Surgery for primary malignant tumors of the abdominal wall: experiences of three African surgical oncology units and review of the literature

Abdominal wall tumors are uncommon but diverse [1‐4]. They can be locally malignant or frankly invasive with a tendency to metastasize [2‐5]. The surgical challenge is double: not only must the tumor be treated, but a solid abdominal wall must also be left in place, ideally during the same operation [1, 6, 7]. The surgical procedure depends on the tumor’s size, topography, histological type, but mostly the layers of the abdominal wall involved [6‐8]. Resections of malignant tumors involving only the skin and sub-skin can be conceived without aponeurotic resection [6, 7]. On the other hand, malignant tumors invading the muscular aponeurotic plane require deep resections taking out the muscles and the aponeurosis [6, 7]. In all cases, surgery must repair the abdominal wall at the same time or later, to allow the patient have a normal life [8‐10]. Several parietal repair techniques are described in the literature, including the use of a bifacial prosthesis to avoid intestinal complications [1, 11, 12]. The use of adjuvant treatments such as chemotherapy, targeted therapies, or radiotherapy depends on the histological type and the stage of the tumor [10, 13, 14]. The evolution depends on the histological type and the quality of the resections [15‐17]. Besides tumor recurrences, parietal complications such as incisional hernias are noted in the literature [9, 18‐20]. In the African context, few studies have focused specifically on tumors of the abdominal wall. Furthermore, they are not specifically devoted to surgical aspects. That is why, we undertook this study which reports the experience of three West African surgical oncology units, to better explain the indications, techniques and results of surgery for primary malignant tumors of the abdominal wall in a context of limited resources.

Primary malignant tumors of the abdominal wall are all malignant tumors which develop at the level of the anterolateral abdominal wall, that is, those located in the parietal region bordered above by the costal edges (margins), below by the inguinal ligaments and laterally by the posterior axillary lines [7, 8]. They are uncommon [2‐4]. Dermatofibrosarcomas are the most common, accounting for 77.4% of primary malignant tumors of the abdominal wall in our series. However, all histological types can be found, in particular liposarcomas, rabdomysosarcomas, lymphomas, and desmoid tumors [1‐4, 21]. The therapeutic modalities are as diverse as the histological types and the stages at diagnosis [10, 13, 22]. There is a clear contrast between early diagnosis with small tumors in the West and late diagnosis with large sizes in black Africa [17, 23, 24]. Although surgery is the main curative treatment, it is not always feasible [17, 23]. In our series, we sometimes opted to refrain from surgery, because of the unresectability of the tumor and/or the patient’s inability to afford the exorbitant cost of a two-sided prosthesis for parietal repair. In fact, it is not only a matter of performing oncological surgery, but also of ensuring repair after lumpectomy, allowing the viscera to be covered by a solid wall [7, 9, 22, 25]. Abdominal wall tumor surgery is a major surgery involving multiple specialties [7]. Successful reconstruction of the abdominal wall requires a prior multidisciplinary consultation between surgical oncologists, medical oncologists and reconstructive surgeons [6]. In our African context, these teams are difficult to bring together because certain specialties do not exist yet. This is why oncological surgery, parietal reconstruction and drug management are often left to the sole responsibility of the surgical oncologist who has strong background in oncoplastic surgery and medical oncology. All the patients in this series were attended to, operated, and followed up by surgical oncologists in the three surgical oncology units concerned. Several types of surgical procedures were described. In the literature, two types of resections are particularly common [26‐28]. First, there is wide lumpectomy removing the tumor, the skin and the sub-skin [6, 7]. The parietal repair is then done by a direct cutaneous suture, a controlled wound healing, or a cutaneous covering thanks to the mobilization of flaps, pedunculated or not [7, 12]. In our series, it was mainly about the mobilization of non-pedicled flaps allowing O to Z oncoplasty. Dermatofibrosarcomas represented 80.5% of the tumors in our series. These tumors tend to adhere and to ulcerate the skin, leaving the muscular aponeurotic plane free. They may therefore allow the muscular aponeurotic plane to be spared during their resections [6, 7]. However, desmoid tumors and sarcomas tend to involve the muscular aponeurotic plane and most often require muscular aponeurotic resections [2, 29, 30]. That is why, the second most common resections method described in the literature consists of muscular aponeurotic resections concomitantly with lumpectomy [11, 14, 19]. This is in line with the concept of Khansa et al. who distinguish three parietal defects after oncological surgery for primary abdominal wall tumors [6]. Type 1 defects involve the skin and subcutaneous tissue only. Type 2 defects involve muscle and fascia only. Type 3 defects involve at the same time the skin, subcutaneous tissue, muscle and fascia [6]. Most type I defects require primary suturing; type II or III defects usually require good repair using flaps and/or prosthesis [6, 7, 21]. In addition to the structures involved in defining the three levels of parietal defects, Anderson proposes to consider the topography of the tumor by dividing the abdominal wall into 4 zones corresponding to different anatomical realities involved in the reconstruction [7]. In some cases, we performed a single-piece resection removing the tumor, the skin, and the sub-skin, as well as the muscular aponeurotic plane, leaving the intra-abdominal viscera bare. Simple polypropylene prosthesis is not suitable after muscular aponeurotic resections, because of the risk of adhesions of the intestines to the prosthesis with consequent occlusions and digestive fistulas. This requires parietal repair with the use of a two-sided prosthesis. Applying the smooth side of the mesh to the intestines prevents their adhesion. Instead of the use of a two-sided prosthesis, the large omentum was used in Egypt after extensive resections of abdominal wall tumor [1]. A pedicle of the greater omentum is anchored to the edges of the muscular aponeurotic resections. This separates the simple polypropylene prosthesis that will be fixed in front of the greater omentum. This prosthesis which is much less expensive than a two-sided prosthesis, will be in contact with the greater omentum and not with the intestines [1]. In our African countries with limited resources, this is a good alternative, because the two-sided prosthesis that we use cost four times more than the simple polypropylene prosthesis used in combination with the omentum.

Other abdominal wall reconstruction methods can be used. Muscle flap mobilizations are possible for abdominal wall reconstruction. Some authors admit that release of the transverse abdominis muscle is an acceptable method in the treatment of large defects and hernias of the abdominal wall, associated with low perioperative morbidity and low recurrence rates [31, 32]. They are good alternatives, especially in our context of limited resources where not all patients have access to mesh.

In our African context of work, the large size of the tumors due to late diagnosis, and sometimes the presence of necrosis, explains why in addition to the surgical methods most commonly used in the literature, we also used other procedures. We performed tumor resections removing the skin and sub-skin, as well as the aponeurosis without closing the skin or repairing the wall immediately. This was related to a significant risk of infection given the necrosis of the tumor. Concomitant prosthesis repair and mobilization of skin flaps are not recommended because of the high risk of infection. In fact, the use of synthetic mesh can lead to complications in infected areas. An alternative not used in our series would be the use of biological mesh such as Permacol® biological mesh [33]. The use of Permacol® surgical implants for abdominal wall repair is safe. The presence of contaminated fields does not seem to influence hernia recurrence when Permacol® biological mesh is used [33]. It would be a good alternative for immediate reconstruction of the abdominal wall, even after the resections of necrotic tumors.

We note that all the surgical procedures adopted for primary malignant tumors of the abdominal wall share with all oncological surgeries the need for resections with healthy margins (R0 resections) [2, 27, 34‐36]. It is undoubtedly the parietal repair with its two imperatives of covering the viscera to avoid infections and leaving a solid wall in place to avoid eviscerations and incisional hernias that make surgery for tumors of the abdominal wall unique [2, 27, 34, 35]. In addition, the assessment of evolution after surgical treatment must take into account oncological complications such as recurrences and metastatic evolution, but also parietal complications such as suppuration, evisceration and incisional hernia [9, 13, 18‐20, 28, 37]. In our series, we noted 12.2% recurrence. These were mainly Darier and Ferrand dermatofibrosarcomas that had already recurred before being admitted to our centers. This tumor is also known for its high tendency of recurrence [5, 15‐17]. In our countries, their large sizes at diagnosis increase their risk of recurrence. Fibrous tumors also have a tendency to recur [38]. However, in our series, we did not note any recurrence, despite the absence of radiotherapy. This was attributed to a wide resection with healthy margins. The resections in sano is the best guarantee of evolution without recurrence of desmoid fibrous tumors although adjuvant treatments also minimize the risk of recurrence [38].

In our series, recurrence was associated with histological type in a very highly statistically significant way (p < 0.0001). There was no statistically significant difference in the risk of recurrence between the types of resections removing or not removing the aponeurosis (p = 0.92). Whatever the histological type and the characteristics of the tumor, in our series, all the resections were either in sano, and in the contrary case, a revision surgery was made after obtaining the histological results of the operative part. Many other authors also had the same option [17, 23]. The presence of extemporaneous in some countries allows surgeons to perform these resections during the same operation [5, 16]. In the three centers we used for our study framework, frozen section examination is not available. For this reason, surgical revision is done as soon as the histology is obtained. Survival was statistically and significantly better for dermatofibrosarcomas of Darier and Ferrand than for other tumors. This was in line with data from the literature. In fact, dermatofibrosarcoma of Darrier and Ferrand has a predominantly local evolution giving rise to metastases occurring in less than 5% of cases [5, 17]. Survival is rarely involved. In dermatofibrosarcomas, survival and recurrence-free survival are influenced by the use of targeted therapies [39]. Patient survival has improved with the identification of genetic mutations such as translocation t(17–22) and the use of mysilate imatinib as neoadjuvant therapy in locally advanced, ulcerated and multiply recurrent tumors [40]. Targeted therapy was used as an adjuvant therapy in 21.2% of Darier and Ferrand dermatofibrosarcomas in our study.

We did not use abdominal wall physiotherapy in our series. However, prior to major abdominal surgery, total body rehabilitation including structured exercise, nutritional optimization, psychological support, and cessation of negative health behaviors, reduces complication rates and improves functional outcomes [41, 42]. Our patients should benefit from this before and after surgery.

Surgery is the mainstay of treatment for tumors of the abdominal wall. It must combine tumor resections and parietal repair. The tumor resections must be wide and deep in our countries, even without the possibility of extemporaneous histological examination. The extent of the resections is influenced by the size, topography, histological type of the tumor, extension or not to the muscular aponeurotic plane, but also the experience of the surgeon. The use of two-sided prosthesis is necessary for the coverage of the viscera and the solidity of the abdominal wall in lumpectomies with a major muscular aponeurotic resections. Resections in sano reduces the risk of recurrence. Postoperative follow-up, in addition to tumor-related complications, must also consider the possibility of non-tumoral parietal complications such as incisional hernias. An early diagnosis would make this surgery less mutilating with better results. Training of surgeons in the principles of cancer surgery and abdominal parietal surgery, multidisciplinary care involving oncologists, surgeons and plastic surgeons will improve results.