Postoperative radiation therapy for completely resected invasive thymoma: prognostic value of pleural invasion for intrathoracic control

BACKGROUND

Optimal management of postoperative radiation therapy for completely resected invasive thymoma remains controversial. This study was conducted to assess the efficacy of postoperative mediastinal irradiation in patients with completely resected invasive thymoma.

METHODS

Between 1981 and 1996, 21 patients with completely resected invasive thymoma were referred for postoperative mediastinal irradiation. The distribution of Masaoka stages was stage II in 14 patients and stage III in seven patients. Nine patients had pleural invasion by the tumor. Thirteen patients were treated with a localized field and eight were treated with the whole mediastinal field with boost. The total dose to the primary tumor was 40-61 Gy (median: 52 Gy). The median follow-up time of the 16 living patients was 67 months (range: 29-202 months).

RESULTS

The 5- and 10-year actuarial overall survival rates in all patients were both 77%. Relapses were observed in five patients, in all of whom the sites of the first relapse involved pleural dissemination. There were no relapses within the irradiated field in any of the 21 cases. Five of nine (56%) patients with pleural invasion had relapse of pleural dissemination, while 0 of 12 (0%) patients without pleural invasion had relapse. In univariate analysis, pleural invasion had a statistically significant impact on intrathoracic control (P = 0.01).

CONCLUSIONS

The results indicated that pleural invasion might be predictive of pleural-based relapse for completely resected invasive thymoma. In patients with pleural invasion, mediastinal irradiation alone might be insufficient to avoid pleural-based relapse even after complete resection.

Detection of serum factors enhancing cell mutability from lung cancer patients by application of hypermutable human RS cells

A search for serum factors that modulate the mutability of human cells has been attempted in the peripheral blood of lung cancer patients. Factors were separated by dye-ligand chromatography and first identified as those exhibiting the ability to enhance the frequency of drug-resistance mutations in human RSa cells. The frequency was assessed by estimation of the cloning efficiency of mutant cells resistant to ouabain-mediated cell killing (OuaR) after irradiation with far-ultraviolet light (UV, mainly 254-nm wavelength). Pre-culture of cells with medium containing the factors prior to UV irradiation led to about a 19- to 37-fold increase in the OuaR mutation frequency compared with that of cells irradiated but not treated with the factors. The enhancing activity was detected in the serum of all 7 lung cancer patients, although the serum itself, which had not been treated with chromatography, had little or no enhancing activity in all patients. No enhancing activity was detected in serum preparations from healthy donors. The enhancing activity of lung cancer serum factors on UV-induced mutagenicity was next confirmed by detecting an enhancement of K-ras codon 12 base substitution mutations in human RSb cells, as analyzed by polymerase chain reaction (PCR) and differential dot-blot hybridization. Our results, together with previous findings on suppression of mutagen-induced mutagenicity by human interferons, suggest the existence of extracellular factors that modulate the mutability of human cells.

HLA and tumor necrosis factor beta gene polymorphisms in Okinawa lung cancer patients: comparative study with mainland Japan lung cancer patients

The frequencies of HLA class I and II antigens and TNF-beta polymorphism in lung cancer patients were investigated in two areas with different immunogenetic backgrounds, in Okinawa and in mainland Japan (Honshu). In Okinawa frequencies of HLA-Cw3 in squamous cell lung carcinoma patients were higher and those of HLA-DR, both in all lung cancer and in adeno lung carcinoma patients, were lower compared to those of normal controls. Among serologic HLA-DR4-positive individuals, no difference of DRB1*04 gene allele frequency was shown between patients and controls. In Honshu no statistically significant difference of HLA-class I and II alleles frequencies was found; however, the frequency of TNF-beta 10.5-kb homozygote in lung cancer patients was lower than that of controls. For 2-year survival, there was no difference between DR4-positive and -negative individuals and also between each TNF-beta type in Okinawa. In contrast, Honshu patients with 10.5-kb homozygote showed an improved 5-year survival ratio compared to those with heterozygote. We postulate that different immunogenetic backgrounds or environments might have caused the varying HLA or TNF-beta association in the predisposition to or prognosis of lung cancer.