Mastering laparoscopic colorectal cancer surgery involves a learning curve. Inexperienced surgeons require appropriate case selection. Nonetheless, there are few indicators for predicting the difficulty of laparoscopic colorectal cancer surgery. We established a difficulty scoring system to facilitate appropriate case selection during the learning curve for laparoscopic colorectal cancer surgery until mastery is achieved. We reviewed 1,390 laparoscopic colorectal cancer surgery cases performed at our hospital. Surgical duration was used as an index of surgical difficulty. Factors related to surgical difficulty were identified using a multivariate analysis and were scored using a linear regression analysis. Overall, 889 patients were included in the analysis. Sex, body mass index 〉 25 kg/m², and tumor location were factors that best defined surgical difficulty. The difficulty was determined by the sum of prolonged surgical duration predicted by these three factors. Surgical duration and hospital stay were longer, blood loss was greater, and complications were more common in the high difficulty group than in the low and medium difficulty groups. The developed scoring system showed high reliability in ten-fold cross-validation. The scoring model we developed can predict surgical difficulty for typical laparoscopic colorectal cancer surgery and may be useful in selecting appropriate surgical cases for inexperienced surgeons.

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To improve survival rate, postoperative adjuvant chemotherapy ‹ACT› and surveillance are performed for patients with colorectal cancer ‹CRC›. A recent study demonstrated that a circulating tumor DNA ‹ctDNA›-guided approach to the treatment of stage II CRC reduced ACT use without compromising recurrence-free survival. We examined whether longitudinal ctDNA assays by digital PCR ‹dPCR› can provide early relapse prediction in CRC patients who received ACT. Variant allele frequency ‹VAF› of ctDNA was informative in all 52 patients with dPCR using 87 selected mutations. Among 51 patients who underwent curative resection, patients who had relapse ‹n = 9› showed higher ctDNA VAF than those without relapse at the first postoperative ‹post-op› timepoint ‹n = 42, p < 0.0001›. Among 14 patients who received ACT, 4 out of 6 ‹66.7%› patients who had relapse were ctDNA-negative at post-op. However, all 6 patients with relapse showed ctDNA elevation before relapse was confirmed by computed tomography scan during the postoperative period. Patients with at least one ctDNA-positive timepoint during the postoperative period ‹n = 6› showed a higher risk of relapse than those who had sustained ctDNA-negative status ‹n = 8›‹HR 39.6, 95%CI 6.4-243.9, p < 0.0001›. Longitudinal dPCR-ctDNA assay can complement the postoperative ctDNA-guided approach for both ACT intervention and relapse detection based on conventional surveillance.

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To identify the insertion sites of the medial patellotibial ligament‹MPTL›, eighteen nonpaired human cadaveric knees were used in this study. The MPTL was clearly identified in 16 of 18 knees, and was a thin uniform band-like tissue appearing as a capsular ligament. The insertion site on the patella was located midway between the medial patellofemoral ligament and the patellar tendon and was in contact with the medial side of the patellar tendon. The ratio of the vertical distance from the superior pole of the patella to the superior end of the MPTL to the total patellar height was 70.1 ± 3.3% at the proximal end. At the distal end, the ratio was 84.2± 3.5%. The insertion site on the tibia was 16.2 ± 2.5 mm distal to the tibial anterior edge, which was 21.4 ± 2.9 mm proximal to the medial aspect of the tibial tuberosity groove in which the proximal pes anserinus attached. We clarified the MPTL insertion sites on both the patellar and tibial sides. The clinical relevance of this study is that understanding the anatomy of the MPTL was improved, and our findings may assist surgeons in performing successful reconstruction of the MPTL.

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