Thyroid cancer refers to abnormally growing thyroid cells that have the potential to spread to other body parts. Its symptoms include swelling or a lump in the neck. As per a recent study, global new cases of thyroid cancer in 2019 were 233,847, which meant an increase of 167% over 1990. The incidence is more common in women, and Asian population is more affected (1). The standard system for staging (2) of Thyroid cancers is TNM system (by American Joint Committee on Cancer), based on 3 indicators:
- Extent (size) of tumour (T)
- Spread to nearby lymph nodes (N)
- Spread (metastasis) to distant sites (M)
Thyroid cancers range from stages I through IV. As a notation, lower number indicates lesser cancer, and an earlier letter within a stage means a lower stage. The four main types of thyroid cancers are papillary thyroid cancer, follicular thyroid cancer, medullary thyroid cancer, and anaplastic thyroid cancer (3). Diagnosis involves physical examination, blood tests, ultrasound scan, and fine-needle aspiration. Treatment options may include watchful waiting, hormone therapy, external radiation therapy, radioactive iodine, chemotherapy, targeted drug therapy, and surgery, removing a part or all of the thyroid (4).
Surgical Intervention in Thyroid cancers
Over the past few decades, incidence of thyroid cancer has increased, making thyroid surgery as one of the most commonly performed procedure. Depending upon the patient’s condition, the decision on surgical intervention is taken – whether total / partial / near-total thyroidectomy or thyroid lobectomy, or lymph node dissection. (4) The traditional open thyroidectomy, entailing skin crease incision in the neck, remains the gold standard, but leaves permanent scarring, that may later develop into keloid or hypertrophic scars, causing paraesthesia or hyperaesthesia. The increasing patient concerns about cosmesis led to the development of alternative approaches (both with a minimally-invasive cervical or remote-access approach), aiming to shorten or eliminate the incisional scar (5).
Endoscopic Thyroid Surgeries
Endoscopic Thyroidectomy (ET) is a safe procedure with potential advantages in cosmetic results and postoperative outcomes including shorter scar length and reduced pain as compared to conventional procedures. The first ever ET was done in 1997, leading to an era of minimally invasive and remote-access approaches for thyroidectomy (6). With advances in technology, various techniques through cervical and extra-cervical routes such as chest wall, trans-axillary, trans-oral, post-auricular, trans-luminal approach have been attempted (5). Over these years, thyroid surgery is now being practised with effortless efficiency and complete safety. The guideline for choosing any approach is based on a well thought of selection criteria, considering the patient’s age, medical conditions, technical challenges, and overall oncologic safety and cost.
Minimally Invasive Video-Assisted Thyroidectomy (MIVAT)
This procedure (7) is a gasless intervention, performed using an endoscope for magnification of nerves and vessels via a small (<2 cm) neck incision. First developed in 1999, MIVAT has become a widespread technique for Thyroidectomy. It was initially limited to benign thyroid nodules and has gradually been adopted for all types of thyroid diseases. It has proven advantages of enhanced cosmesis, magnified vision, reduced complications, and lower postoperative pain (8, 9). An ideal candidate for MIVAT should have an ultrasound-estimated thyroid volume < 25 ml, and nodules < 35 mm. It is clearly contraindicated for previous neck surgery or irradiation, large multi-nodular goiters, locally invasive carcinomas, lymph node metastasis, or presence of lateral neck compartment (5).
The Robot-Assisted Trans-Axillary Thyroidectomy (RATT)
With ET presenting concerns like restricted vision and difficult instrument handling, the advent of surgical robots gave a hope, aided with technical advancements like increased degree of freedom to operate, tremor-filtering system and a better magnified 3-D vision (10). Chung et al. utilised the ‘Da Vinci robotic system’ to perform the first trans-axillary thyroidectomy using “four-arm-two-incision” approach (11) in 2007. The most significant development with RATT was the usage of a single access that avoided the accessory sternal incision (12, 13). RATT has been performed on benign pathologies and well-differentiated low risk carcinomas. Careful patient selection criteria (14) limits RATT to patients with by well-circumscribed nodule which is < 3 cm and with thyroid lobe < 5 - 6 cm in the largest dimension. Absolute contraindications include previous neck, shoulder or breast surgeries, shoulder arthrosis or previous shoulder injury, neck radiotherapy, pacemaker implant, sub-sternal extension and Grave’s disease.
Trans-Oral Endoscopic Thyroidectomy with Vestibular Approach (TOETVA)
With time, the natural-orifice trans-luminal endoscopic surgery (NOTES) technique has been deployed for thyroidectomies using the trans-oral endoscopic procedure, approaching the thyroid gland via incisions in the oral cavity. It is the only technique to be considered as ‘scar-less endoscopic thyroidectomy’ (SET) in the true sense. It involves lesser tissue dissection to access the target gland, and there is total avoidance of a skin incision. Witzel et al. performed the first trans-oral thyroidectomy in 2008 using a sublingual approach. Due to many related complications, modifications were made, and eventually, a modified vestibular version was developed and refined to the current state TOETVA (16). The main advantages are an excellent view of the surgical field and equal access to both sides of the central neck (5). The selection criteria include thyroid gland of diameter <10 cm, for either benign thyroid nodule, papillary micro-carcinoma with no evidence of metastasis, follicular neoplasm, or well-controlled Graves’ disease. It can be done in patients with previously undergone surgery or radiation at the chin and neck area (17).
Developed by Ohgami et al. (18) in 2000, this involves two circum-areolar incisions measuring 12–15 mm and uses CO2 insufflation. It was the first of the remote-access techniques, but not very popular due to the amount of dissection involved and CO2 diffusion into remote tissue planes.
Bilateral Axillo-Breast Approach (BABA)
It is performed through four very small incisions - one in each axilla and one along with each areola, using CO2 insufflation. It was developed by Choe et al. (19) in 2007 and subsequently, robotic adaptation was done by Lee et al. in 2009 (20). Though the approach provides good midline access to the gland, the disadvantages are similar to the breast approach.
Described by Terris et al. (21) on principles of gasless surgery, it uses a facelift incision in or adjacent to the retro-auricular crease, crossing over to occipital hairline, which eventually obscures by the ear. Of all the remote-access techniques, this has the shortest flap distance. But the top-down view and limited access to the contralateral lobe makes it less popular.
Endoscopic techniques v/s Open technique
Various studies have been conducted to compare ET with the Open technique, on various parameters, beyond just cosmesis. Apart from longer operative time and associated hospital stay, a few other complications similar to open technique have been noticed in ET – like vocal fold paralysis, hematoma, seroma, and hypo-parathyroidism. With the usage of CO2 insufflation, unusual complications may occur, including CO2 embolism, surgical space infection, skin perforation, burns, trauma (22). Another study revealed a higher visual-analog score (VAS) of swallowing disturbance and prolonged post-surgical chest wall paraesthesia was noticeable in ET patients (23). Also, concerns involving transient/permanent hypocalcaemia and transient/permanent Recurrent Laryngeal Nerve palsy have been noticed (24). Taking account of such complications, it is essential to understand the invasiveness of dissection required to achieve proper working space. Adequate training and expertise of skillful hands are very crucial for ET success.
Endoscopic Manual v/s Endoscopic Robotic
The evolution of Thyroidectomy techniques was largely driven by cosmetic results but eventually taken over by other operative parameters and post-op quality outcomes. Endoscopic manual approaches are soon getting replaced by robotics, to help achieve better results. A surgical robot provides 3D imaging of the operative zone with a high-definition camera, better freedom of movement, physiological tremor elimination, and motion scaling. Endoscopic approaches have a limited 2D view and provide reduced dexterity of movement. If surgeons are to be believed, robotic techniques have a shorter learning curve than the endoscopic or open thyroidectomy. Robotic techniques have shown similar or superior results for clinical outcomes and patient safety. With these advantages (25-28), the only concern for robotic methods is the operating time and associated cost of the procedure.
Advancements in science and technology over the past decades have led to the development of many alternative approaches for endoscopic thyroidectomy. With many studies still ongoing, the quality outcomes for these methods are under continuous monitoring, though MIVAT and TOETVA have obtained significant popularity and acceptance. Having said it all, the quintessential success rate of any approach mainly lies in accurate patient selection and skilled endoscopic surgeons.
- Wen‐Qi Bao, Hao Zi, Qian‐Qian Yuan, Lu‐Yao Li, Tong Deng, Global burden of thyroid cancer and its attributable risk factors in 204 countries and territories from 1990 to 2019, Thoracic Cancer, 10.1111/1759-7714.14099, 12, 18, (2494-2503), (2021). Wiley Online Library. Available from: https://onlinelibrary.wiley.com/doi/10.1111/1759-7714.14099
- American Cancer Society : https://www.cancer.org/cancer/thyroid-cancer/detection-diagnosis-staging/staging.html. Accessed on 8th January, 2021
- The Mayo Clinic : https://www.mayoclinic.org/diseases-conditions/thyroid-cancer/symptoms-causes/syc-20354161. Accessed on 7th January, 2021.
- The Mayo Clinic : https://www.mayoclinic.org/diseases-conditions/thyroid-cancer/diagnosis-treatment/drc-20354167. Accessed on 7th January, 2021.
- Rossi L., Materazzi G., Bakkar S., Miccoli P. Recent Trends in Surgical Approach to Thyroid Cancer. Front. Endocrinol. 2021;12:699805. doi: 10.3389/fendo.2021.699805. Available from: https://www.ncbi.nlm.nih.gov/pmc/articles/PMC8206549/
- Hüscher CS, Chiodini S, Napolitano C, et al. Endoscopic right thyroid lobectomy. Surg Endosc 1997;11:877. 10.1007/s004649900476. Available from: https://pubmed.ncbi.nlm.nih.gov/9266657/
- Miccoli P., Fregoli L., Rossi L., Papini P., Ambrosini C.E., Bakkar S., De Napoli L., Aghababyan A., Matteucci V., Materazzi G. Minimally invasive video-assisted thyroidectomy (MIVAT) Gland. Surg. 2020;9:S1–S5. doi: 10.21037/gs.2019.12.05. Available from: https://www.ncbi.nlm.nih.gov/pmc/articles/PMC6995905/
- Miccoli P, Biricotti M, Matteucci V, Ambrosini CE, Wu J, Materazzi G. Minimally Invasive Video-Assisted Thyroidectomy: Reflections After More Than 2400 Cases Performed. Surg Endosc (2016) 30(6):2489–95. 1007/s00464-015-4503-4. Available from: https://pubmed.ncbi.nlm.nih.gov/26335076/
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