Surgical Approaches for Thymic Carcinoids

Introduction

Carcinoid tumors usually originate from the neural crest and commonly cause symptoms in the gastrointestinal tract. There was initial documentation of eight cases of thymic carcinoid tumors, which were associated with Cushing's syndrome and multiple endocrine neoplasia, according to a research study. This rare tumor commonly affects males. Individuals with these tumors usually do not show any symptoms, and the tumors are frequently found unintentionally during routine chest X-ray examinations pertaining to some other complaints.

What Is a Thymic Carcinoid?

Thymoma and thymic carcinoma are the most frequently occurring tumors in the mediastinum (front part of the chest), and they are a very rare type of chest cancer. Studies that involve molecular analysis, genetics, and multi-omics have helped pinpoint the characteristics of thymoma that can provide fresh insights into predicting thymic tumor occurrence, recurrence, and response created by drug treatments.

A thymic carcinoid can present itself clinically based on its location, size, and metastatic patterns. Since the symptoms of this tumor are vague and discontinuous, diagnosis can be challenging. Common signs and symptoms seen in a large tumor include abdominal pain, cutaneous flushing in the form of an unpleasant warm feeling, rashes, itchiness, palpitations, etc. There can be diarrhea and malabsorption, along with gastrointestinal bleeding. Hypertension, wheezing, cough, and dyspnea (shortness of breath) are other serious symptoms. Carcinoid crisis is a life-threatening symptom of carcinoid tumors, which can cause severe episodes of flushing, breathing difficulty, and confusion.

How to Diagnose Thymic Carcinoids?

Contrast-enhanced computed tomography (CE-CT) is one of the widely utilized and important imaging technologies that help reveal the connection between a tumor and its surrounding structures and organs. Importantly, if this imaging tool is combined with a surgeon's expertise, CE-CT can be used to identify signs of tumor infiltration.

How to Manage Thymic Carcinoids?

• The option to have surgery depends on the stage of the disease and the assessment of the patient's factors during the operation, which are dependent on and guided by medical imaging.

• The best possible way to manage thymic epithelial tumors is to surgically remove the affected organ and adjacent tissue that may have been affected.

• There are various techniques for this surgery, which may include open surgery or other less invasive approaches.

• Surgeons nowadays implement various innovations to improve the procedure's effectiveness.

• Choosing the appropriate technique depends on the patient's factors and individual characteristics.

• The first step in surgically removing thymic tumors that have not spread is evaluating if they can be removed.

• The decision to choose if a tumor is not suitable for surgical removal is made by the treating surgeon with utmost caution.

• During the advanced or later stages of chemoradiotherapy or chemotherapy, it is essential to reconsider whether the tumor can be surgically removed or not.

• Though there are advancements in surgical methods for treating thymic tumors, some issues still remain in debate.

• These include choosing the appropriate surgical approaches for challenging cases, using the minimally invasive surgery option for advanced thymic tumors, implementing video-assisted thoracoscopic methods, assessing if a tumor can be removed, performing debulking surgery, considering lymph node removal, opting for neoadjuvant therapy, and resorting to salvage surgery.

• Assessing and calculating these challenges solely lies in the surgeon's judgment, experience, and surgical skills.

What Are the Surgical Approaches for Thymic Carcinoids?

Surgery remains the primary treatment protocol for thymic tumors, and a multidisciplinary approach can greatly benefit patients. Though there are advancements in surgical technology for treating thymic tumors, several debates still exist. A multimodal approach has proven beneficial for many patients. Total surgical resection is a notable factor affecting recurrence and survival after these conditions. Open surgery, particularly through median sternotomy, is the commonly used surgical approach for treating thymic tumors. In complicated cases, during the surgical approach, the incision can be modified to a clamshell incision, inverted-T incision, or a hemi-clamshell incision. In challenging cases, while doing open surgery, the surgeons choose clamshell or hemi-clamshell incision under the following conditions:

1. Involvement of Lung Hilum: If there is suspicion that the lung hilum or both of the lung hilums are affected.

2. High-Level Superior Vena Cava (SVC) Replacement: When there is a need to replace SVS at a very high level, nearly at the bifurcation of the right subclavian vein (RSV) and the internal jugular vein (IJV).

3. Synchronous Lung Cancer Surgery: In surgical cases where standard mediastinal lymphadenectomy is required for simultaneous lung cancer surgery.

4. Difficulty Exposing Huge Tumors: For exceptionally and unusually large tumors that are impossible to be adequately exposed through a median sternotomy.

5. Potential Invasion of Sternum: If there is a suspicion that the tumor might have invaded the sternum.

6. History of Previous Sternotomy: In cases where there is a history of prior sternotomy.

When compared with open surgery, video-assisted thoracoscopic surgery (VATS) thymectomy and robotic video-assisted thoracoscopic surgery (R-VATS) thymectomy have demonstrated equal or better oncological effectiveness and more manageable perioperative complications. This has also provided improved survival outcomes for the patients. Predictors of patient survival include the pathological stage of the disease and the extent of surgical resection radicality.

What Is the Prognosis?

A positive outcome has been linked to the local recurrence of a thymic tumor, especially when the recurrent tumor is completely removed. Also, conversely, an incomplete surgical resection or failure to remove recurrent thymic tumor predicts a less favorable prognosis. Many tumors that were previously thought to be benign have been identified to have the potential to spread and recur post-surgery. Hence, it is very important and necessary for the surgeon to evaluate whether a tumor is removable or not. Still, multiple issues exist, which include the choice of surgical approach for challenging cases. Researchers are also still exploring emerging methods like targeted drugs and immune therapies, although some outcomes could be more consistently favorable.

Conclusion

The thymic carcinoma, being a rare carcinoma, is still debatable for its diagnostic and treatment approaches. However, effective participation and decision-making by a multidisciplinary team can improve the prognosis of the affected patients. Advances in diagnostic techniques and treatment approaches have exponentially increased favorable surgical outcomes and better quality of life in affected patients. Surgery still continues to be the immediate primary approach for managing cancer-related symptoms and extending life. The surgeon's experience and expertise in dealing with complex cases play a crucial role.