Local relapse of nasopharyngeal cancer and Voxel-based analysis of FMISO uptake using PET with semiconductor detectors.

Abstract

BACKGROUND:

Hypoxic cancer cells are thought to be radioresistant and could impact local recurrence after radiotherapy (RT). One of the major hypoxic imaging modalities is [18F]fluoromisonidazole positron emission tomography (FMISO-PET). High FMISO uptake before RT could indicate radioresistant sites and might be associated with future local recurrence. The predictive value of FMISO-PET for intra-tumoral recurrence regions was evaluated using high-resolution semiconductor detectors in patients with nasopharyngeal carcinoma after intensity-modulated radiotherapy (IMRT).

METHODS:

Nine patients with local recurrence and 12 patients without local recurrence for more than 3 years were included in this study. These patients received homogeneous and standard doses of radiation to the primary tumor irrespective of FMISO uptake. The FMISO-PET image before RT was examined via a voxel-based analysis, which focused on the relationship between the degree of FMISO uptake and recurrence region.

RESULTS:

In the pretreatment FMISO-PET images, the tumor-to-muscle ratio (TMR) of FMISO in the voxels of the tumor recurrence region was significantly higher than that of the non-recurrence region (p < 0.0001). In the recurrent patient group, a TMR value of 1.37 (95% CI: 1.36-1.39) corresponded to a recurrence rate of 30%, the odds ratio was 5.18 (4.87-5.51), and the area under the curve (AUC) of the receiver operating characteristic curve was 0.613. In all 21 patients, a TMR value of 2.42 (2.36-2.49) corresponded to an estimated recurrence rate of 30%, and the AUC was only 0.591.

CONCLUSIONS:

The uptake of FMISO in the recurrent region was significantly higher than that in the non-recurrent region. However, the predictive value of FMISO-PET before IMRT is not sufficient for up-front dose escalation for the intra-tumoral high-uptake region of FMISO. Because of the higher mean TMR of the recurrence region, a new hypoxic imaging method is needed to improve the sensitivity and specificity for hypoxia.

• Authors: Yukiko Nishikawa, Koichi Yasuda, Shozo Okamoto, Yoichi M Ito, Rikiya Onimaru, Tohru Shiga, Kazuhiko Tsuchiya, Shiro Watanabe, Wataru Takeuchi, Yuji Kuge, Hao Peng, Nagara Tamaki, Hiroki Shirato
• Journal: Radiation oncology (London, England) (Radiat Oncol) Vol. 12 Issue 1 Pg. 148 (Sep 06 2017) ISSN: 1748-717X [Electronic] England
• PMID: 28877734 (Publication Type: Journal Article)

Chemical References

• Radiopharmaceuticals
• fluoromisonidazole
• Misonidazole

Topics

• Adult
• Aged
• Carcinoma (diagnostic imaging, radiotherapy)
• Female
• Humans
• Image Interpretation, Computer-Assisted
• Male
• Middle Aged
• Misonidazole (analogs & derivatives)
• Nasopharyngeal Carcinoma
• Nasopharyngeal Neoplasms (diagnostic imaging, radiotherapy)
• Neoplasm Recurrence, Local (diagnostic imaging)
• Positron-Emission Tomography (methods)
• Radiopharmaceuticals
• Radiotherapy, Intensity-Modulated