Prognostic value of primary tumor and lymph node volumetric metabolic parameters at pre-treatment F-18 FDG PET/CT in nasopharyngeal carcinoma

BACKGROUND

The aim of this study was to evaluate the prognostic significance of volumetric metabolic parameters of pre-treatment PET/CT along with clinical characteristics in patients with non-metastatic nasopharyngeal carcinoma.

MATERIAL AND METHODS

Seventy-nine patients with nasopharyngeal carcinoma underwent F18- FDG PET/CT for pretreatment evaluation and included in this study. The patient features (patient age, tumor histopathology, T and N stage, size of primary tumor and the largest cervical lymph node) and PET parameters were analyzed: maximum, mean and peak standardized uptake values (SUVmax, SUVmean, SUVpeak), metabolic tumor volume (MTV), and total lesion glycolysis (TLG) for primary tumor and largest cervical lymph node. After treatment, patients were evaluated for disease progression and mortality. Survival analysis for progression-free survival (PFS) and over-all survival (OS) was performed with Kaplan-Meier method using PET findings and clinical characteristics.

RESULTS

The median follow-up duration was 29.7 months (range 3-125 months). Among clinical characteristics, no parameters had significance association for PFS. Primary tumor-MTV and cervical lymph node-MTV were independent prognostic factors for PFS (p = 0.025 and p = 0.004, respectively).Patients with primary tumor-MTV >19.4 and patients with lymph node-MTV>3.4 had shorter PFS. For OS, age and the size of the lymph node were independent prognostic factor (p = 0.031 and p = 0.029).Patients with age over 54 years and patients with lymph node size >1 cm were associated with decreased OS.

CONCLUSION

Primary tumor-MTV and lymph node-MTV on pre-treatment PET/CT are significant prognostic factors for long-term PFS in non-metastatic nasopharyngeal carcinoma. We consider that measuring MTV as volume-based metabolic parameter on pretreatment PET/CT may contribute decision of treatment intensity and individualized risk stratification and may improve long-term PFS. Additionally, age and the size of lymph node are independent prognostic factors for mortality.

The prognostic role of PET/CT in small-cell lung cancer

OBJECTIVE

The aim in the present study is to determine the prognostic value of metabolic parameters related to the primary tumors detected in pretreatment Fluorine-18 2-fluoro-2-Deoxy-D-glucose (¹⁸F FDG) positron emission tomography/computerized tomography (PET/CT) scans of patients diagnosed with small-cell lung cancer (SCLC).

MATERIAL AND METHODS

Enrolled in this retrospective study were 63 patients with a histopathologically confirmed diagnosis of SCLC who underwent an ¹⁸F FDG PET/CT scan at baseline. Disease stage, age at diagnosis, gender, albumin level and maximum standardized uptake value (SUVmax), SUVmean, metabolic tumor volume (MTV) and total lesion glycolysis (TLG) values related to the primary tumor at the baseline PET scan were recorded, and the relationship of these factors with progression-free survival (PFS) and overall survival (OS) was evaluated.

RESULTS

The study included a total of 63 patients (10 female, 53 male, mean age of 64.8 and age range of 43-82 years), 22 of which had limited disease (LD) and 41 had extensive disease (ED). The OS and PFS were significantly higher in patients with LD than in patients with ED (15±2.9 vs. 10±0.9 months, p = 0.002 for OS; 10± 0.7 vs 6±0.6 months, p = 0.014 for PFS). However, no statistically significant relationship was identified between gender, albumin level, age and SUVmax, SUVmean, MTV, TLG values related to the primary tumor and PFS or OS.

CONCLUSION

The present study found that pretreatment PET parameters were of not predictive value for PFS and OS in patients with SCLC.

Volumetric PET parameters can predict overall survival in advanced lung adenocarcinoma

OBJECTIVE

The present study evaluates the prognostic value of metabolic parameters related to the primary tumor on pretreatment ¹⁸F FDG PET/CT in patients with advanced stage lung adenocarcinoma.

MATERIAL AND METHODS

This retrospective study included 258 patients with advanced stage lung adenocarcinoma who underwent pretreatment PET/CT scan, and for whom epidermal growth factor receptor (EGFR)/anaplastic lymphoma kinase (ALK) status was available. The maximum standardized uptake value (SUVmax), SUVmean, metabolic tumor volume (MTV) and total lesion glycolysis (TLG) related to the primary tumor at the baseline PET and various clinical factors were recorded. The relation between these factors and overall survival (OS) and progression-free survival (PFS) was evaluated.

RESULTS

The study included 258 patients with stage IIIB-IV lung adenocarcinoma (72 female, 186 male, mean age 60.4±10.4 years), 210 of which died and 243 of which progressed at the time of analysis. The median OS and PFS of the patients were 16±1.9 and 5±0.5 months, respectively. The present study revealed no significant relation between OS or PFS and gender, smoking status, presence of distant metastasis, age and tumor size. There was no significant difference in the OS and PFS of patients testing negative for EGFR mutations/ALK rearrangements and those testing positive for both or either of the EGFR mutations and ALK rearrangements. OS was significantly longer in patients with low MTV(p=0.011) and those with low TLG(p=0.012) than high ones. However, no significant relation was found between SUVmax and SUVmean values and OS, and between all PET parameters and PFS.

CONCLUSION

MTV and TLG reflecting the metabolic tumor burden can predict OS in patients with advanced lung adenocarcinoma.

Role of 18F-FDG PET/CT in the detection of primary malignancy in patients with bone metastasis of unknown origin

OBJECTIVE

The present study investigates the role of ¹⁸F-FDG PET/CT in the detection of primary malignancy in patients with bone metastasis of unknown primary origin (BMUO).

MATERIAL AND METHODS

This retrospective study considered histopathological examination findings or clinical follow-up data as the standard reference in the diagnosis of primary tumors, and results were compared with results of PET/CT scans.

RESULTS

The study included 100 patients with BMUO (74 males, 26 females, mean age 61 years). The primary origin was identified in 92 of the 100 patients. Adenocarcinoma was the most common histopathological subtype in patients in whom the primary origin of tumor was detected (65.2%). The most common primary tumor was lung carcinoma (n=52) followed by prostate (n=13), breast (n=7), colon (n=4), gastric (n=3), ovarian (n=2), renal cell (n=2), adrenal (n=1), thyroid (n=1), endometrial (n=1) and parotid (n=1) carcinoma, hepatobiliary cancers (n=2), leiomyosarcoma (n=2) and maxillary sinus tumor (n=1). The numbers of patients in whom PET/CT showed true positive, true negative, false positive (FP) and false negative (FN) results were 72, 7, 8 and 13, respectively. The sensitivity, specificity, accuracy and detection rate of PET/CT in detecting the primary tumor were 84.7%, 46%, 79% and 72%, respectively. The overall survival was significantly lower in lung cancer group when compared to non-lung cancer group, whereas it was significantly higher in prostate cancer group than in non-prostate cancer group.

CONCLUSIONS

PET/CT, as a non-invasive method, can be preferred as the first choice in the detection of primary tumor in patients with BMUO.

Is there any improvement in clinical staging with 18F-FDG PET/CT compared to surgical staging in cases of lung cancer?

OBJECTIVE

¹⁸F-Fluorine fluorodeoxyglucose positron emission tomography/computed tomography (¹⁸F-FDG PET/CT) imaging is considered the standard imaging modality for patients with non-small cell lung carcinoma. The aim of this study was to compare clinical staging (cTNM) performed with ¹⁸F-FDG PET/CT and surgical staging (sTNM) in patients with non-small cell carcinoma treated with surgery.

MATERIAL AND METHODS

We performed a retrospective analysis of 99 surgical patients with non-small cell carcinoma who underwent ¹⁸F-FDG PET/CT examination. Semiquantitative measures were calculated from the primary lesions and mediastinal lymph nodes. Findings of cTNM were compared with final surgical-pathological evaluation. Subjects were divided into two groups as postsurgical cTNM changed and cTNM unchanged. Patients in the cTNM changed group were further classified as postsurgical upstaged (US) and downstaged (DS). Results of the US patients were compared with the results of the remaining patients consisting of cTNM unchanged and DS to evaluate the predictable roles of semiquantitative parameters for postsurgical upstaging. To determine mediastinal tumoral involvement, cut-off values were obtained from calculated semiquantitative results of FDG uptakes in lymph nodes. A p value<0.05 was considered statistically significant.

RESULTS

Subjects were aged 40-82 years with a mean age of 64.78±8.70 years. Classification agreement was observed in 43 patients (43%) and in 57%, postsurgical stage migration was seen. Concurrence of cTNM and sTNM was more pronounced in the T1 and N0 subsets which were 84% and 74%, respectively. The lowest concurrence was observed in N1 classification followed by T4 and N2 (1%, 50% and 58%, respectively). Change in T staging occurred in 20 of 56 (36%), in N staging 22 of 56 (39%) and change in T and N in 14 patients (25%). Distribution of US and DS patients in the cTNM changed group was 43% (24 of 56) and 57% (32 of 56), respectively. Results of semiquantitative measures were significantly higher in US patients than the results of the group consisting of DS patients and cTNM unchanged patients, for all parameters. Cut-off value calculated from mediastinal uptakes was most specific for metastases in MTV (metabolic tumor volume) with an acceptable sensitivity (90% and 67%, respectively).

CONCLUSIONS

The concordance between cTNM and sTNM was better in staging T category compared to N stations. Semiquantitative measures of primary tumor may play a role in predicting postsurgical upstaging. Taking MTV into consideration in the mediastinal region may be more valuable than other parameters in the assessment of nodal involvement.

Role of 18F-FDG PET/CT in establishing new clinical and therapeutic modalities in lung cancer. A short review

Lung cancer is a fairly common malignancy. An early diagnosis and a reliable staging and re-staging with the aim to detect both local and distant relapse are of utmost importance in planning the therapeutic management. The imaging diagnostic work-up of patients with lung cancer usually includes conventional imaging (chest X-ray, contrast-enhanced CT, bone scan) and more recently ¹⁸F-FDG PET/CT. Great advances in the management of lung cancer are based on the information provided by ¹⁸F-FDG PET/CT, as it supplies both metabolic and anatomic information (better localisation). There is vast evidence in the literature demonstrating its utility in (a) characterising benign versus malignant solitary nodules, (b) staging and re-staging lung cancer, (c) guiding the type of therapy, (d) monitoring treatment response and (e) predicting outcome. In particular, given its specificity in differentiating ¹⁸F-FDG-avid relapse from post-surgical changes or post-radiation fibrosis (which do not take up ¹⁸F-FDG), PET/CT can detect recurrent disease after initial treatment and (being a whole-body technique) has demonstrated high accuracy in the detection of distant metastases or secondary tumours. In conclusion, ¹⁸F-FDG PET/CT can be considered a highly accurate and reliable method for staging and re-staging lung cancer, and is highly effective in guiding personalised therapies.

Use of semiquantitative analysis in local recurrence of colorectal carcinoma with 18F-FDG PET/CT: A myth or a truth?

OBJECTIVE

Recurrence of colorectal cancer is mostly seen within the first 2 years after surgery. The most frequent site of recurrence is the postsurgical areas and its surroundings. The purpose of this study was to evaluate the usefulness of semiquantitative analysis of ¹⁸Fluorine fluorodeoxyglucose (FDG) positron emission tomography/computed tomography (PET/CT) in determining recurrence of colorectal carcinoma in the operation site.

MATERIAL AND METHODS

Files of 35 patients with colorectal carcinoma (25 men, 10 women, mean age: 59.25±2.82 years, range: 27-80 years) who were treated with surgery and underwent FDG PET/CT scanning for restaging of colorectal carcinoma and showing increased FDG uptake in the postsurgical area, were retrospectively analysed. Besides calculating SUVmax of the areas showing FDG uptake, SUVmax of physiological colonic activity was also obtained and SUVmax of lesion/SUVmax of colonic wall (RSUVmax), was calculated. Characteristics of FDG uptake were classified according to histological analysis or clinical and imaging follow-up.

RESULTS

In 17 of 35 patients (49%) the standard of reference for the final diagnosis was histologic analysis and in 18 (51%), final diagnosis was based on imaging and clinical follow-up. In 15 of 35 patients (43%) the etiology of increased FDG uptake was recurrence and in 20 (57%), FDG accumulation was observed due to benign etiology. The difference between the mean of the results of SUVmax in patients with recurrent disease and with no evidence of recurrence was statistically significant (P=.030). For SUVmax, a cut-off value for recurrence was calculated as 9.51 with a sensitivity of 80% and a specificity of 70%. In terms of RSUVmax results, a statistically significant difference was also observed between mean values in patients with recurrent disease and in those without (P=.002). ROC analysis demonstrated that the best predictive value of RSUVmax for recurrence was 1.75 with a sensitivity of 67% and specificity of 95%.

CONCLUSIONS

Semiquantitative analysis of FDG PET/CT may be used in detecting recurrent disease of patients with colorectal carcinoma. Eliminating interfering physiological colonic activity in analysis may have an incremental effect on the success of this technique, by means of increasing the specificity.

An unusual presentation of primary hyperparathyroidism: multiple brown tumors and coexisting thyroid carcinoma

We present a patient with a complex clinical picture of primary hyperparathyroidism with multiple destructive skeletal lesions suspicious of bone metastases and concomitant multifocal papillary thyroid carcinoma with a metastatic central lymph node. He presented with progressively worsening right hip pain and restricted motion. Magnetic resonance imaging revealed multiple lytic lesions involving predominantly the right trochanter minor and the left inferior and posterior pubic rami. Biochemical tests were consistent with primary hyperparathyroidism. Neck ultrasound and parathyroid scintigraphy revealed a single parathyroid adenoma and a thyroid nodule, preoperative cytology of which confirmed papillary thyroid carcinoma, as did the final surgical specimen. Biochemical results, regarding hyperparathyroidism, declined to normal levels and his complaints gradually decreased after surgery. Postoperative whole body bone scintigraphy showed increased tracer uptakes at multiple sites, but they were proved to be metabolically inactive by fluorodeoxyglucose positron emission tomography/computed tomography.

Early detection of encephalitis with (18)F-FDG PET/CT

Encephalitis is a relatively rare condition for which making an accurate diagnosis can be challenging. In fact, clinical features are not specific and structural imaging can be normal in a considerable number of cases. However, an early diagnosis is important as many forms of treatment are effective if started promptly. Even though recent guidelines do not recommend (18)F-FDG PET/CT for patients with suspected encephalitis, the case presented suggests that (18)F-FDG PET/CT may play a relevant role for the early diagnosis of this clinical condition.

Impact of 18F-FDG PET/CT in the treatment of patients with non-small cell lung cancer

INTRODUCTION

Disease stage is the most important prognostic factor in lung cancer, and optimal staging is important to determine the best therapeutic option. FDG-PET/CT has demonstrated its value in early stage non-small cell lung cancer (NSCLC) but there is still insufficient data to define its role in other stages.

HYPOTHESIS

Information provided by FDG-PET/CT has an impact on the therapeutic management of patients with NSCLC.

METHODS

A retrospective review was made of patients who underwent FDG-PET/CT between January 2008 and December 2010 for the diagnosis of NSCLC. Clinical stage before and after FDG-PET/CT and information about any change in therapeutic decision due to information provided by FDG-PET/CT were collected. Using pathologic evaluation as the gold standard, sensitivity, specificity, and positive and negative predictive values for CT and FDG-PET/CT were calculated.

RESULTS

Of the 522 patients diagnosed of NSCLC, FDG-PET/CT was performed in 246 (47.1%). In 85 cases (34.6%) FDG-PET/CT led to stage migration. Treatment was modified in 60 patients (24.4% of all FDG-PET/CT performed), avoiding a futile thoracotomy in 13 cases (5.2%), and allowing treatment with curative intent in 26 (10.5%). Out of 90 patients (36.5%) evaluated as stage iii by CT staging, FDG-PET/CT modified the therapeutic approach in 36 (40%). For the 133 cases (54%) with pathological assessment of the mediastinal lymph nodes, sensitivity, specificity, positive predictive value and negative predictive value were 0.57, 0.64, 0.48 and 0.72 for CT, and 0.68, 0.86, 0.75 and 0.81 for FDG-PET/CT.

DISCUSSION

Our data support previous reports that FDG-PET/CT is essential in the staging process not only for patients with potentially operable NSCLC but also for stage iii patients, as demonstrated by our data.