Thyroid cancer is one of the most common endocrine malignancies with an increasing incidence worldwide over the past two decades (1, 2). According to the Chinese cancer statistics in 2018, thyroid cancer is the 4th most common malignancy in women, accounting for approximately 4.46% of all malignancies in China (3). In thyroid cancer, differentiated thyroid cancers (DTCs), including papillary thyroid carcinoma (PTC) and follicular thyroid carcinoma (FTC), are the most prevalent histological types with a male-to-female ratio of 1:4 (4, 5).

Traditional low collar incision (TLCI) is the conventional surgical approach of thyroidectomy for treating DTCs. However, the following shortcomings of this approach are found in practice: 1) the surgery space is limited, making it challenging to dissect the superior thyroid vessels, the recurrent laryngeal nerve, and the superior parathyroid glands. For this reason, the anterior cervical band is cut sometimes to expose the surgical area more extensively. 2) Traditional surgical approach causes great damage to the neck tissues, leading to postoperative neck tissue edema and scar growth on the anterior neck. 3) Postoperative scars formed on the front of the middle neck (usually 6–8 cm in length) can cause serious aesthetic problems. Therefore, more effective and aesthetically satisfying procedures have been attempted.

The supraclavicular oblique incision (SOI) is a unilateral 2- to 3-cm incision above the clavicle along the lateral border, which was developed to achieve a better esthetic result over the past decade (6, 7). The postoperative scar resulting from such an incision is less remarkable and more easily to be concealed than that from TLCI. However, the efficacy and long-term outcomes of the approach with SOI in thyroid lobectomy were poorly studied. This study aimed to compare perioperative and long-time outcomes of the TLCI thyroidectomy (TLCIT) with the SOI thyroidectomy (SOIT) in patients with DTC.

After screening a total of 482 patients admitted to our center from October 2020 to October 2021, we finally included 128 patients in this study (as shown in Figure 2 ). Thirty-eight patients (30.5%) were operated on with SOIT and 89 patients (69.5%) with TLCIT.

Thyroid surgery is the mainstay of treatment for thyroid tumors, which targets complete removal of the thyroid lesion without damaging the surrounding vital tissues (11). Traditional thyroid surgery by low collar incision approach usually involves a long incision and may cause postoperative discomfort such as swallowing dysfunction and swelling in the free flap area. To better satisfy the cosmetic and other life-quality demands of patients, various surgical methods have been developed (12).

One surgical approach development is accessing the thyroid compartment through the creation of a subcutaneous tunnel from the chest wall, axilla, or other positions using endoscopy, hence leaving no scar on the neck (13–15). However, the creation of extensive subcutaneous tunnels may lead to postoperative localized scar growth, and patients are prone to discomfort such as skin tugging. Another is minimally invasive surgery, including small incision thyroidectomy with or without endoscopic assistance (16, 17). However, this approach has strict indications and a probability of conversion to the TLCI approach. It was reported that minimally invasive surgery can be applied to 20%–30% of patients who need thyroidectomy (18, 19).

In our center, SOIT, which was first reported by Chen (7), has been performed since 2018. However, the safety and efficacy of this incision were yet to be confirmed due to a small number of related studies. In this retrospective study, we found that the patients who received SOIT had a smaller incision, shorter duration of postoperative drainage, a smaller volume of postoperative drainage, and shorter postoperative hospitalization, as compared with those who received TLCIT. At 1-month and 6-month follow-ups, the SOIT group also showed better patient-related outcomes, including voice assessment, swallowing function, cosmetic satisfaction, and neck sensation and movement. These advantages over TLCIT may benefit from the following characteristics of SOIT summarized in our center during a 3-year practice: 1) the surgical field can be accessed by the natural anatomical gap between neck muscles without severing the anterior cervical band; 2) it is easier and safer to perform dissection and ligation under direct visual inspection, especially for the upper pole of the thyroid; 3) the parathyroid glands and important vessels in the neck, such as the internal jugular vein, can be identified more accurately without accidental removal or injury; 4) the postoperative neck tissue damage reaction and scar adhesions are milder than those caused by TLCIT.

It is widely accepted that LN yield (LNY) can reflect the extent and quality of central neck dissection (20, 21). The LNY (unilateral) and positive LN number in all included patients are (expressed by median (IQR)) 1.0 (0, 3.0) and 0 (0, 1.0) respectively. It seems that LNY in this study is a smaller number compared with that in previous studies (20–22). We consider that there may be several reasons: the patients included in this study were planned to undergo thyroid lobectomy without the preoperative ultrasonography evidence of positive LN. In these patients, central compartment neck dissection (CND) was performed prophylactically rather than therapeutically based on the current guideline (3). It is reported that the LNY is significantly lower in prophylactic CND than in therapeutic CND (1), as clearing the central compartment LN tends to be rather conservative in prophylactic CND. Nevertheless, for LNY and the positive LN, no significant difference was found between the SOIT and TLCIT groups.

According to our practice and studies reported before, the indications of SOIT should be limited to patients with the following characteristics: with low-to-intermediate risk, well DTC of a diameter < 4 cm, and a thyroid gland volume < 30 cc (19, 23). On the other hand, the patients with a history of thyroiditis, previous neck surgery or head/neck irradiation, palpable lymphadenopathy, large goiters, or aggressive and poorly DTCs are not suitable for SOIT. Moreover, for bilateral thyroid lesions needing total thyroidectomy, it appeared that thyroidectomy by two-sided SOI was not easier or more effective than TLCIT in our 20 cases of practice. More studies are required to determine the efficacy of the two-sided SOI approach in patients who need total thyroidectomy.

Our research has two limitations. First, this single-center retrospective study enrolled only a small number of patients, and further research with larger sample sizes is needed. Second, some of the questionnaires, such as those for evaluating cosmetic satisfaction, and neck sensation and movement, are highly subjective and yet to be validated.

Our study suggests that minimally invasive surgery using the SOI provides superior surgical and patient-related outcomes compared with conventional surgery using a TLCI for the treatment of DTC. SOIT is potentially a valuable alternative operative technique to TLCIT.

The raw data supporting the conclusions of this article will be made available by the authors, without undue reservation.

The studies involving human participants were reviewed and approved by the institutional review board of a thyroid database (TDatabase) at the Affiliated Drum Tower Hospital of Nanjing University Medical School (No. 2021 GLTDMC-008). The patients/participants provided their written informed consent to participate in this study.

CQ and BJ: study design. CQ, BJ, and SS: acquisition of data and statistical analysis. CQ, BJ, CJ, and CZ: analysis and interpretation of data. CQ and CZ: drafting of the manuscript. SS, YL, and LS: critical revision of the manuscript. YL and LS: study supervision and guidance. All authors have read and approved the final version of this manuscript, including the authorship.

The authors declare that the research was conducted in the absence of any commercial or financial relationships that could be construed as a potential conflict of interest.

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