Predictive Value of Early Post-Treatment Diffusion-Weighted MRI for Recurrence or Tumor Progression of Head and Neck Squamous Cell Carcinoma Treated with Chemo-Radiotherapy

Abstract

Aims: To investigate the predictive capacity of early post-treatment diffusion-weighted magnetic resonance imaging (MRI) for recurrence or tumor progression in patients with no tumor residue after chemo-radiotherapy (CRT) for head and neck squamous cell carcinoma, and, to assess the predictive capacity of pre-treatment diffusion-weighted MRI for persistent tumor residue post-CRT.

Materials and method: A single center cohort study was performed in one French hospital. All patients with squamous cell carcinoma receiving CRT (no surgical indication) were included. Two diffusion-weighted MRI were performed: one within 8 days before CRT and one 3 months after completing CRT with determination of median tumor apparent diffusion coefficient (ADC).

Main outcome: The primary endpoint was progression-free survival.

Results: 59 patients were included prior to CRT and 46 (78.0%) completed CRT. A post-CRT tumor residue was found in 19/46 (41.3%) patients. In univariate analysis, initial ADC was significantly lower in patients with residue post CRT (0.56 ± 0.11 versus 0.79 ± 0.13; p < 0.001). When initial ADC was dichotomized at the median, initial ADC lower than 0.7 was significantly more frequent in patients with residue post CRT (73.7% versus 11.1%, p < 0.0001). In multivariate analysis, only initial ADC lower than 0.7 was significantly associated with tumor residue (OR = 22.6; IC [4.9-103.6], p < 0.0001). Among 26 patients without tumor residue after CRT and followed up until 12 months, 6 (23.1%) presented recurrence or progression. Only univariate analysis was performed due to a small number of events. The only factor significantly associated with disease progression or early recurrence was the delta ADC (p = 0.0009). When ADC variation was dichotomized at the median, patients with ADC variation greater than 0.7 had time of disease-free survival significantly longer than patients with ADC variation lower than 0.7 (377.5 [286-402] days versus 253 [198-370], p < 0.0001). Conclusion and relevance: Diffusion-weighted MRI could be a technique that enables differentiation of patients with high potential for early recurrence for whom intensive post-CRT monitoring is mandatory. Prospective studies with more inclusions would be necessary to validate our results.

Keywords: chemo-radiotherapy; diffusion-weighted magnetic resonance imaging (MRI); head and neck neoplasm; recurrence.

Figure 1

75-year-old female patient before treatment: (A) Axial T2, (B) high b-value (b = 1000), diffusion-weighted Magnetic Resonnance (MR) images show a 2 cm large lesion on the right tonsil extending anteriorly to the posterior border of the base of the tongue (arrow), along with a 2 cm large adenopathy in the II B area (curved arrow). These lesions exhibit markedly high signal intensity in image (B). (C) Apparent diffusion coefficient (ADC) map show restriction of diffusion in both the lymph node and the lesion, with a mean value of the ADC of 0.75 s/mm².

Figure 2

Flow-chart of the study.

Figure 3

Factors associated with tumor residu (A) and early recurrence (B). (A) Box plot presenting ADC tumor value on pre-treatment MRI according to tumor residu, (B) Box plot presenting delta ADC tumor between post-treatment MRI and pre-treatment MRI according to recurrence. Each box shows median (as line), quartiles and mean (as cross). The whiskers represent values below the first quartile and above the third quartile within the 1.5-fold inter-quartile range respectively, and outliers beyond the whiskers are shown as circles.

Figure 4

Recurrence-free survival according to tumor delta ADC (greater or lower than 0.7).