Impact of preoperative radiotherapy on lymph node status in patients with rectal cancer: Experience of the radiotherapy department–EHSO Emir Abdelkader-Oran

The aim of the study was to report the histopathological response rate of lymph nodes in patients operated for rectal adenocarcinoma after preoperative radiotherapy alone or combined with chemotherapy.

From March 2015 to September 2021, one hundred and sixty-one patients with rectal adenocarcinoma with nodal involvement received preoperative 3D conformal radiotherapy;of which one hundred and twenty patients (74.5%) received chemoradiotherapy and forty-one (25.5%) received radiotherapy alone. The dose of radiotherapy delivered was 25 Gy( 5Gy by fraction) in thirty-eight patients, 39 Gy( 3 Gy by fraction) in seventy-nine and 46 Gy (2 Gy by fraction) in forty-four patients.

The median age was 57 years (range 24-85 years). The sex ratio was 1.4. Symptoms were dominated by rectal bleeding in 79.5% of cases. One hundred and fifty two patients (94.4%) were classified as stage III, and nine (5.6%) stage IV; the lymph node status being dominated by N2 in eighty-eight patients (54.7%) followed by N1 in seventy-one (44.1%) and N3 in two (1.2%) and staging being done by MRI and according to the American Joint Committee on Cancer (AJCC). The surgery was radical in eighty-three patients (51.6%) and conservative in seventy-eight patients (48.4%); while lymph node dissection was less than 12 nodes in 60.9% of cases and greater than 12 in 39.1% of cases, with an average number of lymph nodes removed from 11. The histopathological study of the lymph nodes removed did not find any pathological lymph nodes (PN 0) in one hundred and twenty four patients (77%), less than 3 infiltrated lymph nodes (PN1) in twenty-seven patients (16.8%) and more than 4 (PN2) in ten patients (6.2%). The locoregional survival rate and overall survival at 24 months was 96.5% and 87.1 respectively.

Preoperative radiotherapy alone or combined with chemotherapy in patients with rectal cancer leads to an improvement in histological results, especially lymph nodes, which remains the main risk factor for later relapse.

The authors.

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All authors have declared no conflicts of interest.