eISSN: 1897-4309
ISSN: 1428-2526
Contemporary Oncology/Współczesna Onkologia
Current issue Archive Manuscripts accepted About the journal Supplements Addendum Special Issues Editorial board Reviewers Abstracting and indexing Subscription Contact Instructions for authors Publication charge Ethical standards and procedures
Editorial System
Submit your Manuscript
SCImago Journal & Country Rank
3/2021
vol. 25
 
Share:
Share:
Original paper

Prognostic significance of metabolic tumour volume and maximum standard uptake value of fluor-18-fluorodeoxyglucose positron emission tomography with computed tomography in nasopharyngeal carcinoma

Christopher John
1
,
Jeyaanth Venkatasai
1
,
Satish Srinivas Kondaveeti
1
,
Arunan Murali
2
,
Gokulakrishnan Periakaruppan
2
,
Venkatachalapathy E
3
,
Manickavasagam Meenakshisundaram
4
,
Ravi Chandran Ambalathandi
4
,
Hemavathi Masilamani
1

  1. Department of Radiation Oncology, Sri Ramachandra Institute of Higher Education and Research, Porur, Chennai, India
  2. Department of Radio-Diagnosis, Sri Ramachandra Institute of Higher Education and Research, Porur, Chennai, India
  3. Department of Nuclear Medicine, Sri Ramachandra Institute of Higher Education and Research, Porur, Chennai, India
  4. Department of Medical Oncology, Sri Ramachandra Institute of Higher Education and Research, Porur, Chennai, India
Contemp Oncol (Pozn) 2021; 25 (3): 153–159
Online publish date: 2021/10/01
Article file
Get citation
 
PlumX metrics:
 

Introduction

The standard of care in nasopharyngeal carcinoma (NPC) management is concurrent chemoradiation followed by adjuvant chemotherapy. Nasopharyngeal carcinoma differs from other head and neck cancers by virtue of its unique clinical behaviour and aetiological differences. This malignancy has shown higher incidence in Southeast Asia (annual incidence rate [AIR] of 6.4/100,000 in males and 2.4/100,000 in females). In India, its geographic distribution is heterogeneous, with higher incidence in Northeastern states (AIR of 19.4/100,000 population) [1]. Data from our hospital registry from South India revealed a lower prevalence of this condition in comparison to other head and neck malignancies

Currently, as per World Health Organisation pathological classification, these malignancies are categorized into keratinising squamous cell carcinoma and non-keratinising carcinoma variants [2]. However, there is no clear demonstration of clinical improvement when a specific histological subtype is considered as a prognostic predictor. Although outcomes in terms of local control have significantly improved using treatment protocols like chemo radiation as well as newer radiotherapy treatment techniques such as intensity-modulated radiotherapy (IMRT) [3], distant failure rates continue to be dismal in the locally advanced subset [4, 5]. Hence, various other prognostic factors such as Ebstein-Barr virus-related biomarkers are being hypothesised and evaluated [6, 7]. However, there is still a growing need to analyse other indices to quantify prognosis.

Fluor-18-fluorodeoxyglucose positron emission tomography with computed tomography (18F-FDG-PET-CT) has been used as the preferred imaging modality for staging nasopharyngeal cancer patients [8]. Apart from its use as a staging modality, the use of the same as a prognostic marker has been explored in a few studies [9, 10]. The standard uptake value maximum (SUVmax) for primary tumour and nodal disease has been explored as a potential prognostic biomarker for nasopharyngeal cancers; however, a uniform consensus on the same is still lacking [11, 12]. The drawback of SUVmax is that it represents the areas of active uptake within the tumour but does not provide an estimate of the entire tumour volume; hence, other metabolic parameters such as metabolic tumour volume (MTV) are also being studied to overcome the above-mentioned limitations [13, 14].

In this study, we have calculated the value of MTV, and SUVmax of primary tumour (SUVmax-P) and nodal disease (SUVmax-N) in pre-treatment PET-CT of patients with non-metastatic nasopharyngeal cancer treated with chemoradiation and correlation were drawn in terms of treatment response, overall survival (OS) and progression-free survival (PFS). Thereby we evaluated the role of these PET-CT metabolic parameters as a prognostic tool in non-metastatic nasopharyngeal cancer.

Material and methods

Patient population: We retrospectively analysed image datasets and follow-up data of NPC patients who presented at our institute between January 2017 and January 2020. Informed consent was obtained from each patient prior to radiotherapy and chemotherapy on the use of their data and image data for subsequent research.

Eligible patients were those with biopsy-proven nasopharyngeal carcinoma, including those who had received concurrent chemoradiation with IMRT followed by adjuvant chemotherapy. Pre-therapy evaluation included those who had been evaluated with 18F-FDG-PET-CT as part of the staging and metastatic workup and had subsequently been staged in accordance with 8th edition of the American Joint Committee on Cancer Staging Manual (2016). Patients with a Karnofsky index value below 70% and a prior history of other malignancies were excluded from the study.

18F-FDG-PET-CT parameters: the patients were administered an intravenous injection of 18F-FDG-PET-CT at a dose of 0.22 mCi (8.14 MBq)/kg (10–15 mCi/370-555 MBq) FDG. Forty-five minutes after the injection, patients were imaged from vertex to knee level with a 120 kV, 50 mA CT scan with a slice thickness of 3 mm using a Siemens Biograph Horizon device.

Treatment details: For radiotherapy planning, the patients were simulated in the supine position and immobilised with a thermoplastic mould. A CT simulation was performed with a slice thickness of 3 mm extending from the vertex to the D8 spine using a Siemens Biograph Horizon. The contouring was done with PET fusion-based delineation as per the international guidelines by Lee et al. [15]. Radiotherapy was administered to a total dose of 66 Gy to the GTV, 60 Gy to the high-risk clinical target volumes, and to a dose of 54 Gy in elective nodal regions in 1.8–2 Gy daily fractionation. With regard to chemotherapy, the patients were administered cisplatin (CDDP) 40 mg/m2 weekly concurrent with radiation and adjuvant chemotherapy using CDDP (70 mg/m2) and 5FU (1000 mg/m2 D1-5) 3-weekly following concurrent chemoradiation.

Follow-up: All patients were reviewed weekly during RT to assess the acute reactions, and post-therapy assessment with PET-CT was performed at 3 months post-RT after completion of adjuvant chemotherapy. Response assessment was performed in accordance with PERCIST criteria.

18F-FDG-PET-CT Metabolic Parameters: The SUV values were obtained using attenuation-corrected images, patient body weight, amount of FDG injected, and cross-calibration factors between the dose calibrator and FDG-PET CT.

The MTV of the primary tumour was calculated and derived automatically under a fixed threshold of the SUV at 2.5. The contouring margin contained the entire primary MTV2.5, where the MTV was a quantitative measurement of 18F-FDG uptake within the tumour lesions and volume of interest.

Study design and statistical analysis: To evaluate the role of MTV and SUVmax of the primary and node and its significance in terms of treatment outcomes: OS and PFS. The software used for statistical analysis was SPSS version 11, the survival fractions were estimated using the Kaplan-Meier method, and its correlation with treatment response and prognostic factors were analysed using the log-rank test. Statistical significance was set at p < 0.05. Chi-square and Fisher’s exact test were used to compare characteristics between the 2 groups SUVmax-P and SUVmax-N.

Results

Patient characteristics

The patient characteristics are shown in Table 1, and a total of 20 patients were analysed in this study, of whom 17 were alive at the last follow-up. The median follow-up period was 34.7 months (range, 20–48 months). The common histological variant was non-keratinising carcinoma, comprising of 85%, with most patients presenting in the locally advanced stages (III and IVA). The median nodal size measured on the short axis was 20 mm (range, 8–42 mm).

Table 1

Patient characteristics

CharacteristicsNumber
of patients (%)
Sex
Male13 (65)
Female7 (35)
Age
< 4511 (55)
> 459 (45)
Pathology
SCC3 (15)
Poorly differentiated non-keratinising carcinoma8 (40)
Un-differentiated non-keratinising carcinoma9 (45)
Stage
T stage
T1–T24 (20)
T3–T416 (80)
N stage
N0–N17 (35)
N2–N313 (65)
Stage group
I–II2 (10)
III–IVA18 (90)

[i] Values are presented as number (%), SCC – squamous cell carcinoma

Maximum standard uptake cut-off value

Based on pre-therapy PET-CT, the mean SUVmax-P was 13.55, (range, 8.75 to 26.17) and the mean value of SUVmax-N was 10.20, (range, 2.27 to 20.49). The reference cut-off value for SUVmax-N was obtained by receiver operating characteristics (ROC) curve analysis for progression for a value of 10.58 (area under curve – AUC, 0.845; p = 0.017). In terms of MTV, the mean value was 22.04 cm3 (range, 8.53–56.92) and the reference cut-off value was 25.8 cm3 (AUC, 0.786; p = 0.048) by ROC curve analysis for progression as shown in Figure 1.

Fig. 1

Receiver operating characteristics curve for metabolic tumour volume and nodal maximum standard uptake value for predicting progression

/f/fulltexts/WO/45340/WO-25-45340-g001_min.jpg

Based on the cut-off values for SUVmax at primary and node and MTV calculated using the ROC method, the distribution of these values with respect to disease stage and pathological variants in our study is depicted in Table 2.

Table 2

Characteristics mapped to maximum standard uptake values

CharacteristicsSUVmax-PSUVmax-NMTV (cm3)
≤ 13.55> 13.55≤ 10.58> 10.58≤ 25.8> 25.8
n = 10n = 10n = 12n = 8n = 12n = 8
Histology
SCC0 (0%)4 (40%)2 (16.7%)2 (25%)3 (25%)1 (12.5%)
Poorly differentiated carcinoma6 (60%)1 (10%)3 (25%)4 (50%)4 (33.3%)3 (37.5%)
Un-differentiated non-keratinising carcinoma4 (40%)5 (50%)7 (58.3%)2 (25%)5 (41.7%)4 (50%)
MTV stage
T1–T22 (20%)2 (20%)4 (33.3%)0 (0%)3 (25%)1 (12.5%)
T3–T48 (80%)8 (80%)8 (66.7%)8 (100%)9 (75%)7 (87.5%)
N0–N13 (30%)4 (40%)6 (50%)1 (12.5%)5 (41.7%)2 (25%)
N2vN37 (70%)6 (60%)6 (50%)7 (8.75%)7 (58.3%)6 (75%)
Stage group
I–II0 (0%)2 (20%)2 (16.7%)0 (0%)1 (8.3%)1 (12.5%)
III–IVA10 (100%)8 (80%)10 (83.3%)8 (100%)11 (91.7%)7 (87.5%)

[i] Values are presented as number (%), SUV – standard uptake value, MTV – metabolic tumour volume

Prognostic significance of maximum standard uptake value and metabolic tumour volume treatment outcomes

In terms of treatment outcomes, patients were evaluated with post-therapy PET-CT at 3 months post-radiotherapy. Among the 20 patients analysed, 14 (70%) had complete metabolic response, 2 (10%) were partial responders, and the remaining 4 (20%) had progressive disease.

When stratified and compared against the average SUVmax-P, there were no significant differences in response rates (p = 1.0). However, in terms of SUVmax-N, there was a significant difference of 91.7% versus 37.5% in terms of complete response rates for patients with SUVmax-N < 10.58, showing significantly better response rates (p = 0.05). In terms of histological variants, the poorly differentiated variant had a poorer outcome, as shown in Table 3 (statistically insignificant). The MTV cut-off value of 25.8 cm3 was also statistically significant in terms of complete responders (91.7% vs. 37.5% p = 0.018).

Table 3

Treatment outcomes

Prognostic parametersNo of patientsTreatment responsep-value
CR (%)PR (%)PD (%)
Primary1.00
SUVmax-P ≤ 13.55107 (70)1 (10)2 (20)
SUVmax-P > 13.55107 (70)1 (10)2 (20)
NODE0.05
SUVmax-N ≤ 10.581211 (91.7)0 (0)1 (8.3)
SUVmax-N > 10.5883 (37.5)2 (25)3 (37.5)
MTV0.018
≤ 25.8 cm31211 (91.7)1 (8.3)0 (0)
> 25.8 cm383 (37.5)1 (12.5)4 (50)
Histology0.715
SCC – keratinising43 (75)1 (25)0 (0)
Non-keratinising poorly differentiated74 (57.1)1 (14.3)2 (28.6)
Non-keratinising undifferentiated97 (77.8)0 (0)2 (22.2)

[i] Values are presented as number (%), SUV – standard uptake value, MTV – metabolic tumour volume, CR – complete response, PR – partial response, PD – progressive disease

During the follow-up period, 2 patients who had partial response developed progressive disease (6 out of n = 20, 30%) of whom 4 patients had succumbed to the disease, 1 patient had distant progression, and 1 had local progression, and they were salvaged with second-line chemotherapy. Among the above-mentioned patients who had progressed, 5 had an SUVmax-N of > 10.58 and an MTV of > 25.8 cm3. The sensitivity and specificity regarding the use of these metabolic markers for prognostic significance is shown in Table 4.

Table 4

Metabolic markers as a predictor of response

SensitivitySpecificityPositive
predictive
value
Negative
predictive
value
SUVmax-N83.3%71.4%55.6%91%
MTV83.3%78.6%62.5%91.7%

[i] Values are presented as number (%), SUV – standard uptake value, MTV – metabolic tumour volume

Survival outcomes

The 2-year PFS and OS for all patients were 70% and 79%, respectively. In univariate analysis, high SUVmax-P > 13.55 did not show any significant difference in terms of OS and PFS (p = 0.582).

However, a higher SUVmax-N level > 10.58 was a negative prognostic factor. The 2-year PFS was (91% vs. 46%; p = 0.035) and the 2-year OS was (95% vs. 58%; p = 0.015) for the SUVmax-N < 10.58 and SUVmax-N > 10.58, respectively, which was statistically significant (Table 5). When the SUVmax-N was stratified by stage or across histologies, there was no difference in PFS or OS (p = 0.715). A high SUVmax-N of > 10.58 was a negative predictor of OS (95% confidence interval [CI]: 0.93–1; p = 0.003) as well as PFS (95% CI: 0.64–1; p = 0.017), as shown in Figure 2.

Table 5

Survival outcomes for nodal maximum standard uptake value and metabolic tumour volume

Prognostic
parameters
SUVmax-N ≤ 10.58SUVmax-N > 10.58p-value
2-year PFS91%46%0.035
2-year OS95%58%0.015
Prognostic parametersMTV ≤ 25.8MTV > 25.8p-value
2-year PFS90%38%0.006
2-year OS99%55%0.008

[i] Values are presented as number (%), SUV – standard uptake value, OS – overall survival, PFS – progression-free survival

Fig. 2

Receiver operating characteristics curve for metabolic tumour volume and nodal maximum standard uptake value for predicting survival

/f/fulltexts/WO/45340/WO-25-45340-g002_min.jpg

In terms of MTV, the 2-year PFS was (90% vs. 38%; p = 0.006) and 2-year OS was (99% vs. 55%; p = 0.008) for the cut-off values of MTV ≤ 25.8 cm3 and MTV > 25.8 cm3, respectively. A high MTV of > 25.8 was also a negative predictor of OS (95% CI: 0.56–0.97; p = 0.108) as well as PFS (95% CI: 0.58–0.98; p = 0.048). The Kaplan-Meier curves for PFS and OS are shown in Figures 3 and 4.

Fig. 3

A – Kaplan-Meier curves for progression-free survival, B – overall survival (nodal maximum standard uptake value)

/f/fulltexts/WO/45340/WO-25-45340-g003_min.jpg
Fig. 4

A – Kaplan-Meier curves for progression-free survival, B – overall survival (metabolic tumour volume)

/f/fulltexts/WO/45340/WO-25-45340-g004_min.jpg

Hence, SUVmax-N and MTV are significant independent predictors of PFS and OS in univariate analysis, whereas it was not significant in the Cox regression multivariate analysis.

Discussion

Although NPC is sensitive to chemoradiation, the OS rates for locally advanced cancers is around 71.3% with dismal distant failures rates. Hence, there is a need to identify factors that may predict prognostic outcomes, thereby leading to intensification of treatment for the poor prognostic subset. Among the prognostic factors in vogue are stage grouping, histological subgrouping, and assessment of tumour tissue microarrays [16, 17]. The main drawbacks of the previously mentioned factors are the lack of genetic expression of the entire tumour. Hence, identifying additional prognostic factors that can predict treatment outcomes, particularly non-invasive diagnostic methods, may enhance the development of individualised strategies, thereby improving treatment outcomes. PET-CT is a modality that is non-invasive and can obtain the entire tumour metabolic information.

18F-FDG-PET-CT is the gold standard imaging modality for staging and assessing treatment response in nasopharyngeal cancers. In addition to its use for staging workup, its metabolic parameters are being explored as prognostic markers that may dictate the treatment response as well as a marker to determine long-term survival outcomes. SUVmax is one such marker that has been evaluated in the reviewed literature. SUV is defined as the ratio of the radioactivity concentration measured in the tissue to body weight in kilograms. SUVmax is a convenient parameter that is commonly used in clinical practice. It represents the highest voxel value within the volume of interest; however, it does not reveal heterogeneity within the tumour volume. Hence, other parameters, such as MTV, have been explored to offset this issue. In our study, we analysed the value of SUVmax-P, SUVmax-N, and MTV as significant prognostic markers.

In terms of SUVmax-P, Xie et al. found the best cut-off value to be 8.0 for the SUVmax of primary although in multivariate analysis it was not statistically significant in terms of 5-year OS and 5-year PFS benefit [18]. Lee et al. also deemed a cut-off value of 8 to be optimum for prognosis prediction [19]. In contrast, in this study, the SUVmax-P cut-off of 13.55 did not have any major bearing on the response rates or long-term survival outcomes, but the SUVmax-N had a bearing on the outcomes. In an earlier retrospective study on locally advanced head and neck cancer patients from India Srinivas et al. [20] failed to identify a cut-off value for pretherapy SUVmax that could predict the probable outcome of therapy.

In continuation of the above data obtained in this study in terms of SUVmax-N, it should be noted that lymph node metastasis has long been an important independent prognostic factor for nasopharyngeal cancer patients. Various parameters for quantifying the prognostic value of lymph node status, such as MTV and SUV, have been studied by many investigators, although with conflicting data. Yecai et al. reported that SUVmax, MTV of metastatic nodes did not have a bearing as an independent prognostic factor [21]. However, in a study by Hung et al. SUVmax-N was deemed an independent prognostic factor, with distant metastasis-free survival of 79.9% [22, 23]. Similarly, Lee et al. in their study also confirmed that the SUVmax-N was a more sensitive marker with a higher pre-treatment value > 13.4, which was a negative prognostic factor in terms of survival and disease progression (93.1% vs. 55.5% for OS and 92.7% vs. 38.5% for PFS) [24]. The data from this study are also in agreement with a PFS of 91% vs. 46% (p = 0.035) and an OS of 95% vs. 58% (p = 0.015), which was statistically significant in our study.

Regarding MTV, the follow-up data of 20 patients in the present study showed that for a definite SUV threshold, the most distinct MTV cut-off value had prognostic merit. This suggests that the 2-year PFS rate was inversely related to the MTV cut-off value of 25.8 cm3 for an SUV threshold of 2.5, with the PFS being 91% vs. 46% (p = 0.048). Fei et al. also confirmed MTV as an independent prognostic factor for predicting treatment and survival outcomes in patients and deemed MTV at an SUV threshold of 4 as an ideal sub-volume to be chosen for best therapeutic effect [25]. Similarly, Chan et al. further highlighted the role of MTV as an independent risk factor in patients with metastatic NPC [14].

Thus, it may be reasonable to use MTV as a biological target volume for the sub-set of patients with higher MTV value. The functional information provided by the MTV and its application as a biological target volume and dose escalation volume in radiation planning may improve the therapeutic efficacy for patients with NPC, who receive concurrent chemoradiation. The threshold by which the MTV can be considered the biological target volume needs to be explored in future studies. The MTV, as measured by PET-CT, tends to be smaller than the gross tumour volume defined by MRI or CT [26, 27]. Hence, the benefit regarding the use of dose escalation to a subregion within the GTV for a particular threshold of MTV and its effect on treatment or survival outcomes needs to be analysed exhaustively. This is beyond the scope of the present study and should be prospectively analysed in future studies.

A major limitation of our study was the retrospective nature and the limited sample size owing to the relatively low incidence of nasopharyngeal cancers in the southern districts of India. A well-designed prospective study is needed to validate the results of this study. Nevertheless, our report is still worthwhile because we have compared various metabolic parameters and conclusions were drawn with regard to MTV and SUVmax-N, which has been shown to be a superior prognostic marker to SUVmax-P.

Conclusions

High values of MTV and SUVmax-N can be considered as independent prognostic factors of OS and PFS in nasopharyngeal cancer patients treated with concurrent chemoradiation, highlighting the need for more intense treatment for this subset.

Notes

[6] Conflicts of interest The authors declare no conflict of interest.

References

1 

Ferlay J, Soerjomataram I, Dikshit R, et al. Cancer incidence and mortality worldwide: Sources, methods and major patterns in GLOBOCAN 2012. Int J Cancer 2015; 136: E359-86.

2 

Stelow EB, Wenig BM. Update from the 4th edition of the World Health Organization classification of head and neck tumours: nasopharynx. Head Neck Pathol 2017; 11: 16-22.

3 

Lu H, Peng L, Yuan X, et al. Concurrent chemoradiotherapy in locally advanced nasopharyngeal carcinoma: a treatment paradigm also applicable to patients in Southeast Asia. Cancer Treat Rev 2009; 35: 345-353.

4 

Zhao W, Lei H, Zhu X, Li L, Qu S, Liang X. Investigation of long-term survival outcomes and failure patterns of patients with nasopharyngeal carcinoma receiving intensity-modulated radiotherapy: a retrospective analysis. Oncotarget 2016; 7: 86914-86925.

5 

Guo Q, Lu T, Lin S, et al. Long-term survival of nasopharyngeal carcinoma patients with Stage II in intensity-modulated radiation therapy era. Jpn J Clin Oncol 2016; 46: 241-247.

6 

Aribas BK, Cetindag F, Ozdogan Z, et al. Nasopharyngeal carcinomas: prognostic factors and treatment features. J Egypt Natl Canc Inst 2008; 20: 230-236.

7 

Feng M, Wang W, Fan Z, et al. Tumor volume is an independent prognostic indicator of local control in nasopharyngeal carcinoma patients treated with intensity-modulated radiotherapy. Radiat Oncol 2013; 8: 208.

8 

Ou X, Yang Z, Hu C. Use of 18F-FDG-PET-CT in the diagnosis, staging, response assessment and prognosis of nasopharyngeal carcinoma: an updated review. Clin Cancer Res 2014; 13: 2627-2633.

9 

Higgins KA, Hoang JK, Roach MC, et al. Analysis of pretreatment FDG-PET SUV parameters in head-and-neck cancer: tumor SUV mean has superior prognostic value. Int J Radiat Oncol Biol Phys 2012; 82: 548-553.

10 

Schwartz DL, Rajendran J, Yueh B, et al. FDG-PET prediction of head and neck squamous cell cancer outcomes. Arch Otolaryngol Head Neck Surg 2004; 130: 1361-1367.

11 

Chang KP, Tsang NM, Liao CT, et al. Prognostic significance of 18F-FDG-PET parameters and plasma Epstein-Barr virus DNA load in patients with nasopharyngeal carcinoma. J Nucl Med 2012; 53: 21-28.

12 

Chan WK, Kwong DL, Yeung DW, et al. Prognostic impact of standardized uptake value of F-18 FDG PET/CT in nasopharyngeal carcinoma. Clin Nucl Med 2011; 36: 1007-1011.

13 

Dibble EH, Alvarez ACL, Truong MT, et al. 18F-FDG metabolic tumor volume and total glycolytic activity of oral cavity and oropharyngeal squamous cell cancer: adding value to clinical staging. J Nucl Med 2012; 53: 709-715.

14 

Sheng-Chieh C, Cheng-Lung H, Tzu-Chen Y, et al. The role of 18F-FDG-PET-CT metabolic tumour volume in predicting survival in patients with metastatic nasopharyngeal carcinoma. Oral Oncol 2013; 49: 71-78.

15 

Lee AW, Ng WT, Pan JJ, et al. International guideline for the delineation of the clinical target volumes (CTV) for nasopharyngeal carcinoma. Radiother Oncol 2018; 126: 25-36.

16 

Nakao K, Mochiki M, Nibu K, Sugasawa M, Uozaki H. Analysis of prognostic factors of nasopharyngeal carcinoma: impact of in situ hybridization for Epstein-Barr virus encoded small RNA 1. Otolaryngol Head Neck Surg 2006; 134: 639-645.

17 

Lee SW, Cho KJ, Park JH, et al. Expressions of Ku70 and DNAPKcs as prognostic indicators of local control in nasopharyngeal carcinoma. Int J Radiat Oncol Biol Phys 2005; 62: 1451-1457.

18 

Xie P, Yue JB, Fu Z, Feng R, Yu JM. Prognostic value of 18F-FDG-PET-CT before and after radiotherapy for locally advanced nasopharyngeal carcinoma. Ann Oncol 2010; 21: 1078-1082.

19 

Lee SW, Nam SY, Im KC, et al. Prediction of prognosis using standardized uptake value of 2-18F-fluoro-2-deoxy-d-glucose positron emission tomography for nasopharyngeal carcinomas. Radiother Oncol 2008; 87: 211-216.

20 

Srinivas KS, Arunan M, Venkatachalapathy E, John C, Manickavasagam M, Divyambika CV. The prognostic role of maximum standardized uptake value of 18F-flourodeoxy glucose positron emission tomography-computed tomography in head and neck cancer patients undergoing chemoradiotherapy. J Int Soc Prev Community Dent 2019; 9: 159-165.

21 

Huang Y, Feng M, He Q, et al. Prognostic value of pretreatment 18F-FDG-PET-CT for nasopharyngeal carcinoma patients, Medicine (Baltimore) 2017; 96: e6721.

22 

Hung TM, Fan KH, Kang CJ, et al. Lymph node-to-primary tumor standardized uptake value ratio on PET predicts distant metastasis in nasopharyngeal carcinoma. Oral Oncol 2020; 110: 104756.

23 

Hung TM, Wang HM, Kang CJ, et al. Pretreatment (18)F-FDG PET standardized uptake value of primary tumor and neck lymph nodes as a predictor of distant metastasis for patients with nasopharyngeal carcinoma. Oral Oncol 2013; 49: 169-174.

24 

Lee SJ, Kay CS, Kim YS, et al. Prognostic value of nodal SUVmax of 18F-FDG-PET-CT in nasopharyngeal carcinoma treated with intensity-modulated radiotherapy. Radiat Oncol J 2017; 35: 306-316.

25 

Fei Z, Chen C, Huang Y, et al. Metabolic tumor volume and conformal radiotherapy based on prognostic PET/CT for treatment of nasopharyngeal carcinoma. Medicine (Baltimore) 2019; 98: e16327.

26 

Liu F, Xi XP, Wang H, et al. PET/CT-guided dose-painting versus CT-based intensity modulated radiation therapy in locoregional advanced nasopharyngeal carcinoma. Radiat Oncol 2017; 12: 15.

27 

Wang J, Zheng J, Tang T, et al. A randomized pilot trial comparing position emission tomography (PET)-guided dose escalation radiotherapy to conventional radiotherapy in chemoradiotherapy treatment of locally advanced nasopharyngeal carcinoma. PloS One 2015; 10: e0124018.

Copyright: © 2021 Termedia Sp. z o. o. This is an Open Access article distributed under the terms of the Creative Commons Attribution-NonCommercial-ShareAlike 4.0 International (CC BY-NC-SA 4.0) License (http://creativecommons.org/licenses/by-nc-sa/4.0/), allowing third parties to copy and redistribute the material in any medium or format and to remix, transform, and build upon the material, provided the original work is properly cited and states its license.
 
Quick links
© 2024 Termedia Sp. z o.o.
Developed by Bentus.