Technical feasibility of laparoscopic extended surgerybeyond total mesorectal excision for primary or recurrentrectal cancer

Relatively little is known about the oncologic safety of laparoscopic surgery for advanced rectal cancer.Recently, large randomized clinical trials showed that laparoscopic surgery was not inferior to open surgery, as evidenced by survival and local control rates. However, patients with T4 tumors were excluded from these trials. Technological advances in the instrumentation and techniques used by laparoscopic surgery have increased the use of laparoscopic surgery for advanced rectal cancer. High-definition, illuminated, and magnified images obtained by laparoscopy may enable more precise laparoscopic surgery than open techniques, even during extended surgery for T4 or locally recurrent rectal cancer. To date, the quality of evidence regarding the usefulness of laparoscopy for extended surgery beyond total mesorectal excision has been low because most studies have been uncontrolled series, with small sample sizes, and long-term data are lacking. Nevertheless, laparoscopic extended surgery for rectal cancer, when performed by specialized laparoscopic colorectal surgeons, has been reported safe in selected patients, with significant advantages, including a clear visual field and less blood loss. This review summarizes current knowledge on laparoscopic extended surgery beyond total mesorectal excision for primary or locally recurrent rectal cancer.

Treatment of colorectal carcinoids:A new paradigm

It is often difficult to evaluate the grade of malignancy and choose an appropriate treatment for colorectal carcinoids in clinical settings. Although tumor size and depth of invasion are evidently not enough to stratify the risk of this rare tumor, the present guidelines or staging systems do not mention other clinicopathological variables. Recent studies, however, have shed light on the impact of lymphovascular invasion on the outcome of colorectal carcinoids. It has been revealed that the presence of lymphovascular invasion was among the strongest risk factors for metastasis along with tumor size and depth of invasion. Furthermore, tumors smaller than 1 cm, within submucosal invasion and without lymphovascular invasion, carry minimal risk for metastasis with 100% 5-year survival in the studies from Japan as well as from the USA. This would suggest that these tumors could be curatively treated by endoscopic resection or transanal local excision. On the other hand, colorectal carcinoids with either lymphovascular invasion or tumor size larger than 1 cm carry the risk for metastasis equivalent to adenocarcinomas. Therefore, it should be emphasized that histological examination of lymphovascular invasion is mandatory in the specimens obtained by endoscopic resection or transanal local excision, as this would provide useful information for determining the need for additional radical surgery with regional lymph node dissection. Although the present guidelines or TNM staging system do not mention the impact of lymphovascular invasion, this would be among the next promising targets in order to establish better guidelines and staging systems, particularly in early-stage colorectal carcinoids.

Preoperative chemoradiation and extended pelvic lymphadenectomy for rectal cancer:Two distinct principles

Extended pelvic lymphadenectomy(EPL) with total mesorectal excision(TME) has been reported to provide oncological benefit in lower rectal cancer in Japan.In Western countries EPL is not widely accepted because of frequent morbidity but instead preoperative chemoradiation(CRT) followed by TME has been established as a standard treatment for decreasing local recurrence.Recently,several studies have focused on the comparison between these two distinct therapeutic approaches in Western countries and Japan.A study comparing Dutch trial data and Japanese data revealed that EPL and RT are almost equivalent in decreasing local recurrence in lower rectal cancer as compared with TME alone.Considering that almost 45 survival can be achieved by EPL even in the presence of metastatic lateral lymph nodes(LLNs),EPL performed by experienced surgeons definitely contributes to decrease local recurrence.On the other hand,a randomized controlled trial in Japan that compared EPL with conventional TME following preoperative RT revealed that EPL is associated with a higher frequency of sexual and urinary dysfunction without oncological benefits in the presence of preoperative RT.On this point,preoperative CRT followed by conventional TME without EPL would be a better therapeutic approach in patients without evident metastatic LLNs.For future treatment,it would be desirable to have a narrower indication for EPL using full advantage of recent improvement in image diagnosis.Although objective comparison of these two principles between Japan and the West is difficult due to differences in patient groups,further studies would lead to the next great step towards future improvement in treating lower rectal cancer.

Is rectal cancer prone to metastasize to lymph nodes than colon cancer?

The biology of colorectal cancer differs according to its location within the large intestine.A report published in a previous issue of World Journal of Gastroenterology (November 2010) evaluated the importance of tumor location as a risk factor for lymph node metastasis in colorectal cancer,and showed that rectal cancer is prone to metastasize to lymph nodes as compared with colon cancer.However,in order to conclude that the tumor location is independently associated with the occurrence of lymph node metastasis,it is necessary to consider a selection bias or other patientand tumorrelated factors carefully.