Compared to other malignancies, thyroid cancer has a higher reoperation rate of 30%-40%. Most of the reoperated patients have their first surgery performed in another hospital. There are two main reasons for reoperation; one is the recurrence of thyroid cancer; the other is the residual or suspected residual cancer caused by the improper choice of the first operation.
Reoperation of thyroid cancer is more difficult and the complication rate is higher. Therefore, it is necessary to discuss the indications for thyroid cancer reoperation and the selection of surgical procedure.
I. Indications for reoperation (when reoperation is needed)
1. Residual primary carcinoma The residual primary carcinoma can be caused by improper first surgery or insufficient resection.
The rate of residual cancer is higher in patients who have undergone mass resection, partial glandular lobe resection and subtotal glandular lobe resection in the first surgery than in patients with total resection. Therefore, depending on the pathology of the tumor at the time of the first surgery, it is important to consider whether to perform another surgery, i.e., to selectively perform another surgery. If the diameter of tumor at the time of first surgery is greater than 4cm, invaded the thyroid envelope or the tumor is multiple primary foci, reoperation should be performed; otherwise, reoperation should not be performed urgently, and close follow-up can be performed.
According to statistics, the rate of cervical lymph node metastasis in differentiated thyroid cancer is about 60%. If the cervical lymph node dissection is not complete during the first surgery (some of them only perform enlarged lymph node removal) or if the first surgery is mistakenly performed for benign disease, it may lead to residual cervical lymph node metastasis.
The indications for reoperation for additional lymph node dissection are
1. Only the enlarged lymph nodes were removed during the first operation, and the postoperative pathology confirmed that the metastasis of the removed lymph nodes was 100%.
2. Tumor diameter greater than 4 cm at the time of first surgery, invasion of the thyroid envelope or extra-envelope tissue, and poorly differentiated tumor without cervical lymph node dissection. Most of the literature reports that the risk factors for cervical lymph node metastasis of thyroid cancer are: large tumor diameter, poor differentiation, invasion of thyroid peritoneum or extraperitoneum, obvious clinical symptoms, male and patient’s age over 40 years.
Second, the surgical choice of reoperation
1.Negative cervical lymph nodes and re-operation after local excision of primary foci
Clinically, there are still differences in whether to choose total thyroidectomy or lobectomy including the tumor, but it is considered that any local excision is incomplete; therefore, for patients with negative cervical lymph nodes and local excision of the primary foci, they should be operated again to remove at least the residual lobes and isthmus. If the tumor is larger than 4 cm in diameter at the time of the first surgery, has invaded the thyroid envelope or the tumor is multifocal, a large part or all of the contralateral glandular lobe and the affected cervical strap muscle should also be removed, but there is no agreement on whether to include cervical lymph node dissection. Although many scholars at home and abroad do not advocate prophylactic cervical lymph node dissection, it is a special case when re-operation is performed, because the traumatic inflammation of the first operation may lead to enlarged cervical lymph nodes, and these enlarged lymph nodes may not be found clinically, and it is not certain whether they are lymph node metastases when they are found by intraoperative exploration. In such cases, cervical dissection has been advocated. At present, we believe that it is more appropriate to take several large lymph nodes for rapid frozen section examination, and if they are metastatic lymph nodes, perform functional cervical dissection; if they are inflammatory reactive lymph nodes, terminate the operation.
2.Positive cervical lymph nodes, local excision of the primary foci and then surgery
After local excision of the primary foci, there are indications for reoperation. However, if the cervical lymph nodes are progressively enlarged after surgery (inflammatory lymph nodes mostly shrink on their own after the inflammation is eliminated), the indication for reoperation is more clear.
Reoperation includes complementary resection of the primary focus and cervical lymph node dissection. The extent of thyroid excision is the same as in the first case above. The choice of cervical lymph node dissection depends on the condition of the metastatic lymph nodes. If there are not many enlarged lymph nodes and the lymph node envelope is not involved, functional cervical dissection can be performed; if the metastases involve the internal jugular vein and surrounding important organs, classical cervical dissection should be performed.
3.Recurrence of cancer after surgery
Recurrence of thyroid cancer after surgery is common, and the reasons for recurrence are medical implantation and residual of occult cancer foci. The site of recurrence is usually within the thyroid gland (including the contralateral lobe), the affected neck area and the incision. When cancer recurrence is found, as long as there is no contraindication to surgery. Re-operation should be performed in time and the main focus of re-operation is to remove the recurrence. If the recurrent laryngeal nerve is invaded by the cancer, it can be removed to protect the contralateral recurrent laryngeal nerve. If the laryngeal nerve is removed bilaterally, a permanent tracheotomy should be made. Some people have also anastomosed the laryngeal nerve with part of the vagus nerve, but the efficacy is not sure.
4. Reoperation for contralateral cervical lymph node metastasis
In case of postoperative contralateral cervical lymph node metastasis, contralateral cervical lymph node dissection should be performed. If classical neck dissection is needed, the internal jugular vein should be preserved as much as possible (in case the internal jugular vein of the affected side is removed during the neck dissection), or at least the external jugular vein should be preserved, because the external jugular vein and the internal jugular vein have a traffic branch in the parotid gland, and the venous return through this traffic branch can be compensated. If cancer foci or suspected cancer foci are found in the contralateral thyroid lobe during the contralateral neck clearance, most or all of the contralateral lobe should be removed. Even if the entire lobe is removed, the posterior tegmentum should be preserved to avoid the possibility of posterior tegmentation. The posterior tegument should also be preserved to avoid severe postoperative hypocalcemia due to removal of the parathyroid glands.
The timing of reoperation
The shorter the interval between two surgeries, the less chance of cancer growth and near metastasis. However, there are 2 cases that should be taken seriously.
One is that after the first surgery, either local thyroidectomy or irregular neck clearance. All have varying degrees of traumatic inflammatory reaction, edematous adhesions of the trauma and its surrounding tissues, unclear inter-tissue boundaries, and normal tissues that are not easily identifiable. The inflammation and edema of the tissues are most obvious within 2 weeks postoperatively.
Secondly, most thyroid cancers are better differentiated and less malignant and will not progress significantly in the short term.
For thyroid cancer that was not completely removed in the first surgery, the best time for reoperation is within 3 weeks of the first surgery or 3 months after the first surgery. This is because, within 3 weeks, the post-operative thyroid response is still dominated by edema response, and the adhesions between tissues after surgery during this period are still dominated by loose adhesions. Therefore, during this period of surgery, the postoperative adhesions can usually be separated, and therefore, there is usually no damage to normal tissues such as the recurrent laryngeal nerve and parathyroid glands.
However, as the scar reaction increases after 3 weeks postoperatively, the original loose edematous adhesions will be replaced by dense fibrinous adhesions, especially from 3 weeks to 3 months postoperatively. On the one hand, dense fibrinous adhesions can make the normal laryngeal nerve and parathyroid gland adhere to other tissues; on the other hand, they also make the laryngeal nerve and parathyroid gland indistinguishable from fibrinous tissues, so once fibrinous adhesions are formed, the chance of reoperation to damage the laryngeal nerve and parathyroid gland increases greatly, and the risk of reoperation also increases greatly.
However, for experienced surgeons, they can generally determine the site of the residual thyroid gland initially through some special tests, such as CT, so that they can have a preliminary estimate of the risk of reoperation. Secondly, experienced surgeons have a deeper understanding of the anatomical site variation of the recurrent laryngeal nerve and parathyroid glands due to postoperative adhesions, and therefore, the risk of reoperation can be relatively reduced.
IV. Efficacy of reoperation
Most thyroid cancers are less malignant and progress slowly. Many patients who are not treated properly at the first time often have the opportunity for reoperation and cannot be given up easily. Some data show that the survival rates of thyroid cancer patients who are operated again due to contralateral cervical lymph node metastasis are 95%, 85.6% and 81.7% in 5, 10 and 15 years, respectively. This indicates that reoperation for thyroid cancer can still achieve good results.