Tumour regression grading after chemoradiotherapy for locally advanced rectal cancer: A near pathologic complete response does not translate into good clinical outcome

• Published in: Radiotherapy and oncology Vol. 112; no. 1; pp. 44 - 51
• Main Authors: Swellengrebel, Hendrik A.M, Bosch, Steven L, Cats, Annemieke, Vincent, Andrew D, Dewit, Luc G.H, Verwaal, Vic J, Nagtegaal, Iris D, Marijnen, Corrie A.M
• Format: Journal Article
• Language: English
• Published: Ireland Elsevier Ireland Ltd 01.07.2014
• Subjects: Adenocarcinoma - pathology; Adenocarcinoma - therapy; Adenocarcinoma, Mucinous - pathology; Adenocarcinoma, Mucinous - therapy; Adult; Aged; Aged, 80 and over; Antimetabolites, Antineoplastic - therapeutic use; Capecitabine; Chemoradiotherapy; Deoxycytidine - analogs & derivatives; Deoxycytidine - therapeutic use; Female; Fluorouracil - analogs & derivatives; Fluorouracil - therapeutic use; Hematology, Oncology and Palliative Medicine; Humans; Lymph Nodes - pathology; Male; Middle Aged; Neoadjuvant Therapy; Neoplasm Grading; Neoplasm Staging; Neoplasm, Residual; Outcome; Preoperative Care; Proportional Hazards Models; Radiotherapy, Conformal; Radiotherapy, Intensity-Modulated; Rectal cancer; Rectal Neoplasms - pathology; Rectal Neoplasms - therapy; Rectum - surgery; Remission Induction; Retrospective Studies; Survival Rate; Tumour regression grade; Tumour regression grade; Rectal cancer; Chemoradiotherapy; Outcome
• ISSN: 0167-8140; 1879-0887
• DOI: 10.1016/j.radonc.2014.05.010

Abstract Background After preoperative chemoradiotherapy (CRT) for rectal cancer, clinically undetectable residual tumour deposits or pathologic lymph nodes may remain in the mesorectum. Aim The aim of this study was to report histopathological effects of CRT and factors affecting outcome in a uniformly treated series of locally advanced rectal cancer (LARC) patients. Methods Between 2004 and 2008, 107 patients with cT3 (threatening the mesorectal fascia or <5 cm from the anal verge), cT4 or cN2 rectal cancer were treated with preoperative CRT (25 × 2 Gy with capecitabine) and TME 6–8 weeks later. Central histopathological review followed. Tumour regression grade (TRG) was scored in pCR, near-pCR, response and no response. Cox regression was performed to identify prognosticators. Results The 3-year distant metastasis-free interval, disease-free rate and overall survival rate were 82%, 73% and 87% (median 44 months follow-up). TRG consisted of 20% pCR, 11% near-pCR, 55% response and 14% no response. 6/21 pCR patients harboured nodal metastases. 5/12 near-pCR had ypT3 disease, while 6 harboured node metastases. 5/12 near-PCR patients developed distant metastases. ypN and TRG were powerful outcome discriminators. Conclusion The high number of near-pCR with ypT3 or ypN1/2 and their poor outcome demonstrates that “watch-and-wait” in LARC patients should be applied with care.