Colorectal cancer is, together with breast cancer, the most common malignancy in the Netherlands. The incidence of colorectal cancer was over 12,000 in the year 2009. About 28,000 patients have an enterostomy, of which roughly 60% to 70% have a colostomy (Dutch Cancer Registry, Dutch Stoma Association). About half of the patients with a colostomy develop a parastomal hernia [1, 2].
Probably, the true incidence is underestimated because many of these hernias are asymptomatic. Cingi et al. showed that 52% of their patients with a colostomy had a parastomal hernia at clinical examination, while additional computed tomography yielded an incidence of 78% .
Symptoms include pain due to stretching of the abdominal wall, leakage due to poor fitting appliances, skin problems, and cosmetic complaints. Moreover, bowel obstruction and strangulation of the hernia contents may be life-threatening. Despite evolution of surgical techniques, incidence rates have not declined the past 20 years .
Ultimately, one-third of the patients with a parastomal hernia needs surgical correction [5, 6]. Parastomal hernia repair is challenging and results vary markedly between techniques. Suture repair, narrowing the opening in the fascia, is considered an obsolete procedure because the recurrence rates are over 70%. Relocation of the stoma is associated with a recurrence rate of 33% with an additional risk of developing an incisional hernia in the midline or at the old ostomy site of 20% [2, 7–9]. Nowadays, prosthetic repair is the gold standard of parastomal hernia repair. Several techniques have been developed having similar results with respect to morbidity and recurrence rate (Hansson et al., 2012 ). In the last decade, laparoscopic repair of PSH is developing. Basically two techniques are used, the modified Sugarbaker technique and the keyhole technique, of which the last seems to have a significantly higher risk of recurrence.
Because of the high incidence, inconsistent results of available data on parastomal repair and lack of sufficient treatment options, surgeons started focusing on prevention of the hernia with local reinforcement of the abdominal wall using a prosthetic mesh. At time of writing the PREVENT-trial protocol in 2009, only a few reports on this topic were published.
Two recent reviews showed that parastomal hernias can be prevented by the placement of a preperitoneal, retromuscular mesh around the stoma [11, 12]. Randomized trials from Jänes and Serra-Aracil, both using a light-weight polypropylene mesh in a preperitoneal retromuscular position, found significantly more parastomal hernias in the group with a conventional stoma (53.7%) as compared to the mesh group (14.8%; P <0.001). Mesh related complications are rare. Serra reported one patient with a peristomal infection and one with a stenosis of the stoma. Jänes reported no mesh-related complications.
The percentage of patients with a parastomal hernia who required surgical intervention decreased in the mesh group in comparison with the non-mesh group. Both studies combined seven out of 29 patients who developed a PSH in the non-mesh group required surgical repair versus none of the eight in the mesh group with a PSH [13, 14] (Additional file 1: Table S1).
Unfortunately the trials were small, 27 patients per group. Although a meta-analysis offers compensation for this flaw, sample size still be too small for detecting a difference when events occur infrequent. With these small numbers of patients less common complications could be missed. Furthermore the risk of bias increases due to a variability of clinical factors and non-uniform reporting of clinical parameters such as stoma site, patient characteristics, and type of surgery all contributed to the heterogeneity. To make more reliable statements on the actual decline of the incidence of PSHs, larger groups are needed.
Due to these shortcomings there is need for more methodologically sound trials.