Prognostic utility of serial 18F-FDG-PET/CT in patients with locally advanced rectal cancer who underwent tri-modality treatment

Sumal Fernando; Michael Lin; Trang Thanh Pham; Shanley Chong; Emilia Ip; Karen Wong; Wei Chua; Weng Ng; Peter Lin; Stephanie Lim

doi:10.1259/bjr.20190455

Prognostic utility of serial ¹⁸F-FDG-PET/CT in patients with locally advanced rectal cancer who underwent tri-modality treatment

Br J Radiol. 2020 Jan;93(1105):20190455. doi: 10.1259/bjr.20190455. Epub 2019 Oct 23.

Authors

Sumal Fernando¹, Michael Lin^{1

2

3}, Trang Thanh Pham^{1

2

4

5}, Shanley Chong^{1

6}, Emilia Ip^{5

7}, Karen Wong^{1

4

5}, Wei Chua^{5

7}, Weng Ng^{1

5

7}, Peter Lin^{1

2

3}, Stephanie Lim^{1

5}

Affiliations

¹ University of New South Wales, Sydney, Australia.
² Western Sydney University, Sydney, Australia.
³ Department of Nuclear Medicine and PET, Liverpool Hospital, Sydney, Australia.
⁴ Department of Radiation Oncology, Liverpool Hospital, Sydney, Australia.
⁵ Ingham Institute for Applied Medical Research, Sydney, Australia.
⁶ Population Health Intelligence, Healthy People and Places Unit, South Western Sydney Local Health District, Sydney, Australia.
⁷ Department of Medical Oncology, Liverpool Hospital, Sydney, Australia.

Abstract

Objective: This study explored the value of serial 18-fludeoxyglucose-positron emission tomography (¹⁸F-FDG-PET/CT) in predicting disease-free survival (DFS) in locally advanced rectal cancer (LARC) treated with neoadjuvant chemoradiation (NCRT) and surgery.

Methods: We prospectively studied 46 patients with LARC who underwent NCRT and surgery. ¹⁸F-FDG-PET/CT scans were performed at three time-points before surgery (pre-NCRT-PET1, during NCRT-PET2 and following completion of NCRT-PET3). The following semi-quantitative PET parameters were analysed at each time point: maximum standardized uptake value (SUVmax), SUVmean, metabolic tumour volume (MTV) and tumour lesion glycolysis (TLG). Absolute and percentage changes in these parameters were analysed between time points. Statistical analysis consisted of median tests, Cox regression and Kaplan-Meier analysis for DFS.

Results: The median follow-up time was 24 months. A reduction in PET parameters showed statistically significant differences for patients with recurrence compared to those without; percentage changes in MTV between PET1 and PET3 (cut-off: 87%, p = 0.023), percentage changes in TLG between PET1 and PET3 (cut-off: 94%, p = 0.02) and absolute change in MTV PET1 and PET2 (cut-off: 10.25, p = 0.001).An absolute reduction in MTV between PET1 and PET3 (p=0.013), a percentage reduction in TLG between PET1 and PET2 (p=0.021), SUVmax and SUVmean at PET2 (p = 0.01, p = 0.027 respectively)were also prognostic indicators of recurrence.MTV percentage change between PET1 and PET2 and SUVmean percentage change between PET1 and PET3 were also trending towards significance (p = 0.052, p = 0.053 respectively).

Conclusion: Serial ¹⁸F-FDG-PET/CT is a potentially reliable non-invasive method to predict recurrence in patients with LARC. Volumetric parameters were the best predictors. This could allow risk-stratification in patients who may benefit from conservative management.

Advances in knowledge: This paper will add to the literature in risk-stratifying patients with LARC based on prognosis, using ¹⁸F-FDG-PET/CT. This may improve patient outcomes by selecting suitable candidates for conservative management.

MeSH terms

Aged
Chemoradiotherapy
Combined Modality Therapy
Female
Fluorodeoxyglucose F18
Glycolysis
Humans
Kaplan-Meier Estimate
Male
Middle Aged
Neoadjuvant Therapy
Neoplasm Recurrence, Local / diagnostic imaging
Neoplasm Recurrence, Local / pathology
Neoplasm Staging
Positron Emission Tomography Computed Tomography*
Prospective Studies
Radiopharmaceuticals
Rectal Neoplasms / diagnostic imaging*
Rectal Neoplasms / pathology
Rectal Neoplasms / therapy*
Tumor Burden

Substances

Radiopharmaceuticals
Fluorodeoxyglucose F18