Single nucleotide polymorphism in the 5' tandem repeat sequences of thymidylate synthase gene predicts for response to fluorouracil-based chemotherapy in advanced colorectal cancer patients

Thymidylate synthase (TS) is the primary target of 5-fluorouracil (5-FU). A VNTR polymorphism in the TS promoter region is associated with the efficacy of 5-FU-based chemotherapy in colorectal cancer. A common G>C SNP at the 12th nucleotide of the second repeat in the TS*3 alleles has been recently described. The combination of SNP and VNTR allows the definition of 3 TS alleles: *2, *3G and *3C. The aim of our study was to evaluate the predictive value of clinical response and survival of these new defined TS alleles. TS genotypes of 89 patients diagnosed with metastatic colorectal cancer and undergoing 5-FU-based chemotherapy were carried out. The clinical outcome was evaluated according to the genotype (high expression genotype: *2R/*3G; *3C/*3G; *3G/*3G; and low expression genotype: *2R/*2R; *2R/*3C; *3C/*3C. A higher overall response was observed in the group of patients with a low expression genotype (p = 0.035). The probability of achieving a clinical response of patients with a low expression-related genotype was 2.9 higher than that of the other group (95% CI = 1.03-5.6, p = 0.04). The median time to progression was 12 months and 9 months in the low and high expression groups, respectively (p = 0.07, log rank test). Overall survival was significantly longer in the low expression group. In this group the median OS was not achieved at 50 months of follow-up in contrast to the 20 months observed in the high expression group (p = 0.03). TS genotype was an independent predictor of progression-free and overall survival in the Cox regression models after adjustment to the other clinical variables. The selection of patients who are likely to respond to 5-FU therapy may be considerably improved if the TS genotype were to include both the VNTR and the SNP located within the promoter region of the gene.     

Prognostic significance of dihydropyrimidine dehydrogenase expression in breast cancer

We have investigated dihydropyrimidine dehydrogenase expression as a prognostic marker in breast cancer. A total of 119 women with breast cancer undergoing surgery between 1985 and 1996 were included in this study. Eighty-seven patients were treated with postoperative chemotherapy including 5-fluorouracil or 5-fluorouracil derivatives. Fifty-nine (50%) of 119 patients were determined to be immunostaining-positive for dihydropyrimidine dehydrogenase. There was no significant difference between dihydropyrimidine dehydrogenase staining and tumour size, lymph node status, clinical stage, oestrogen receptor status, histologic grade, or 5-fluorouracil administration. When evaluated in patients treated with 5-fluorouracil or 5-fluorouracil derivatives, patients with dihydropyrimidine dehydrogenase-positive tumours had a significantly (P<0.05) poorer disease-free survival compared to those with dihydropyrimidine dehydrogenase-negative tumour. No conclusion can be drawn about the prognostic impact of dihydropyrimidine dehydrogenase status in patients who were not treated with 5-fluorouracil regimes due to the small number of such cases in this series. Lymph node and dihydropyrimidine dehydrogenase status were independent prognostic factors for disease-free survival, and lymph node status for overall survival using multivariate analysis. In conclusion, dihydropyrimidine dehydrogenase is a possible prognostic factor in patients with breast cancer treated with 5-fluorouracil or 5-fluorouracil derivatives.     

A preliminary study on dihydropyrimidine dehydrogenase activity in breast cancer

We studied dihydropyrimidine dehydrogenase (DPD) and thymidylate synthase (TS), key enzymes in regulating the pharmacokinetics and chemosensitivity to 5-FU, in 36 breast cancer patients as a control group and 18 patients as a 5-FU group, in which 5-FU was given orally for 2 weeks before surgery at a dose of 200 mg/day. Cancer tissues with adjacent normal tissue were sampled and stored until the assay. The DPD activity and TS amount were determined according to the radio-enzymatic assay and radiobinding assay, respectively. The DPD activity was significantly higher in breast cancer than in the adjacent breast tissue. This finding was observed in T1 and T2, node negative and ER positive breast cancers in the control group as well as in the 5-FU group. The DPD activity in T3 was significantly lower than in T1, and that of the adjacent breast tissue in T3 was significantly higher than in T1; therefore, the tumoral/non-tumoral ratio of DPD activity was significantly lower in T3 than T1. TS was significantly elevated in both groups, without significant differences. The clinical implication of elevated DPD activity in T1, T2, node negative or ER positive breast cancer compared to the respective normal breast tissue activity remains to be studied, because it is still unclear whether or not the tumoral DPD activity regulates the local concentration of 5-FU within the tumor. The amount of TS and DPD activity was not influenced by the oral administration of 5-FU for 2 weeks at the dose of 200 mg/day.     

氟尿嘧啶对胃肠道肿瘤细胞DPD和TP表达的影响

背景与目的：氟尿嘧啶（5-FU）足胃肠道肿瘤化疗的首选和基本用药，其分解代谢的限速酶——二氢嘧啶脱氢酶（DPD）和激活酶——胸苛磷酸化酶（TP）决定了肿瘤区域的药物浓度和作用，且与5-FU的化疗敏感性有一定相关性。本研究旨在观察胃肠道肿瘤细胞中，5-Fu对DPD和TP的表达有无调节作用。方法：选取胃癌细胞株SGC7901、大肠癌细胞株SW1116和人脐静脉内皮细胞ECV-304，用不同浓度的5-FL作用不同时间后，以RT-PCR，ELISA和免疫组化等方法分别榆测DPD和TP的mRNA和蛋白含量，观察药物作用对不同细胞代崩酶表达的影响。结果：5-FU作用于不同细胞后表现不同：其中SGC7901、SW1116两株肿瘤细胞的DPD蛋白水平均上调，且表现为时间依赖性；在上述两株细胞中，TP蛋白表达呈小剂量上调、大剂量下凋的双重效应，并随时间延长表达增加；5-FU作用后DPD和TP mRNA水平则无显著改变。ECV-304细胞株的DPD和TP mRNA与蛋白表达不受5-FU影响。结论：胃肠道肿瘤细胞内，DPD和TP表达在蛋白水平上受5-Fu调控，而正常细胞不受影响。     

Clinical importance of risk variants in the dihydropyrimidine dehydrogenase gene for the prediction of early‐onset fluoropyrimidine toxicity

We investigated the clinical relevance of dihydropyrimidine dehydrogenase gene (DPYD) variants to predict severe early‐onset fluoropyrimidine (FP) toxicity, in particular of a recently discovered haplotype hapB3 and a linked deep intronic splice site mutation c.1129–5923C>G. Selected regions of DPYD were sequenced in prospectively collected germline DNA of 500 patients receiving FP‐based chemotherapy. Associations of DPYD variants and haplotypes with hematologic, gastrointestinal, infectious, and dermatologic toxicity in therapy cycles 1–2 and resulting FP‐dose interventions (dose reduction, therapy delay or cessation) were analyzed accounting for clinical and demographic covariates. Fifteen additional cases with toxicity‐related therapy delay or cessation were retrospectively examined for risk variants. The association of c.1129–5923C>G/hapB3 (4.6% carrier frequency) with severe toxicity was replicated in an independent prospective cohort. Overall, c.1129–5923G/hapB3 carriers showed a relative risk of 3.74 (RR, 95% CI = 2.30–6.09, p = 2 × 10^?5) for severe toxicity (grades 3–5). Of 31 risk variant carriers (c.1129–5923C>G/hapB3, c.1679T>G, c.1905+1G>A or c.2846A>T), 11 (all with c.1129–5923C>G/hapB3) experienced severe toxicity (15% of 72 cases, RR = 2.73, 95% CI = 1.61–4.63, p = 5 × 10^?6), and 16 carriers (55%) required FP‐dose interventions. Seven of the 15 (47%) retrospective cases carried a risk variant. The c.1129–5923C>G/hapB3 variant is a major contributor to severe early‐onset FP toxicity in Caucasian patients. This variant may substantially improve the identification of patients at risk of FP toxicity compared to established DPYD risk variants (c.1905+1G>A, c.1679T>G and c.2846A>T). Pre‐therapeutic DPYD testing may prevent 20–30% of life‐threatening or lethal episodes of FP toxicity in Caucasian patients.     

Relationship between 5-fluorouracil disposition, toxicity and dihydropyrimidine dehydrogenase activity in cancer patients

Background:Previous work demonstrated that 5-fluorouracil(5-FU) metabolism is a critical factor for treatment tolerability. Inorder to study the predictivity of pharmacokinetics with respect to theoccurrence of 5-FU toxicity, this study investigates the relationshipbetween the pharmacokinetics of 5-FU and its metabolite5-fluoro-5,6-dihydrouracil (5-FDHU), dihydropyrimidine dehydrogenase(DPD) activity in peripheral blood mononuclear cells (PBMNC) andtreatment tolerability. Patients and methods:Pharmacokinetics and metabolismof 5-FU and activity of DPD in PBMNC were examined in110 colorectal cancer patients given adjuvant 5-FU 370mg/m² plus L-folinic acid 100 mg/m² for five daysevery four weeks. Drug levels were examined by HPLC, while toxicitieswere graded according to WHO criteria. Results:DPD activity in patients with mild toxicities (WHOgrade 1) was 197.22 ± 11.34 pmol of 5-FDHU/min/mg of protein,while in five patients with grade 3–4 gastrointestinal toxicity,DPD ranged from low to normal values (range 31.12–182.37pmol/min/mg of protein). In these patients, 5-FU clearance (CL) waslower (range 14.12–25.17 l/h/m²), and the area underthe curve (AUC) was higher (range 14.70–26.20 h×µg/ml)than those observed in 84 patients with mild toxicities (CL, 56.30± 3.60 l/h/m²; AUC, 7.91 ± 0.44h×µg/ml). The severity of adverse events was associated withincreased 5-FU/5-FDHU AUC ratio and reduced 5-FU CL, while 5-FU and5-FDHU pharmacokinetics were not related to DPD activity. Conclusion:This study shows that DPD activity in PBMNC isunrelated to 5-FU/5-FDHU disposition and patients with severe toxicitydisplay marked pharmacokinetic alterations while a reduction of DPDactivity may not occur.     

Continuous 5-fluorouracil infusion in refractory carcinoma of the breast

Twenty-five patients with refractory, metastatic carcinoma of the breast were treated with continuous ambulatory 5-fluorouracil (5 FU) infusion (200 to 300 mg/m²/day) through a chronic indwelling central venous catheter. All patients had had extensive previous treatment, including hormonal therapy in 20/25 patients (80%), radiation therapy in 18/25 patients (72%), and an average of 4.6 previous chemotherapy drugs per patient (range 1–10). Twenty-three of 25 patients (92%) had had previous bolus 5 FU. Seventeen of 25 patients (68%) had two or more metastatic sites of involvement and 17/25 patients (68%) had visceral involvement. Results: complete remission –1/25 (4%), partial remission –7/25 (28%), stable disease –6/25 (24%), and progressive disease –11/25 (44%), for an overall response rate of 8/25 (32%). Median duration of response was 6 months. Toxicities included hand-foot syndrome, mucositis, diarrhea, and nausea and vomiting, and required treatment interruption and/or dose attenuation in 9/25 patients (36%). No myelosuppression or serious catheter-related problems were seen. We conclude that continuous 5 FU infusion is a potentially effective salvage treatment that may provide meaningful palliation in some patients with carcinoma of the breast, in spite of extensive previous treatment.     

Augmentation of the antitumor activity of capecitabine by a tumor selective dihydropyrimidine dehydrogenase inhibitor,RO0094889

Capecitabine is an orally available fluoropyrimidine and is finally converted to 5-FU selectively in tumor tissues. In our study, we examined whether the antitumor activity of capecitabine is directly affected by a modulation of dihydropyrimidine dehydrogenase (DPD). The modulations were carried out by the overexpression of DPD in tumor cells and by tumor selective DPD inhibition. The DPD-overexpressing cells were obtained by transfection of human DPD cDNA into HCT116 human colorectal cancer cells. The HCT116 cells bearing DPD cDNA expressed about 13 times higher DPD activities than the parental HCT116 cells, and they became significantly less susceptible to capecitabine than the parental cells when transplanted into nude mice. Administration of RO0094889 that is converted to a DPD inhibitor 5-vinyluracil selectively in tumor tissues restored the antitumor activity of capecitabine against the tumor of the HCT116 cells carrying DPD cDNA and various tumors expressing DPD. As compared to 5-ethynyluracil or 5-vinyluracil, which inhibited DPD not only in tumor tissues but also in other non-cancerous tissues, the effective dose range of RO0094889 in augmenting the efficacy of capecitabine was much broader. These results indicate that the antitumor activity of capecitabine is directly affected by DPD activities in tumor tissues and therefore, the combination of capecitabine and a tumor selective DPD inhibitor, RO0094889, will be beneficial to patients who have tumors with high levels of DPD.     

Microsatellite instability in colorectal cancer

Approximately 20 percent of right-sided colon cancers and 5 percent of left-sided colon and rectal cancers have a deficient DNA mismatch repair system. This results in the widespread accumulation of mutations to nucleotide repeats, some of which occur within the coding regions of cancer-related genes such as TGFβRII and BAX. A standardized definition for microsatellite instability (MSI) based on the presence of deletions to mononucleotide repeats is gaining widespread acceptance in both research and the clinic. Colorectal cancer (CRC) with MSI are characterized histologically by an abundance of tumor-infiltrating lymphocytes, poor differentiation and a signet ring or mucinous phenotype. In younger patients these tumors usually develop along the chromosomal instability pathway, in which case the mismatch repair genes are inactivated by germline mutation, somatic mutation and loss of heterozygosity. In older patients MSI CRC usually develops against a background of widespread hypermethylation that includes methylation-induced silencing of the mismatch repair gene MLH1. The overall biological and clinical phenotype of MSI CRC that arise in these two pathways is likely to be different and may account for some of the discordant results reported in the literature relating to the clinical properties of these tumors. The available evidence indicates that MSI is unlikely to be a clinically useful marker for the prognostic stratification of early-stage CRC. The predictive value of MSI for response to 5-fluorouracil-based chemotherapy remains controversial, while for other agents the predictive value is difficult to assess because they are used in combination regimens. The MSI phenotype is being actively investigated for novel therapeutic approaches based on the principle of synthetic lethality. Finally, the MSI status of CRC is an extremely useful marker for population-based screening programs that aim to identify individuals and families with the hereditary cancer condition known as Lynch syndrome.     

Chemotherapy for colorectal cancer prior to liver resection for colorectal cancer hepatic metastases does not adversely affect peri-operative outcomes

BACKGROUND: Systemic chemotherapy is being used increasingly in patients with colorectal cancer. The effects of prior systemic adjuvant or palliative chemotherapy on morbidity following hepatic resection for metastases are not well defined. OBJECTIVES: To assess the peri-operative impact of systemic chemotherapy on liver resection for colorectal cancer hepatic metastases. METHODS: Ninety-six resections for colorectal cancer hepatic metastases performed from July 2001 to July 2003 (93% > or =2 segments) were reviewed. Pre-operative demographics, peri-operative features, and post-operative outcomes were collected prospectively. Type of chemotherapy and the temporal relationship of chemotherapy to the liver resection were analyzed. RESULTS: Fifty-three of 96 patients (55%) received a mean of 5.7 cycles (6.1 months) of systemic chemotherapy prior to hepatic resection, with a median interval of 12 months from end of chemotherapy to liver resection (range 1-75 months). Thirty-five received 5-fluorouracil/leucovorin (5-FU/LV) alone, nine had irinotecan (CPT-11) in addition to 5-FU/LV, and nine were not specified. Pre-operative age, sex, co-morbidities, ASA score, biochemical and liver enzyme profiles, tumor number, and extent and technique of hepatic resection were the same in the chemotherapy and non-chemotherapy cohorts. Mean tumor size was smaller (4.5 cm vs. 5.8 cm) and synchronous metastases were half as common (25% vs. 49%) in the chemotherapy group. Liver resection operative time was equivalent (270 min) in the two groups. Higher estimated blood loss (EBL) (1,000 ml vs. 850 ml), but fewer transfusions (23% vs. 15%) were associated with the chemotherapy group. Although not statistically significant, post-operative liver enzyme peaks were higher in the chemotherapy group (AST = 402 U/L vs. 302 U/L, P = 0.09 and ALT = 433 U/L vs. 312 U/L, P = 0.1). Peak changes in INR and serum bilirubin did not differ. Complications and length of stay (LOS) did not differ between the groups. The only post-operative death was in the non-chemotherapy group. Interestingly, hepatic steatosis was present in 28% of the non-chemotherapy cases and 57% of the chemotherapy resection specimens (P = 0.005) and was marked (>30%) in 7% and 10%, respectively. Further analysis of the chemotherapy group based on the interval between completion of chemotherapy and the hepatic resection (<6 months, 7-12 months, 1-2 years, and >2 years) revealed a trend towards worse outcomes in most categories for those in the >2 years cohort. When comparing the 5-FU/LV alone, to the CPT-11 group there were no significant differences except higher intra-operative blood loss in the group receiving 5-FU/LV alone (1,295 ml vs. 756 ml, P = 0.01). CONCLUSION: Despite variations in biochemical function and hepatic steatosis, short-term clinical outcomes are not affected by the administration of chemotherapy prior to hepatic resection. Furthermore, there is no detrimental effect of close timing of chemotherapy prior to resection, and there are no appreciable differences between irinotecan containing regimes and more traditional 5-FU-only based therapies, although the subset sample sizes were small in this study.     

Retrospective review of mitomycin C use as third‐line chemotherapy in metastatic colorectal cancer

The aim of this review was to determine the therapeutic value of the combination of mitomycin C with either infusional 5‐fluorouracil or oral capecitabine in metastatic colorectal cancer when used as third‐line treatment or beyond in the setting of routine clinical practice. We retrospectively reviewed 18 patients with advanced colorectal cancer who received this combination at our institution after the failure of two lines of prior treatment. All the patients were assessable for toxicity and survival and 14 for tumor response. The median age of the patients was 61 (range 39–78). Of these, 72% were male and 78% had Eastern Cooperative Oncology Group performance status 0 or 1. Eighty nine percent of the patients had metastatic involvement of the liver and five patients had at least three sites of metastatic involvement. All patients had received at least two lines of chemotherapy and had progressed on an oxaliplatin‐containing regimen. Most of the patients had previously received an irinotecan‐containing regimen, and a third had received prior biological agents. Overall, none of the patients achieved either complete or partial responses. Two patients (11%) achieved stable disease and 12 patients (67%) had progressive disease. The median progression‐free survival was 2.7 months (range 0.5–8.8) and the median overall survival was 5.4 months (range 1.3–31.2). This chemotherapy regimen was well tolerated with an acceptable toxicity profile. The results of our review confirm the low efficacy of combination mitomycin C in heavily pretreated Australian patients with advanced colorectal cancer. This review confirms that it has no role after two lines of modern combination chemotherapy regimens and recommends that focus should be placed on investigating newer agents for good performance status patients progressing after these treatments.     

Phase I/II study of CPT-11 plus UFT in patients with advanced/recurrent colorectal cancer: Osaka Gastrointestinal Cancer Chemotherapy Study Group (OGSG): Protocol 0102

OBJECTIVE: The primary objective of this study was to explore the efficacy and safety of combined chemotherapy with CPT-11 and UFT in patients with advanced/metastatic colorectal cancer. METHODS: Twenty-two patients with metastatic colorectal cancer were enrolled in the phase I trial and 35 patients (including eight patients treated at level 4 during phase I) were evaluated in the phase II trial. Treatment consisted of two 35-day cycles of combination chemotherapy with CPT-11 and UFT. During phase I, CPT-11 was administered on days 1 and 15 as an intravenous infusion over 90 min at four different dose levels, starting from a dose of 80 mg/m2 (level 1). During phase II, the dose of CPT-11 was fixed at 150 mg/m2 based on the results of the phase I study. UFT was administered orally at a fixed dose of 300 mg/m2 on days 1-28, followed by a 1-week drug holiday, during each course (35 days). RESULTS: The maximum tolerated dose (MTD) of CPT-11 was determined to be 150 mg/m2 during the phase I trial. The major toxicities detected during phase II in 35 patients receiving CPT-11 at this recommended dose were grade 3/4 neutropenia in nine patients (25.7%) and grade 3/4 anorexia in six patients (11.4%). No severe adverse events occurred. The overall response rate and the median overall survival time was 22.9% (8/35) and 23.9 months for all patients, respectively. For pre-treated patients they were 26.3% (5/19) and 25.1 months, respectively. CONCLUSION: This combination of CPT-11 and UFT is considered to be both feasible and relatively safe. The response rate of the patients receiving CPT-11 at a dose of 150 mg/m2 was comparable to that reported previously for 5-FU-based regimens coupled with CPT-11, and this regimen can probably be beneficial for patients with pre-treated advanced colorectal cancer on an outpatient basis.     

5-fluorouracil sensitivity and dihydropyrimidine dehydrogenase activity in advanced gastric cancer

BACKGROUND: Dihydropyrimidine dehydrogenase (DPD) is the rate-limiting enzyme of 5-fluorouracil (5-FU) catabolism. Several studies have demonstrated the clinical importance of DPD in cancer patients, suggesting that the efficacy of 5-FU may be related to DPD activity in tumor tissue. In the present study, DPD activity and chemosensitivity to 5-FU were evaluated in advanced gastric cancer. Materials and METHODS: Thirty-four gastric cancers from 32 patients were studied and chemosensitivity to 5-FU was evaluated by histoculture drug response assay. RESULTS AND CONCLUSION: DPD activity and tumor inhibition of 5-FU among all cases showed no significant correlation, but among 14 histologically differentiated cases significant correlation was observed. DPD activity may be useful in determining the 5-FU sensitivity of differentiated gastric cancer.     

Thymidylate synthase and dihydropyrimidine dehydrogenase mRNA expression after administration of 5-fluorouracil to patients with colorectal cancer

This study explores the effect of 5-fluorouracil (5FU) exposure on mRNA levels of its target enzyme thymidylate synthase (TS) and the rate-limiting catabolic enzyme dihydropyrimidine dehydrogenase (DPD) in tumors of colorectal cancer patients. TS and DPD mRNA levels were determined in primary tumor and liver metastasis samples from patients who were either not pretreated (n = 29) or given one presurgery bolus of 5FU (n = 67). In both groups a wide variation in TS mRNA levels was observed. Median TS mRNA expression in 17 primary tumors of exposed patients was 3.0-fold higher than in 19 primary tumors of unexposed patients (p = 0.015). TS mRNA expression in liver metastasis samples of exposed patients (n = 16) was also higher (5.2-fold) than that of unexposed patients (n = 48; p < 0.001). Also DPD mRNA expression displayed a large degree of interpatient variation. No difference in DPD expression in liver metastasis samples was observed between exposed and unexposed patients. However, median DPD mRNA expression in 15 primary tumors of exposed patients was 3.2-fold lower than in 18 primary tumors of unexposed patients (p = 0.027). In conclusion, administration of 5FU in vivo influences the gene expression of TS and DPD.     

Novel 5-fluorouracil-resistant human esophageal squamous cell carcinoma cells with dihydropyrimidine dehydrogenase overexpression

5-Fluorouracil (5-FU) is a key drug for the treatment of esophageal squamous cell carcinoma (ESCC); however, resistance to it remains a critical limitation to its clinical use. To clarify the mechanisms of 5-FU resistance of ESCC, we originally established 5-FU-resistant ESCC cells, TE-5R, by step-wise treatment with continuously increasing concentrations of 5-FU. The half maximal inhibitory concentration of 5-FU showed that TE-5R cells were 15.6-fold more resistant to 5-FU in comparison with parental TE-5 cells. TE-5R cells showed regional copy number amplification of chromosome 1p including the DPYD gene, as well as high mRNA and protein expressions of dihydropyrimidine dehydrogenase (DPD), an enzyme involved in 5-FU degradation. 5-FU treatment resulted in a significant decrease of the intracellular 5-FU concentration and increase of the concentration of α-fluoro-ureidopropionic acid (FUPA), a metabolite of 5-FU, in TE-5R compared with TE-5 cells in vitro. Conversely, gimeracil, a DPD inhibitor, markedly increased the intracellular 5-FU concentration, decreased the intracellular FUPA concentration, and attenuated 5-FU resistance of TE-5R cells. These results indicate that 5-FU resistance of TE-5R cells is due to the rapid degradation of 5-FU by DPD overexpression. The investigation of 5-FU-resistant ESCC with DPYD gene copy number amplification and consequent DPD overexpression may generate novel biological evidence to explore strategies against ESCC with 5-FU resistance.     

The significance of dihydropyrimidine dehydrogenase (DPD) activity in bladder cancer

Dihydropyrimidine dehydrogenase (DPD) is the rate-limiting enzyme in the pathway of uracil and thymine catabolism. DPD is also the principal enzyme involved in the degradation of 5-fluorouracil (5-FU), which is one of the anticancer chemotherapeutic agents currently used in the treatment of bladder cancer. Little is known about the significance of DPD activity in human cancers. We investigated the activity of DPD in 74 bladder cancers and the relationship between the DPD activity and the sensitivity to 5-FU. The levels of DPD activity in bladder cancer and normal bladder tissues were determined by the 5-FU degradation assay. The sensitivity to 5-FU was assessed by the microculture tetrazolium dye (dimethylthiazolyl-2-5-diphenyltetrazolium bromide; MTT) assay. The activity of DPD was approximately 2-fold higher in bladder cancer tissues compared with normal bladder tissues. DPD activity in invasive bladder cancers was approximately 2-fold higher than that in superficial cancers. In addition, the levels of DPD activity in grade 2 and grade 3 bladder cancers were approximately 3-fold and 4-fold higher than that in grade 1 cancers, respectively. Patients with superficial bladder cancer with a low DPD activity had a slightly longer postoperative tumour-free period than those with a high DPD activity over a 2-year follow-up period, but this was not significant. There was an inverse correlation between DPD activity in bladder cancer cells and their sensitivity to 5-FU. Furthermore, 5-chloro-2,4-dihydroxypyridine (CDHP), a potent DPD inhibitor, enhanced the sensitivity to 5-FU. The present study has demonstrated that the level of DPD activity correlated with the progression of the stage and an increase in the grade of the bladder cancer. These results suggest that an elevated DPD activity might be associated with the malignant potential of the bladder cancer. In addition, it might be possible to overcome 5-FU insensitivity by using DPD inhibitors in the treatment protocols of 5-FU-based chemotherapy for bladder cancers.     

Increased risks of third primary cancers of non-breast origin among women with bilateral breast cancer

Background:

This study examined the risk of third cancer of non-breast origin (TNBC) among women with bilateral breast cancer (BBC; either synchronous or metachronous), focussing on the relation with breast cancer treatment.

Methods:

Risk was assessed, among 8752 Dutch women diagnosed with BBC between 1989 and 2008, using standardised incidence ratios (SIR) and Cox regression analyses to estimate the hazard ratio (HR) of TNBC for different treatment modalities.

Results:

Significant increased SIRs were observed for all TNBCs combined, haematological malignancies, stomach, colorectal, non-melanoma skin, lung, head and neck, endometrial, and ovarian cancer. A 10-fold increased risk was found for ovarian cancer among women younger than 50 years (SIR=10.0, 95% confidence interval (CI)=5.3–17.4). Radiotherapy was associated with increased risks of all TNBCs combined (HR=1.3; 95%CI=1.1–1.6, respectively). Endocrine therapy was associated with increased risks of all TNBCs combined (HR=1.2; 95%CI=1.0–1.5), haematological malignancies (HR=2.0; 95%CI=1.1–3.9), and head and neck cancer (HR=3.3; 95%CI=1.1–10.4). After chemotherapy decreased risks were found for all TNBCs combined (HR=0.63; 95%CI=0.5–0.87).

Conclusion:

Increased risk of TNBC could be influenced by genetic factors (ovarian cancer) or an effect of treatment (radiotherapy and endocrine therapy). More insight in the TNBC risk should further optimise and individualise treatment and surveillance protocols in (young) women with BBC.     

The stability of dihydropyrimidine dehydrogenase activity in colorectal cancer tissue after resection

Dihydropyrimidine dehydrogenase (DPD) is the first and rate-limiting enzyme in the catabolism of 5-fluorouracil (5-FU). DPD activity in tumor tissue may consequently serve as a predictive factor for sensitivity to 5-FU. The purpose of this study was to elucidate the stability of DPD activity over time in resected colorectal cancer tissue. DPD activity was measured in samples frozen immediately after the tumor was resected and in samples that had been allowed to stand at room temperature for 15, 30, 60, 120, and 180 min before being frozen. Surgical specimens obtained from 15 cases with advanced colorectal cancer were analyzed. The effects of differences among individuals and differences in time between collection and freezing were assessed by two-way analysis of variance (ANOVA). Significant differences in DPD activity were found among tumors (p=0.001), but there were no significant differences in the same tumor depending on the time between collection and freezing (p=0.496). Based on these results, it appears possible to make comparative assessments of DPD activity in colorectal cancer tissue without strictly stipulating the time between resection and freezing.     

Significance of thymidylate synthase (TS) and dihydropyrimidine dehydrogenase (DPD) activity in breast cancer tissue

TS, DPD, uridine phosphorylase and thymidine phosphorylase are enzymes involved in the metabolism of the anticancer drug pyrimidine fluoride. In this study, levels of these enzymes were measured in 47 women with primary breast cancer. These enzyme levels were then compared to levels determined from breast cancer patients who received either preoperative chemotherapy or nothing, in order to determine whether they might predict clinical outcome. The TS inhibition rate was significantly higher (p < 0.05) in patients receiving preoperative chemotherapy (20.4 +/- 13.3%) than in the untreated group (11.4 +/- 9.8%). No other significant differences in activity were noted between the treated and untreated groups for any of the other enzymes studied. The activity of each enzyme at the tumor site and the tumor/normal (T/N) ratio were also compared between patients with and without recurrence. The TS inhibition rate at the tumor site was lower in recurring cases than in non-recurring cases, and the T/N ratio tended to be higher for DPD in patients with recurrences. These findings indicate that the TS inhibition rate and DPD activity may be useful predictors for early recurrence of breast cancer following surgery.     

Peripheral blood mononuclear cell dihydropyrimidine dehydrogenase activity in volunteers with and without diabetes mellitus

 It has been reported that cancer patients with diabetes mellitus receiving a continuous infusion of 5-fluorouracil (5-FU) have more toxicity and higher plasma 5-FU levels than patients without diabetes mellitus. Dihydropyrimidine dehydrogenase (DPD) is the initial and rate-limiting enzyme in the catabolism of 5-FU. DPD activity in peripheral blood mononuclear cells has been reported to correlate inversely with 5-FU plasma levels in patients. We therefore undertook a study to compare the activity of DPD in peripheral blood mononuclear cells of human subjects with and without diabetes mellitus. The study groups comprised 43 volunteers with and 39 without diabetes mellitus, and peripheral blood mononuclear cell DPD activity was assayed on samples obtained between 8 a.m. and 11 a.m. DPD activity was not decreased in diabetic subjects. There was no relationship between DPD activity and gender, body mass index, or race. There was a modest correlation between DPD activity and age (r=0.19, P=0.08). We conclude that increases in 5-FU-related toxicities in diabetics must be related to factors other than peripheral blood mononuclear cell DPD activity. Received: 24 March 1995/Accepted: 21 July 1995