Evidence of Partial Seniority Conservation in the πg_{9/2} Shell for the N=50 Isotones.

The reduced transition probabilities for the 4_{1}^{+}→2_{1}^{+} and 2_{1}^{+}→0_{1}^{+} transitions in ^{92}Mo and ^{94}Ru and for the 4_{1}^{+}→2_{1}^{+} and 6_{1}^{+}→4_{1}^{+} transitions in ^{90}Zr have been determined in this experiment making use of a multinucleon transfer reaction. These results have been interpreted on the basis of realistic shell-model calculations in the f_{5/2}, p_{3/2}, p_{1/2}, and g_{9/2} proton valence space. Only the combination of extensive lifetime information and large scale shell-model calculations allowed the extent of the seniority conservation in the N=50 g_{9/2} orbital to be understood. The conclusion is that seniority is largely conserved in the first πg_{9/2} orbital.

Stromal gene signatures in large-B-cell lymphomas.

BACKGROUND: The addition of rituximab to combination chemotherapy with cyclophosphamide, doxorubicin, vincristine, and prednisone (CHOP), or R-CHOP, has significantly improved the survival of patients with diffuse large-B-cell lymphoma. Whether gene-expression signatures correlate with survival after treatment of diffuse large-B-cell lymphoma is unclear. METHODS: We profiled gene expression in pretreatment biopsy specimens from 181 patients with diffuse large-B-cell lymphoma who received CHOP and 233 patients with this disease who received R-CHOP. A multivariate gene-expression-based survival-predictor model derived from a training group was tested in a validation group. RESULTS: A multivariate model created from three gene-expression signatures--termed "germinal-center B-cell," "stromal-1," and "stromal-2"--predicted survival both in patients who received CHOP and patients who received R-CHOP. The prognostically favorable stromal-1 signature reflected extracellular-matrix deposition and histiocytic infiltration. By contrast, the prognostically unfavorable stromal-2 signature reflected tumor blood-vessel density. CONCLUSIONS: Survival after treatment of diffuse large-B-cell lymphoma is influenced by differences in immune cells, fibrosis, and angiogenesis in the tumor microenvironment.

Low proliferative activity is associated with a favorable prognosis in peripheral T-cell lymphoma.

Peripheral T-cell lymphoma (PTCL) consists of a diverse group of post-thymic tumors bearing a mature T-cell phenotype and, excluding mycosis fungoides, comprises approximately 10-20% of the non-Hodgkin's lymphomas in the United States. This category of non-Hodgkin's lymphomas exhibits considerable morphological, immunological, and clinical diversity and is generally considered to be a high-grade malignancy. In the present study, paraffin-embedded biopsy specimens of lymph nodes from 31 patients with PTCL who were treated with curative intent were evaluated by flow cytometry for DNA ploidy and proliferative activity (PA). DNA ploidy was not predictive of the clinical outcome. However, low PA, defined by less than or equal to 10% of cells in S + G2M phase of cell cycle, was associated with a favorable prognosis. Patients with tumors having low PA had a significantly higher complete remission rate (100%) as compared to those with high PA (55%; P less than 0.02), and the predicted actuarial 4-year survival of those with low PA was 85% versus only 50% for those with high PA (P less than 0.04). This is the first report of the effects of PA and DNA ploidy in patients with PTCL who were treated with curative intent. Additional studies of similar patients are needed to confirm these findings.

Bone marrow involvement by non-Hodgkin's lymphoma: the clinical significance of morphologic discordance between the lymph node and bone marrow. Nebraska Lymphoma Study Group.

Bone marrow specimens from 317 patients with non-Hodgkin's lymphoma (NHL) obtained at initial staging were evaluated for the presence of lymphoma or benign lymphoid aggregates. Thirty-two percent (102 patients) had lymphoma in their bone marrow, and 9% had benign lymphoid aggregates. Bone marrow lymphoma was present in 39% of low-grade, 36% of intermediate-grade, and 18% of high-grade lymphomas. The bone marrow was involved in 25% of patients with diffuse large-cell or immunoblastic NHL (ie, diffuse histiocytic lymphoma of Rappaport). Bone marrow involvement did not affect survival of patients with low-grade NHL, but survival was significantly shorter (P = .03) for patients with intermediate- and high-grade NHL with bone marrow involvement. Bone marrow involvement was equally common in B-cell and T-cell NHL (31% v 32%). However, patients with T-cell NHL and bone marrow involvement had shorter survival than B-cell NHL with marrow involvement (P = .02) or T-cell NHL without marrow involvement (P = .05). A high incidence of morphologic discordance between lymph node and bone marrow was observed (ie, 40%), always with a more aggressive subtype in the lymph node than in the bone marrow. Presence of large-cell lymphoma in the bone marrow predicted for short survival. Survival for patients with small-cell lymphoma in their bone marrow did not differ significantly from patients with negative bone marrows. We conclude that bone marrow involvement in large-cell NHL, especially in those of T-cell origin, portends a poor prognosis. However, the subgroup of patients with an aggressive histologic subtype of NHL in a lymph node biopsy and small-cell NHL in the bone marrow do not have a poorer outlook than those without bone marrow involvement.

Clinical and prognostic significance of bone marrow involvement in patients with diffuse aggressive B-cell lymphoma.

PURPOSE: We studied the effect of morphology and extent of bone marrow (BM) infiltrate on the survival of patients with diffuse aggressive B-cell non-Hodgkin's lymphoma (NHL), along with clinical features. PATIENTS AND METHODS: Sixty adult patients with diffuse aggressive B-cell NHL and BM involvement at the time of presentation were studied. All patients were uniformly staged and treated with a curative high-dose chemotherapy regimen. BM involvement was assessed according to the cytology, pattern of infiltration, and extent of involvement, and was correlated with overall survival (OS) and failure-free survival (FFS). RESULTS: Patients with BM involvement that consisted of > or = 50% large cells or BM involvement of > or = 70% had a poorer OS (P = .065 and P = .055, respectively). Those who presented with an infiltrate of less than 50% large cells and an international prognostic index (IPI) of < or = 3 had a significantly longer postrelapse survival time (P = .003). A diffuse or interstitial pattern of BM involvement was predictive of both poor OS and FFS (P = .008 and .009, respectively). Multivariate analysis indicated that only IPI (P = .0005) and pattern of BM infiltration (P = .009) were independent predictors of OS, and only the former was predictive of FFS (P = .03). CONCLUSION: The IPI is predictive of OS and FFS, while BM involvement with a diffuse or interstitial pattern is associated with significantly poorer OS. Patients with BM infiltration that involved > or = 70% of the marrow or contained > or = 50% large cells had poor OS, but more patients need to be studied to determine the significance. Two parameters, IPI < or = 3 and BM large cells less than 50%, identify a group of patients with long-term survival after relapse.

Clinical features and prognosis of follicular large-cell lymphoma: a report from the Nebraska Lymphoma Study Group.

PURPOSE: Our purpose was to describe the treatment outcome of patients with follicular large-cell lymphoma (FLCL) and to identify prognostic factors that affect the treatment outcome. PATIENTS AND METHODS: Between 1980 and 1991, 107 newly diagnosed, previously untreated patients with FLCL were prospectively treated using treatment plans of the Nebraska Lymphoma Study Group (NLSG). Most stage I/II patients received two to three cycles of one of four closely related six-drug combination chemotherapy regimens (cyclophosphamide, doxorubicin or mitoxantrone, and procarbazine, plus bleomycin, vincristine, and prednisone or dexamethasone [CAP/BOP I-IV]) plus involved-field radiotherapy; 10 patients received involved-field irradiation only. Stage III/IV patients received six to eight cycles of CAP/BOP. RESULTS: Forty-four percent of patients had stage I/II disease. Stage I/II patients were older and more often female than stage III/IV patients. Cytogenetic studies were available on 35 patients: seven were normal; the most common abnormality was a translocation involving 14q32. Abnormalities of 1p or 1q were also common, often secondary to a 14q32 abnormality. The median follow-up of surviving patients is 2 years. The complete response rates observed were stage I/II, 88%; stage III/IV, 49%. Complete response rates were affected by both age and tumor bulk. Failure-free survival (FFS; time to first occurrence of progression, relapse after response, or death from any cause) at 3 years was estimated to be 61% for stage I/II patients and 34% for stage III/IV patients. Survival at 3 years was estimated to be 76% and 61%, respectively. FFS of stage III/IV patients was poorer for stage IV patients and those with composite lymphomas. Significantly poorer survival was only seen in patients older than 70 years of age. CONCLUSION: A proportion of stage I/II FLCL patients may obtain long-term disease control with combination chemotherapy plus radiotherapy. Results for patients with stage III/IV FLCL are similar to those seen for other follicular lymphomas.

Primary mediastinal large B-cell lymphoma: a clinicopathologic study of 43 patients from the Nebraska Lymphoma Study Group.

PURPOSE: To investigate whether primary mediastinal large B-cell lymphoma (PMLBL) is a distinct clinicopathologic entity with a more aggressive course than other diffuse large B-cell lymphomas (DLBL). MATERIALS AND METHODS: All patients with CD20-positive DLBL who presented with a mediastinal mass measuring at least 5.0 cm and were treated with curative intent were identified. A control group of 352 patients with nonmediastinal DLBL was selected for comparison. RESULTS: The 43 patients with PMLBL had a male to female ratio of 20:23 and a median age of 42 years. Stage I/II disease was present in 58% of the patients, with only 9% having bone marrow involvement. A complete remission was achieved in 63% of the patients, and the 5-year overall and failure-free survivals were 46% and 38%, respectively. Among the clinical variables, an elevated serum lactate dehydrogenase level, a low performance score, more than one extranodal site, and an intermediate or high International Prognostic Index score were predictive of poor survival. When compared with the DLBL group, a younger median age was the only clinical feature that was significantly different in the PMLBL group. CONCLUSION: The clinical features of PMLBL do not appear to be significantly different from those of nonmediastinal DLBL. Although the younger age of onset, slight female predominance, mediastinal location, and size of the mass may justify the recognition of PMLBL as a clinical syndrome, additional evidence is needed to define it as a distinct disease entity.

Cholinergic enhancement of megakaryocytopoiesis and granulocytopoiesis in culture: mediation via T-lymphocytes.

Addition of carbamylcholine, a cholinergic analogue, to bone marrow cultures enhanced megakaryocytic and granulocytic growth by 60% and 42%, respectively. When carbamylcholine was added to spleen cells cultured in the presence of pokeweed mitogen, the resulting conditioned medium (PWM-SCM) increased the number of megakaryocytic and granulocytic colonies to 159% +/- 6% and 146% +/- 10%, respectively, compared to control cultures stimulated by PWM-SCM alone. To determine if this cholinergic augmentation of colony formation was direct or mediated via accessory marrow cells, cyclosporin A (CyA), a potent T-lymphocyte function inhibitor known to suppress the production of colony-stimulating activity (CSA) by spleen cell cultures, was added to marrow cultures. CyA (3 micrograms/ml) abrogated the enhancement of megakaryocytic and granulocyte-macrophage colony growth but had no effect on colony formation when added alone. To confirm the role of T-lymphocytes in the augmented proliferation of megakaryocytopoiesis and granulocytopoiesis, bone marrow cells from T-lymphocyte-deficient nude mice were cultured in the presence of carbamylcholine. No significant change was observed in the number of megakaryocyte colony-forming units (CFU-M) and committed granulocyte-macrophage colony-forming units (CFU-C) derived from the marrow of nude mice when cultured in the presence of carbamylcholine. The data suggest that carbamylcholine-induced enhancement of megakaryocytopoiesis and granulocytopoiesis in culture is indirect, requiring a T-lymphocyte population.

Lymphomatous polyposis. A neoplasm of either follicular mantle or germinal center cell origin.

Lymphomatous polyposis (LP) is generally thought to be an expression of non-Hodgkin's lymphoma (NHL) of follicular mantle cell (MC) origin. We report nine patients with LP from more than 3,500 cases of NHL studied by the Nebraska Lymphoma Study Group. Our patients differed from those reported previously in that LP represented a follicular center cell (FCC) NHL in two of the nine cases, with the remainder consisting of MC NHL. Three patients developed LP during a relapse of previously diagnosed and treated extraintestinal MC NHL (parotid gland, tonsil, and inguinal lymph node, respectively), whereas the other six patients presented with primary LP. In seven of the nine LP cases, a large mass predominated among a myriad of small polyps. The FCC cases were confined to the small intestine, whereas the MC cases were either pan-intestinal or colonic on their localization. Two MC cases studied by Southern blotting exhibited rearrangement of the bcl-1 locus. Bcl-2 rearrangement was not detected in any of the nine cases when studied by either a polymerase chain reaction-based assay (seven cases) or by Southern blotting (two cases). To date, four patients (three MC, one FCC) have experienced recurrent NHL in gastrointestinal sites. With follow-up ranging from 13 to 147 months, the entire group had a median survival of 41 months (primary MC LP:13, 13, 41, and 77 months; primary FCC LP:45 and 147 months; secondary MC LP:17, 41 and 76 months), and only one patient has died. We conclude that LP is a rare manifestation of NHL of either follicular MC or germinal center cell origin.

Malignant lymphoma in Nebraska and Guangzhou, China: a comparative study.

Two hundred thirty-four consecutive cases of malignant lymphoma (192 non-Hodgkin's lymphomas and 42 Hodgkin's disease) from Guangzhou, China, and 589 cases (498 non-Hodgkin's lymphomas and 91 Hodgkin's disease) from the University of Nebraska Lymphoma Registry were examined in a retrospective histopathologic analysis and the results compared to those of the National Cancer Institute (NCI) Working Formulation Summary. Aggressive non-Hodgkin's lymphoma was excessive in Guangzhou (82.3 per cent; P less than 0.001) and Nebraska (80.3 per cent; P less than 0.001) when compared with the NCI data (54.2 per cent). The small noncleaved cell, lymphoblastic, and diffuse mixed-cell subtypes were more frequent in China (15.6 per cent each; P less than 0.001), whereas the small lymphocytic, follicular large cell, and immunoblastic subtypes predominated in Nebraska (8 per cent, 8.4 per cent, and 21.8 per cent, respectively; P less than 0.001). The overall median age of onset for non-Hodgkin's lymphoma was 42.0 years in Guangzhou and 63.5 years in Nebraska. Hodgkin's disease represented 18 per cent of the malignant lymphomas in Guangzhou and 15 per cent in Nebraska. The mixed-cellularity type was most common in Guangzhou (52 per cent; P less than 0.001) and the nodular-sclerosing type in Nebraska (56 per cent; P less than 0.010). The low median age and excess of certain aggressive subtypes of non-Hodgkin's disease in Guangzhou suggest a possible viral etiology, whereas the excess of certain subtypes of non-Hodgkin's lymphoma in Nebraska may be related to intense agricultural activity.

Immunoblastic lymphoma with abundant clear cytoplasm. A comparative study of B- and T-cell types.

The morphologic, phenotypic, molecular genetic, and clinical features of 34 cases of clear-cell immunoblastic lymphoma (IBLC) are described. Sixteen cases were of B-cell type (IBLC-B) and 18 cases were of T-cell type (IBLC-T). There were no significant differences in the morphologic characteristics of the neoplastic cells in the two types, although IBLC-B was less likely to be polymorphic than IBLC-T. Interfollicular proliferation, a higher mitotic rate, infiltration by eosinophils, and an increase in capillary-sized blood vessels were also features of IBLC-T, whereas necrosis and fibrosis were more extensive in IBLC-B. Patients with IBLC-B were predominantly female, whereas those with IBLC-T were predominantly male. The mean age was 62 years for those with IBLC-B and 46 years for those with IBLC-T. Patients with IBLC-B usually had lower-stage disease, but there was no significant difference in survival rate between those with IBLC-B and those with IBLC-T. Although most cases of IBLC have been considered to be of peripheral T-cell origin, the authors conclude that IBLC-B is more common than previously considered and that clear-cell morphologic characteristics are not a reliable indicator of T-cell type.

Comparison of DNA content in non-Hodgkin's lymphoma as measured by flow cytometry and cytogenetics.

Specific cytogenetic changes such as t(14;18) and t(8;14) are associated with specific histologic subtypes of non-Hodgkin's lymphoma (NHL) and may predict disease outcome. Nonspecific cytogenetic changes include other structural rearrangements or numerical changes such as monosomies and trisomies, which may cause changes in total cellular DNA content. In many solid tumors, the presence of abnormal DNA content may be predictive of clinical behavior. NHL biopsies, however, contain normal (diploid) as well as abnormal cells, and DNA changes in the peridiploid range are detectable by cytogenetic analysis, but not consistently by flow cytometry. In the present study, we performed flow cytometric and cytogenetic analysis of DNA on biopsies from 129 patients with non-Hodgkin's lymphoma (NHL). Cytogenetic studies were successful on 88 (68%) of the samples. There was 55% concordance between flow cytometric and cytogenetic techniques in detecting aneuploid DNA content, with the majority of discrepancies occurring in the peridiploid range. We also detected six samples which were aneuploid by flow cytometry, but diploid by cytogenetics. We suggest that a reasonable approach to determine DNA content, as it relates to prediction of outcome in NHL, would be to combine data from both of these techniques and analyze the results in terms of ranges of DNA rather than by categorizing as diploid versus aneuploid.

Limited stage I and II follicular non-Hodgkin's lymphoma: the Nebraska Lymphoma Study Group experience.

The purpose of this study was to evaluate the outcome and prognostic factors of patients with limited stage follicular non-Hodgkin's lymphoma treated prospectively by the Nebraska Lymphoma Study Group (NLSG). Forty previously untreated patients, median age 64 years, with limited stage follicular lymphoma were prospectively treated according to the protocols of the NLSG between January 1980 and December 1990. The follicular large cell type represents 75% of the cases, and 14 of the biopsies also had a diffuse component (composite lymphoma). The initial treatment was radiation therapy (RT) to the involved field in 15 patients, anthracycline-containing combination chemotherapy (CT) in 20, and combined RT and CT in 5. Thirty-seven patients (92.5%) achieved a complete remission (CR). The median follow-up is 120 months (range, 20 to 214). Of the 37 patients achieving a CR, 7 patients are alive in first CR, one died due to sepsis, another because of a myeloproliferative disorder at 77 months following chemotherapy, 6 died because of unrelated causes in first CR. Twenty-two patients relapsed between 1 to 128 months following a CR. The estimated 10-year event-free survival is 21% (95% CI: 7 to 35). Two patients received no or palliative therapy after relapse and both died of progressive disease. Nineteen patients received salvage therapy and 15 achieved a second remission. The median survival after first relapse is 55 months. The estimated 10-year overall survival is 44% (95% CI: 28 to 60). Various factors including sex, histologic subtype, stage, and degree of follicularity do not influence the overall survival or event-free survival. CT with or without RT resulted in a better trend for 10-year event-free survival in stage IA patients compared to RT alone but estimated 10-year overall survival is no different. The overall survival is worse in the > or = 60 age group but this difference is not evident if data is adjusted for cause specific death. In conclusion, limited stage follicular lymphoma has an excellent initial response to radiation therapy or chemotherapy; however the recurrence rate is high and cure is limited.

Cytogenetic abnormalities in B-immunoblastic lymphoma.

We have considered the cytogenetic abnormalities present in 27 unpublished cases of B-immunoblastic lymphoma. Among these 27 patients, the chromosome changes were heterogeneous and complex. The chromosomes most commonly gained were 3 (44% of cases), 18 (44%), 6 (30%) and 11 (30%). The most common structural abnormalities involved band 14q32 (26%), band 18q21 (15%) and bands 6q16-21 (19%). Study of these 27 immunoblastic lymphomas did not allow us to tentatively identify a common primary cytogenetic abnormality unique to B-immunoblastic lymphoma, however, a translocation at 14q32 may be the primary cytogenetic lesion in some of the cases. Rather, we have added to the number of abnormalities reported in immunoblastic lymphoma and in non-Hodgkin's lymphoma in general.

Proliferative fraction and DNA content are lower in B-cell non-Hodgkin's lymphomas with the t(14;18).

The t(14;18), which juxtaposes the immunoglobulin enhancer region from chromosome 14 to the bcl-2 gene on chromosome 18, is a recurrent cytogenetic abnormality in the majority of follicular lymphomas (FL). This translocation results in overexpression of bcl-2, which increases cellular life span of the mutated cells by decreasing apoptosis. The t(14;18) also occurs in a subgroup of diffuse large cell lymphomas (DLCL), and current thought is that the majority of these represent transformation of FL. Low grade FL are characterized by low proliferation, and diploid/peridiploid DNA content. In this study, we compared proliferative activity (PF) and DNA content (DI) in FL containing the t(14;18) to DLCL with and without the t(14;18). The mean PF and DI were lower in the NHL containing t(14;18) irregardless of histologic subtype. We conclude that increased life span due to the presence of t(14;18) provides the conditions for accumulation of a different set of mutations as compared to those NHL developing from mutations in more rapidly proliferating precursors. This has implications for prognosis of patients with DLCL depending upon the presence or absence of t(14;18).

The effect of 2'-2' difluorodeoxycytidine (dFdC, gemcitabine) on radiation-induced cell lethality in two human head and neck squamous carcinoma cell lines differing in intrinsic radiosensitivity.

PURPOSE: The present study investigated in vitro radio-enhancement by gemcitabine (dFdC) in two head and neck squamous cell carcinomas with different intrinsic cellular radiosensitivity. MATERIALS AND METHODS: Radiosensitive (SCC61, SF2=0.16) and radioresistant (SQD9, SF2=0.49) human head and neck squamous cell carcinomas were used. Confluent cells were incubated with dFdC and irradiated in drug-free medium with a single dose of 250 kV X-rays (0-12Gy). Cell survival curves were corrected for the toxicity of the drug alone. RESULTS: In both cell lines, radio-enhancement was observed with 5 microM dFdC incubated for 3 h prior to irradiation. Dose modification factors (DMF) at a surviving fraction level of 0.5 reached 1.3 (95% CI 1.1-1.6) and 1.5 (95% CI 1.4-1.5) for SQD9 and SCC61 cells, respectively. Radio-enhancement was associated with a modest increase in the alpha term of the linear-quadratic model. In SQD9 cells, radio-enhancement increased with dFdC incubation time. At 24h, DMF reached a value of 1.5 (95% CI 0.9-3.2). In SCC61 cells at 24h, DMF reached a value of 1.1 (95% CI 0.9-1.2). In both cell lines, radio-enhancement increased with dFdC concentration up to 5-10 microM from which values it levelled off up to 100 microM. CONCLUSIONS: The data indicated that dFdC induced a modest radio-enhancement in both cell lines. For a short incubation time, dFdC did not radio-enhance preferentially the more radio-resistant cells, whereas the opposite was observed for a longer time. In both cell lines, radio-enhancement was saturated above a dFdC concentration of 5-10 microM.

Determination of tumour hypoxia with [18F]EF3 in patients with head and neck tumours: a phase I study to assess the tracer pharmacokinetics, biodistribution and metabolism.

PURPOSE: The aim of this study was to assess the pharmacokinetics, biodistribution and metabolism of [(18)F]EF3, a labelled 2-nitroimidazole hypoxia marker, in ten patients with head and neck cancer. METHODS: [(18)F]EF3 was administered intravenously (group 1, n=5, mean dose+/-SD: 324+/-108 MBq; group 2, n=5, mean dose+/-SD: 1,134+/-138 MBq) to patients (nine male, one female). Blood and urine samples and whole-body PET scans were obtained from 20 s to 4-6 h. Radioactivity was determined in several regions of interest. RESULTS: No serious adverse event was reported. [(18)F]EF3 concentration in blood exhibited a bi-exponential decline. [(18)F]EF3 was mainly eliminated in the urine. By 7 h 40 min after injection, 53+/-14% of the injected dose was collected in the urine. There was no significant difference between the low- and high-dose groups. A progressive accumulation occurred also in the colon, indicating a hepatobiliary excretion. Except in organs involved in the elimination of [(18)F]EF3, the tumour-to-organ ratio remained close to or below unity in muscle, lungs, heart and brain at various times after injection. In one patient, tumour hypoxia was observed with a tumour-to-blood ratio ranging from 1.4 to 1.9. Last, [(18)F]EF3 remained very stable after injection, with percentage of native tracer above 87% in the serum and 84% in the urine. CONCLUSION: Administration of [(18)F]EF3 in head and neck cancer patients is feasible and safe. Uptake and retention in tumour was observed, indicating the presence of hypoxia.

Detection of tumour hypoxia: comparison between EF5 adducts and [18F]EF3 uptake on an individual mouse tumour basis.

In the framework of the preclinical validation of the hypoxic tracer [(18)F]EF3, a comparison was performed between uptake of [(18)F]EF3 and EF5 adducts detected by immunofluorescence in MCa-4, FSA, FSAII, Sa-NH and NFSA tumour-bearing mice. Mice were allowed to breath carbogen (5% CO(2), 95% O(2)), 21% oxygen or 10% oxygen. A significant correlation (r (2)=0.57; p<0.01) was found between the [(18)F]EF3 tumour-to-muscle ratio and the fluorescence intensity of EF5.