Changes of hypoxia in primary lesion of nasopharyngeal carcinoma during the treatment course and the clinical value thereof

Abstract

To investigate the hypoxia status in the primary lesion of nasopharyngeal carcinoma (NPC) during the treatment and the clinical value thereof. Sixty-two patients with untreated NPC were examined by 99m Tc-4, 9-diaza-3, 3, 10, 10-tetramethy ldodecan-2, 11-dione dioxime (99 Tcm-HL91) SPECT imaging and CT-simulation (CT-Sim) scan before the treatment, in the mid-treatment (after receiving about 40 Gy) and at the end of treatment respectively. (1) All hypoxia images obtained at the 3 time pints were analyzed by visual analysis and semi-quantitative analysis, the radioactivity ratio of the high density region in the nasopharyngeal lesion to the normal nasopharyngeal tissue (T+/N) was calculated with the technique of region of interesting (ROI). Then the changes of hypoxia status during the treatment were evaluated according to the changes of the visual results and the ratios of T+/N. (2) The tumor volumes in different time points were measured by relevant CT-Sim images in the CT-Sim working station (Exomio 2.0, Medintec), and the percentage of tumor shrinkage in the mid-treatment and at the end of treatment were calculated to evaluate the tumor's response to treatment. The relationships between the hypoxia status before treatment, hypoxic changes during the treatment, and the tumor's response to treatment were analyzed finally. Fifty-six of the 62 NPC cases were hypoxia-positive before the treatment, the hypoxic location in the same patient remained in the same site in different time points, and no new hypoxic area was found during the treatment. Eight cases changed to negative in the mid- treatment and 19 changed to negative at the end of treatment. The ratio of T+/N decreased gradually in the same case (F = 109.073, P = 0.000). The tumor shrinkage rates in the mid-treatment and at the end of treatment of those with high-grade hypoxia (T+/N >or= 1.52) were all both significantly lower than those of the cases with low-grade hypoxia (T+/N < 1.52) (P = 0.019 and 0.000) and those of the hypoxia-negative group (P = 0.038 and 0.000). The ratios of T+/N variation in the mid-treatment and at the end of treatment were both positively correlated with the percentages of tumor shrinkage in the mid-treatment and at the end of treatment (r = 0.587, P = 0.003 and r = 0.655, P = 0.001). The hypoxia of the primary lesion of NPC alleviates gradually or disappears along with the treatment course. Hypoxia has some negative effects on the tumor response to treatment.