About 20 years ago, gallium-67 planar scintigraphy was introduced for the evaluation of advanced esophageal squamous cell carcinoma (AESCC). Although single-photon emission tomography (SPET) is now available in many institutions, there have been no reports regarding the evaluation of AESCC using 67Ga SPET. The aims of this preliminary study were to assess the potential of 67Ga SPET for the detection of AESCC and to further evaluate whether 67Ga SPET can predict the effect of preoperative chemoradiotherapy on AESCC. Thirty-eight patients with histologically proven AESCC (35 men and 3 women, mean age 62±6.9 years) underwent 67Ga SPET before and after preoperative chemoradiotherapy. The histological response to the chemoradiotherapy was determined from a surgical specimen of the esophagus: grade 0, 100% viable tumor cells; grade 1a, 99%-67%; grade 1b, 66%-34%; grade 2, 33%-1%; grade 3, no viable cells. Thirty-seven out of 38 AESCCs (97.4%) were detected on pre-chemoradiotherapy SPET. In these 37 cancers, the tumor-to-lung ratio (TLRpre) was 3.5±2 (range 1.5-9.6). Post-chemoradiotherapy SPET exhibited positive results in 22 cancers, with a TLRpost of 1.8±0.4 (range 1.1-2.6). No patient exhibiting a pathologically complete response had a positive post-chemoradiotherapy SPET result, whereas 80% of patients with negative post-chemoradiotherapy SPET (12/15) results had residual tumor. The percent reduction rate was defined as (TLRpre-TLRpost)/TLRpre x100 and did not correlate with histological response grade (P=0.5169 for Kruskal-Wallis test). These results suggest that 67Ga SPET is a powerful tool for the detection of AESCC. However, 67Ga SPET seems to be of little use in predicting the effects of preoperative chemoradiotherapy on AESCC. Further studies are warranted in order to further clarify the clinical usefulness of 67Ga SPET in patients with AESCC.
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