The impact of subdivisions of microscopically positive (R1) margins on patterns of relapse in stage III colorectal cancer - A retrospective cohort study

The Association of Mismatch Repair Status with Microscopically Positive (R1) Margins in Stage III Colorectal Cancer: A Retrospective Cohort Study

BACKGROUND

There is mounting evidence that microscopically positive (R1) margins in patients with colorectal cancer (CRC) may represent a surrogate for aggressive cancer biology rather than technical failure during surgery. However, whether detectable biological differences exist between CRC with R0 and R1 margins is unknown. We sought to investigate whether mismatch repair (MMR) status differs between Stage III CRC with R0 or R1 margins.

METHODS

Patients treated for Stage III CRC from January 1, 2016 to December 31, 2019 were identified by using the Danish Colorectal Cancer Group database. Patients were stratified according to MMR status (proficient [pMMR] vs. deficient [dMMR]) and margin status. Outcomes of interest included the R1 rate according to MMR and overall survival.

RESULTS

A total of 3636 patients were included, of whom 473 (13.0%) had dMMR colorectal cancers. Patients with dMMR cancers were more likely to be elderly, female, and have right-sided cancers. R1 margins were significantly more common in patients with dMMR cancers (20.5% vs. 15.2%, p < 0.001), with the greatest difference seen in the rate of R1 margins related to the primary tumour (8.9% vs. 4.7%) rather than to lymph node metastases (11.6% vs. 10.5%). This association was seen in both right- and left-sided cancers. On multivariable analyses, R1 margins, but not MMR status, were associated with poorer survival, alongside age, pN stage, perineural invasion, and extramural venous invasion.

CONCLUSIONS

In patients with Stage III CRC, dMMR status is associated with increased risks of R1 margins following potentially curative surgery, supporting the use of neoadjuvant immunotherapy in this patient group.

Neoadjuvant treatment of colorectal cancer: comprehensive review

BACKGROUND

Neoadjuvant therapy has an established role in the treatment of patients with colorectal cancer. However, its role continues to evolve due to both advances in the available treatment modalities, and refinements in the indications for neoadjuvant treatment and subsequent surgery.

METHODS

A narrative review of the most recent relevant literature was conducted.

RESULTS

Short-course radiotherapy and long-course chemoradiotherapy have an established role in improving local but not systemic disease control in patients with rectal cancer. Total neoadjuvant therapy offers advantages over short-course radiotherapy and long-course chemoradiotherapy, not only in terms of increased local response but also in reducing the risk of systemic relapses. Non-operative management is increasingly preferred to surgery in patients with rectal cancer and clinical complete responses but is still associated with some negative impacts on functional outcomes. Neoadjuvant chemotherapy may be of some benefit in patients with locally advanced colon cancer with proficient mismatch repair, although patient selection is a major challenge. Neoadjuvant immunotherapy in patients with deficient mismatch repair cancers in the colon or rectum is altering the treatment paradigm for these patients.

CONCLUSION

Neoadjuvant treatments for patients with colon or rectal cancers continue to evolve, increasing the complexity of decision-making for patients and clinicians alike. This review describes the current guidance and most recent developments.

Survival and safety after neoadjuvant chemotherapy or upfront surgery for locally advanced colon cancer: meta-analysis

BACKGROUND

Neoadjuvant chemotherapy is increasingly used to treat locally advanced (T3-4 Nx-2 M0) colon cancer due to its potential advantages over the standard approach of upfront surgery. The primary objective of this systematic review and meta-analysis was to analyse data from comparative studies to assess the impact of neoadjuvant chemotherapy on oncological outcomes.

METHODS

A systematic review was conducted by searching the MEDLINE and Scopus databases. The search encompassed RCTs, propensity score-matched studies, and controlled prospective studies published up to 1 April 2023. As a primary objective, overall survival and disease-free survival were compared. As a secondary objective, perioperative morbidity, mortality, and complete resection were compared using the DerSimonian and Laird models.

RESULTS

A total of seven studies comprising a total of 2120 patients were included. Neoadjuvant chemotherapy was associated with a reduction in the hazard of recurrence (HR 0.73, 95% c.i. 0.59 to 0.90; P = 0.003) and death (HR 0.67, 95% c.i. 0.54 to 0.83; P < 0.001) compared with upfront surgery. Additionally, neoadjuvant chemotherapy was significantly associated with higher 5-year overall survival (79.9% versus 72.6%; P < 0.001) and disease-free survival (73.1% versus 64.5%; P = 0.028) rates. No significant differences were observed in perioperative mortality (OR 0.97, 95% c.i. 0.28 to 3.33), overall complications (OR 0.95, 95% c.i. 0.77 to 1.16), or anastomotic leakage/intra-abdominal abscess (OR 0.88, 95% c.i. 0.60 to 1.29). However, neoadjuvant chemotherapy was associated with a lower risk of incomplete resection (OR 0.70, 95% c.i. 0.49 to 0.99).

CONCLUSION

Neoadjuvant chemotherapy is associated with a reduced hazard of recurrence and death, as well as improved overall survival and disease-free survival rates, compared with upfront surgery in patients with locally advanced colon cancer.

Variations in the definition and perceived importance of positive resection margins in patients with colorectal cancer - an EYSAC international survey

INTRODUCTION

Microscopically positive resection margins (R1) are associated with poorer outcomes in patients with colorectal cancer. However, different definitions of R1 margins exist. It is unclear to what extent the definitions used in everyday clinical practice differ within and between nations. This study sought to investigate variations in the definition of R1 margins in colorectal cancer and the importance of margin status in clinical decision-making.

MATERIALS AND METHODS

A 14-point survey was developed by members of The European Society of Surgical Oncology (ESSO) Youngs Surgeons and Alumni Club (EYSAC) Research Academy targeting all members of the multidisciplinary team (MDT) treating patients with colorectal cancer. The survey was distributed on social media, in ESSO's monthly newsletter and via national societies.

RESULTS

In total, 137 responses were received. Most respondents were from Europe (89.7%), with the majority from Denmark (56.9%). Less than 2/3 of respondents defined R1 margins as the presence of viable cancer cells ≤1 mm of the margin. Only 60% reported that subdivisions of R1 margins (primary tumour vs tumour deposit vs metastatic lymph node) are routinely available. More than 20% of respondents reported that pathology reports are not routinely reviewed at MDT meetings. Less than half of respondents considered margin status in decision-making for type and duration of adjuvant chemotherapy in Stage III colon cancer.

CONCLUSION

The definitions and perceived clinical importance of microscopically positive margins in patients with colorectal cancer appear to vary. Adoption of an international dataset for pathology reporting may help to standardise current practices.

Do differences in surgical quality account for the higher rate of R1 margins to lymph node metastases in right- versus left-sided Stage III colon cancer: A retrospective cohort study

AIM

Microscopically positive (R1) margins to lymph node metastases (R1LNM) are associated with poorer oncological outcomes in patients with Stage III colon cancer. R1LNM margins are more common in right-sided cancer, although the cause of this phenomenon is unknown. We sought to investigate whether differences in surgical quality account for the higher rate of R1LNM in right-sided cancers.

METHOD

Patients treated for Stage III colon cancer from 1 January 2016 to 31 December 2018 were identified using the Danish national cancer registry. Indicators of surgical quality (mesocolic resection grade, median lymph node yield, and length to the distal colonic margin) were compared according to tumour site and margin status.

RESULTS

In all, 1765 patients were included, 981 (55.6%) with right-sided cancers. R1LNM margins were more common in right-sided cancers (14.4% vs. 6.1%, P < 0.001). All three surgical quality indicators were higher in patients with right-sided cancers (mesocolic resection planes 81.7% vs. 69.5%, P < 0.001; median lymph node yield 28 vs. 25, P < 0.001; ≥5 cm to the distal colon margin 81.2% vs. 53.6%, P < 0.001). When stratified according to margin status, no differences in mesocolic resection planes or resectate length were noted, whilst median lymph node yield was higher in patients with R1LNM margins (29 vs. 27, P = 0.009).

CONCLUSION

Surgical quality does not appear to be poorer in patients undergoing surgery for right-sided versus left-sided colon cancers in Denmark. Suboptimal surgery does not appear to be responsible for R1LNM margins, implying that these margins may be a surrogate for more aggressive biology.