Resection margins, lymph node harvest and 3 year survival in open and laparoscopic colorectal cancer surgery; a prospective cohort study

INTRODUCTION: Laparoscopic colorectal cancer surgery has been gaining popularity in the last decade. However, there are concerns about adequate lymph node dissection and safe resection margins in laparoscopic colorectal cancer surgery. This study was aimed at comparing the lymph node (LN) clearance and surgical resection margins and 3-year survival for open and laparoscopic colorectal cancer surgery. METHOD: A pre-tested interviewer administered questionnaire was used to assess the adoption of the laparoscopic approach by Sri Lankan surgeons. Data was collected prospectively from patients who underwent open or laparoscopic colorectal cancer surgery at the University Surgical Unit of the National Hospital of Sri Lanka from April 2016 to May 2019. The histopathology records were analysed to determine the longitudinal and circumferential resection margins(CRM) and the number of lymph nodes harvested. The resection margins were classified as positive or negative. The total number of LN examined was evaluated. Presence of local recurrence and liver metastasis was determined by contrast enhanced CT scan during 3-years of follow up. Chi square, T test and z test for proportions were used to compare CRM, LN harvest and survival rates between the groups. RESULTS: Of the surgeons interviewed only 11 (18.4%) performed laparoscopic colorectal cancer surgery. A total of 137 patients (83 males and 54 females) were studied. Eighty-one procedures were laparoscopic and 56 procedures were open. All patients had clear longitudinal resection margins. Seventy-eight patients in the laparoscopic group (96%) and 51 patients (91%) in the open group had clear CRM (p > 0.05). A total of 2188 LNs (mean 15.9) were resected in all procedures. Six-hundred-eighty-nine lymph nodes were removed during open procedures (mean 12.3, SD 0.4) and 1499 (mean 18.5, SD 0.6) were removed during laparoscopy (p < 0.05). At 3 years follow-up the disease-free survival in the laparoscopic and open colon cancer patients was 27/41 (65.8%) and 16/29 (55.1%) respectively (p = 0.35). Disease free survival in the laparoscopic and open rectal cancer patients was 23/38 (60.5%) and 13/25 (52.0%) respectively (p = 0.40). Four patients were lost during follow-up. DISCUSSION AND CONCLUSION: CRM was comparable in the two groups. Laparoscopic group had a significantly higher LN harvest. Three-year survival rates were similar in the two groups. Acceptable results can be obtained with laparoscopic colorectal cancer surgery.