Anastomotic recurrence of colon cancer: Genetic analysis challenges the widely held theories of cancerous cells' intraluminal implantation and metachronous carcinogenesis

Association of resection margin distance with anastomotic recurrence in stage I-III colon cancer: data from the National Colorectal Cancer Cohort (NCRCC) study in China

PURPOSE

Few studies have focused on anastomotic recurrence (AR) in colon cancer. This study aimed to clarify the association of resection margin distance with AR and compare the prognosis with nonanastomotic local recurrence (NAR).

METHODS

This retrospective cohort study included the clinical data of patients who underwent radical colon cancer surgery between January 1, 2009, and December 31, 2019.

RESULTS

A total of 1958 colon cancer patients were included in the study. 34 of whom (1.7%) had AR and 105 of whom (5.4%) had NAR. Multivariate analysis revealed that the lower distal resection margin distance, advanced N stage, and number of lymph nodes dissected were risk factors for AR. In the proximal resection margin, the risk of AR was lowest at a distance of 6 cm or greater, with a 3-year rate of 1.3%. In the distal resection margin, the 3-year AR risk increased rapidly if the distance was less than 3 cm. The prognosis of patients in the AR group was similar to that of patients in the NAR group, regardless of synchronous distant metastases. Furthermore, the radical surgery rate for AR was significantly higher than that for NAR, but the prognosis of AR was comparable to that of NAR.

CONCLUSIONS

The distal resection margin distance, advanced N stage, and less number of lymph nodes dissected are associated with AR of colon cancer. The prognosis of patients with AR was similar to that of patients with NAR.

TRIAL REGISTRATION

Clinical Trial Numbers NCT04074538 ( clinicaltrials.gov ), August 26, 2019, registered, retrospectively registered.

Recurrence Patterns and Risk Factors after Curative Resection for Colorectal Cancer: Insights for Postoperative Surveillance Strategies

This study aimed to assess recurrence patterns and related risk factors following curative resection of colorectal cancer (CRC). This retrospective observational study was conducted at a tertiary care center, including 2622 patients with stage I-III CRC who underwent curative resection between 2008 and 2018. Hazard rates of recurrence were calculated using a hazard function. The primary outcome was the peak recurrence time after curative resection and secondary outcomes were prognostic factors associated with recurrence. Over a median follow-up period of 53 months, the overall, locoregional and systemic recurrence rates were 8.9%, 0.7%, and 8.5%, respectively. Recurrence rates were significantly higher for rectal cancer (14.9% overall, 4.4% locoregionally, and 12.3% systemically) than for colon cancer (all p < 0.001). The peak recurrence time was 11 months, with variations in hazard rates and curves depending on the tumor location, stage, and risk factors. Patients with AL or CRM involvement exhibited a distinct pattern, with a high hazard rate in the early postoperative period. Understanding these recurrence patterns and risk factors is crucial for establishing effective postoperative surveillance strategies. Our findings suggested that short-interval surveillance should be considered during the first 2 years post-surgery, particularly for high-risk patients who should receive early attention.

Implantation metastasis from sigmoid colon cancer to rectal anastomosis proved by whole exome sequencing and lineage inference for cancer heterogeneity and evolution analysis: Case report and literature review

It was estimated that 70% of patients with colorectal cancer were found to have viable exfoliated malignant cells in adjacent intestinal lumen. Exfoliated malignant cells had been reported to implant on raw surfaces, such as polypectomy site, anal fissure, anal fistula, hemorrhoidectomy wound, and anastomotic suture line. Tumors at anastomosis could be classified into four groups: local recurrence, local manifestation of widespread metastasis, metachronous carcinogenesis, and implantation metastasis. However, all of the previous studies only reported the phenomena of implantation metastasis at anastomosis. No study had proved the origin of anastomotic metastasis by genomic analysis. In this study, a 43-year-old woman presented with persistent hematochezia was diagnosed as having severe mixed hemorrhoids. She was treated by procedure for prolapse and hemorrhoids (PPH), without receiving preoperative colonoscopy. Two months later, she was found to have sigmoid colon cancer by colonoscopy due to continuous hematochezia and received radical sigmoidectomy. Postoperative histological examination confirmed the lesion to be a moderately differentiated adenocarcinoma (pT3N1M0). Six months later, she presented with hematochezia again and colonoscopy revealed two tumors at the rectal anastomosis of PPH. Both tumors were confirmed to be moderately differentiated adenocarcinoma without lymph node and distant metastasis and were finally removed by transanal endoscopic microsurgery (TEM). Pathological examination, whole exome sequencing (WES), and Lineage Inference for Cancer Heterogeneity and Evolution (LICHeE) analysis demonstrated that the two tumors at the rectal anastomosis were probably implantation metastases arising from the previous sigmoid colon cancer. This is the first study to prove implantation metastasis from colon cancer to a distal anastomosis by WES and LICHeE analysis. Therefore, it is recommended to rule out colorectal cancer in proximal large bowel before performing surgery with a rectal anastomosis, such as PPH and anterior resection. For patients with a suspected implanted tumor, WES and LICHeE could be used to differentiate implantation metastasis from metachronous carcinogenesis.

Western Diet Promotes Intestinal Colonization by Collagenolytic Microbes and Promotes Tumor Formation After Colorectal Surgery

BACKGROUND & AIMS

The Western diet, which is high in fat, is a modifiable risk factor for colorectal recurrence after curative resection. We investigated the mechanisms by which the Western diet promotes tumor recurrence, including changes in the microbiome, in mice that underwent colorectal resection.

METHODS

BALB/c male mice were fed either standard chow diet or Western-type diet (characterized by high fat, no fiber, and decreased minerals and vitamins) for 4 weeks; some mice were given antibiotics or ABA-PEG20k-Pi20 (Pi-PEG), which inhibits collagenase production by bacteria, but not bacterial growth, in drinking water. Colorectal resections and anastomoses were then performed. The first day after surgery, mice were given enemas containing a collagenolytic rodent-derived strain of Enterococcus faecalis (strain E2), and on the second day they were given mouse colon carcinoma cells (CT26). Twenty-one days later, distal colons were removed, and colon contents (feces, distal colon, and tumor) were collected. Colon tissues were analyzed by histology for the presence of collagenolytic colonies and by 16S ribosomal RNA sequencing, which determined the anatomic distribution of E faecalis at the site of the anastomosis and within tumors using in situ hybridization. Mouse imaging analyses were used to identify metastases.

RESULTS

Colorectal tumors were found in 88% of mice fed the Western diet and given antibiotics, surgery, and E faecalis compared with only 30% of mice fed the standard diet followed by the same procedures. Colon tumor formation correlated with the presence of collagenolytic E faecalis and Proteus mirabilis. Antibiotics eliminated collagenolytic E faecalis and P mirabilis but did not reduce tumor formation. However, antibiotics promoted emergence of Candida parapsilosis, a collagenase-producing microorganism. Administration of a Pi-PEG reduced tumor formation and maintained diversity of the colon microbiome.

CONCLUSIONS

We identified a mechanisms by which diet and antibiotic use can promote tumorigenesis by colon cancer cells at the anastomosis after colorectal surgery. Strategies to prevent emergence of these microbe communities or their enzymatic activities might be used to reduce the risk of tumor recurrence in patients undergoing colorectal cancer surgery.

Anastomotic leak in colorectal cancer patients: New insights and perspectives

Anastomotic leak (AL) remains a potentially life-threatening sequela of colorectal surgery impacting on mortality, short- and long-term morbidity, quality of life, local recurrence (LR) and disease-free survival. Despite technical improvements and the identification of several surgery- and patient-related factors associated to the risk of AL, its incidence has not significantly changed over time. In this context, the clarification of the mechanisms underlying anastomotic healing remains an important unmet need, crucial for improving patients' outcomes. This review concentrates on novel key findings in the etiopathogenesis of AL, how they can contribute in determining LR, and measures which may contribute to reducing its incidence. AL results from a complex, dynamic interplay of several factors and biological processes, including host genetics, gut microbiome, inflammation and the immune system. Many of these factors seem to act in concert to drive both AL and LR, even if the exact mechanisms remain to be elucidated. The next generation sequencing technology, including the microbial metagenomics, could lead to tailored bowel preparations targeting only those pathogens that can cause AL. Significant progress is being made in each of the reviewed areas, moving toward translational and targeted therapeutic strategies to prevent the difficult complication of AL.

Laparoscopic segmental left colectomy for splenic flexure carcinoma: a single institution experience

BACKGROUND

There is ongoing debate regarding surgical treatment of splenic flexure cancer. The main points of controversy include the appropriate extent of colon resection, either to the right or to the left, and the appropriate extent of lymph-node dissection. The aim of this study was to review our experience in laparoscopic treatment of splenic flexure cancer cases and to compare our data to the recent literature.

METHODS

Consecutive patients, operated on for splenic flexure colon carcinoma at a single institution between April 2005 and January 2013, were included in the study. Exclusion criteria were a previous history of colorectal cancer, recurrent colonic cancer, emergency cases with an obstructive tumor or a perforated tumor with peritonitis, synchronous cancer, palliative surgery, and a past history of colorectal resection. Patients underwent laparoscopic segmental left colectomy with ligation of the left branch of the middle colic and of the left colic artery. Patient characteristics, operative and postoperative outcomes, and long-term technical, functional, and oncological results from a prospectively maintained database were retrospectively analyzed. After hospital discharge, standardized follow-up was performed at 1 month postoperatively, then every 3 months during the first 2 years, and every 6 months thereafter, for a total of 5 years.

RESULTS

A total of 28 consecutive patients (16 males) with a median age of 71.8 years (range 42.5-88.8 years) were included. Ninety-day mortality was 3.5% and surgical morbidity was 21.5% with anastomotic leak rate of 10.7%. All survivors experienced good or very good functional results. During a median follow-up period of 50.9 months, eight patients (28.5%) presented with a recurrence. The 5-year overall and disease-free survival rates were 46.3% and 39.2%, respectively.

CONCLUSIONS

Segmental left colectomy for splenic flexure carcinoma is associated with reasonably low morbidity and very good functional results. However, survival rates are low.

Association between KRAS G13D mutations and anastomotic recurrence in colorectal cancer: Two case reports

RATIONALE

The prevalence of anastomotic recurrence (AR) in colorectal cancer (CRC) after resection of the primary tumor (PT) is 5% to 14%. However, no association has been observed between specific somatic genetic alterations and AR. Such associations may shed light on the mechanism of AR.

PATIENT CONCERNS

We experienced 2 patients with AR of CRC. The first patient was a 42-year-old woman who underwent resection of an AR of rectal cancer 2 times within 19 months after resection of the PT. The second patient was a 77-year-old woman who underwent resection of an AR of ascending colon cancer twice within 38 months after resection of the PT.

DIAGNOSIS

Both cases were diagnosed as repetitive AR.

INTERVENTIONS

Loss of heterozygosity analysis, microsatellite instability (MSI) study of 9 microsatellite loci, and mutational analysis of KRAS, BRAF, APC, TP53, and SMAD4 were performed.

OUTCOMES

All the lesions, except 1, harbored mutations in APC, KRAS, and TP53, without MSI, after neoadjuvant chemoradiotherapy. The APC, KRAS, and TP53 mutations were pathogenic or likely pathogenic in the PTs and ARs. Both women harbored the same KRAS G13D mutation, which accounts for 8% of all KRAS mutations in sporadic CRC s. The probability of the incidental occurrence of KRAS G13D mutations in both cases is 0.64%, provided that the mutations were independent of AR.

LESSONS

Our findings may shed light on the mechanism of AR in CRC, namely, that the PT harbored the same mutations as the AR and the lesions in both cases harbored the KRAS G13D mutation.

Gut microbiome influences on anastomotic leak and recurrence rates following colorectal cancer surgery

BACKGROUND

The pathogenesis of colorectal cancer recurrence after a curative resection remains poorly understood. A yet-to-be accounted for variable is the composition and function of the microbiome adjacent to the tumour and its influence on the margins of resection following surgery.

METHODS

PubMed was searched for historical as well as current manuscripts dated between 1970 and 2017 using the following keywords: 'colorectal cancer recurrence', 'microbiome', 'anastomotic leak', 'anastomotic failure' and 'mechanical bowel preparation'.

RESULTS

There is a substantial and growing body of literature to demonstrate the various mechanisms by which environmental factors act on the microbiome to alter its composition and function with the net result of adversely affecting oncological outcomes following surgery. Some of these environmental factors include diet, antibiotic use, the methods used to prepare the colon for surgery and the physiological stress of the operation itself.

CONCLUSION

Interrogating the intestinal microbiome using next-generation sequencing technology has the potential to influence cancer outcomes following colonic resection.