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.

Recurrent colorectal cancer after endoscopic resectionwhen additional surgery was recommended

AIM: To evaluate the type of recurrence after endoscopic resection in colorectal cancer patients and whether rescue was possible by salvage operation.METHODS: Among 4972 patients who underwent surgical resection at our institution for primary or recurrent colorectal cancers from January 2005 to February 2015, we experienced eight recurrent colorectal cancers after endoscopic resection when additional surgical resection was recommended.RESULTS: The recurrence patterns were: intramural local recurrence(five cases), regional lymph node recurrence(three cases), and associated with simultaneous distant metastasis(three cases). Among five cases with lymphatic invasion observed histologically in endoscopic resected specimens, four cases recurred with lymph node metastasis or distant metastasis. All cases were treated laparoscopically and curative surgery was achieved in six cases. Among four cases located in the rectum, three cases achieved preservation of the anus. Postoperative complications occurred in two cases(enteritis).CONCLUSION: For high-risk submucosal invasive colorectal cancers after endoscopic resection, additional surgical resection with lymphadenectomy is recommended, particularly in cases with lymphovascular invasion.