Coverage of lateral lymph nodes in rectal cancer patients with routine radiotherapy practice and associated locoregional recurrence rates

Sluckin, T.C.; Hazen, S.M.J.A.; Horsthuis, K.; Beets-Tan, R.G.H.; Antonisse, I.E.; Berbee, M.; ... ; Dutch Snapshot Res Grp (2023)

Article / Letter to editor

Background & purpose: Involved internal iliac and obturator lateral lymph nodes (LLNs) are a known risk factor for ipsi-lateral local recurrences (LLR) in rectal cancer. This study examined coverage of LLNs with routine radiotherapy practice in the Netherlands and associated LLR rates. 

Materials & methods: Patients with a primary tumor ≤8cm of the anorectal junction, cT3-4 stage and at least one internal iliac or obturator LLN with short-axis ≥5mm who received neoadjuvant (chemo)radiotherapy, were selected from a national, cross-sectional study of rectal cancer patients treated in the Netherlands in 2016. MR-images and radiotherapy treatment plans were reviewed regarding segmented LLNs as gross-tumor volume (GTV), location of LLNs within clinical target volume (CTV), and received proportion of the planned radiotherapy dose.  

Results: A total of 223 out of 3057 patients with at least one LLN ≥5mm were selected. Of those, 180 (80.7%) LLNs were inside the CTV, of which 60 (33.3%) were segmented as GTV. Overall, 202 LLNs (90.6%) received >95% of the planned dose. Four-year LLR rates were not significantly higher for LLNs situated outside the CTV compared to inside (4.0% vs. 12.5%, p=.092) or when receiving <95% versus >95% of the planned radiotherapy dose (7.1% vs. 11.3%, p=.843), respectively. Two of seven patients who received a dose-escalation of 60Gy developed a LLR (4-year LLR rate 28.6%). 

Conclusion: This evaluation of routine radiotherapy practice showed that adequate coverage of LLNs was still associated with considerable 4-year LLR rates. Techniques resulting in better local control for patients with involved LLNs need to be explored further. 

• All authors: Sluckin, T.C.; Hazen, S.M.J.A.; Horsthuis, K.; Beets-Tan, R.G.H.; Antonisse, I.E.; Berbee, M.; Bockel, L.W. van; Boer, A.H.; Ceha, H.M.; Cnossen, J.S.; Geijsen, E.D.; Hartogh, M.D. den; Hendriksen, E.M.; Intven, M.P.W.; Leseman-Hoogenboom, M.M.; Meijnen, P.; Muller, K.; Oppedijk, V.; Rozema, T.; Rutten, H.; Spruit, P.H.; Stam, T.C.; Velema, L.A.; Verrijssen, A.S.E.; Vos-Westerman, J.; Tanis, P.J.; Marijnen, C.A.M.; Kusters, M.; Dutch Snapshot Res Grp
• Date: 2023-10-01
• Journal: International Journal of Radiation Oncology - Biology - Physics
• Volume: 117
• Issue: 2
• Pages: 422 - 433
• DOI: doi:10.1016/j.ijrobp.2023.04.013
• Link: https://www.sciencedirect.com/science/article/pii/S0360301623003802?via%...