Implant-Based Breast Reconstruction after Mastectomy, from the Subpectoral to the Prepectoral Approach: An Evidence-Based Change of Mind?

Does the use of acellular dermal matrices (ADM) in women undergoing pre-pectoral implant-based breast reconstruction increase operative success versus non-use of ADM in the same setting? A systematic review protocol

BACKGROUND

Breast cancer is the most common malignancy among women in the UK. Following mastectomy, reconstruction is now integral to the surgical management of breast cancer, of which implant-based reconstruction (IBBR) is the most common type. IBBR initially evolved from pre-pectoral to post-pectoral due to complications, but with developments in oncoplastic techniques and new implant technology, interest in pre-pectoral IBBR has increased. Many surgeons use acellular dermal matrices (ADM); however, there is little evidence in literature as to whether this improves surgical outcomes in terms of complications, failure and patient satisfaction. This review aims to assess the available evidence as to whether there is a difference in surgical outcomes for breast reconstructions using ADM versus non-use of ADM.

METHODS

A database search will be performed using Ovid MEDLINE, Embase, Cochrane Central Register of Controlled Trials, Cochrane Database of Systematic Reviews and Clinicaltrials.org. The search timeframe will be 10 years. Studies will be screened using inclusion and exclusion criteria and data extracted into a standardised spreadsheet. Risk of bias will be assessed. Screening, extraction and risk-of-bias assessments will be performed independently by two reviewers and discrepancies discussed and rectified. Data analysis and meta-analysis will be performed using Microsoft Excel and R software. Forest plots will be used for two-arm studies to calculate heterogeneity and p-value for overall effect.

DISCUSSION

With the renaissance of pre-pectoral IBBR, it is important that surgeons have adequate evidence available to assist operative decision-making. Assessing evidence in literature is important to help surgeons determine whether using ADM for IBBR is beneficial compared to non-use of ADM. This has potential impacts for patient complications, satisfaction and cost to healthcare trusts.

SYSTEMATIC REVIEW REGISTRATION

PROSPERO 2023 CRD42023389072.

Exosomes from Adipose-Tissue-Derived Stem Cells Induce Proapoptotic Gene Expression in Breast Tumor Cell Line

Lipofilling is an option for breast reconstruction after tumor resection to avoid the complications of an implant-based reconstruction. Although some concerns exist regarding the oncological safety of tissue rich in mesenchymal stem cells with their proangiogenic and proliferation-supportive properties, there are also reports that adipose-tissue-derived stem cells can exhibit antitumoral properties. We isolated primary adipose-tissue-derived stem cells. Both conditioned medium and exosomes were harvested from the cell culture and used to treat the breast cancer cell line MCF-7. Cell viability, cytotoxicity, and gene expression of MCF-7 cells in response to the indirect co-culture were evaluated. MCF-7 cells incubated with exosomes from adipose-tissue-derived stem cells show reduced cell viability in comparison to MCF-7 cells incubated with adipose-tissue-derived stem-cell-conditioned medium. Expression of proapoptotic genes was upregulated, and expression of antiapoptotic genes was downregulated. The debate about the oncological safety of autologous fat grafting after tumor resection continues. Here, we show that exosomes from adipose-tissue-derived stem cells exhibit some antitumoral properties on breast cancer cell line MCF-7.

Immediate post-mastectomy prepectoral breast reconstruction with animal derived acellular dermal matrices: A systematic review

BACKGROUND

Animal-derived acellular dermal matrices (ADMs) are increasingly being used in prepectoral direct-to-implant (DTI) breast reconstruction. However, the indications and complication profile associated with this type of reconstruction remain unclear. This study aimed to perform a systematic review of the available literature on the use of animal-derived ADM in prepectoral DTI breast reconstruction.

METHODS

Three different literature databases, namely, PubMed, Web of Sciences, and Embase were screened using the following keywords: "immediate" AND "pre-pectoral" OR "prepectoral" AND "ADM breast reconstruction." Animal-derived ADM used (porcine - Braxon® and non-Braxon® - and bovine - Surgimend®) anthropometric information, clinical data, and complications profile were considered.

RESULTS

A total of 340 articles were initially identified, of which only 45 articles (5089 patients and 6598 reconstructed breasts) satisfied our inclusion criteria. The most widely used ADM was Braxon® in the context of conservative mastectomies. In most studies, a subcutaneous layer > 1 cm and lack of previous radiotherapy were considered prerequisites for this type of reconstruction. An increased risk of complications was found in smokers, patients who underwent radiation treatment, patients with high breast volumes, and patients with cancers requiring axillary dissection. Data related to the role of diabetes, high body mass index, and breast implant size on surgical outcomes were instead inconcludent. Age was not directly proportional to the complications.

CONCLUSION

The complications associated with different animal-derived ADMs are generally comparable. The profile of patients required for eligibility for this type of reconstruction appears to have been identified and is in line with current recommendations.

A prospective randomized clinical trial to assess antibiotic pocket irrigation on tissue expander breast reconstruction

Bacterial infection is the most common complication following staged post-mastectomy breast reconstruction initiated with a tissue expander (TE). To limit bacterial infection, antibiotic irrigation of the surgical site is commonly performed despite little high-quality data to support this practice. We performed a prospective randomized control trial to compare the impact of saline irrigation alone to a triple antibiotic irrigation regimen (1 g cefazolin, 80 mg gentamicin, and 50,000 units of bacitracin in 500 mL of saline) for breast implant surgery. The microbiome in breasts with cancer (n = 16) was compared to those without (n = 16), as all patients (n = 16) had unilateral cancers but bilateral mastectomies (n = 32). Biologic and prosthetic specimens procured both at the time of mastectomy and during TE removal months later were analyzed for longitudinal comparison. Outcomes included clinical infection, bacterial abundance, and relative microbiome composition. No patient in either group suffered a reconstructive failure or developed an infection. Triple antibiotic irrigation administered at the time of immediate TE reconstruction did not reduce bacterial abundance or impact microbial diversity relative to saline irrigation at the time of planned exchange. Implanted prosthetic material adopted the microbial composition of the surrounding host tissue. In cancer-naïve breasts, relative to saline, antibiotic irrigation increased bacterial abundance on periprosthetic capsules (P = 0.03) and acellular dermal matrices (P = 0.04) and altered the microbiota on both. These data show that, relative to saline only, the use of triple antibiotic irrigation in TE breast reconstruction does impact the bacterial abundance and diversity of certain biomaterials from cancer-naïve breasts. IMPORTANCE The lifetime risk of breast cancer is ~13% in women and is treated with a mastectomy in ~50% of cases. The majority are reconstructed, usually starting with a tissue expander to help restore the volume for a subsequent permanent breast implant or the women's own tissues. The biopsychosocial benefits of breast reconstruction, though, can be tempered by a high complication rate of at least 7% but over 30% in some women. Bacterial infection is the most common complication, and can lead to treatment delays, patient physical and emotional distress and escalating health care cost. To limit this risk, plastic surgeons have tried a variety of strategies to limit bacterial infection including irrigating the pocket created after removing the breast implant with antibiotic solutions, but good-quality data are scarce. Herein, we study the value of antibiotics in pocket irrigation using a robust randomized clinical trial design and molecular microbiology approaches.

MRI-Conditional Breast Tissue Expander: First In-Human Multi-Case Assessment of MRI-Related Complications and Image Quality

This study aims to assess potential complications and effects on the magnetic resonance imaging (MRI) image quality of a new MRI-conditional breast tissue expander (Motiva Flora^®) in its first in-human multi-case application. Twenty-four patients with 36 expanders underwent non-contrast breast MRI with T1-weighted, T2-weighted, and diffusion-weighted imaging (DWI) sequences on a 3 T unit before breast tissue expander exchange surgery, being monitored during and after MRI for potential complications. Three board-certified breast radiologists blindly and independently reviewed image quality using a four-level scale ("poor", "sufficient", "good", and "excellent"), with inter-reader reliability being assessed with Kendall's τ_b. The maximum diameters of RFID-related artifacts on T1-weighted and DWI sequences were compared with the Wilcoxon signed-rank test. All 24 examinations were completed without patient-related or device-related complications. The T1-weighted and T2-weighted sequences of all the examinations had "excellent" image quality and a median 11 mm (IQR 9-12 mm) RFID artifact maximum diameter, significantly lower (p < 0.001) than on the DWI images (median 32.5 mm, IQR 28.5-34.5 mm). DWI quality was rated at least "good" in 63% of the examinations, with strong inter-reader reliability (Kendall's τ_b 0.837, 95% CI 0.687-0.952). This first in-human study confirms the MRI-conditional profile of this new expander, which does not affect the image quality of T1-weighted and T2-weighted sequences and moderately affects DWI quality.

[The Value of Synthetic and Biologic Meshes in Implant-Based Breast Reconstruction]

Implant based breast reconstruction (IBBR) keeps evolving and has been influenced heavily by the use of synthetic and biologic meshes in the last years. In both, subpectoral as well as prepectoral approaches the use of synthetic and biologic meshes has made it possible to place implants precisely according to the breast's footprint and strengthen soft-tissue coverage, particularly in the lower pole of the breast with lower complication rates and better cosmesis. Various mesh options that differ in material, processing, size and cost are currently in clinical use. This review aims to define the role of biologic and synthetic meshes in IBBR regarding the advantages and disadvantages of their use.