Title: Complete Response to Neoadjuvant Chemoradiation in Locally Advanced Rectal Cancer: Will DW MRI Hold the Key to Deciding Non Surgical Management?
Authors: Dr Sumod Mathew Koshy MD, FRCR, Dr Anil Prahladan DNB, EDiR, Dr Sonia Abraham MD, Dr Krishnankutty Nair Ramachandran MD
DOI: https://dx.doi.org/10.18535/jmscr/v5i3.28
Abstract
Rectal carcinomas are among the more common malignancies diagnosed worldwide in both genders. Over the last couple of decades, MRI has gradually replaced transrectal ultrasound and CT as the imaging modality of choice in staging of rectal carcinoma. Of late, several studies have been conducted to assess the feasibility of conservative or non surgical management of carcinoma rectum. Patients who show complete pathological response, post chemoradiation may benefit from an organ preserving approach. Multiparametric MR, in addition to its pre eminent role in staging, also plays an important role in the post treatment setting. Our study was designed to assess the ability of DWI in predicting complete pathological response to neoadjuvant chemoradiation in locally advanced carcinoma rectum, to examine the need for MR imaging in the setting of post neoadjuvant chemoradiation and to evaluate the role of DWI in staging of carcinoma rectum. Receiver operating characteristic curves and area under curve (AUC) analysis of multiple variables showed that AUC of ADCmean was higher. Cut off ADC values were also calculated applying Youden’s statistics. Applying the cut off ADCmax of ≤1.53 x 10-3 mm2/s , complete and partial responders were accurately predicted with a sensitivity of 73.33% and specificity of 86.67%. Our study shows that DW imaging if done properly, can predict complete pathological response with reasonably good accuracy thus obviating the need for aPET – CT and also reduce the frequency / or, increase the interval between scopy and biopsy during follow up. Quantitative Diffusion Weighted MR Imaging can potentially provide a single non invasive test to determine complete pathological response and thus decide treatment strategy.
References
1. International Agency for Research on Cancer, WHO GLOBOCON 2012: Rectal cancer- Estimated Cancer Incidence, Mortality and Prevalence Worldwide in 2012, Cancer Factsheets.
2. Kapiteijn E, Marijnen CA, Nagtegaal ID, et al. Preoperative radiotherapy combined with total mesorectal excision for resectable rectal cancer. N Engl J Med 2001; 345:638 - 646
3. Habr-Gama A, Perez RO, Nadalin W, et al. Operative versus nonoperative treatment for stage 0 distal rectal cancer following chemoradiation therapy: longterm results. Ann Surg 2004;240(4):711–7[discussion: 717–8]
4. Hughes R, Harrison M, Glynne-Jones R. Could a wait and see policy be justified in T3/4 rectal cancers after chemo-radiotherapy? Acta Oncol 2010;49(3):378–81.
5. Maas M, Beets-Tan RG, Lambregts DM, et al. Wait-and-see policy for clinical complete responders after chemoradiation for rectal cancer. J Clin Oncol 2011;29(35):4633–40
6. Smith JD, Ruby JA, Goodman KA, et al. Nonoperative management of rectal cancer with complete clinical response after neoadjuvant therapy. Ann Surg 2012;256(6):965–72.
7. Seshadri RA, Kondaveeti SS, Jayanand SB, et al. Complete clinical response to neoadjuvant chemoradiation in rectal cancers: can surgery be avoided? Hepatogastroenterology 2013;60(123):410–4
8. Habr-Gama A, Perez O, Wynn G, et al. Complete clinical response after neoadjuvant chemoradiation therapy for distal rectal cancer: characteri-zation of clinical and endoscopic findings for standardization. Dis Colon Rectum 2010; 53(12):1692–8
9. Habr-Gama A. Assessment and management of the complete clinical response of rectal cancer to chemoradiotherapy. Colorectal Dis 2006;8(Suppl 3):21–4.
10. Barbaro B, Fiorucci C, Tebala C, et al. Locally advanced rectal cancer: MR imaging in prediction of response after preoperative chemotherapy and radiation therapy. Radiology 2009;250(3):730–9.
11. Curvo-Semedo L, Lambregts DM, Maas M, et al. Rectal cancer: assess ment of complete response to preoper-ative combined radiation therapy with chemotherapy–conventional MR volumetry versus diffusion-weighted MR imaging. Radiology 2011; 260(3):734–43.