Endoscopic submucosal dissection (ESD) is widely used for early colorectal cancer as a curative treatment. ESD enables endoscopists to perform en block resection with a higher success rate as compared with conventional endoscopic mucosal resection (EMR) [Citation1,Citation2]. In addition, accurate histopathological evaluation is easier in ESD than in EMR [Citation1,Citation2]. The introduction of ESD has expanded the indication of endoscopic treatments for colorectal tumors and now large tumors exhibiting submucosal invasion can be treated with ESD. One major issue arising from the expansion of ESD indication is how to treat colorectal cancer cases in which ESD producers result in non-curative resection. Given the fact that the rates of lymph node metastasis and recurrences in the non-endoscopically curable patients were not negligible [Citation3], additional surgery is usually recommended for such cases. It should be noted, however, that few patients have residual tumors or lymph node metastasis in the additional surgery. Therefore, identification of factors, highly suggestive of residual tumors and/or lymph node metastasis, is extremely important.
In this issue of the Journal of Investigative Surgery, Cheng P et al have identified risk factors associated with the residual cancers and lymph node metastasis in additional surgery after non-curative ESD for early colorectal cancers [Citation4]. They investigated clinicopathological features of 62 patients who underwent additional surgery. Residual cancer and lymph node metastasis were detected in 12 patients in a total of 62 patients. Thus, around 20% patients required additional surgery in this study. Initial univariate analysis by they revealed that piecemeal resection, submucosal invasion greater than 2,000 μm, lymphovascular infiltration, and perineuronal invasion were more frequent in patients with residual cancer and lymph node metastasis. Subsequent multivariate analysis identified the presence of lymphovascular infiltration as a solitary risk factor associated with residual cancer and lymph node metastasis. Based on these data, they propose that additional surgery needs to be performed after non-curative ESD, especially in cases positive for lymphovascular infiltration [Citation4].
The results of this study are useful in that risk factors associated with residual cancer and/or lymph node metastasis after non-curative ESD have been identified. We need to consider the possibility of residual cancer and lymph node metastasis upon encounter with cases positive for one of four factors, i.e. piecemeal resection, deep submucosal invasion, perineuronal invasion, and lymphovascular infiltration. Moreover, additional surgery is highly recommended in cases with lymphovascular infiltration. Consistent with this idea, previous studies also reported the association between lymphovascular infiltration and regional LNM [Citation1,Citation5,Citation6]. Thus, this study sheds light on the management of colorectal cancers after non-curative ESD.
The proportion of patients treated with piecemeal resection was significantly higher in cases with residual cancer and lymph node metastasis. Thus, piecemeal resection was identified the only procedure-related factor for residual cancer and lymph node metastasis. Although endoscopists are sometimes compelled to perform piecemeal resection in colorectal tumors with large size, no correlation was seen between the tumors size and residual cancer. In contrast, submucosal invasion greater than 2,000 μm was associated with residual cancer and lymph node metastasis. Unfortunately, the proportion of patients treated with piecemeal resection for colorectal cancers exhibiting deep submucosal invasion has not been clarified in this study. However, these findings strongly suggest that endoscopists need to avoid piecemeal resection as much as possible, especially in cases suspected of deep submucosal invasion. Another concern regarding the piecemeal resection is that the proportion of recurrence is much higher in patients treated with piecemeal resection for colorectal tumors than in those with en bloc resection as shown by our previous report [Citation7].
This study had a few drawbacks. Firstly, this was a retrospective study with a single hospital setting. Secondly, the decision to perform additional surgery is not always related to the assessment of clinicopathological risk factors after ESD resection. Some surgeons might have taken into consideration the patient’s intention in the decision making in surgery. As the authors recognize, future prospective multi-center studies are absolutely required to establish risk factors associated with residual cancer and lymph node metastasis after non-curative ESD for colorectal cancers. Determination of requirements for additional surgery is very important to avoid unnecessary surgery.
Disclosure statement
No potential conflict of interest was reported by the author(s).
References
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