The Evolving Landscape of Treatment Paradigms for Locally Advanced Rectal Cancer: A Survey Study of Gastrointestinal Radiation Oncology Experts.

PURPOSE/OBJECTIVE(S): To assess current practice patterns in the treatment of locally advanced rectal cancer among radiation oncologists specializing in gastrointestinal (GI) malignancies.

MATERIALS/METHODS: Radiation oncologists specialized in GI malignancies at an ACGME affiliated institution were invited to complete an online survey and select management recommendations for seven locally advanced rectal cancer clinical vignettes, consisting of variable T and N staging, tumor location and high-risk features (presence of enlarged lateral lymph nodes, mesorectal fascia involvement and extramural vascular invasion). Answer choices representing the diversity of current treatment paradigms for rectal cancer included variable sequences of chemotherapy (CHT), radiation (long-course chemoradiation [LC-CRT] or short-course radiation [SCRT]), surgery or non-operative management (NOM). Participation was voluntary and all responses remained anonymous. The survey was open from January to February 2021.

RESULTS: Of 207 GI experts invited to participate, 36 replied, resulting in a response rate of 17.4% (36/207). For low rectal tumors (cT3N2) without threatened margins, 80.6% (29/36) recommended total neoadjuvant therapy (TNT) of which 41.4% (12/29) preferred NOM if a clinical complete response was achieved upon restaging. Of those who chose TNT and surgery (17/29), 76.5% preferred LC-CRT (consolidation CHT [53.8%] vs. induction CHT [46.2%]) and 23.5% preferred SCRT. For mid to upper rectal tumors (cT3N1-2) without threatened margins, 66.6% (24/36) recommended TNT and surgery with 38.9% (14/36) electing for SCRT then consolidation CHT, and 22.2% (8/36) for induction CHT then LC-CRT. After TNT, neoadjuvant LC-CRT (16.7%, 6/36) or neoadjuvant SCRT (11.1%, 4/36) followed by surgery and adjuvant CHT were most favored. In patients with mid to upper rectal tumors and threatened margins, SCRT with consolidation CHT and surgery remained the most accepted treatment paradigm (44.4%, 16/36). LC-CRT followed by consolidation CHT was the preferred choice to maximize likelihood of NOM. For a clinical node negative upper rectal tumor (cT3N0), 38.9% (14/36) recommended SCRT, then surgery with adjuvant CHT, 19.4% (7/36) recommended induction CHT then surgery, and 16.7% (6/36) recommended LC-CRT, then surgery with adjuvant CHT.

CONCLUSION: Total neoadjuvant therapy has been widely adopted in the management of locally advanced rectal cancer. For mid to upper rectal tumors, most GI experts recommended SCRT, consolidation CHT and surgery. For low rectal tumors, LC-CRT was preferred with significant variability between consolidation versus induction CHT. As compared to mid and upper rectal tumors, clinicians were more likely to recommend NOM following a clinical complete response for low rectal tumors.