FGFR3 and TP53 gene mutations define two distinct pathways in urothelial cell carcinoma of the bladder

FGFR3 and TP53 mutations are frequent in superficial papillary and invasive disease, respectively. We used denaturing high-performance liquid chromatography and sequencing to screen for FGFR3 and TP53 mutations in 81 newly diagnosed urothelial cell carcinomas. Tumors were classified as follows: 31 pTa, 1 carcinoma in situ, 30 pT1, and 19 pT2-T4. Tumor grades were as follows: 10 G1, 29 G2, and 42 G3. FGFR3 mutations were associated with low-stage (P < 0.0001), low-grade (P < 0.008) tumors, whereas TP53 mutations were associated with high-stage (P < 0.003), high-grade (P < 0.02) tumors. Mutations in these two genes were almost mutually exclusive. Our results suggest that FGFR3 and TP53 mutations define separate pathways at initial diagnosis of urothelial cell carcinoma.     

BCL-2, TP53 and BAX protein expression in superficial urothelial bladder carcinoma

Whether TP53, BCL-2 and BAX expressions add independent prognostic information in patients with Ta/T1bladder urothelial carcinoma remains unclear. TP53 overexpression correlated with high tumor grade (p = 0.004), WHO grading categories (0.045), BAX expression (p = 0.043) and pathologic stage (p = 0.05). BCL-2 immunostaining was inverse associated with tumor grade (p = 0.008). Lack of BAX expression was related to reduced patient’s survival (p = 0.028). Mortality was higher in patients with BCL-2+/TP53+ (p = 0.023) or TP53+/BAX− (p = 0.027) phenotype. BAX and pathologic stage were independent predictors of progression-free and overall survival, respectively. Therefore, BAX expression might be relevant in patient’s prognosis.     

FGFR3 and P53 characterize alternative genetic pathways in the pathogenesis of urothelial cell carcinoma

Fibroblast growth factor receptor 3 (FGFR3) and P53 mutations are frequently observed in bladder cancer. We here describe the distribution of FGFR3 mutations and P53 overexpression in 260 primary urothelial cell carcinomas. FGFR3 mutations were observed in 59% and P53 overexpression in 25%. Interestingly, FGFR3 and P53 alterations were mutually exclusive, because they coincided in only 5.7% of tumors. Consequently, we propose that they characterize two alternative genetic pathways in urothelial cell carcinoma pathogenesis. The genetic alterations were reflected in the pathology and the clinical outcome, i.e., FGFR3 mutations were found in low-stage/-grade tumors and were associated with a favorable disease course, whereas P53 alterations were tied to adverse disease parameters.     

Occupational exposure to polycyclic aromatic hydrocarbons influenced neither the frequency nor the spectrum of FGFR3 mutations in bladder urothelial carcinoma

Occupational exposure to polycyclic aromatic hydrocarbons (PAH) is associated with an increased risk of urothelial carcinoma (UC). FGFR3 is found mutated in about 70% of Ta tumors, which represent the major group at diagnosis. The influence of PAH on FGFR3 mutations and whether it is related to the emergence or shaping of these mutations is not yet known. We investigated the influence of occupational PAH on the frequency and spectrum of FGFR3 mutations. We included on 170 primary urothelial tumors from five hospitals from France. Patients (median age, 64 yr) were interviewed to gather data on occupational exposure to PAH, revealing 104 non‐ and possibly PAH exposed patients, 66 probably and definitely exposed patients. Tumors were classified as follows: 75 pTa, 52 pT1, and 43 ≥pT2. Tumor grades were as follows: 6 low malignant potential neoplasms (LMPN) and 41 low‐grade and 123 high‐grade carcinomas. The SnaPshot method was used to screen for the following FGFR3 mutations: R248C, S249C, G372C, Y375C, A393E, K652E, K652Q, K652M, and K652T. Occupational PAH exposure was not associated with a particular stage or grade of tumors. Thirty‐nine percent of the tumors harbored FGFR3 mutations. After adjustment for smoking, occupational exposure to PAH did not influence the frequency [OR, 1.10; 95% CI, 0.78–1.52], or spectrum of FGFR3 mutations. Occupational exposure to PAH influenced neither the frequency nor the spectrum of FGFR3 mutations and there was no direct relationship between these mutations and this occupational hazard. © 2009 Wiley‐Liss, Inc.     

p53 mutations in bladder cancer: evidence for exogenous versus endogenous risk factors

Bladder cancer is associated with smoking, occupational exposures, and glutathione S-transferase (GST) M1 and N-acetyltransferase (NAT) 2 polymorphisms that may influence carcinogen metabolism, but somatic p53mutations are often CpG dinucleotide G:C-A:T transitions that can occur spontaneously. We conducted a case-control study to determine whether p53mutation characteristics might distinguish cases with environmental versus endogenous causes. p53exons 4-9 were amplified from 146 bladder tumors by PCR, screened by single-strand conformational polymorphism analysis, and sequenced. Thirty-one cases were p53-positive, and 112 were p53-negative (germ line or silent). G:C-A:T transitions were also subclassified as CpG or non-CpG. Cases and 215 clinic controls were interviewed. GSTM1, NAT1, and NAT2 polymorphisms were assayed from peripheral blood. Odds ratios (ORs) and 95% confidence intervals (CIs) were estimated using logistic and polytomous regression. Case-control ORs for smoking, occupations, and NAT1*10genotype were similar for p53-positive and p53-negative cases. Associations with GSTM1-null and NAT2-slow genotypes were somewhat stronger for p53-positive [OR, 3.3; CI, 1.4-7.8 (GSTM1 null); OR, 1.8; CI, 0.8-4.0 (NAT2 slow)] than p53-negative cases [OR, 1.5; CI:0.9-2.3 (GSTM1 null); OR, 0.9; CI, 0.6-1.4 (NAT2 slow)]. Smoking was strongly associated with CpG G:C-A:T (OR, 15.3; CI:3.6-65) versus other G:C-A:T (OR, 1.8; CI, 0.3-9.8). NAT2 slow genotypes were also associated with CpG G:C-A:T (OR, 6.2; CI:0.7-52), whereas GSTM1 null was associated with non-CpG G:C-A:T (OR, 7.8; CI, 0.9-65). Associations were not substantially different for case subtypes defined by p53mutation status alone. Estimates for p53 subtypes were imprecise but support in vitro evidence that some CpG G:C-A:T transitions may be caused by smoking and other environmental mutagens.     

FGFR3 and Ras gene mutations are mutually exclusive genetic events in urothelial cell carcinoma

Fibroblast growth factor receptor 3 (FGFR3) mutations are frequent in superficial urothelial cell carcinoma (UCC). Ras gene mutations are also found in UCC. As oncogenic activation of both FGFR3 and Ras is predicted to result in stimulation of the mitogen-activated protein kinase (MAPK) pathway, we hypothesized that these might be mutually exclusive events. HRAS mutation has been widely studied in UCC, but all three Ras gene family members have not been screened for mutation in the same sample series. We screened 98 bladder tumours and 31 bladder cell lines for mutations in FGFR3, HRAS, NRAS and KRAS2. FGFR3 mutations were present in 54 tumours (55%) and three cell lines (10%), and Ras gene mutations in 13 tumours (13%) and four cell lines (13%). These included mutations in all three Ras genes; ten in HRAS, four in KRAS2 and four in NRAS and these were not associated with either tumour grade or stage. In no cases were Ras and FGFR3 mutation found together. This mutual exclusion suggests that FGFR3 and Ras gene mutation may represent alternative means to confer the same phenotype on UCC cells. If these events have biological equivalence, Ras mutant invasive UCC may represent a novel subgroup.     

Mutations in BHD and TP53 genes, but not in HNF1beta gene, in a large series of sporadic chromophobe renal cell carcinoma

BHD, TP53, and HNF1beta on chromosome 17 were studied in 92 cases of renal cell carcinoma (46 chromophobe, 19 clear cell, 18 oncocytoma, and nine papillary). Six, thirteen, and zero cases had, respectively BHD, TP53, and HNF1beta mutations, (84% mutations involved chromophobe), suggesting a role for BHD and TP53 in chromophobe subtype.     

No mutations of FGFR3 in normal urothelium in the vicinity of urothelial carcinoma of the bladder harbouring activating FGFR3 mutations in patients with bladder cancer

Mutations in the fibroblast growth factor receptor 3 (FGFR3) gene causing constitutive oncogenic protein activation have been shown to be frequent in papillary noninvasive bladder tumours and are associated with a low risk of progression and a favourable outcome. FGFR3 alterations have also been found in benign urothelial papilloma and flat urothelial hyperplasia suggesting FGFR3 alterations as an early event in bladder tumorigenesis. To date there is no data available on FGFR3 mutations in normal urothelium from patients with bladder cancer. We therefore analysed 64 samples of histopathological unsuspicious normal urothelium from 38 patients with FGFR3 mutated bladder tumours and 15 samples of urothelium from patients (n = 15) without any urothelial malignancy as a control group. Urothelial cells were microdissected from formalin‐fixed, paraffin‐embedded material. After DNA isolation whole genome amplification was done by I‐PEP‐PCR. FGFR3 mutations were detected using SNaPshot analysis. All samples could successfully be investigated. FGFR3 analyses did not reveal any mutation in the urothelium from neither the control group nor the bladder cancer group. All urothelial samples showed a wildtype sequence for FGFR3. These data suggest that mutations in the FGFR3 gene are not the earliest genetic alterations in bladder carcinogenesis and are associated with a hyperproliferative (hyperplastic) phenotype in the urothelium. Chromosomal alterations like deletions on chromosome 9q or aberrant promoter hypermethylation could play more important roles in early urothelial transformation than mutational FGFR3 activation. © 2009 UICC     

High Frequency of TP53 but not K-ras Gene Mutations in Bolivian Patients with Gallbladder Cancer

Although genetic characteristics are considered to be a factor influencing the geographic variation in the prevalence of gallbladder cancer (GBC), they have not been well studied in Bolivia, which has a high prevalence rate of GBC. The purpose of this study was to examine the frequency of TP53 and K-ras mutations in Bolivian patients with GBC and to compare them with our previous data obtained in other high-GBC-prevalence countries, namely Japan, Chile, and Hungary. DNA was extracted from cancer sites in paraffin-embedded tissue from 36 patients using a microdissection technique. TP53 mutations at exons 5 to 8 and K-ras mutations at codons 12, 13 and 61 were examined using direct sequencing techniques. The data obtained were compared with those in the other high-GBC-prevalence countries. Of the 36 patients, 18 (50.0%) had a TP53 mutation (one mutation in each of 17 patients and three mutations in one patient), and only one (2.8%) had a K-ras mutation. Of the 20 TP53 mutations, 12 were of the transition type (60.0%). This rate was significantly lower than that in Chile (12/12, P<0.05). In addition, three mutations were of the CpG transition type (15.0%), which is a feature of endogenous mutation. All three were found in the hot spot region of the TP53 gene. In contrast, G:C to T:A transversion was found in Bolivia, suggesting the presence of exogenous carcinogens. Our findings suggest that the development of GBC in Bolivia is associated with both exogenous carcinogens and endogenous mechanisms. The identification of an environmental risk factor for GBC is needed to confirm these findings.     

Chromosome 9 deletions are more frequent than FGFR3 mutations in flat urothelial hyperplasias of the bladder

Flat urothelial hyperplasias (FUHs) in patients with papillary bladder tumours frequently show deletions of chromosome 9, suggesting that FUH could be the first neoplastic step in the development of papillary bladder cancer. FGFR3 mutations are frequent in non-invasive papillary tumours with low risk of progression. Our aim was to investigate the frequency of FGFR3 mutations and deletions of chromosomes 9p/q and 8p/q in FUH. Thirty FUH and 9 simultaneous or consecutive tumours were detected by 5-ALA-based photodynamic cystoscopy. DNA was isolated from frozen sections and whole genome amplification was done by I-PEP-PCR, followed by LOH analysis on chromosomes 8p/q and 9p/q. FGFR3 mutations were detected by SNaPshot analysis. LOH analysis on FUH revealed deletions at 9p/q (11/30, 37%) and 8p/q (3/30, 10%). FGFR3 mutations were found in 7/30 FUH (23%). Only 2 FUH showed an FGFR3 mutation without deletions of chromosome 9. In contrast, 6 FUH revealed chromosome 9 deletions but wild type FGFR3 (p = 0.03). These results suggest that chromosome 9 deletions are the earliest genetic alterations in bladder cancer. The detection of FGFR3 mutations in FUH further supports the role of this lesion as precursor of papillary bladder cancer.     

CDKN2A but not TP53 mutations nor HPV presence predict poor outcome in metastatic squamous cell carcinoma of the skin

Genetic alterations in metastatic cutaneous squamous cell carcinoma (CSCC) which might serve as prognostic biomarkers are not well investigated. We investigated the mutation status and protein expression of the CDKN2A (INK4a‐ARF) and TP53 genes in metastatic CSCCs and correlated this with clinicopathological variables, HPV presence, and survival data. Sequence analysis was performed on formalin‐fixed and paraffin‐embedded tissue of 35 metastases and their primary tumors, and was correlated with immunohistochemical stainings for p53, p16 and p14. Beta‐PV and alpha‐PV DNA was detected using PCR‐based assays. Kaplan–Meier and Cox regression methods were used for survival assessment. CDKN2A was mutated in 31% of the metastases and their primary tumors, while the TP53 gene was mutated in 51% of the metastases. P53 protein expression was significantly associated with missense type of mutations (p = 0.002). No persistent HPV types were detected. CDKN2A mutations were significantly associated with disease‐specific death (p = 0.001). A significant difference was observed in disease‐specific survival between patients with or without a CDKN2A mutation (p = 0.010), while this was not the case for TP53. At univariate Cox's regression analysis tumor size (p = 0.010), invasion depth (p = 0.030) and CDKN2A mutations (p = 0.040) were significantly related to shorter disease‐specific survival. At multivariate Cox's regression only tumor size had an adverse effect on survival (p = 0.002). In conclusion, our study indicates that the CDKN2A mutation status might be of prognostic value in metastatic CSCCs. In most cases, CDKN2A and TP53 mutations are early genetic events in CSCC tumorigenesis. The possible role of HPV in metastatic CSCC needs further exploration.     

Mutations in DNA polymerase eta are not detected in squamous cell carcinoma of the skin

The major etiological agent in skin cancer is exposure to UV-irradiation and the concomitant DNA damage. UV-induced DNA lesions, such as thymine dimers, block DNA synthesis by the major DNA polymerases and inhibit the progression of DNA replication. Bypass of thymine dimers and related lesions is dependent on the translesion polymerase DNA polymerase eta (Poleta). In the inherited disorder, xeroderma pigmentosum variant (XPV), inactivation of Poleta results in extreme sensitivity to UV light and a marked increase in the incidence of skin cancer. Here, we tested the hypothesis that somatic mutations and/or polymorphisms in the POLH gene that encodes Poleta are associated with the induction of UV-dependent skin cancers. We sequenced the exonic regions of the Poleta open reading frame in DNA from 17 paired samples of squamous cell skin carcinoma and adjacent histologically normal tissue. We analyzed approximately 120,000 nucleotides and detected no mutations in POLH in the tumors. However, we identified 6 different single-nucleotide polymorphisms, 3 of them previously undocumented, which were present in both the tumor and paired normal tissue. We conclude that neither mutations nor polymorphisms in the coding regions of POLH are required for the generation of human skin squamous cell carcinoma.     

Chromosome instability and progression in urothelial cell carcinoma of the bladder

Superficial urothelial cell carcinoma (UCC) is a heterogeneous group of neoplasia with an unpredictable clinical course. Numerical alterations of chromosomes 7, 9 and 17 in superficial and invasive UCCs were analysed to evaluate the importance of chromosome instability in the progression of these tumours. Our sample consisted of 75 patients (47 with superficial and 28 with invasive bladder tumours). In situ hybridization using centromeric probes for chromosomes 7, 9 and 17 was done for the chromosome analysis in paraffin-embedded tissues. From the results obtained it can be concluded that losses of genetic material seem to be important early events in the carcinogenesis of the urothelium, but during progression of UCCs there seems to be a selection of those cells with gains of genetic material. This chromosome instability may be due to the acquisition of mechanisms involved in aneuploidization, namely p53 function disorders.     

Mutations of TP53 do not correlate with the sensitivity to paclitaxel--a study using 27 gynaecological cancer cell lines

The correlation between inactivation of the TP53 gene through mutation or the presence of high-risk human papillomavirus (HPV) DNA and intrinsic paclitaxel sensitivity was studied in 27 gynaecological cancer cell lines. IC(50) values, as a measure of drug sensitivity, were determined using a 96-well clonogenic assay. TP53 mutations were investigated with polymerase chain reaction-single-strand conformation polymorphism (PCR-SSCP) and direct DNA sequencing. HPV status was studied with PCR using HPV consensus primers. TP53 mutations were found in 7/11 vulvar SCC cell lines. Only 2/9 endometrial and 1/7 ovarian cancer cell lines carried TP53 mutations. One vulvar and one endometrial cancer cell line were HPV-positive; both carrying HPV type-16 DNA. Thus, TP53 was functionally normal in 3/11 vulvar, 6/9 endometrial and 6/7 ovarian cancer cell lines. The IC(50) values for paclitaxel were 0.60-2.9, 0.49-2.3 and 0.40-3.4 nM in the vulvar, endometrial and ovarian cancer cell lines, respectively. No correlation could be demonstrated between inactivation of the TP53 gene and paclitaxel sensitivity in vitro; the cell lines were evaluated as one group or according to their anatomical origin or histology. Previous reports have given inconclusive results, partly due to the cell types used, i.e. normal, cancerous or transformed cells. Our results support the view that paclitaxel sensitivity of tumour-derived cancer cell lines is not related to the TP53 status.     

Upregulation of TRAG3 gene in urothelial carcinoma of the bladder

Conventional chemotherapy is commonly used for advanced stages of bladder cancer with modest success and high morbidity. Identifying markers of resistance will allow clinicians to tailor treatment to a specific patient population. T24‐tumorigenic cell line was grown orthotopically in nude mice and monitored using bioluminescence imaging and microcomputed tomography until they developed metastases. Stable sublines were then developed from primary bladder (T24‐P), lung (T24‐L) and bone (T24‐B) tissues. Chromosomal analysis and DNA microarray were used to characterize these sublines. Real‐time quantitative polymerase chain reaction and immunohistochemistry were used for validation. Epigenetic modifiers were used to study gene regulation. The cell viability was quantified with MTT assay. Chromosomal analysis revealed multiple alterations in metastatic cell lines compared to T24‐P. DNA microarray analysis showed that taxol resistance‐associated gene (TRAG) 3 was the most upregulated gene. From real‐time quantitative polymerase chain reaction and immunohistochemistry, TRAG3 was significantly higher in T24‐L and T24‐B than T24‐P. TRAG3 gene expression is likely controlled by DNA methylation but not histone acetylation. Interestingly, T24‐B and T24‐L cells were more resistant than T24‐P to treatment with antimicrotubule agents such as docetaxel, paclitaxel and vinblastine. TRAG3 mRNA expression was higher in 20% of patients with ≤pT2 (n = 10) and 60% of patients with ≥pT3 (n = 20) compared to normal adjacent tissue (p = 0.05). In addition, the median TRAG3 expression was 6.7‐fold higher in ≥pT3 tumors compared to ≤pT2 tumors. Knowing the status of TRAG3 expression could help clinicians tailor treatment to a particular patient population that could benefit from treatment, while allocating patients with resistant tumors to new experimental therapies.     

The TP53 codon 72 polymorphism may affect the function of TP53 mutations in breast carcinomas but not in colorectal carcinomas.

An Arg/Pro polymorphism in codon 72 of the TP53 gene was analyzed in blood samples from 390 breast and 162 colorectal cancer patients previously investigated for TP53 mutations in their tumors. Among the breast cancer cases, 228 were homozygous for the Arg72 allele, of which, 65 (28.5%) also had a TP53 mutation in their tumors. In contrast, of 26 cases that were homozygous for the Pro72 allele, only 1 case (3.8%) had a TP53 mutation in the tumor (P = 0.004). Cloning the TP53 gene from tumor DNA followed by sequencing was performed in 14 heterozygotes with tumor mutation, and 9 of the mutations resided on the Arg72 allele. Among the colorectal cancer cases, no difference in mutation frequency was seen between the two different homozygotes, 40 TP53 mutations in 97 Arg72 homozygous cases (41.2%) versus 7 in 16 Pro72 homozygous cases (43.8%). These results suggest a selective growth advantage for cells carrying a type of TP53 mutation seen in breast carcinomas when the mutation resides on an Arg72 allele.     

Alterations of TP53 in microdissected transitional cell carcinoma of the human urinary bladder: high frequency of TP53 accumulation in the absence of detected mutations is associated with poor prognosis.

We have used microdissection of paraffin-embedded histological sections and polymerase chain reaction (PCR)-based direct DNA sequencing for 54 transitional cell carcinoma (TCC) of the bladder, to examine critically the association between TP53 nuclear accumulation determined by immunohistochemistry and the presence of TP53 mutations, and to examine their relationship to tumour stage and grade, as well as patient survival. There was a significant association between the presence of TP53-positive nuclei (> 10%) and a higher histological stage and grade (P = 0.0115, P = 0.0151 respectively; Fisher''s exact). A significant association between TP53 gene mutations and TP53 nuclear reactivity in more than 10% of tumour cell nuclei was also observed (P = 0.0003; Fisher''s exact). Mutations were detected in 18/54 (33%) cases together with the wild-type sequence when analysed from bulk frozen samples, with significant clustering of mutations in exons 7 and 8. The microdissection method distinguished more clearly between heterozygous and/or homozygous alterations of the TP53 tumour-suppressor gene, and clearly showed frequent accumulation of TP53 in the absence of mutations. When microdissecting immunonegative regions from the same paraffin sections, three out of ten samples showed the identical mutations detected in the immunopositive regions. There was a significant association between TP53 immunoreactivity in more than 50% of tumour cell nuclei and decreased survival among all patients (P = 0.0325; log-rank test). The patients with TP53 mutations showed a trend for a shorter survival period; however, the association was not statistically significant at the 95% confidence level (P = 0.132; log-rank test). In conclusion, our observations show that accumulation of TP53 occurs frequently in the absence of mutations, and that such accumulation is nevertheless associated with poor survival when it occurs in a high proportion (> 50%) of tumour cell nuclei.     

Urinary tuberculosis is associated with the development of urothelial carcinoma but not renal cell carcinoma: a nationwide cohort study in Taiwan

Background:

Obstructive uropathy and chronic urinary tract infection increase the risk of urinary tract cancer. Urinary tuberculosis (UTB) can cause chronic urinary tract inflammation, lead to obstructive uropathy, and potentially contribute to the development of urinary tract cancer. However, the association between UTB and urinary tract cancer has not been studied.

Methods:

This study enrolled 135 142 tuberculosis (TB) cases (male, 69%) from a nationwide health insurance research database in Taiwan and investigated the risk factors for urinary tract cancer, with emphasis on a history of UTB. The incidence of urinary tract cancer in the general population without TB was also calculated for comparison.

Results:

The TB patients had a mean age of 57.5±19.5 years. Of the 1287 UTB and 133 855 non-UTB patients, 15 (1.2%) and 396 (0.3%) developed urothelial carcinoma, respectively (P<0.001); and 2 (0.2%) and 96 (0.1%) developed renal cell carcinoma, respectively (P=0.240). Cox regression analysis revealed that age, male sex, end-stage renal disease, obstructive uropathy, arsenic intoxication, organ transplantation, and UTB (hazard ratio: 3.38 (2.01–5.69)) were independent risk factors for urothelial carcinoma. The hazard ratio of UTB was higher among female patients (5.26 (2.12–13.06)) than that among male patients (2.96 (1.57–5.60)).

Conclusion:

Urinary tuberculosis had a strong association with urothelial carcinoma, but not with renal cell carcinoma. In TB endemic areas, the urinary tract of TB patients should be scrutinised. It is also imperative that these patients be followed-up carefully in the post-treatment period, and urinalysis, ultrasonography or endoscopy should be an integral part of the follow-up.     

p53 mutation, but not p53 overexpression, correlates with survival in head and neck squamous cell carcinoma.

Survival in squamous cell carcinoma of the head and neck (HNSCC) was compared with overexpression and mutation of the p53 gene. Archival tissue from 77 tumours was analysed for protein expression using immunohistochemistry (IHC) with the monoclonal antibody Do-7, and for the presence of mutation in exons 5-8 using single-stranded conformation polymorphism (SSCP), followed by DNA sequencing in SSCP-positive cases. p53 expression was scored as high (>70% nuclei stained) in 25 (32%) tumours, as intermediate (10-70% nuclei stained) in 19 (25%) tumours and as low (<10% nuclei stained) in 33 (43%) tumours. Twelve (18%) tumours exhibited gene mutation (ten missense and two nonsense mutations) and an additional five tumours contained changes that could not result in amino acid substitution or protein truncation. There was no correlation between gene expression and mutation, mutations being equally frequent in tumours with either high (4/25), intermediate (4/19) or low protein expression (4/33). Fifty-eight patients were eligible for survival analysis. There was a strong correlation between p53 mutation and cause-specific survival; median survival among mutated cases was 12.5 months compared with >160 months among non-mutated patients (P < 0.005). There was no correlation between p53 overexpression and survival. The results suggest that p53 mutation status is an important prognostic factor in HNSCC, and that IHC analysis of protein overexpression is an inadequate measure of gene mutation in these tumours.