Accuracy and Clinical Impact of Persistent Disease Diagnosed on Diffusion-Weighted Imaging and Accuracy of Pelvic Nodal Assessment on Magnetic Resonance Imaging for Squamous Cell Carcinoma of the Anus in the 6-Month Interval Post Chemoradiotherapy

Maria Clara Fernandes; Charlotte Charbel; Paul B Romesser; Burcin Agridag Ucpinar; Maria El Homsi; Onur Yildirim; James L Fuqua 3rd; Lee A Rodriguez; Junting Zheng; Marinela Capanu; Marc J Gollub; Natally Horvat

doi:10.1016/j.ijrobp.2024.02.056

Accuracy and Clinical Impact of Persistent Disease Diagnosed on Diffusion-Weighted Imaging and Accuracy of Pelvic Nodal Assessment on Magnetic Resonance Imaging for Squamous Cell Carcinoma of the Anus in the 6-Month Interval Post Chemoradiotherapy

Int J Radiat Oncol Biol Phys. 2024 Mar 8:S0360-3016(24)00380-8. doi: 10.1016/j.ijrobp.2024.02.056. Online ahead of print.

Affiliations

¹ Department of Radiology, Memorial Sloan Kettering Cancer Center, New York, New York.
² Department of Radiation Oncology, Memorial Sloan Kettering Cancer Center, New York, New York.
³ Department of Epidemiology and Biostatistics, Memorial Sloan Kettering Cancer Center, New York, New York.
⁴ Department of Radiology, Memorial Sloan Kettering Cancer Center, New York, New York. Electronic address: horvatn@mskcc.org.

PMID: 38462017
DOI: 10.1016/j.ijrobp.2024.02.056

Abstract

Purpose: To evaluate the diagnostic performance of diffusion-weighted imaging (DWI) in the 6-month interval post chemoradiation therapy (CRT) in determining persistent disease and whether persistent diffusion restriction on DWI at 6 months is associated with overall survival; and secondarily, to investigate the accuracy of pelvic lymph node assessment on T2-weighted imaging and DWI in the 6-month interval post CRT, in patients with squamous cell carcinoma of the anus.

Methods and materials: This retrospective study included patients with squamous cell carcinoma of the anus who underwent CRT followed by restaging rectal MRI from January 2010 to April 2020, with ≥1 year of follow-up after CRT. DW images were qualitatively evaluated by 2 junior and 2 senior abdominal radiologists to determine anal persistent disease. The reference standard for anal persistent disease was digital rectal examination/endoscopy and histopathology. Diagnostic performance was estimated using sensitivity, specificity, negative predictive value, and positive predictive value. Survival outcomes were evaluated via Kaplan-Meier analysis, and associations between survival outcomes and DWI status were tested for significance using the log-rank test. Additionally, DW and T2-weighted images were evaluated to determine lymph node status.

Results: Among 84 patients (mean age, 63 ± 10.2 years; 64/84 [76%] female), 14 of 84 (17%) had confirmed persistent disease. Interreader agreement on DWI between all 4 radiologists was moderate (Light's κ = 0.553). Overall, DWI had a sensitivity of 71.4%, specificity of 72.1%, positive predictive value of 34.5%, and negative predictive value of 92.5%. Patients with a negative DWI showed better survival than patients with a positive DWI (3-year overall survival of 92% vs 79% and 5-year overall survival of 87% vs 74%), although the difference did not reach statistical significance (P = .063). All patients with suspicious lymph nodes (14/14, 100%) showed negative pathology or decreased size during follow-up.

Conclusions: At 6 months post CRT, DWI showed value in excluding anal persistent disease. Persistent diffusion restriction on DWI was not significantly associated with overall survival. Pelvic nodal assessment on DWI and T2-weighted imaging was limited in predicting persistent nodal metastases.