes in the neck or if the enlarged lymph nodes are not metastatic as confirmed by intraoperative frozen section. Prophylactic cervical lymph node dissection is generally considered unnecessary.
Stage II cancer.
At this stage, removal of the affected thyroid lobe is appropriate. A simplified cervical dissection with a major or near-total lobectomy of the contralateral gland, plus preservation of the sternocleidomastoid muscle, internal jugular vein and paraneoplastic nerves is recommended. However, if the tumor is of intraperitoneal type. However, if the tumor is intraperitoneal and is not accompanied by enlarged cervical lymph nodes, prophylactic neck dissection can be dispensed with. The recurrence rate can be reduced by suppressing TSH secretion and reducing its stimulation of the thyroid gland.
Stage III cancer (primary foci or cervical lymph node bar adhesions fixed).
Surgical excision and removal should be more thorough. The extent of resection should include subtotal removal of the affected thyroid lobe and the contralateral gland lobe. Add ipsilateral classical neck dissection (together with excision of the internal jugular vein and sternocleidomastoid muscle as a whole), and in case of contralateral cervical lymph node enlargement. Simplified neck debridement or stage II neck debridement should be performed simultaneously. It has been proved that after complete resection of stage III cancer, the survival rate of 10 days can still reach more than 80%.
Stage IV cancer (with distant metastasis).
The current view is more towards aggressive surgery. The entire thyroid gland and bilateral cervical lymph node dissection should be removed. For distant metastases, try to remove them, and if metastases cannot be removed, I131 scan should be performed after surgery. If the tumor has iodine uptake function, it will be treated with I131. If there is no iodine uptake, take thyroid preparations (to the extent that they do not cause medical hyperthyroidism). To suppress TSH secretion. Reduce the size of the metastases. At least slow down their growth rate. For metastases that do not take up shyness. Some people advocate to try TSH to stimulate co-iodine uptake, and then treat with I131 after the iodine uptake ability is confirmed by I131 scan.
In conclusion, although some patients with papillary thyroid carcinoma have advanced stage of disease, they should still be treated surgically with a positive attitude.
Prognosis.
Papillary thyroid cancer has the best prognosis compared to other pathological types of thyroid cancer. Most investigators point out that the overall 10-year postoperative survival rate for papillary carcinoma is about 90%. However, it is not uncommon to find papillary carcinoma with a poor prognosis. The prognosis of this type of cancer is mainly related to the following factors;
1.Patient’s age and gender, the prognosis is worse for men over 45 years old.
2. Tumor tissue grading, differentiated thyroid cancer is generally classified into 3 grades.
Grade 1, highly differentiated; Grade II, moderately differentiated; Grade III, poorly differentiated. The prognosis is best for highly differentiated and worst for poorly differentiated.
The prognosis of stage I and II patients is better, while the prognosis of stage III and IV patients is worse. The prognosis does not seem to be related to the structural components of the tumor, and some literature reports that the prognosis is not affected by the surgical approach.
Follicular carcinoma of the thyroid
Overview.
Follicular carcinoma of the thyroid accounts for 5% to 20% of all thyroid cancers. Follicular carcinoma accounts for a greater proportion of cases in areas with endemic goiter. The average age of patients at presentation is 45-50 years, which is slightly older than the average age of papillary carcinoma. However, it is also well documented that patients with follicular carcinoma are between 35-40 years of age at the time of presentation. Seventy percent of follicular carcinomas are well differentiated and those with intact envelopes are not easily distinguished from follicular adenomas. Measurement of intracellular DNA content may help in the differential diagnosis. Hypodifferentiated types account for about 15% of cases, and cancer masses are often large (more than 3 cM), mostly seen in women over 40 years of age.
Eosinophilic cell carcinoma composed of eosinophilic cells accounts for 3%-9% of follicular carcinomas and has a poor prognosis. Clear cell carcinoma, which is composed of clear cells, is relatively rare. It has a higher degree of malignancy. Follicular carcinoma invades less lymphatic system, and the rate of lymph node metastasis at the time of consultation is less than 10%; however, it invades more blood vessels, and the rate of distant metastasis (hematologic metastasis) at the time of consultation is 15%-20%; there are also rare cases that can spread within the gland to form satellite nodes. Follicular carcinoma is the largest iodine uptake among thyroid malignancies, and the amount of TsH receptors in cancer tissue is about 70% of that in normal thyroid tissue; these 2 features should be used for treatment.
Diagnosis.
Follicular carcinoma has a clinical presentation similar to that of papillary carcinoma. However, the cancer mass is generally larger, with less local lymph node metastasis and more distant metastasis (metastasis to lung, bone, liver, etc.), and the detection of distant metastatic foci is earlier than that of primary foci.
The diagnosis of follicular carcinoma is mainly based on pathological diagnosis. However, pathological diagnosis is sometimes quite difficult. It is often difficult to distinguish benign follicular adenoma from follicular adenocarcinoma by thyroid aspiration cytology, and the false negative rate is over 20%. Therefore, for all tumors with follicular structures, even if the cytologic or histologic findings are benign, it is necessary to be vigilant. Therefore, for all tumors with follicular structures, even if the cytological or histological findings are benign, it is still necessary to be vigilant. The serum Tg level is helpful for diagnosis, and the DNA content of tumor cells and its ploidy can also be used as auxiliary indicators. Estrogen and progesterone receptor assay is also sometimes used for differential diagnosis. However, the positive rate is not high.
Treatment.
The principles of surgical treatment for follicular carcinoma are the same as those for papillary carcinoma. It also has its own special aspects. In general, thyroidectomy for follicular carcinoma should be as complete as possible. If the diagnosis is confirmed, the affected lobe plus the isthmus should be removed, and the contralateral lobe should be removed at least for the most part, preferably completely or nearly completely; if malignancy cannot be confirmed, complete removal of the affected lobe plus the isthmus is also preferable. This can reduce the difficulty of re-operation.
If the lymph nodes in the neck have metastases, the lymph nodes in the middle cervical region should be cleared. However, local lymph node metastasis in follicular carcinoma is rare, and in fact, less than 10% of the lymph nodes need to be cleared. The biological characteristics of follicular carcinoma (iodine uptake, tumor cells rich in TsH receptors) determine that I131 therapy and TSH suppression therapy (thyroxine administration) are important components of its treatment after surgery. I131 therapy is effective not only for possible residual primary cancer but also for local recurrence and metastasis, but the premise is that the minimum amount of residual thyroid gland (zero residual is ideal), and if there is a lot of residual glandular tissue, the residual gland must be killed first before I131 can be applied to the tumor tissue. If necessary. Co or high-energy X-rays can also be useful for external irradiation of tumors that cannot be completely removed.
Monitoring.
Follicular carcinoma of thyroid and papillary carcinoma both require close follow-up observation and monitoring after surgery. After meticulous physical examination and relevant adjuvant examinations, recurrent and metastatic lesions can be detected in time and treated accordingly. In general, serum Tg is reviewed every 6 months for 2 years after surgery and every 1 – 2 years thereafter. In follicular carcinoma patients, if total thyroidectomy has been performed or residual thyroid tissue has been killed by I131 after surgery, serum Tg level should be o. If it is greater than 0, it indicates metastatic foci or residual cancer. Patients with papillary carcinoma with serum Tg level greater than 10ug/L suggest the possibility of cancer recurrence or metastasis, and should be examined closely to find the lesion.
Prognosis.
The prognosis of follicular carcinoma is worse than papillary carcinoma, but overall it is still one of the better prognoses among thyroid cancers. The 10-year survival rate has been reported to be 30%-60% in the literature. The factors that affect the prognosis are;
1.The presence or absence of intact envelope;
2. the degree of differentiation of the cancer tissue;
3.Whether the cancer invades the blood vessels outside the cancer mass;
4. whether there is distant metastasis.
If all 4 factors are favorable to the prognosis, the 10-year survival rate can be more than 80%.
C. Differentiated thyroid cancer in children and adolescents
Overview.
Thyroid cancer accounts for a higher proportion of systemic malignant tumors than adults. There are controversies about many aspects of thyroid cancer, such as pathology, treatment, follow-up prevention and prognostic factors, and there are different views on the type and scope of surgery, the role of I131 therapy, thyroid hormone suppression therapy and external irradiation therapy. In particular, there is disagreement about the treatment of thyroid cancer in children and adolescents.