Magnetic resonance tumour regression grade and pathological correlates in patients with rectal cancer

J K Jang; J L Lee; S H Park; H J Park; I J Park; J H Kim; S H Choi; J Kim; C S Yu; J C Kim

doi:10.1002/bjs.10898

Magnetic resonance tumour regression grade and pathological correlates in patients with rectal cancer

Br J Surg. 2018 Nov;105(12):1671-1679. doi: 10.1002/bjs.10898. Epub 2018 Jun 12.

Authors

J K Jang¹, J L Lee², S H Park¹, H J Park¹, I J Park², J H Kim³, S H Choi¹, J Kim⁴, C S Yu², J C Kim²

Affiliations

¹ Department of Radiology and Research Institute of Radiology, University of Ulsan College of Medicine, Asan Medical Centre, Seoul, South Korea.
² Division of Colon and Rectal Surgery, Department of Surgery, University of Ulsan College of Medicine, Asan Medical Centre, Seoul, South Korea.
³ Department of Radiation Oncology, University of Ulsan College of Medicine, Asan Medical Centre, Seoul, South Korea.
⁴ Department of Pathology, University of Ulsan College of Medicine, Asan Medical Centre, Seoul, South Korea.

PMID: 29893988
DOI: 10.1002/bjs.10898

Abstract

Background: Evidence to support the specific use of magnetic resonance tumour regression grade (mrTRG) is inadequate. The aim of this study was to investigate the pathological characteristics of mrTRG after chemoradiotherapy (CRT) for rectal cancer and the implications for surgery.

Methods: Patients undergoing long-course CRT (45-50 Gy plus a booster dose of 4-6 Gy) for mid or low rectal cancer (cT3-4 or cN+ without metastasis) between 2011 and 2015 who had post-CRT rectal MRI before surgery were included retrospectively. Three board-certified experienced radiologists assessed mrTRG. mrTRG was correlated with pathological tumour regression grade (pTRG), ypT and ypN. In a subgroup of patients with mrTRG1-2 and no tumour spread (such as nodal metastasis) on MRI, the projected rate of completion total mesorectal excision (TME) if they underwent transanal excision (TAE) and had a ypT status of ypT2 or higher was estimated, and recurrence-free survival was calculated according to the operation (TME or TAE) that patients had actually received.

Results: Some 439 patients (290 men and 149 women of mean(s.d.) age 62·2(11·4) years) were analysed. The accuracy of mrTRG1 for predicting pTRG1 was 61 per cent (40 of 66), and that for ypT1 or less was 74 per cent (49 of 66). For mrTRG2, these values were 22·3 per cent (25 of 112) and 36·6 per cent (41 of 112) respectively. Patients with mrTRG1 and mrTRG2 without tumour spread were ypN+ in 3 per cent (1 of 29) and 16 per cent (8 of 50) respectively. Assuming mrTRG1 or mrTRG1-2 with no tumour spread on post-CRT MRI as the criteria for TAE, the projected completion TME rate was 26 per cent (11 of 43) and 41·0 per cent (41 of 100) respectively. For the 100 patients with mrTRG1-2 and no tumour spread, recurrence-free survival did not differ significantly between TME (79 patients) and TAE (21) (adjusted hazard ratio 1·86, 95 per cent c.i. 0·42 to 8·18).

Conclusion: Patients with mrTRG1 without tumour spread may be suitable for TAE.

Publication types

Observational Study

MeSH terms

Aged
Chemoradiotherapy, Adjuvant / methods*
Female
Humans
Intraoperative Care
Magnetic Resonance Imaging
Male
Middle Aged
Postoperative Care
Rectal Neoplasms / pathology
Rectal Neoplasms / therapy*
Retrospective Studies
Treatment Outcome