Occult systemic Non-Hodgkin's Lymphoma (NHL) in patients initially diagnosed as Primary Central Nervous System Lymphoma (PCNSL): How much staging is enough?

Objective To demonstrate the extent of staging necessary to exclude occult systemic stage IV NHL before making a diagnosis of stage I AE PCNSL.Background The diagnosis of PCNSL requires the demonstration of malignant lymphocytes within the CNS (usually by biopsy) and finding no evidence of systemic NHL. Different staging approaches have been recommended, ranging from extensive systemic evaluation (including bone marrow examination) to a more focused approach (abdominal and pelvic CT) to no systemic evaluation. We have employed a staging regimen that included: ophthalmologic evaluation (including slit lamp examination); CT of chest, abdomen, and pelvis; bilateral iliac crest aspirate and biopsy; flow cytometry of circulating lymphocytes; and, in men, testicular ultrasound.Design/methods We carried out a retrospective review of 128 patients entered into the Mayo Lymphoma Project data bank (1975–1994).Results Between the years 1975 and 1994, five patients (3.9%) were identified who fulfilled criteria for the diagnosis of PCNSL (typical clinical history, pathognomonic neuro-imaging, and histologie proof of NHL in brain tissue) but who had occult systemic NHL on staging (bone marrow 1, abdominal lymph nodes 3), or at autopsy (colon 1). Case histories are presented.Conclusions Patients with apparent PCNSL may have systemic NHL. Complete staging is essential to the initial management of patients presenting as PCNSL to exclude systemic stage IV disease.Presented at the First Congress of the European Association for Neuro-Oncology October 17, Maastricht, The Netherlands     

Frequent impact of [18F]fluorodeoxyglucose positron emission tomography on the staging and management of patients with indolent non-Hodgkin's lymphoma

[18F]fluorodeoxyglucose (FDG) positron emission tomography (PET) is useful in staging aggressive non-Hodgkin's lymphoma (NHL). However, its role in indolent NHL has not been established. This retrospective study assessed the sensitivity and clinical impact of PET findings in patients with indolent NHL. Patients with indolent NHL who underwent FDG-PET scanning between May 1997 and August 2001 were identified. Case records were reviewed for FDG-PET and conventional staging/restaging results and compared for concordance. Forty-seven patients were identified. Twelve staging FDG-PET scans and 37 restaging FDG-PET scans were obtained. The FDG-PET case sensitivity rate was 98%. Forty-two percent of staging FDG-PET scans were concordant with conventional staging, with the remaining patients exhibiting more extensive disease on PET. At progression, FDG-PET and conventional assessments were discordant in 46% of cases. Positron emission tomography findings downstaged disease in 30% of these patients and upstaged disease in 16%. Computed tomography (CT) and FDG-PET identified 150 and 146 individual sites of disease, respectively. Among "definite" sites on structural imaging, 74% were also seen on PET. For equivocal lesions, only 19% were seen on both modalities. Clinical management was changed in 34% of patients as a result of FDG-PET findings. Of 22 discordant lesions in which true disease status could be evaluated, the PET findings were confirmed to be correct in 21 (95%; P < 0.0001). These findings demonstrate that FDG-PET has a high sensitivity for indolent NHL and often leads to alteration of disease staging and management. This high accuracy of FDG-PET in assessing discordant lesions suggests a greater diagnostic utility compared with CT.     

Treatment of primary central nervous system lymphoma

Primary central nervous system lymphoma (PCNSL) describes a malignant non-Hodgkin's lymphoma (NHL) whose sole site of involvement is the central nervous system (CNS). The diagnosis of PCNSL must be differentiated from systemic NHL with metastasis to the CNS, which usually occurs late in the course of systemic disease. PCNSL accounts for approximately 4% to 7% of primary brain tumors, and its incidence has been increasing since the mid-1970s. Compared with other more common malignant primary brain tumors, PCNSL tends to be more amenable to radiotherapeutic and chemotherapeutic intervention. In this article, the authors review the standard treatment for upfront and recurrent PCNSL.     

Treatment of primary CNS lymphoma (PCNSL) following successful treatment of systemic non-Hodgkin’s lymphoma (NHL): a case series

Management of PCNSL occurring after successful treatment of systemic non-Hodgkin’s lymphoma (NHL) is poorly defined. Illustrate a treatment approach for PCNSL following prior treatment of a systemic NHL. A retrospective case series of 6 patients (mean age 60 years; range 46–65) diagnosed with a diffuse large B cell lymphoma of the CNS following prior successful treatment of a systemic NHL (low-grade in 2; high-grade in 4). Mean interval to diagnosis of PCNSL after diagnosis of systemic NHL was 12 months (range 7–18). In 4/6 patients in whom genetic analysis could be performed, the PCNSL and NHL differed. Treatment utilized high-dose methotrexate and rituximab (immunochemotherapy) followed in patients with a radiographic complete response by autologous peripheral stem cell transplant (ASCT) with total body irradiation (TBI) and multi-agent conditioning chemotherapy (BEAM: carmustine, etoposide, cytarabine, melphalan). 5/6 patients had a radiographic complete response to immunochemotherapy and were treated with ASCT. 4/5 patients were free of disease following ASCT with a mean follow-up of 3 years (range 0.5–4 years). There were no toxic deaths and all patients transplanted successfully engrafted within 28 days (mean 18). Using a treatment paradigm similar to that utilized for recurrent systemic NHL (induction chemotherapy followed by ASCT) for PCNSL occurring metachronously after successful treatment of systemic NHL appears safe and effective.     

The value of bone marrow biopsy for staging of patients with primary CNS lymphoma

BackgroundIn patients with presumed primary CNS lymphoma (PCNSL), a systemic manifestation is found only in a small minority. Although bone marrow biopsy (BMB) is recommended for staging, its diagnostic value is unclear.MethodsA retrospective analysis of 392 patients with presumed PCNSL from 3 university hospitals and 33 patients with secondary CNS lymphoma (SCNSL) and initial CNS involvement from a multicenter Germany-wide prospective registry was performed.ResultsA BMB was performed and documented in 320/392 patients with presumed PCNSL; 23 had pathologic results. One harbored the same lymphoma in the brain and bone marrow (BM), 22 showed findings in BM discordant to the histology of brain lymphoma; n = 12 harbored a low-grade lymphoma in the BM, the other showed B-cell proliferation but no proof of lymphoma (n = 5), monoclonal B cells (n = 3), or abnormalities not B-cell-associated (n = 2). In the group of SCNSL with initial CNS manifestation, 32/33 patients underwent BMB; 7 were documented with bone marrow involvement (BMI); 1 had concordant results in the brain and BM with no other systemic manifestation. Six had additional systemic lymphoma manifestations apart from the brain and BM.ConclusionsIn only 2 out of 352 (0.6%) patients with CNS lymphoma (320 presumed PCNSL and 32 SCNSL), BMB had an impact on diagnosis and treatment. While collected in a selected cohort, these findings challenge the value of BMB as part of routine staging in presumed PCNSL.     

Exploring the role of FDG-PET in the assessment of bone marrow involvement in lymphoma patients as interpreted by qualitative and semiquantitative disease metabolic activity parameter

Bone marrow biopsy (BMB) is currently the standard method to evaluate marrow involvement in malignant lymphomas. However, there exist a number of pitfalls in this technique that can have important implications for initial staging, prognostification, and treatment of the disease. The present study was undertaken to investigate the utility of FDG-PET imaging in the detection of bone marrow involvement in untreated lymphoma patients. Forty untreated patients (36 males and 12 females) with either Hodgkin's disease (HD) (n = 17) or non-Hodgkin's lymphoma (NHL) (n = 31) underwent whole body FDG-PET study for disease evaluation. Bone marrow uptake of FDG was graded as absence or presence of disease activity at marrow sites by qualitative assessment. Semiquantitative analysis involved deriving disease metabolic index (DMI) using the following formula: DMI = SUV max of suitable circular ROI over PSIS or trochanteric region/ SUVmax of similar ROI over adjoining background. Findings of BMB and FDG-PET were compared for final analysis. Eleven out of 17 HD patients (12 males and 5 females) demonstrated concordance between FDG PET findings and BMB reports. Remaining 6 cases showed discordance of FDG-PET demonstrating presence of marrow involvement at marrow sites and uninvolved marrow on BMB. Twenty six of the 31 NHL cases (24 males and 7 females) demonstrated concordance between FDG PET findings and BMB reports. Remaining 5 cases showed discordance of FDG-PET demonstrating presence of marrow involvement at marrow sites and uninvolved marrow on BMB. All the BMB positive patients (2 of HD and 5 of NHL) demonstrated disease activity in bone marrow on FDG-PET study. All patients with absence of disease activity at marrow sites on FDG-PET scan (9 of HD and 21 of NHL) had histology proven uninvolved marrow. The quantitative assessment by DMI showed a mean of > 2.5 in HD and NHL patients at the PSIS region and the trochanteric region bilaterally in cases of bone marrow involvement by the disease. FDG-PET is a useful adjuvant to BMB for the evaluation of bone marrow involvement in lymphoma patients. The disease metabolic index of > 2.5 at the marrow sites can serve as a semiquantitative parameter for such diagnosis on FDG-PET in untreated patients of lymphoma.     

Comparison of (18)F Flurodeoxyglucose PET with Ga-67 scintigraphy and conventional imaging modalities in pediatric lymphoma

Flurodeoxyglucose PET (FDG PET) is very useful for staging and restaging adult lymphomas. Its effectiveness in childhood lymphomas is less established. To evaluate the potential utility of FDG PET in the care of pediatric patients with lymphomas, we examined the clinical data and imaging findings of 26 patients, 8 - 19 years of age (14 HD, 12 NHL) who underwent 55 FDG PET studies. Results were compared with CT/MRI and gallium scans. FDG PET provided incremental, clinically important information in 21% of HD cases and 33% of NHL cases. It was especially useful in distinguishing scar tissue from residual disease at the end of therapy. In both HD and NHL, FDG PET had higher sensitivity (94%, 90%) and specificity (100%, 88%) than CT/MRI and gallium scanning. These results indicate that FDG PET is useful in the management of pediatric lymphomas.     

Treatment of primary central nervous system lymphoma

Primary central nervous system lymphoma (PCNSL) is a rare neoplasm that has captured popular attention because of its rising incidence and marked chemosensitivity. It is a non-Hodgkins B-cell lymphoma (NHL) that appears confined to the central nervous system (CNS) at presentation but may be multifocal within the brain or involve the leptomeninges or eyes at diagnosis. Like systemic lymphoma, it is highly sensitive to corticosteroids, and administration of steroids should be withheld until the diagnosis has been confirmed histologically. Currently, the initial treatment of choice incorporates high-dose methotrexate (HD-MTX) either as a single agent or in combination with other systemic chemotherapies. Whole-brain radiotherapy (WBRT) can be a highly effective treatment modality when combined with MTX, but the combination causes an unacceptably high incidence of severe permanent neurotoxicity, particularly in patients over age 60. Therefore, chemotherapy alone is the initial treatment of choice in older patients. This approach is also being explored in younger patients, but it is possible that deferring radiotherapy may compromise disease control. Consequently, the role of radiotherapy remains to be clarified in newly diagnosed younger patients with PCNSL.     

High SUV uptake on FDG–PET/CT predicts for an aggressive B-cell lymphoma in a prospective study of primary FDG–PET/CT staging in lymphoma

BackgroundData assessing the role of positron emission tomography (PET)/computed tomography (CT) imaging in lymphoma staging is still being accumulated and current staging is based primarily on CT. This study aims to compare the value of PET/CT over conventional CT and bone marrow biopsy (BMB) in the initial evaluation of patients with lymphoma.MethodsData on 122 patients with PET/CT scans as part of their initial staging were prospectively collected and reviewed. All patients had complete staging, including BMB.ResultsAmong the 122 patients, 101 had non-Hodgkin's lymphoma (NHL) and 21 had Hodgkin's lymphoma (HL). Compared with conventional CT, PET/CT upstaged 21 (17%) cases [B-cell non-Hodgkin's lymphoma (B-NHL), 12; T-cell non-Hodgkin's lymphoma (T-NHL), 3; HL, 6]. Of significance, in 13 patients with 2-[fluorine-18]fluoro-2-deoxy-D-glucose (FDG)-avid splenic lesions, four had normal CT findings. A maximum FDG uptake of >10 standardized uptake value (SUV) seems to significantly correlate with an aggressive B-cell lineage (odds ratio 2.47, 95% confidence interval 2.23–2.70). Overall, PET scan was concordant with BMB results in 108 (89%) and discordant in 14 (11%) cases. In HL, our data show that PET scan and marrow results agreed in 19 of the cases (90%), being concordantly negative in 18 cases and concordantly positive in one, giving a negative predictive value (NPV) of 100%, sensitivity of 100% and specificity of 90%. Of note, all 13 with early-stage HL had negative PET/CT scan and BMB. In NHL, all 17 cases of T-NHL had concordant PET and BMB results. In patients with aggressive B-NHL, BMB and PET/CT agreed in 58 patients (92%) and disagreed in five (8%), while the corresponding rates in indolent B-cell lymphoma were 14 (67%) and seven patients (33%), respectively. All seven were falsely negative.ConclusionsPET/CT upstages 17% of cases and detects occult splenic involvement. This may have potential therapeutic and prognostic implications. SUV >10 may predict for an aggressive histology. Except for indolent B-NHL, our data show that PET scans have a good overall NPV in excluding lymphomatous bone marrow involvement. This is particularly true of early-stage HL, suggesting that BMB may be safely omitted in this group.     

Positron emission tomography (PET) with 18F-fluorodeoxyglucose (18F-FDG) for the staging of low-grade non-Hodgkin's lymphoma (NHL).

Background:Although PET has been shown to be highlysensitive in the primary staging of lymphoma, previous studies withsmall numbers of patients indicated that low-grade NHL may not always beadequately detected by PET. We undertook this study to determine factorsinfluencing the detection of lesions by PET in low-grade NHL and toevaluate the utility of PET in this indication. Patients and methods:Forty-two patients underwentconventional staging procedures (clinical examination,oto-rhino-laryngologic examination, computed tomography of the chest,abdomen and pelvis, gastroscopy and bone marrow biopsy as well aswhole-body non-attenuation corrected ¹⁸F-FDG-PET. Results:PET detected 40% more abnormal lymph nodeareas than conventional staging in follicular lymphoma but wasinappropriate for the staging of small lymphocytic lymphoma where itdetected less than 58% of abnormal lymph node areas. PET showedmore lesions than conventional staging for peripheral (34% morelymph node areas detected) and thoracic lymph node (39% more)areas but not for abdominal or pelvic lymph nodes (26% fewerareas detected). The sensitivity to detect bone marrow infiltration wasunacceptably low for PET. In contrast, PET was as effective as standardprocedures for the detection of other extranodal localizations, althougha few localizations were detected only by PET and a few others only byconventional procedures. Conclusions:PET may contribute to the management ofpatients with low-grade follicular NHL. For the other low-grade lymphomasubtypes, the role of PET is less evident. Further studies using PET toevaluate the results of treatment or to diagnose disease recurrence arewarranted in low-grade follicular NHL.     

Impact of [18f] fluorodeoxyglucose positron emission tomography on staging and management of early-stage follicular non-hodgkin lymphoma

PURPOSE: Accurate staging is critical to select patients with early-stage (I-II) follicular lymphoma (ESFL) suitable for involved-field radiotherapy (IFRT) and to define the radiotherapy portal. We evaluated the impact of fluorodeoxyglucose (FDG) PET on staging, treatment, and outcome for patients with ESFL on conventional staging. METHODS AND MATERIALS: Forty-two patients with untreated ESFL (World Health Organization Grade I-IIIa, or "low grade") following a minimum of physical examination, computerized tomography, and bone marrow examination (conventional assessment) and who had staging PET from June 1997 to June 2006 were studied retrospectively. Stage allocation was based on routine imaging reports. Disease sites, stage, and management plan were recorded based on conventional assessment or conventional assessment plus PET. RESULTS: FDG avidity was demonstrated in 97% of patients in whom disease was evident on conventional assessment after biopsy. PET findings suggested a change of stage or management in 19 patients: 13 (31%) who were upstaged to Stage III-IV, altering ideal management from IFRT to systemic therapy, and 6 (14%) who had the involved field enlarged, including 4 upstaged from Stage I to II. Of these 19 cases, PET findings were considered true positive in 8 patients, indeterminate in 10, and false positive in only 1 patient. CONCLUSIONS: Our data confirm that ESFL is usually FDG-avid. In routine practice, PET has the potential to upstage and thereby alter management in a high proportion of patients with apparent ESFL.     

Positron emission tomography (PET) for staging low-grade non-Hodgkin's lymphomas (NHL)

Although positron emission tomography (PET) imaging is now recognized as a useful tool for staging intermediate and high-grade non-Hodgkin's lymphoma (NHL), few data are available regarding its accuracy in low grade NHL. We therefore studied 36 patients with histologically proven low-grade NHL. Whole-body 2-(fluorine-18) fluoro-2-deoxy-D-glucose (FDG) PET was performed at the time of initial diagnosis (n = 21) or for disease recurrence (n = 15) prior to any treatment. PET results were compared to those of physical examination and computed tomography (CT). PET studies were read without knowledge of any clinical data. Any focus of increased activity was described and given a probability of malignancy using a 5 point-scale (0: normal to 4: definitively malignant). An individual biopsy was available for a total of 31 lesions. The sensitivity and specificity were 87% and 100% for FDG-PET, 100% and 100% for physical examination and 90% and 100% for CT respectively. In addition, 42 of 97 peripheral lymph node lesions observed by FDG-PET were clinically undetected, whereas the physical examination detected 23 additional nodal lesions. PET and CT both indicated 12 extranodal lymphomatous localizations. FDG-PET showed 7 additional extranodal lesions while 5 additional unconfirmed lesions were observed on CT. Regarding bone marrow infiltration, PET and biopsy were concordant in 24 patients with 11 true positive (TP) and 13 true negative (TN). However PET was FN in 11 patients and no biopsy was performed in one patient. The combination PET/CT/physical examination seems to be more sensitive than the conventional approach for staging low grade NHL. Its sensitivity however is unacceptably low for diagnosing bone marrow infiltration.     

Prevention of recurrence and prolonged survival in primary central nervous system lymphoma (PCNSL) patients treated with adjuvant high-dose methylprednisolone

Five patients at risk for primary central nervous system lymphoma (PCNSL) recurrence were treated with high-dose methylprednisolone (HDMP) to prevent 'trafficking' of malignant lymphocytes into the central nervous system (CNS). HDMP was chosen because of its ability to stabilize the 'blood brain barrier (BBB)'. Three men with newly diagnosed PCNSL, ages 62, 76 and 78y, whose survival was projected to be 6.6 months, began treatment after achieving complete response (CR) to initial radiation therapy alone and survived 27, 37 and 59 months after treatment. In none was death from recurrent disease in CNS but one patient did die of systemic non-Hodgkin's lymphoma (NHL) five years after PCNSL diagnosis. A 20 y old man was treated with HDMP after successful combined modality therapy and is alive 75+ months after initial diagnosis without evidence of disease recurrence. A 34 y old man relapsed after combined modality initial treatment and failed to respond to HDMP when treatment was begun after unsuccessful salvage therapy; he died of disease 12 months after initial diagnosis. There were no treatment complications. The promising results in this pilot study from the basis for a North Central Cancer Treatment Group (NCCTG) 96-73-51, a Phase 2 clinical trial of brain radiotherapy and HDMP for PCNSL patients 70y of age and older, a group of patients at high risk for toxicity from intensive combined modality therapy.     

PET scans in the staging of lymphoma: current status

Positron emission tomography (PET) is a novel functional imaging technique that provides several inherent advantages over conventional nuclear scintigraphy. Several studies have suggested a role for PET using the positron emitter fluorine-18 in the diagnosis and follow-up of patients with lymphoma. This review summarizes the existing data evaluating the role of 2-fluoro-2-deoxy-D-glucose (FDG)-PET in both the staging and follow-up of patients with lymphoma. Most studies of PET involve patients with either Hodgkin's disease or diffuse large B-cell non-Hodgkin's lymphoma. PET detects more disease sites above and below the diaphragm on staging of lymphoma than gallium scintigraphy and may have particular utility in the evaluation of the spleen. Moreover, persistently positive PET scans during and after chemotherapy appear to have a high sensitivity for predicting subsequent relapse. A negative PET scan at the end of therapy provides very favorable prognostic information. Persistently positive PET scans at the end of therapy warrant close follow-up or additional diagnostic procedures, since some of those patients may remain in prolonged remission. Clearly, additional studies, including prospective blinded trials and cost-effectiveness analyses, are warranted to determine which subsets of patients with lymphoma ultimately will benefit from this modality.     

Treatment of CNS dissemination in systemic lymphoma

Summary The frequency of central nervous system (CNS) dissemination in non-Hodgkin’s lymphoma (NHL) varies and is dependent on NHL histology. More than 50% of patients with CNS involvement have advanced and progressive systemic disease. While CNS involvement at initial diagnosis may be treated curatively, treatment of CNS involvement in systemic relapsing or refractory lymphoma is challenging and most often palliative. Due to a paucity of randomized trials, treatment of lymphomatous metastases is not standardized. Nonetheless, treatment of LM entails administration of both CNS-directed and systemic chemotherapy that often includes high-dose chemotherapy regimens with stem cell support. Gleissner and Chamberlain contributed equally.     

Positron emission tomography in non-Hodgkin's lymphoma (NHL): relationship between tracer uptake and pathological findings,including preliminary experience in the staging of low-grade NHL

Advances in imaging techniques have allowed more precise staging and better evaluation of the effect of new treatment modalities. The limitations of conventional morphologic imaging techniques are well known. Positron emission tomography (PET) using fluorine-18-labeled fluorodeoxyglucose is now routinely used for initial staging and re-evaluation during or after treatment of Hodgkin's disease and aggressive non-Hodgkin's lymphoma (NHL), but not in low-grade NHL. In the first part of this review, the relationship between glucose metabolism as measured by PET, pathological findings including histological grade and proliferative activity, and prognosis are analyzed. In the second part, the potential role of PET in the staging and follow-up of low-grade NHL is discussed. Published data indicate that PET may contribute to the management of low-grade follicular NHL.     

Is CT scan still necessary for staging in Hodgkin and non-Hodgkin lymphoma patients in the PET/CT era?

BACKGROUND: The clinical impact of fused PET/CT data on staging and patient management of Hodgkin disease (HD) and non-Hodgkin lymphoma (NHL) was assessed. PATIENTS AND METHODS: A total of 103 consecutive patients with newly diagnosed NHL (n = 68) and HD (n = 35) were assessed retrospectively. Three comparisons were carried out in an attempt to assess the added value of each modality. RESULTS: For NHL patients, there were significant differences between staging by CT versus PET/CT (P = 0.0001). Disease was upstaged by PET/CT in 31% (mostly in stages I and II) and downstaged in only 1% of patients. In 25% of the patients, the treatment approach was changed according to CT versus PET/CT findings. For HD patients, disease was upstaged by PET/CT in 32% and downstaged by PET/CT in 15% (P = NS). As for NHL, upstaging by PET/CT versus CT was evident mostly for stages I and II. The treatment strategy was altered as determined by CT versus PET/CT in 45% of the patients. CONCLUSIONS: The addition of PET/CT to CT changed the management decisions in approximately a quarter of NHL and a third of HD patients, mostly in early disease stages. Thus, PET/CT performed as the initial staging procedure may well obviate the need for additional diagnostic CT in the majority of patients.     

Diagnosis and treatment of central nervous system involvement in non-Hodgkin's lymphoma

The diagnosis of lymphoma of the central nervous system (CNS) has been facilitated by advances in neuroimaging and laboratory analysis of cerebrospinal fluid. The most common form of central nervous system CNS involvement in non-Hodgkin's lymphoma (NHL) is leptomeningeal disease. After a diagnosis is established, the use of intrathecal or systemic chemotherapy and radiotherapy can improve survival and palliate symptoms. High-dose systemic chemotherapy with hematopoietic stem cell transplantation is an important treatment option at central nervous system relapse of NHL and for primary CNS lymphoma. The prognosis for disease-free survival and cure is better for patients who have treatment of CNS disease before transplantation than for patients who have active central nervous system disease at the time of transplant.     

The value of [18F]fluoro-2-deoxy-D-glucose positron emission tomography in the selection of patients with stage IIIA-N2 non-small cell lung cancer for combined modality treatment

Combined modality treatment (CMT) for patients with stage IIIA-N2 non-small cell lung cancer (NSCLC) is at present studied extensively. To select patients with truly stage IIIA-N2 disease, however, proves to be difficult with current diagnostic tests. Distant metastases may become clinically overt during induction chemotherapy (IC) or shortly after, revealing the inaccuracies of current staging algorithms. A prospective study with [18F]fluoro-2-deoxy-D-glucose positron emission tomography (FDG PET) in IIIA-N2 NSCLC patients was performed to assess its value in the selection of this patient group. Fifty-seven patients received a whole body FDG PET scan as part of an ongoing response monitoring trial. Results were compared with conventional staging. In 32/57 (56%) PET suggested upstaging, which was confirmed in 17/57 (30%) with a median follow-up of 16 (range 2-49) months. These results show that using the conventional staging algorithm a substantial group of patients was understaged. FDG PET improves the selection of patients suitable for CMT.