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Accuracy of positron emission tomography/computed tomography and clinical assessment in the detection of complete rectal tumor regression after neoadjuvant chemoradiation†
Long-term results of a prospective trial (National Clinical Trial 00254683)
Article first published online: 15 NOV 2011
Copyright © 2011 American Cancer Society
Volume 118, Issue 14, pages 3501–3511, 15 July 2012
How to Cite
Perez, R. O., Habr-Gama, A., Gama-Rodrigues, J., Proscurshim, I., Julião, G. P. S., Lynn, P., Ono, C. R., Campos, F. G., Silva e Sousa, A. H., Imperiale, A. R., Nahas, S. C. and Buchpiguel, C. A. (2012), Accuracy of positron emission tomography/computed tomography and clinical assessment in the detection of complete rectal tumor regression after neoadjuvant chemoradiation. Cancer, 118: 3501–3511. doi: 10.1002/cncr.26644
All authors were involved in the study design, development and interpretation of results. Drafting and revision of the article was undertaken by all authors. All authors approved the final version of the article. The first author had full access to all data and had final responsibility for the decision to submit the article for publication.
- Issue published online: 2 JUL 2012
- Article first published online: 15 NOV 2011
- Manuscript Accepted: 26 SEP 2011
- Manuscript Revised: 14 SEP 2011
- Manuscript Received: 20 AUG 2011
- rectal cancer;
- neoadjuvant chemoradiation;
- positron emission tomography/computed tomography;
- tumor response;
- complete clinical response
Neoadjuvant chemoradiation (CRT) therapy may result in significant tumor regression in patients with rectal cancer. Patients who develop complete tumor regression have been managed by treatment strategies that are alternatives to standard total mesorectal excision. Therefore, assessment of tumor response with positron emission tomography/computed tomography (PET/CT) after neoadjuvant treatment may offer relevant information for the selection of patients to receive alternative treatment strategies.
Patients with clinical T2 (cT2) through cT4NxM0 rectal adenocarcinoma were included prospectively. Neoadjuvant therapy consisted of 54 grays of radiation and 5-fluorouracil-based chemotherapy. Baseline PET/CT studies were obtained before CRT followed by PET/CT studies at 6 weeks and 12 weeks after the completion of CRT. Clinical assessment was performed at 12 weeks after CRT completion. PET/CT results were compared with clinical and pathologic data.
In total, 99 patients were included in the study. Twenty-three patients were complete responders (16 had a complete clinical response, and 7 had a complete pathologic response). The PET/CT response evaluation at 12 weeks indicated that 18 patients had a complete response, and 81 patients had an incomplete response. There were 5 false-negative and 10 false-positive PET/CT results. PET/CT for the detection of residual cancer had 93% sensitivity, 53% specificity, a 73% negative predictive value, an 87% positive predictive value, and 85% accuracy. Clinical assessment alone resulted in an accuracy of 91%. PET/CT information may have detected misdiagnoses made by clinical assessment alone, improving overall accuracy to 96%.
Assessment of tumor response at 12 weeks after CRT completion with PET/CT imaging may provide a useful additional tool with good overall accuracy for the selection of patients who may avoid unnecessary radical resection after achieving a complete clinical response. Cancer 2012;3501–3511. © 2011 American Cancer Society.