Factors associated with lymph node retrieval in surgery for colorectal cancer

Accurate staging of cancers of the colon and rectum (CRC) requires adequate lymph node (LN) evaluation, and many studies have demonstrated an association between the number of LNs examined and survival. The number of lymph nodes which are retrieved during resections for CRC may however vary and has been associated with various factors in the literature. The aim of the present study was to identify such factors in our CRC surgical practice.

The study included specimens from 115 male and 177 female patients with a mean age of 69.2±11.9 years (31-94) who were treated for CRC in a Surgical Oncology Department over a 5-year period. The number of LNs harvested per patient was the main endpoint of interested. The analysed parameters were the patient's age and sex, the site of resection, the depth of tumour invasion (T stage), the grade of differentiation, the size of the tumour (maximal diameter) and the length of the resected colon. Neoadjuvant radiotherapy in rectal cancer cases was also taken into consideration. Analysis was applied using the statistical software PASW version 18. A p value<0.05 was considered statistically significant.

Female sex, right location of tumour and age younger than 65, were factors associated with significantly higher LN yield in resected specimens of CRC. Furthermore, the length of the resected bowel and the size of the tumour were positively correlated with the LN yield. In patients with rectal cancer, where neoadjuvant radiotherapy was applied, the LN yield was significantly lower. Lastly, the depth of invasion and the grade of tumour's differentiation did not have any impact on the number of harvested LNs.

LN harvest in patients with CRC is highly variable and may be determined by multiple factors. Meticulous surgical technique and an adequate length of specimen are required in order to obtain as many LNs as possible.