Dose painting based on tumor uptake of Cu-ATSM and FDG: a comparative study.

BACKGROUND: Hypoxia and increased glycolytic activity of tumors are associated with poor prognosis. The purpose of this study was to investigate differences in radiotherapy (RT) dose painting based on the uptake of 2-deoxy-2-[(18) F]-fluorodeoxyglucose (FDG) and the proposed hypoxia tracer, copper(II)diacetyl-bis(N(4))-methylsemithiocarbazone (Cu-ATSM) using spontaneous clinical canine tumor models. METHODS: Positron emission tomography/computed tomography scans of five spontaneous canine sarcomas and carcinomas were obtained; FDG on day 1 and (64)Cu-ATSM on day 2 and 3 (approx. 3 and 24 hours pi.). Sub-volumes for dose escalation were defined by a threshold-based method for both tracers and five dose escalation levels were formed in each sub-volume. Volumetric modulated arc therapy plans were optimized based on the dose escalation regions for each scan for a total of three dose plans for each dog. The prescription dose for the GTV was 45 Gy (100%) and it was linearly escalated to a maximum of 150%. The correlations between dose painting plans were analyzed with construction of dose distribution density maps and quality volume histograms (QVH). Correlation between high-dose regions was investigated with Dice correlation coefficients. RESULTS: Comparison of dose plans revealed varying degree of correlation between cases. Some cases displayed a separation of high-dose regions in the comparison of FDG vs. (64)Cu-ATSM dose plans at both time points. Among the Dice correlation coefficients, the high dose regions showed the lowest degree of agreement, indicating potential benefit of using multiple tracers for dose painting. QVH analysis revealed that FDG-based dose painting plans adequately covered approximately 50% of the hypoxic regions. CONCLUSION: Radiotherapy plans optimized with the current approach for cut-off values and dose region definitions based on FDG, (64)Cu-ATSM 3 h and 24 h uptake in canine tumors had different localization of the regional dose escalation levels. This indicates that (64)Cu-ATSM at two different time-points and FDG provide different biological information that has to be taken into account when using the dose painting strategy in radiotherapy treatment planning.

Consortium analysis of gene and gene-folate interactions in purine and pyrimidine metabolism pathways with ovarian carcinoma risk.

SCOPE: We reevaluated previously reported associations between variants in pathways of one-carbon (1-C) (folate) transfer genes and ovarian carcinoma (OC) risk, and in related pathways of purine and pyrimidine metabolism, and assessed interactions with folate intake. METHODS AND RESULTS: Odds ratios (OR) for 446 genetic variants were estimated among 13,410 OC cases and 22,635 controls, and among 2281 cases and 3444 controls with folate information. Following multiple testing correction, the most significant main effect associations were for dihydropyrimidine dehydrogenase (DPYD) variants rs11587873 (OR = 0.92; p = 6 × 10⁻5) and rs828054 (OR = 1.06; p = 1 × 10⁻4). Thirteen variants in the pyrimidine metabolism genes, DPYD, DPYS, PPAT, and TYMS, also interacted significantly with folate in a multivariant analysis (corrected p = 9.9 × 10⁻6) but collectively explained only 0.2% of OC risk. Although no other associations were significant after multiple testing correction, variants in SHMT1 in 1-C transfer, previously reported with OC, suggested lower risk at higher folate (p(interaction) = 0.03-0.006). CONCLUSION: Variation in pyrimidine metabolism genes, particularly DPYD, which was previously reported to be associated with OC, may influence risk; however, stratification by folate intake is unlikely to modify disease risk appreciably in these women. SHMT1 SNP-by-folate interactions are plausible but require further validation. Polymorphisms in selected genes in purine metabolism were not associated with OC.

Neoadjuvant chemotherapy with cisplatin and methotrexate in patients with muscle-invasive bladder tumours.

This prospective, randomized study based on two associated trials was designed to evaluate the effect of neoadjuvant chemotherapy with cisplatin and methotrexate with folinic acid rescue or no chemotherapy prior to local treatment in patients with T2-T4b, NX-3, MO transitional cell carcinoma of the bladder. In the first trial, local treatment consisted of cystectomy (DAVECA 8901) and in the other trial the treatment was radiotherapy (DAVECA 8902); 153 eligible patients were randomized. The majority of the patients (89%) completed the protocol. The overall time to progression for all 153 patients was 12.9 months. Median time to progression was 14.2 months with chemotherapy and 11.4 months without chemotherapy. The actuarial 5-year overall survival rate for all 153 patients was 29%, and 29% for both treatment groups. Multivariate analyses showed that T-stage, tumour size and serum creatinine were independent prognostic factors for survival. The cystectomy trial included 33 patients. Median survival was 78.9 months, 82.5 months with chemotherapy and 45.8 months without chemotherapy (p = 0.76). The radiotherapy trial included 120 patients. The median survival was 17.6 months. Median survival was 19.2 months in the group receiving chemotherapy and 16.3 in the group not receiving chemotherapy. The 5-year survival rate was 19% in the group receiving chemotherapy and 24% in the groups not receiving chemotherapy (p = 0.98). Late toxicity grade 3 or 4 of the bladder was recorded in 25% of the patients (actuarial rate). Neoadjuvant chemotherapy with cisplatin and methotrexate did not significantly improve disease-free or overall survival in 153 randomized patients with invasive bladder cancer.