Does a fine line exist between regional and metastatic pelvic lymph nodes in rectal cancer-striking discordance between national guidelines and treatment recommendations by US radiation oncologists

Background: Management of rectal cancer with involved lateral pelvic lymph nodes (LPLNs) at the time of diagnosis-the stage we refer institutionally to as Stage 3.5-is controversial. The American Joint Committee on Cancer's 7th edition classifies internal iliac lymph nodes (LNs) as regional (Stage III), but both external and common iliac LNs as metastatic (Stage IV). However, in many Asian countries all LPLNs are considered regional and patients are treated with curative intent, with literature supporting improved outcomes with LPLN dissection. Management patterns of these patients by US radiation oncologists (ROs) are unknown. Methods: American ROs completed an anonymous institutional review board-approved online questionnaire regarding rectal cancer management. Results: Among the 220 completed responses, 45% treat more than 10 patients annually and 39% work in academia. We found 10.5% and 34.2% recommend biopsy of clinically involved internal and common iliac LNs, respectively. The vast majority of responders-98.6% and 94.5%-treat involved internal and common iliac LNs with curative intent, respectively. Respondents recommend treatment intensification to involved internal iliac LNs by dissection of the nodal basin (88.2%) and radiation therapy (RT) boost (59.1%), and treatment intensification to involved common iliac LNs by LN dissection (76.4%) and RT boost (63.6%). Conclusions: Our analysis reveals that the vast majority of US ROs approach patients with involved LPLNs, both regional (internal iliac) and metastatic (common iliac), with curative intent. They recommend treatment intensification with surgical resection and/or RT boost to involved nodes. Prospective clinical trials need to determine the appropriate management of patients with Stage 3.5 rectal cancer.