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Page 2 of 7 Thomas et al. Mini-invasive Surg 2018;2:17 I http://dx.doi.org/10.20517/2574-1225.2018.25

[1-3]
surgery . Nevertheless, the debate with regards to the necessity to completely remove the mesorectum
in the setting of early rectal cancer is still not fully resolved. What is clear from the evidence is that
involvement of the circumferential resection margin (CRM) remains one of the most powerful predictors
of local recurrence in rectal cancer.

The Swedish Rectal Cancer and Dutch TME trials gave credence to the concept that local control could
[3,4]
be enhanced by the addition of neoadjuvant short course radiotherapy (SCRT) . Indeed, the National
Institute of Clinical Excellence in the United Kingdom currently recommends that neoadjuvant treatment
is administered in the form of SCRT for moderate-risk tumours (cT3b or greater or suspected nodal
involvement or venous invasion) and as long course chemoradiotherapy (LCCRT) for high-risk tumours
[5]
that either threaten the circumferential resection margin or encroach on the levator plate . Radical surgery
remains the cornerstone of treatment for locally advanced rectal cancer with 5-year local recurrence (LR)
[1,2]
and disease-free survival rates of 4% and 86%, respectively , and a 30-day mortality rate of 0.9%-1.5% [4,6-8] .
The down side of radical surgery is that, even in experienced hands, morbidity occurs in 38%-54% of
patients [4,6-8] and is associated with a significant adverse impact on quality of life with elevated levels of
bowel, urinary, and sexual dysfunction [9-12] . In addition, there is a perception in the UK that local control is
enhanced in disease that threatens the mesorectal rectal fascia with the use of LCCRT. Moreover, the use
of LCCRT may result in a pathological complete response (pCR) in 15% to 25% of cases with contemporary
neoadjuvant LCCRT regimens [13-15] . This has led to the concept of watchful waiting, the success of which is
clearly dependent on the accurate prediction of a complete clinical response (cCR) and does not necessarily
correspond to a pCR. Of note, in a pooled analysis of neoadjuvant treatment studies, cCR was associated
[16]
with pCR in only 30% of patients . It is noteworthy, however, that a pCR is heavily dependent on the
quality of the surgical specimen received and the accuracy of pathological examination, which may vary
considerably [17,18] .

In view of the downstaging effect of LCCRT and the potential to obtain a pCR, there is increasing evidence
to suggest that patients with pCR could be safely managed by local excision. Local procedures, such as
transanal endoscopic microsurgery (TEM), which was first described in the 1980s, and more recently,
transanal endoscopic operation (TEO) and transanal minimally invasive surgery (TAMIS), can potentially
[19]
avoid the morbidity associated with radical surgery and enable organ preservation . A recent systematic
review by our own group suggested that local excision after neoadjuvant therapy for rectal cancer should
only be considered as curative, with an acceptable level of local control, if a pCR was obtained. Pooled local
recurrence rates were significantly greater and median disease-free survival significantly lower among
[20]
tumours staged as ypT1 or above compared to ypT0 tumours . In this article we describe our approach
to the management of early rectal cancer, its staging and our evidence-based rationale for the use of
neoadjuvant and adjuvant therapies.

STAGING EARLY RECTAL CANCER
The accurate staging of colorectal neoplasia can improve the stratification of patients for adjuvant
treatment. We strongly believe that endoluminal ultrasound is a powerful tool in staging early disease. In
support of this view, our initial work focussed on predicting the mural extent of neoplasia. Colonoscopic
endoluminal ultrasonography (EUS) was used in a prospective study to determine the stage of rectosigmoid
neoplasia in 121 patients. Mural tumour (T) stage was designated by EUS as uT0/1-uT4 in 121 patients.
Specific nodal (N) staging was performed in 39 of these cases. EUS staging was compared with histological
stage (pT and pN) in 93 patients who underwent resection. Mural staging of disease using colonoscopic
EUS showed good correlation with histopathological stage (κ = 0.85; 95% confidence interval 0.76-0.95).
[21]
Overall pT and pN stage accuracy of EUS was 92% and 65% respectively .