Can FDG-PET be used to predict growth of stage I lung cancer?

Relationships between SUVmax of lung adenocarcinoma and different T stages, histological grades and pathological subtypes: a retrospective cohort study in China

OBJECTIVES

Cancer cell has aberrant metabolism. The purpose of this study aimed to investigate relationships between maximum standard uptake value (SUVmax）of ¹⁸fluoro-2-deoxy-d-glucose and T stages, histological grades and pathological subtypes of lung adenocarcinoma.

DESIGN

Retrospective cohort study, employing the Kruskal-Wallis, Bonferroni-Dunn and Mann-Whitney tests to compare SUVmax of different T stages, histological grades and pathological subtypes of lung adenocarcinoma.

SETTING

The outpatients who had aberrant positron emission tomography/CT (PET/CT) images in chest were enrolled this study from August 2016 to November 2018 in Shanghai, China.

PARTICIPANT

Initial 11 270 patients with suspected lung cancer who underwent PET/CT examinations were surveyed. A total of 1454 patients who were diagnosed as lung adenocarcinoma by pathologist were included in this project.

PRIMARY OUTCOME MEASURES

SUVmax value at different tumour-node-metastasis stages of lung adenocarcinoma before surgery.

RESULTS

The mean SUVmax of patients with lung adenocarcinoma was significantly elevated with the increase in T stages. There were significant evident differences in SUVmax among T1a-T1c (p<0.05). However, after the staging of patients was more than T1 stage, SUVmax of T2a, T2b, T2 visceral pleural invasion, T3 and T4 had not dramatic changes. SUVmax value of lung adenocarcinoma in the same T stage group was the highest in patients with the high grade of malignancy and solid-predominant invasive adenocarcinoma.

CONCLUSIONS

SUVmax value was significantly associated with T stages, grades of malignancy and pathological subtypes of lung adenocarcinoma.

Clinical correlates of circulating cell-free DNA tumor fraction

BACKGROUND

Oncology applications of cell-free DNA analysis are often limited by the amount of circulating tumor DNA and the fraction of cell-free DNA derived from tumor cells in a blood sample. This circulating tumor fraction varies widely between individuals and cancer types. Clinical factors that influence tumor fraction have not been completely elucidated.

METHODS AND FINDINGS

Circulating tumor fraction was determined for breast, lung, and colorectal cancer participant samples in the first substudy of the Circulating Cell-free Genome Atlas study (CCGA; NCT02889978; multi-cancer early detection test development) and was related to tumor and patient characteristics. Linear models were created to determine the influence of tumor size combined with mitotic or metabolic activity (as tumor mitotic volume or excessive lesion glycolysis, respectively), histologic type, histologic grade, and lymph node status on tumor fraction. For breast and lung cancer, tumor mitotic volume and excessive lesion glycolysis (primary lesion volume scaled by percentage positive for Ki-67 or PET standardized uptake value minus 1.0, respectively) were the only statistically significant covariates. For colorectal cancer, the surface area of tumors invading beyond the subserosa was the only significant covariate. The models were validated with cases from the second CCGA substudy and show that these clinical correlates of circulating tumor fraction can predict and explain the performance of a multi-cancer early detection test.

CONCLUSIONS

Prognostic clinical variables, including mitotic or metabolic activity and depth of invasion, were identified as correlates of circulating tumor DNA by linear models that relate clinical covariates to tumor fraction. The identified correlates indicate that faster growing tumors have higher tumor fractions. Early cancer detection from assays that analyze cell-free DNA is determined by circulating tumor fraction. Results support that early detection is particularly sensitive for faster growing, aggressive tumors with high mortality, many of which have no available screening today.

PET standardized uptake values of primary lung cancer for comparison with tumor volume doubling times

OBJECTIVE

To determine the relationship between two documented indicators of tumor aggressiveness, SUV and volume doubling time (VDT) for stage I non-small cell lung cancer (NSCLC).

METHODS

116 pathology proven solid NSCLC patients with 2 pretreatment CT and 1 PET/CT scan were retrospectively identified. The 2 CT scans were at least 85 days apart. SUV values were collected from PET/CT reports and CT derived VDT's were calculated assuming an exponential growth rate. Corrected SUV values were also obtained for all cases. Median VDT, SUV and corrected SUV values were reported according to cancer histology. Relationships between VDT, SUV and corrected SUV were examined.

RESULTS

91 Adenocarcinomas and 25 squamous-cell carcinomas had median VDT values of 150.6 and 110.0 days respectively. Median SUV values were 5.1 and 12.3 for adenocarcinoma and squamous-cell carcinoma, respectively (p = 0.0003); median corrected SUV values were 16.8 and 31.7 respectively (p = 0.003). A statistically significant monotonic relationship was observed between increased SUV uptake and faster VDT (p = 0.05) and corrected SUV and VDT (P = 0.0002). When stratified by cancer histology, the relationship between VDT and either SUV or corrected SUV was statistically significant for adenocarcinomas (p = 0.02 and p = 0.0001, respectively), but not for squamous-cell carcinoma (p = 0.85 and p = 0.37, respectively).

CONCLUSION

We demonstrated an overall significant relationship between VDT, SUV and corrected SUV. The relationship, however, was stronger for adenocarcinomas than for squamous-cell carcinomas. This implies that the primary determinant for these relationships is histology and within each cell type, there are other factors that have strong influences.

Relationship between primary lesion metabolic parameters and clinical stage in lung cancer

OBJECTIVES

The relation of PET-derived parameters as maximum standardized uptake value (SUVmax), total lesion glycolysis (TLG), metabolic tumor volume (MTV) with clinical stage in lung cancer and correlation of SUVmax of primary tumor and that of metastatic lesion was studied in lung cancer patients.

MATERIALS AND METHODS

Patients with lung cancer who were referred for FDG PET/CT were included in the study.

RESULTS

PET/CT scans and pathology reports of 168 patients were assessed. A total of 146 (86.9%) of these patients had a diagnosis of non-small cell lung cancer (NSCLC) and 22 (13.1%) had small cell lung cancer (SCLC). Metabolic parameters such as SUVmax, TLG and MTV showed significant differences in all the stages in NSCLC patients (p<0.001). However, after tumors sizes <25 mm were excluded, no significant differences in SUVmax between stages were observed. No significant differences were found between these metabolic parameters and limited or extended disease SCLC. Tumor diameter correlated with primary tumor SUVmax and significant correlations between primary lesion SUVmax and metastatic lesion SUVmax were found.

CONCLUSIONS

Although differences were found regarding indices between stages of NSCLC cases, SUVmax differences between stages seem to be caused by underestimation of SUVmax in small lesions. Other glucose metabolism indexes such as MTV and TLG show promising results in terms of prognostic stratification. Future studies are needed for better understanding of their contribution to clinical cases.

Guidelines for the role of FDG-PET/CT in lung cancer management

Fluoro-2-deoxy-d-glucose (FDG)-positron emission tomography (PET) and PET/computed tomography (FDG-PET/CT) is regarded as a standard of care in the management of non-small-cell lung carcinoma (NSCLC) and is a useful adjunct in the characterization of indeterminate solitary lung nodules (SLN), and pre-treatment staging of NSCLC, notably mediastinal nodal staging and detection of remote metastases. FDG-PET/CT has the ability to assess locoregional lymph node spread more precisely than CT, to detect metastatic lesions that would have been missed on conventional imaging or are located in difficult areas, and to help in the differentiation of lesions that are equivocal after conventional imaging. Increasingly FDG-PET/CT is employed in radiotherapy planning, prediction of prognosis in terms of tumor response to neo-adjuvant, radiation and chemotherapy treatment. Evidence is accumulating of usefulness of PET/CT in small cell lung cancer.

Natural growth and disease progression of non-small cell lung cancer evaluated with 18F-fluorodeoxyglucose PET/CT

PURPOSE

The aims of this study were to: (1) estimate the volumetric and metabolic growth rate of non-small cell lung cancer (NSCLC), (2) evaluate disease progression prior to treatment, and (3) explore the effects of tumor growth rate and time to treatment (TTT) on survival outcome.

METHODS

Patients with inoperable stages I-III NSCLC with serial pre-treatment PET/CT scans were eligible for this study. PET-derived metabolic tumor volumes (PET-MTV) and CT-derived gross tumor volumes (CT-GTV) were contoured using PET/CT information. Normalized standardized uptake values (NSUV) in tumors including the NSUVmean and NSUVmax were measured. Tumor growth rates expressed as doubling time (DT) were estimated using an exponential model. Pre-treatment disease progression defined as the development of any new site of disease on PET/CT and change in TNM stage (AJCC 7th ed.) were recorded. Growth rate and tumor progression were analyzed with respect to overall (OS) and progression free survival (PFS).

RESULTS

Thirty-four patients with a median inter-scan interval (ISI) of 43 days and TTT of 48 days were analyzed. Tumor volumes showed remarkable inter-scan growth while NSUV did not increase significantly. The DT for PET-MTV, CT-GTV, NSUVmean and NSUVmax were 124, 139, 597, and 333 days, respectively. Pre-treatment disease progression occurred in 20.6% patients with longer ISI being a significant risk factor (OR=1.027, p=0.02). The optimal threshold ISI to predict progression was 58 days (4.8% vs. 46.2%, p=0.007). Neither tumor growth rates nor TTT were significantly correlated to OS or PFS.

CONCLUSIONS

NSCLC displays rapid tumor volume growth whereas NSUVmean and NSUVmax are relatively stable over the same time period. Longer delays before initiation of treatment are associated with higher risk of pre-treatment disease progression.

Standard uptake value of positron emission tomography in clinical stage I lung cancer: clinical application and pathological correlation

OBJECTIVES

The aim of this study was to assess the standard uptake value in clinical stage I non-small cell lung cancer (NSCLC) and its correlation with pathological status and prognosis.

METHODS

We retrospectively reviewed 674 patients diagnosed with NSCLC between January 2002 and June 2005. Patients with clinical stage I diseases undergone a preoperative positron emission tomography-computed tomography scan followed by anatomic resection. We reviewed the clinical features of 152 patients with an average follow-up of 87 months.

RESULTS

We analysed the clinical features of 108 patients with stage I NSCLC and 44 patients with non-stage I NSCLC. There were no statistical differences in age, histological type, location or tumour differentiation between the two groups. In the Stage I group, the patients had lower maximum standard uptake value (SUVmax; 3.80 ± 3.17 vs 5.73 ± 3.65, P = 0.001), lower carcinoembryonic antigen (CEA) levels (2.86 ± 4.80 vs 9.11 ± 17.21 ng/ml, P = 0.027) and smaller tumour size (2.39 ± 0.98 vs 3.73 ± 2.04 cm, P < 0.001). The patients with higher SUVmax had a more advanced pathological stage, poorer tumour differentiation and larger tumour size. A higher SUVmax was an independent factor predicting an advanced pathological stage (SUVmax ≥ 3.3, odds ratio 3.246). The median survival of patients with SUVmax ≥ 3.3 and SUVmax <3.3 were 64.32 and 53.08 months, respectively (P = 0.654).

CONCLUSIONS

Higher preoperative 18-fluorodeoxyglucose uptake by a tumour was significantly associated with an advanced pathological stage but not correlated with a poorer prognosis. An aggressive preoperative work-up for occult N2 disease should be emphasized, avoiding inappropriate thoracotomy.

Objective assessment of tumour response to therapy based on tumour growth kinetics

Background:

Current standards for assessment of tumour response to therapy (a) categorise therapeutic efficacy values, inappropriate for patient-specific and deterministic studies, (b) neglect the natural growth characteristics of tumours, (c) are based on tumour shrinkage, inappropriate for cytostatic therapies, and (d) do not accommodate integration of functional/biological means of therapeutic efficacy assessed with, for example, positron emission tomography or magnetic resonance imaging, with data from anatomical changes in tumour.

Methods:

A quantity for tumour response was formulated assuming that an effective treatment may decrease the cell proliferation rate (cytostatic) and/or increase the cell loss rate (cytotoxic) of the tumour. Tumour response values were analysed for 11 non-Hodgkin's lymphoma patients treated with ¹³¹I-labelled anti-B1 antibody and 12 prostate cancer patients treated with a nutritional supplement.

Results:

Tumour response was found to be equal to the logarithm of the ratio of post-treatment tumour volume to the volume of corresponding untreated tumour. Neglecting the natural growth characteristics of tumours results in underestimation of treatment effectiveness based on currently used methods. The model also facilitates the integration of data from tumour volume changes, with data from functional imaging.

Conclusion:

Tumour response to therapy can be assessed with a continuous dimensionless quantity for both cytotoxic and cytostatic treatments.

[What is the role of FDG-PET in thoracic oncology in 2010?]

18F-Fluorodeoxyglucose-Positron Emission Tomography (FGD-PET) has been considered to have a major impact on the management of lung malignancies since the beginning of this century. Its value has been demonstrated by many publications, meta-analysis and European/American/Japanese recommendations. PET combined with computed tomography has provided useful information regarding the diagnosis and staging of lung cancer and allows for the delivery of adaptive radiotherapy. In its more common uses, PET has been shown to be cost-effective. With the widespread use of new radiotracers, PET will play an increasing role in the evaluation of response to treatment.

18-Fluorodeoxyglucose positron emission tomography as a tool for response prediction in solid tumours

Current response guidelines for the treatment of solid tumours are based on CT criteria. Over the last decades new techniques have emerged to evaluate cancer therapy. FDG-PET scanning is a more functional imaging technique, which can measure differences in metabolic activity. Although it has a low specificity, studies show that it can outperform classical CT scanning criteria. Especially in lung, breast and oesophageal cancer it can predict response earlier in the neo-adjuvant setting. This could reduce the use of ineffective cancer therapies, reducing costs and patient toxicity, and direct patients sooner towards effective therapy. The main problem with FDG-PET remains the difficulty in defining thresholds for response, as there is clearly a lack in large prospective randomized studies validating the use of FDG-PET in response guidelines.We give an overview of data on response prediction in solid tumours by the application of PET.

18F-FDG PET and PET/CT in the evaluation of cancer treatment response

Multimodality imaging, as represented by its greatest exponent, PET/CT, has a firm place in the evaluation of a patient presenting with cancer. With 18F-FDG, PET/CT is rapidly becoming the key investigative tool for the staging and assessment of cancer recurrence. In the last 5 y, PET/CT has also gained widespread acceptance as a key tool used to demonstrate early response to intervention and therapy. In this setting, a major clinical need is being addressed with 18F-FDG PET/CT, because of its inherent ability to demonstrate (before other markers of response) if disease modification has occurred. This review presents available evidence to this effect.