Evaluation of the representativeness and generalizability of Japanese clinical trials for localized rectal/colon cancer: Comparing participants in the Japan Clinical Oncology Group study with patients in Japanese registries

Distance of Peritoneum to Inferior Mesenteric Artery Predicts the Operation Time During Laparoscopic Colectomy for Sigmoid or Rectosigmoid Colon Cancer

BACKGROUND/AIM

Obesity is a major technical limiting factor for laparoscopic surgery because abundant visceral fat is known to extend the operation time. However, special hardware is needed to assess it. We hypothesized that the depth from the peritoneum to the bifurcation of the inferior mesenteric artery (IMA) defined as 'peritoneum to IMA distance (PID)' might be a simple predictive factor for extended operation time during laparoscopic colectomy.

PATIENTS AND METHODS

One hundred twenty-four patients who were diagnosed with sigmoid or rectosigmoid colon cancer and underwent laparoscopic colectomy were included. The patients were divided into two groups based on the operation time (210 min). The vertical distance from the peritoneum to the bifurcation of the inferior mesenteric artery was defined as PID. The factors eliciting an operation time longer than 210 min were investigated.

RESULTS

There was significant difference in sex, BMI, cT, cN, and PID between the Early group (<210 min) and Late group (≥210 min). Less blood loss was observed in the Early group than in the Late group. Multivariate analysis showed that PID was the only independent factor that affected operation time (p<0.001).

CONCLUSION

PID predicts the operation time during laparoscopic colectomy for sigmoid or rectosigmoid colon cancer.

Generalizability of Randomized Controlled Trials in Rectal Cancer

BACKGROUND

The generalizability of outcomes from randomized controlled trials (RCTs) in oncology is a frequent concern. Given the prevalence and multidisciplinary management of rectal cancer, understanding the generalizability of rectal cancer RCTs is critical to surgical oncologists.

METHODS

An exhaustive literature review identified 100 non-metastatic rectal cancer RCTs published in English over the past 10 years investigating surgery, chemotherapy, or radiotherapy. In order to evaluate the representativeness of these RCTs compared to the USA and each continent's rectal cancer populations, demographic characteristics were stratified by surgical versus chemoradiotherapy (CRT) trial and by continent then compared with the National Cancer Database and CANCER TODAY using chi-squared and Welch's t-tests.

RESULTS

Of the 100 trials identified, 65% enrolled significantly younger patients, and 38% enrolled a significantly greater proportion of males than the US rectal cancer population. These demographic differences were more prominent among CRT trials than surgical trials. Half of all trials enrolled patients who were on average more than 7 years younger and enrolled a 5% greater proportion of males than their respective continental rectal cancer populations. Patients enrolled in trials had more advanced cancers than their corresponding continental populations. Sociodemographic data was rarely reported.

CONCLUSION

Patients enrolled in trials were younger, predominantly male, and had advanced stage cancer when compared to the rectal cancer population. Sociodemographic variables are underreported, further limiting equal participation in clinical trials. Future rectal cancer RCTs should strive to recruit representative samples. To enhance recruitment of women and underrepresented minorities, tailored recruitment strategies must be implemented.

Challenges needed to be overcome in multi-institutional surgical trials: accumulated experience in the JCOG Colorectal Cancer Study Group (CCSG)

JCOG-CCSG has been conducting several surgical trials and experienced several challenges. The first point is the appropriate timing of conducting the trial. Once a certain number of surgeons acquire the new technique and its utility is accepted, it suddenly becomes difficult to maintain 'equipoise' between the standard and new treatment, which may lead to poor patient accrual. Smooth preparation and commencement of the trial at an appropriate timing is necessary for its success. Second is the appropriate quality assurance of surgery. High-level quality assurance will strengthen the comparability of randomized control trials and minimize the heterogeneity among hospitals. On the other hand, it may impair the generalizability of the trial. Large observational studies help to bridge the gap of heterogeneity among hospitals. Third is the selection of an appropriate endpoint. Overall survival (OS) is the gold-standard primary endpoint; however, the number of events is much less due to more effective treatment. JCOG0212 and JCOG0404 were unable to demonstrate the non-inferiority of omission of lateral lymph node dissection and laparoscopic surgery partly due to a lack of power. Disease-free survival (DFS) is also a promising candidate for primary endpoint, but as in JCOG0603, special attention must be paid when DFS does not correlate with OS. Although careful discussion is required because the precision of the hazard ratio depends on the number of events, an alternative population-level summary of variables, including restricted mean survival time, can be considered as the primary endpoint. Future surgical trials should be planned considering these points.

Institutional variation in survival and morbidity in laparoscopic surgery for colon cancer: From the data of a randomized controlled trial comparing open and laparoscopic surgery (JCOG0404)

BACKGROUND

Institutional variation in outcomes is a key factor to ascertain the generalizability of results and reliability of the clinical trial. This study evaluated institutional variation in survival and postoperative complications using data from JCOG0404 comparing laparoscopic colectomy (LAP) with open colectomy (OP).

METHODS

Institutions with fewer than 10 registered patients were excluded from this analysis. Institutional variation was evaluated in terms of early postoperative complications, overall survival, and relapse-free survival and estimated using a mixed-effect model with institution as a random effect after adjusting for background factors.

RESULTS

This analysis included 1028 patients in the safety analysis and 1040 patients in the efficacy analysis from 26 institutions. In the safety analysis, there was no variation in grades 3-4 early postoperative complications (in OP, median 6.3% [range 6.3%-6.3%]; in LAP, median 2.6% [range 2.6%-2.6%]), but some variation in grades 1-4 early postoperative complications was observed (in OP, median 20.8% [range 13.2%-31.8%]; in LAP, median 11.9% [range 7.2%-28.7%]), and that in grades 2-4 was observed only in LAP (median 8.8% [range 4.7%-24.0%]; in OP, median 12.7% [range 12.7%-12.7%]). Two specific institutions showed especially high incidences of postoperative complications in LAP. In the efficacy analysis, there was no institutional variation in OP, although a certain variation was observed in LAP.

CONCLUSIONS

Some institutional variations in safety and efficacy were observed, although only in LAP. We conclude that a qualification system, including training and education, is needed when new surgical techniques such as laparoscopic surgery are introduced in clinical practice.