Can mesorectal lymph node excision be avoided in rectal cancer surgery?

Session 3: Many ways to organ preserve the rectum but which is correct?

From the patient's perspective, cancer cure with full preservation of function is a crucial goal. There are many advances that have emerged which may make this possible in a greater proportion of patients without compromising oncological outcomes. Professor Tekkis reviews the options and evidence to date for 'organ preservation' and the expert panel discuss the implications for current and future patient care.

Organ preservation for rectal cancer (GRECCAR 2): a prospective, randomised, open-label, multicentre, phase 3 trial

BACKGROUND

Organ preservation is a concept proposed for patients with rectal cancer after a good clinical response to neoadjuvant chemotherapy, to potentially avoid morbidity and side-effects of rectal excision. The objective of this study was to compare local excision and total mesorectal excision in patients with a good response after chemoradiotherapy for lower rectal cancer.

METHODS

We did a prospective, randomised, open-label, multicentre, phase 3 trial at 15 tertiary centres in France that were experts in the treatment of rectal cancer. Patients aged 18 years and older with stage T2T3 lower rectal carcinoma, of maximum size 4 cm, who had a good clinical response to neoadjuvant chemoradiotherapy (residual tumour ≤2 cm) were centrally randomly assigned by the surgeon before surgery to either local excision or total mesorectal excision surgery. Randomisation, which was done via the internet, was not stratified and used permuted blocks of size eight. In the local excision group, a completion total mesorectal excision was required if tumour stage was ypT2-3. The primary endpoint was a composite outcome of death, recurrence, morbidity, and side-effects at 2 years after surgery, to show superiority of local excision over total mesorectal excision in the modified intention-to-treat (ITT) population (expected proportions of patients having at least one event were 25% vs 60% for superiority). This trial was registered with ClinicalTrials.gov, number NCT00427375.

FINDINGS

From March 1, 2007, to Sept 24, 2012, 186 patients received chemoradiotherapy and were enrolled in the study. 148 good clinical responders were randomly assigned to treatment, three were excluded (because they had metastatic disease, tumour >8 cm from anal verge, and withdrew consent), and 145 were analysed: 74 in the local excision group and 71 in the total mesorectal excision group. In the local excision group, 26 patients had a completion total mesorectal excision. At 2 years in the modified ITT population, one or more events from the composite primary outcome occurred in 41 (56%) of 73 patients in the local excision group and 33 (48%) of 69 in the total mesorectal excision group (odds ratio 1·33, 95% CI 0·62-2·86; p=0·43). In the modified ITT analysis, there was no difference between the groups in all components of the composite outcome, and superiority was not shown for local excision over total mesorectal excision.

INTERPRETATION

We failed to show superiority of local excision over total mesorectal excision, because many patients in the local excision group received a completion total mesorectal excision that probably increased morbidity and side-effects, and compromised the potential advantages of local excision. Better patient selection to avoid unnecessary completion total mesorectal excision could improve the strategy.

FUNDING

National Cancer Institute of France, Sanofi, Roche Pharma.

Advances for achieving a pathological complete response for rectal cancer after neoadjuvant therapy

Neoadjuvant therapy has become the standard of care for locally advanced mid-low rectal cancer. Pathological complete response (pCR) can be achieved in 12%–38% of patients. Patients with pCR have the most favorable long-term outcomes. Intensifying neoadjuvant therapy and extending the interval between termination of neoadjuvant treatment and surgery may increase the pCR rate. Growing evidence has raised the issue of whether local excision or observation rather than radical surgery is an alternative for patients who achieve a clinical complete response after neoadjuvant therapy. Herein, we highlight many of the advances and resultant controversies that are likely to dominate the research agenda for pCR of rectal cancer in the modern era.

[Organ preserving strategies for rectal cancer treatment]

For rectal cancers, the current standard of care consists of chemoradiation followed by radical surgery with total mesorectal excision. Oncologic results are good, especially regarding local recurrence rates, but at the cost of high morbidity rates and poor anorectal, urinary and sexual function results. Since chemoradiation yields 15 to 25% pathological complete response, the role of radical surgery is questioned for patients presenting with good response after chemoradiation and two organ preservation strategies have been offered: watch and wait strategy and local excision strategy. The aim of this review is to give the results of organ preservation after chemoradiotherapy series and to highlight different questions regarding initial patient's selection, complete clinical response definition, risk of mesorectal nodal involvement, follow-up modalities as well as oncologic and functional results.

In vivo lymph node mapping and pattern of metastasis spread in locally advanced mid/low rectal cancer after neoadjuvant chemoradiotherapy

PURPOSE

The lymph node status is one of the strongest prognostic determinants in rectal cancers. After chemoradiotherapy (CRT), lymph nodes are difficult to detect. This study aims to evaluate the feasibility of lymph node mapping in the mesorectum after CRT to analyze the pattern of metastasis spread and to assess the reliability of blue dye injection in sentinel lymph node detection.

METHOD

Ten patients with cN+ mid/low RCs after CRT were prospectively enrolled. The protocol scheduled intraoperative blue dye injection, surgery, and specimen examination with fat clearance technique. The mesorectum was divided into three equal "levels" (upper, middle, and lower); each level was divided into three equal "sectors" (right anterolateral, posterior, and left anterolateral). Lymph nodes were defined "small" if ≤5 mm.

RESULTS

Two hundred seventy-six lymph nodes were retrieved in ten patients; 76.5 % were small lymph nodes. Six patients were pN+ (33 metastatic lymph nodes, 76 % small); small lymph node analysis upstaged one patient from N0 to N1 and four patients from N1 to N2. Metastasis distribution across sectors was continuous, without "skip sectors." The blue dye detected the sentinel lymph node in all patients; in half of the cases, it was out of the tumor sector. Blue dye identified 69.7 % of metastatic lymph nodes; its sensitivity decreased together with the metastatic deposit size (84 % macrometastases, 28.6 % micrometastases, 0 % occult tumor cells; p = 0.004).

CONCLUSION

The fat clearance technique should be the standard pathological examination in patients with RCs after CRT; N staging was improved by small lymph node identification. Lymph node metastases have a continuous spread through mesorectal sectors. Blue dye injection is effective in sentinel lymph node detection.