The fine line between regional and metastatic pelvic lymph nodes in rectal cancer: Patterns of care among U.S. radiation oncologists.

758Background: 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. Asian investigators consider internal, external and common iliac lymph nodes (LNs) as regional disease and treat these patients (pts) with curative intent, which often includes LPLN dissection. Conversely, AJCC 7thedition classifies internal iliac LNs as regional, whereas both external and common iliac LNs as metastatic. NCCN guidelines recommend definitive trimodality therapy for Stage III rectal cancer, and palliative chemotherapy for Stage IV disease. Radiation oncologists (ROs) in the U.S. irradiate iliac LNs in the setting of other pelvic malignancies, but it is unknown how they approach newly diagnosed rectal cancer pts with LPLN involvement. Methods: We conducted an anonymous IRB-approved online survey of practicing U.S. ROs, probing their approach to management of rectal cancer pts with clinically involved LPLN...