As a useful alternative to laparoscopic-assisted surgery, we have performed a longitudinal mini-incision (skin incision, <7 cm) for the resection of locally advanced colonic cancer in non-overweight (body mass index <25.0 kg/m²) patients since 2000 and have demonstrated satisfactory outcomes in terms of technical feasibility and safety, minimal invasiveness, and oncological safety.^1–5 The “longitudinal short” or “transverse” incision has been proposed as part of an enhanced recovery after surgery (ERAS) clinical care protocol,⁶ which was developed firstly and mainly for open colectomies. The use of such incision types is considered to reduce postoperative pain, leading to a more rapid return of patient mobility. However, a “transverse mini-incision” has rarely been evaluated, probably because many surgeons likely believe a curative colectomy via such an incision type would be difficult to perform. In April 2009, we began using a “transverse mini-incision” for the curative resection of locally advanced colonic cancer as an alternative approach to the previously used “longitudinal mini-incision.” We herein report the results of a comparison between “transverse mini-incision” and “longitudinal mini-incision” for the resection of locally advanced colonic cancer in terms of technical feasibility and safety as well as minimal invasiveness.

Patients and Methods

This study was approved by the local ethics committee of Saitama Medical Center, Saitama medical University.

Surgical techniques via transverse mini-incision

To standardize the surgical techniques of either transverse mini-incision or longitudinal mini-incision, board-certified surgeons of the Japan Society of Surgery and/or the Japan Society of Coloproctology managed all the surgical techniques as an operating surgeon or a supervisor. Thus, senior residents were occasionally an operating surgeon under the supervision of the board certificated surgeons (data not shown), similarly in conventional open curative colectomy. Drs. HI or JS was the operating surgeon or supervisor in the transverse mini-incision group, while Drs. HI, MY, or HN was the operating surgeon or supervisor in the longitudinal mini-incision group.

All the surgical procedures via the transverse mini-incision were the same as those via the longitudinal mini-incision reported elsewhere,^1–5 except for the method of exposing the abdominal cavity. Each patient was positioned supine. A transverse incision ≤7 cm was placed in principle in the right lower abdomen for cecal or ascending colon cancers, in the lower abdomen for descending colon or sigmoid colon cancers, and in the epigastrium for transverse colon cancers (Fig. 1A). Following the skin incision, the anterior sheath of the rectus abdominis and the peritoneum were also incised transversely, without splitting the rectus muscle. A wound retractor (Alexis, medium size; Applied Medical, Rancho Santa Margarita, CA) was placed against the edge of the wound with the rectus muscle retracted laterally (Fig. 1B). If necessary, 1 to 4 gauze swabs were placed intraperitoneally to retract the small bowel and omentum away from the operative field. We did not use any specific instruments to obtain surgical field. Instead, an assistant slid the wound into position utilizing conventional retractors. Bowel resection along with mesocolic excision and high ligation of the regional vessels (D3-level lymph node dissection according to the Japanese guidelines^7,8) was performed using a medial to lateral approach (Figs. 1C, 1D). All anastomoses were stapled extracorporeally.

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Statistical analysis

A statistical software package (StatFlex version 7.0; Artec, Osaka, Japan) running on a personal computer was used to conduct the analysis. Continuous data were expressed as the median and range and were compared using the Mann-Whitney test. Categorical data were compared using the χ² test or Fisher exact probability test where appropriate. All P values of less than 0.05 were denoted to be statistically significant. Since this study was performed on an intention-to-treat basis, patients with a failed mini-incision approach were included in the analysis.

Results

The site of tumor location was the cecum in 11 patients, the ascending colon in 24 patients, the transverse colon in 9 patients, the descending colon in 1 patient, and the sigmoid colon in 17 patients. Table 1 shows a comparison of the demographic, clinicopathological, and surgical parameters between the two groups. Age (P = 0.92), sex (P > 0.99), BMI (P = 0.53), types of surgery (P = 0.60), maximal tumor diameter (P = 0.36), pathological stage according to the 7th edition of the TNM classification (P = 0.13), and estimated blood loss (P = 0.12) did not differ significantly between the two groups. The median number of lymph nodes harvested tended to be larger in the transverse mini-incision group (21 versus 18, P = 0.12). Duration of surgery tended to be longer in the transverse mini-incision group (130 min versus 120 min, P = 0.07). Concerning the success rate of the mini-incision, 3 patients (5%) in the transverse mini-incision group required extension of the wound up to 9 cm in length because of poor visualization of the surgical field, while 2 patients in the longitudinal mini-incision group required extension of the wound up to 15 cm because of poor visualization in one and severe intra-abdominal adhesions in one. The success rate of the mini-incision did not differ between the 2 groups (95% versus 97%, P > 0.99). Table 2 shows a comparison of the postoperative complications. One patient in the transverse mini-incision group underwent a second laparotomy for re-anastomosis as a result of stricture, while 1 patient in the longitudinal mini-incision group underwent a re-laparotomy because of intra-abdominal bleeding. The frequency of postoperative complications did not differ between the 2 groups (11% versus 8%, P = 0.76). Concerning various parameters related to postoperative recovery, the time to first passage of flatus (P = 0.18) and the time to first passage of stool (P = 0.19) did not significantly differ between the 2 groups. Postoperative analgesic use (pentazocine, 15 mg, intramuscularly) was significantly less in the transverse mini-incision group (P = 0.04), even though the use of epidural anesthesia tended to be less in the transverse mini-incision group (P = 0.09). Postoperative length of the hospital stay was significantly shorter (P < 0.01) in the transverse mini-incision group than in the longitudinal mini-incision group (Table 3).

Table 1 Comparison of demographics, clinicopathological and surgical factors between patients with transverse and those with longitudinal mini-incision

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Table 2 Postoperative complications between patients with transverse and those with longitudinal mini-incision

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Table 3 Comparison of parameters related to postoperative recovery

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Discussion

This study has shown that the transverse mini-incision was equivalent to a longitudinal mini-incision in terms of technical feasibility and safety as well as postoperative complications, although 3 patients required extension of the wound and 1 patient required a second laparotomy for re-anastomosis in the transverse mini-incision group. The duration of surgery tended to be significantly longer in the transverse mini-incision group, but the difference between the 2 groups (median value, 10 minutes) seems to be of little significance in clinical practice. The number of lymph nodes harvested did not significantly differ between the 2 groups and the median number of lymph nodes seems to be oncologically satisfactory^9,10 in both groups. A longer follow-up period is needed to confirm the oncological safety of a transverse mini-incision approach, but we have already demonstrated that a longitudinal mini-incision had a similar oncological outcome, compared with a conventional open procedure. Thus, this approach seems to be acceptable if surgeons are familiar with a longitudinal mini-incision.^{1–5,11–15} There may be a criticism regarding surgeons' experiences on the 2 study periods of different procedures. All the procedures throughout the 2 study periods were exclusively managed by the board-certified surgeons. In addition, surgical procedures related to colorectal surgery were standardized well in Japan according to the spread of the clinical guidelines⁷ for the management of colorectal cancer. Thus, we believe that there might be little difference in surgeons' experiences in the 2 study periods.

More importantly, we should note that a transverse mini-incision resulted in less postoperative pain and a shorter hospital stay in agreement with numerous previous reports. Although this study was retrospective in nature, the preoperative care was similar throughout the study period except for the perioperative bowel preparation and antimicrobial prophylaxis, suggesting a minimal bias in perioperative care between the 2 groups.

The possible mechanisms explaining the lesser pain after a transverse mini-incision are 2-fold. First, our approach could potentially avoid cutaneous somatic nerve injuries. In addition, our approach did not divide the rectus abdominis muscle and retracted it laterally, also avoiding relevant nerve injuries. Second, compared with a longitudinal incision, a transverse incision might decrease the tension on the wound itself as demonstrated in human¹⁶ and animal studies¹⁷, leading to less pain.

Two systematic reviews or meta-analyses^18,19 combining several studies comparing “long longitudinal incisions” and “long transverse incisions” for gastrointestinal and abdominal aortic surgeries demonstrated that postoperative pulmonary complications were fewer, short- and long-term wound complications were fewer, and postoperative pain was lesser in the “long transverse incision” group.

Regarding colorectal surgery, to the best of our knowledge, 3 retrospective studies have compared transverse incision and midline incision, regardless of the length of the incision and with no clear definition for a mini-incision. Stipa et al²⁰ compared “transverse mini-incisions (n = 28)” and “midline incisions (n = 17)” for the curative resection of the right-sided colonic cancer. They reported that the recovery of postoperative bowel function tended to be faster and the postoperative hospital stay was significantly shorter in the “transverse mini-incision” group, though the actual lengths of the incision in both groups were not reported. Donati et al²¹ compared a “limited transverse incision” (median length, 10 cm; n = 62) and a “traditional midline incision” (median length, 20 cm, n = 61) for the resection of right-sided colonic cancer and concluded that the “limited transverse incision” had a significantly shorter operative time, earlier recovery of bowel motility, earlier oral intake, and shorter postoperative stay. Kam et al²² compared a “transverse mini-incision” (median length, 13.5 cm; n = 140) and a “midline incision” (median length, 20 cm; n = 140) for the resection of left-side colonic cancer and concluded that a “transverse min-incision” had significantly shorter operating time, an earlier postoperative recovery, less pain, and a shorter postoperative stay. In addition to these 3 reports, Theodosopoulos et al²³ compared the results of right hemicolectomies for colonic cancer between a subcostal incision (median length, 10 cm; n = 113), and midline incision (median length, 12 cm; n = 100) and concluded that a subcostal incision, which might be a modification of a transverse incision, could achieve the same standards of tumor resection and surgical field accessibility as the midline approach, while reducing the time to postoperative recovery. Concerning a prospective randomized study, only 1 study²⁴ has compared right hemicolectomies between a transverse incision group (n = 14) and a midline incision group (n = 14), but the study did not demonstrate any important difference between the 2 groups because of the insufficient number of cases.

The advantages of mini-incisions include a lower cost, faster completion of the procedure, reduced bulkiness of equipment, less manpower, and the possibility of exploring the entire peritoneal cavity without a loss of tactile sensation,^{1–5,11–15} compared with laparoscopic-assisted approach. We do not deny the utility of a laparoscopic-assisted approach, but a retrospective study,²⁵ comparing the effects of laparoscopic-assisted colectomies (average midline skin incision, 7.7 cm, n = 13) and open colectomies through a right transverse skin incision (average length, 10.3 cm, n = 20) for right-sided colon cancer, showed no significant differences between the 2 groups with regard to short-term surgical outcomes and oncological parameters, with longer operative time in the laparoscopic-assisted group.

This retrospective observational study with a small number of patients compared, possibly for the first time, a “transverse mini-incision” and a “longitudinal min-incision” for the resection of locally advanced colonic cancer with the same maximal incision (≤7cm) in both groups, which was shorter than those in previous reports describing “mini-incisions.” In addition, the tumor site was matched between the 2 groups; thus, this study seems to be more credible than previously reported studies comparing incision methods (transverse or longitudinal) and patients' outcomes, although a prospective randomized study with a larger series is needed to conclude the superiority of either type of mini-incision.

This study excluded patients with a BMI >25kg/m², since we felt that a curative colectomy would be difficult to perform in overweight or obese patients. We previously reported that our “longitudinal mini-incision” would be suitable for most patients with colonic cancer in East Asian countries, since the incidence of overweight (BMI > 25.0 kg/m²) or morbidly obese patients (BMI > 30.0 kg/m²) in East Asian countries is lower than that in Western countries.²⁶ Thus, we should note that the merits of a “transverse mini-incision” also might be restricted to select patients, similar to the situation for “longitudinal mini-incision.”

In conclusion, our preliminary case-match retrospective study demonstrated that a “transverse mini-incision” is similar to a “longitudinal mini-incision” in terms of technical feasibility and safety as well as postoperative morbidity for the surgical treatment of nonoverweight patients with locally advanced colonic cancer. In addition, some postoperative recovery-related parameters seemed to be more favorable in the “transverse mini-incision” group.