Minimal invasive/access surgery has become the mainstream of surgical practice in recent decades (1–3). Endoscopic assisted breast surgery (EABS) (4–6) or robotic assisted breast surgery (RABS) (7–9) performed through minimal axillary and/or peri-areolar incisions has become the representative of minimal access breast surgery (MABS) (10). MABS, either EABS or RABS, has been performed in breast conserving surgery (BCS) (4, 11, 12), mastectomy [mainly nipple sparing mastectomy (NSM) or skin sparing mastectomy (SSM) in some conditions] (7, 8, 13–17), and harvest of autologous flaps [latissimus dorsi flap (LDF) (18–20), omentum flap (21–23), or abdominal flap (14, 24, 25)]. Due to the wide spread of the breast screening program, the number of early breast cancers diagnosed increased dramatically and so is the reported use of MABS in literature around the world (15, 26, 27).

The advantages of MABS (EABS or RABS) include shortening of operation scar while hiding it in inconspicuous locations, which optimize aesthetic outcome and patients’ satisfaction (9, 11, 15, 17). However, the widespread use of MABS in the management of breast cancer is yet to be fully accepted; objections include limited working space, superficial nature of breast lesion, and relative low morbidity of breast surgery (28). Drawbacks include longer operation time, more instruments needed, and higher medical cost (9, 17, 29) Of utter importance, the long-term oncologic outcome is rarely reported (5, 26) and not yet confirmed by large randomized trials.

At our institution, we started performing EABS (4, 13–15, 26, 30, 31) for breast cancer treatment since 2010 and developed RABS (9, 17–19, 32–34) in 2017. After 10 years of work in the field of MABS, much experience and accumulated results of its applications in breast cancer were obtained. The development and trend of MABS (EABS or RABS) versus conventional breast surgery (CBS) in the past decade were evaluated from the principal investigator’s personal perspective. The clinical outcome, complications, and cost of MABS versus CBS were also analyzed and reported.

During 2011 to 2020, a total of 824 breast cancer patients operated by a single surgeon (H-WL) were enrolled in the current study. Among them, 254 received conventional breast surgeries (CBS) and 570 received MABS. These included 476 EABS and 94 RABS. The characteristics and clinicopathologic parameters of enrolled patients are summarized in Table 1 , and types of surgeries performed are shown in flow chart and photos ( Figures 1 , 2 ). The RABS mainly focusing on R-NSM (92/94) related, and most of the patients received immediate gel implant breast reconstruction (IGBR). The only two robotic assisted BCSs were related to partial breast reconstructions (robotic LD flap harvest or robotic omentum flap harvest). In our current MABS cohort, no case (either EABS nor RABS) required conversion to conventional operation method.

In the current study, we report the development and trend of MABS (EABS or RABS) for surgical treatment of breast cancer in the past 10 years from single surgeon at one institute. The proportion of breast cancer patients who received MABS (EABS or RABS) increased gradually ( Figure 3A ). The highlight of MABS is its small and inconspicuous operation wound ( Figure 2 ). This value is more prominent when mastectomy is inevitable. When mastectomy is done via MABS, we can pursue an aesthetic scar-less mastectomy. With case accumulation, the overall operation time of various MABS decreased gradually ( Figure 4 ).

BCS had become the mainstream for small early breast cancer, and our previous publication on the application of endoscopic (4, 38) or robotic (19) assisted techniques in BCS has shown promising results. Adopting E-BCS successfully decreased 23% of median wound length ( Table 2 ) with incisional wound hidden in inconspicuous location ( Supplementary Figure 1 ). We had applied robotic assisted technique in some breast cancer patients receiving BCS; these patients are mainly for partial breast reconstructions with either robotic assisted harvest of LDF (19) or omentum flap (23). From Figure 1 , the major applications of robotic surgery in breast surgeries were total skin and NAC preserving mastectomy (R-NSM) (27) ( Figure 2 ). The application of RABS in BCS alone, however, was not recommended due to high cost and long operation time.

NSM yields better cosmetic outcome and has proven oncologic safety; hence, it is increasingly used in breast cancer patients indicated for mastectomy (39, 40). Mastectomy usually requires larger incisional wound, by adopting E-NSM or R-NSM, about 46.8% to 57.5% of wound length was spared ( Table 2 ), approaching the goal of aesthetic scar-less mastectomy ( Figure 2 ) (35). Compared with about 23% reduction of BCS wound length, the value of MABS was more apparent in NSM, where scar size is nearly halved ( Figures 1 – 3 ). This positive impact had been reflected in our previous patients-reported-outcome studies (9, 17): satisfaction rates of R-NSM (92% excellent, 8% good) and E-NSM (87.5% excellent, 12.5% good) were significantly higher than C-NSM (75.6% excellent, 24.4% good). Current optimal scar incision location had been shifted from inner breast to the anterior axillary line at the level of NAC. This location enables sentinel lymph node biopsy and NSM with IGBR. An asset of this location is that this scar could be well hidden along the bra-line ( Figure 2 ).

Initially, the E-NSM was developed with non-gas inflation retraction type endoscope (5, 13, 41), and for vein harvest from posterior dissection (separation of pectoralis major and breast glandular tissue, Figure 2 ). Then, a semi-areolar incision was made for anterior skin flap dissection using optical port trocar with tunneling method. This dual-areolar-axillary-incision is well-adapted for small- to medium-sized breast, patients without breast reconstruction, and patients receiving tissue expander breast reconstruction. However, for direct gel implant breast reconstruction and large-sized breast patients, NAC ischemia/necrosis risk would be increased (4). The shift from initial dual-areolar-axillary-incision to single-axillary-incision in 2D E-NSM (13, 16) greatly decreased the rate of NAC ischemia/necrosis (Gr II+III) from 22.8% (1.4% total necrosis rate) to 9.4% (0.5% total necrosis rate, p < 0.01). However, this transition also increased operation difficulty and related operation time ( Figure 4 ).

The development of R-NSM successfully solved the difficulties faced by single-axillary-incision 2D E-NSM (7, 8, 27, 34, 42) through better visual acuity with 3D videoscope and wristed articular robotic arms ( Figures 2 , 3B ). The major drawback of R-NSM is the high cost, which is an extra 4,000 USD more ( Figure 5 ) compared to C-NSM (17). Inspired from R-NSM, we started performing single-port 3D endoscopic assisted NSM (E-NSM) in August 2018 ( Figure 3B ) (31). This procedure became widely accepted due to balanced clinical outcome and medical cost (7,760 USD) (15), nearly 3,000 USD could be saved when compared with R-NSM ( Figure 5 ). As medical cost remained an important consideration, we believe that R-NSM can work as a bridge and help surgeons be familiar with techniques of advanced endoscopic breast surgery such as single-port 3D E-NSM (15).

Extended operation time is one criticism of MABS (5, 6, 28, 29), especially towards R-NSM (29). Figure 4A showed that in the past 10 years, operation time had decreased dramatically. When we compare the first vs. last 10 cases of E-NSM and R-NSM, a reduction of 51.5% and 32% operation time was observed respectively ( Figure 4B ). Surgical length of MABS has now decreased to acceptable duration after much accumulated case (33), making surgeons more experienced and able to standardize the performed procedures (27) ( Figure 4 ). From our perspective, air inflation system would be the predominant system in E-NSM (15, 16, 31) and R-NSM (8, 27, 34, 42); however, retraction system might be sufficient for E-BCS (11, 30).

The oncologic safety of E-BCS versus C-BCS was confirmed in our previous study (26) by adopting propensity score matching. Oncologic safety is not shown in the current cohort as patient-selection criteria and case number of C-BCS were quite different from E-BCS ( Table 1 ). The preliminary oncologic safety of minimal access (endoscopic or robotic assisted) NSM versus C-NSM is shown in Table 2 and Supplementary Figure 2 , which present comparable disease-free survival and overall survival for all three procedures. In multivariate analysis for disease recurrence, minimal access breast surgery was not associated with increased recurrence risk. However, difference in various groups and relative short follow-up time in R-NSM should be noted.

Our current study is limited in its retrospective nature, limited case numbers, and single-surgeon experience Nonetheless, data were collected prospectively over a 10-year-period, and the results derived from this study are solid and reliable. The observed trend of increasing MABS performed in early breast cancer and shortening of operation time in various MABS with case accumulated experience could be extrapolated to other centers in the world.

The era of minimal access (endoscopic and robotic assisted) breast surgery is approaching as an increasing number of hospitals around the world adopt these minimal access breast surgical techniques in the treatment of breast cancer. The highlight of MABS lies in its small inconspicuous operation scar and high patient satisfaction. The previously criticized extensive operation time had decreased steadily due to technique refinements and the surgical team’s procedural familiarity. The cost of minimal access mastectomy increased from conventional to E-NSM and nearly doubled in R-NSM. The newly developed single-port 3D E-NSM, which worked just as well as R-NSM while greatly decreased medical cost, could be an alternative choice.

The data analyzed in this study are subject to the following licenses/restrictions: The dataset could be available only by asking the principal investigator, and will be released after permission. Requests to access these datasets should be directed to hwlai650420@yahoo.com.tw.

The studies involving human participants were reviewed and approved by Institutional Review Board of the Changhua Christian Hospital. The patients/participants provided their written informed consent to participate in this study. Written informed consent was obtained from the individual(s) for the publication of any potentially identifiable images or data included in this article.

Study design: H-WL and D-RC. Data collection: S-TC and S-LL. Data analysis: Y-JL and S-JK. Manuscript: H-WL and D-RC. All authors contributed to the article and approved the submitted version.

This study was funded by the Ministry of Science and Technology of Taiwan, and the number of this funding was MOST 110-2314-B-371-009-. This study was also sponsored by research funding provided by the Changhua Christian Hospital 109-CCH-IRP-093 and 110-CCH-IRP-042. We also received research funding from Intuitive Surgery CRG09-08232019.

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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