Morphology of Pararectal Lymph Nodes in Rectal Cancer after Neoadjuvant Therapy

Remodeling and cytograms of pararectal lymph nodes were studied in patients with rectal cancer after neoadjuvant therapy by different protocols. Radiotherapy and its combination with chemotherapy lead to an increase in the volume of connective tissue components and significant reduction of the volume density of lymphoid follicles without germinative centers. The counts of dividing cells, immunoblasts, and plasmoblasts in various compartments of the pararectal lymph nodes changed more significantly after radiotherapy, while changes in the count of monocytes and neutrophils were more pronounced after cytostatic therapy combined with exposure to ionizing radiation. These differences can be explained by the systemic toxic effect of chemotherapeutic drugs and primarily local cytotoxic effects of radiotherapy manifesting largely at the site of exposure.