Impact of surgical proximal and distal margins on the recurrence of resectable colon cancer: a single-center observational cohort study

PURPOSE

Few studies have investigated the impact of the surgical proximal and distal margins on colon cancer recurrence. We conducted this study to investigate the effect of resection margins on the prognosis of resectable colon cancer.

METHODS

We analyzed data on 1458 patients who underwent colorectal resection in our institute between January, 2004 and March, 2020, including 579 patients with resectable colon cancer. The association between the resection margin and recurrence for each oncological status was assessed and the value of the resection length that influenced recurrence was analyzed.

RESULTS

Patients who had pT4 colon cancer with margins of more than 7 cm had a trend of fewer recurrences and longer relapse-free survival (RFS) than those with colon cancer of other stages (P = 0.033; hazard ratio [HR], 0.42; 95% confidence interval [CI], 0.20-0.89). Multivariate analysis identified a margin of < 7 cm as an independent risk factor for RFS in patients with pT4 colon cancer (P = 0.023; HR, 2.65; 95% CI 1.013-6.17). No correlation was found between resection margins and recurrence, depending on the extent of lymph node metastasis and tumor location.

CONCLUSION

A resection margin of at least 7 cm should be maintained for patients with pT4 colon cancer.

The Impact of Narrow and Infiltrated Distal Margin After Proctectomy for Rectal Cancer on Patients' Outcomes: a Systematic Review and Meta-analysis

Rectal cancer is a common tumor within a difficult anatomic constraint. Total mesorectal excision with longitudinal and circumferential free margins is considered imperative for good prognosis. In this article, the authors systematically reviewed all published literature with specific Mesh terms until the end of year 2019. Thereafter, retrieved articles were assessed using the Newcastle-Ottawa Scale and meta-analysis was conducted comparing local recurrence among 1-cm, 5-mm, and narrow (< 1-mm)/infiltrated margins. Thirty-nine articles were included in the study. Macroscopic distal margin < 1 cm carried a higher incidence of recurrence for those who did not receive neoadjuvant radiation, without affecting neither estimated overall nor disease-free survival. Less than 5-mm margin after radiation therapy is accepted oncologically. Infiltrated margins and narrow margins (< 1 mm) microscopically are associated with higher incidence of local recurrence and shorter overall and disease-free survival. Surgeons should aim at 1-cm safety margin in radiotherapy-naïve patients and microscopic free margin > 1 mm for those who received neoadjuvant therapy. The cost/benefit of reoperation for patients with infiltrated margins is still inadequately studied.

Minimum resection length to ensure a pathologically negative distal margin and the preservation of a larger remnant stomach in proximal gastrectomy for early upper gastric cancer

BACKGROUND

In proximal gastrectomy (PG), a longer distal margin (DM) length should be maintained to obtain a pathologically negative DM. However, a shorter DM length is preferred to preserve a large remnant stomach for favorable postoperative outcomes. Evidence regarding the minimum DM length to ensure a pathologically negative DM is useful.

METHODS

Patients who underwent PG or total gastrectomy for cT1N0M0 gastric cancer limited to the upper third were enrolled. A new parameter, ΔDM, which corresponded to the pathological extension distal to the gross tumor boundary towards the resection stump, was evaluated. The maximum ΔDM, which is the length ensuring a pathologically negative DM, was first determined. Furthermore, the possible incidences of pathologically positive DM were calculated for each pathological type and clinical tumor (cTumor) size.

RESULTS

Of 361 patients eligible for this study, 190 and 171 were assigned to differentiated (Dif) and undifferentiated types (Und), respectively. The maximum ΔDM was 30 and 40 mm in Dif and Und, respectively. Considering a correlation between cTumor size and ΔDM, and possible incidences of pathologically positive DM, 10, 20, and 30 mm were the minimal gross DM lengths in Dif when cTumor size was ≤ 15 mm, > 15 and ≤ 50 mm, and > 50 mm, respectively. In Und, the incidences of pathologically positive DM were 0.59% and 2.3% for gross DM lengths of 30 and 20 mm, respectively.

CONCLUSION

The minimum DM lengths to ensure a pathologically negative DM in PG are proposed according to the pathological type of early upper gastric cancer.

Distal resection margins in rectal cancer specimens: differences in assessment between surgeons and pathologists and the influence of neoadjuvant chemoradiation

To investigate the discrepancy between the distal resection margin (DRM) assessed by surgeons and pathologists, and the impact of neoadjuvant chemoradiotherapy (nCRT) on DRM. This study included 67 rectal cancer patients undergoing elective surgery. DRMs were assessed through four different techniques: in vivo subjective estimative, made by the surgeon before the rectal resection (by palpation and visual estimative); in vivo objective, measured with a ruler before the rectal transection; ex vivo objective, measured right after resection of the specimen; post-fixation objective measurement, conducted by the pathologist. The DRMs subjectively and objectively assessed by the surgeons were not significantly different (3.40 cm vs. 3.45 cm). There was a mean reduction in the length of DRMs of 35.6%, from 3.45 cm objectively measured by the surgeon to 2.20 cm measured by the pathologist. This difference was significant among patients that did not receive nCRT (3.90 cm vs. 2.30 cm, P < 0.001), but not among those who received nCRT (2.30 vs. 2.05 cm). Surgeons are accurate in assessing rectal cancer DRMs. There are significant differences between intraoperative measurements of DRMs and the final pathologic results. However, these differences are not seen when nCRT is used, a finding that may be useful when sphincter preservation is being considered.

Clinical factors affecting the distal margin in rectal cancer surgery

PURPOSE

In rectal cancer surgery, an insufficient distal margin (DM) is associated with a high risk of local recurrence, whereas an excessive DM will cause low anterior resection syndrome, impairing quality of life. This study aimed to identify the factors that affect the distance between the colorectal resection site and the tumor to optimize achieving the correct DM.

METHODS

The subjects of this study were 219 patients who underwent resection for primary rectal cancer in our department between January 2006 and July 2014. According to Japanese guidelines, DM (rDM) was based on the tumor location, but the pathological DM (pDM) was measured from surgical specimens. The patients were divided into two groups: the pDM-less-than-rDM group (pDM < rDM) and the pDM-greater-or-equal-to-rDM group (pDM ≥ DM). The factors associated with the DM in the two groups were compared.

RESULTS

In the pDM < rDM group, the tumor distance from the anal verge was shorter (p = 0.001) and significantly more patients underwent laparotomy (p = 0.047).

CONCLUSION

The DM tended to be shorter than that planned by the surgeon in patients with lower rectal cancers and those treated by laparotomy,; therefore, when performing rectal resection, care must be taken to ensure that the pDM is not shorter than the rDM.

Effect of preoperative chemotherapy on distal spread of low rectal cancer located close to the anus

PURPOSE

This study aimed to clarify the frequency of distal spread and the optimal distal margin after preoperative chemotherapy for advanced low rectal cancer.

METHODS

The study included patients with advanced lower rectal cancer who received preoperative chemotherapy and underwent surgery during 2012-2015. We investigated the distal spread of tumor cells, defined as the distal distance from the intramucosal distal tumor edge to the farthest tumor cells located under the submucosal layer. Clinical characteristics were compared for distal spreads ≥ 10 and < 10 mm, and risk factors for distal spread ≥ 10 mm were investigated.

RESULTS

Of the 71 patients, 42 (59%) showed distal spread. Distal spreads of 1-9, 10-19, and ≥ 20 mm were observed in 27 (38%), 11 (15%), and 4 (6%) patients, respectively. Multivariate analysis revealed two independent risk factors for distal spread ≥ 10 mm after preoperative chemotherapy. The first risk factor is the presence of different therapeutic effects between the mucosal and deeper layers (meaning that superficial tumor shrinkage was evident on colonoscopy, but little tumor shrinkage was evident on magnetic resonance imaging) (odds ratio, 11.6; 95% CI, 2.22-61.3). The second risk factor is poorly differentiated or mucinous adenocarcinoma (odds ratio, 8.86; 95% CI, 1.58-49.9).

CONCLUSION

A distal margin of 20 mm is required (10 mm is insufficient) for advanced lower rectal cancer patients who receive preoperative chemotherapy followed by surgery. Independent risk factors for distal spread ≥ 10 mm include (1) the presence of different therapeutic effects between mucosal and deeper layers and (2) poorly differentiated or mucinous adenocarcinomas.

Identification and Quantification of Drug-Resistant Cells in Colorectal Tumor and Distal Margin

Cancer stem cells are cellular subpopulations in tumor, which are highly tumorigenic and drug resistant due to their adaptive molecular mechanism. In the recent years, these cells have attracted researchers' focus because of their unique properties which makes them biologically well evolved than other proliferating tumor cells. We have studied the presence of cancer stem cells in colorectal cancer (CRC) and its surgical margins. We report for the first time the presence of drug-resistant cells in distal resection margins in CRC and showed that a closer distal margin of less than 2 cm could have higher possibility of drug-resistant cells to spread.

Necessary circumferential resection margins to prevent rectal cancer relapse after abdomino-peranal (intersphincteric) resection

PURPOSE

The purpose of this study was to determine the adequate circumferential resection margin (CRM) for abdomino-peranal (intersphincteric) resection (ISR) that would prevent the relapse of rectal cancers.

METHODS

The records of 41 cases that underwent curative ISR for rectal cancer were retrospectively reviewed. The relapse-free survival rates and overall survival rates were evaluated and correlated with the maximum depth of the inner muscularis layer reached during ISR (i.e., the radial margin [RM] and distal margin [DM]). Cases were divided into three groups based on the sizes of the RM and DM: (1) group A (RM >2 mm and DM >1.5 cm), (2) group B (RM >2 mm or DM >1.5 cm but not both), and (3) group C (RM <2 mm and DM <1.5 cm).

RESULTS

The relapse-free survival rates of the cases in group C were lower than those in the cases of group A or group B (p = 0.002 and 0.037, respectively). The resection margins required to prevent rectal cancer relapse were >2 mm for the RM and >1.5 cm for the DM. For these margins, the intersphincteric space had to be entered (i.e., between the internal and external anal sphincters).

CONCLUSION

It is critical to enter the intersphincteric space to ensure an adequate CRM (RM >2 mm and DM >1.5 cm) for preventing rectal cancer recurrence after ISR.