Staging of nasopharyngeal carcinoma investigated by magnetic resonance imaging

Application of Artificial Intelligence in Radiotherapy of Nasopharyngeal Carcinoma with Magnetic Resonance Imaging

The value of automatic organ-at-risk outlining software for radiotherapy is based on artificial intelligence technology in clinical applications. The accuracy of automatic segmentation of organs at risk (OARs) in radiotherapy for nasopharyngeal carcinoma was investigated. In the automatic segmentation model which is proposed in this paper, after CT scans and manual segmentation by physicians, CT images of 147 nasopharyngeal cancer patients and their corresponding outlined OARs structures were selected and grouped into a training set (115 cases), a validation set (12 cases), and a test set (20 cases) by complete randomization. Adaptive histogram equalization is used to preprocess the CT images. End-to-end training is utilized to improve modeling efficiency and an improved network based on 3D Unet (AUnet) is implemented to introduce organ size as prior knowledge into the convolutional kernel size design to enable the network to adaptively extract features from organs of different sizes, thus improving the performance of the model. The DSC (Dice Similarity Coefficient) coefficients and Hausdorff (HD) distances of automatic and manual segmentation are compared to verify the effectiveness of the AUnet network. The mean DSC and HD of the test set were 0.86 ± 0.02 and 4.0 ± 2.0 mm, respectively. Except for optic nerve and optic cross, there was no statistical difference between AUnet and manual segmentation results (P > 0.05). With the introduction of the adaptive mechanism, AUnet can achieve automatic segmentation of the endangered organs of nasopharyngeal carcinoma based on CT images more accurately, which can substantially improve the efficiency and consistency of segmentation of doctors in clinical applications.

Prognostic factors and failure patterns in non-metastatic nasopharyngeal carcinoma after intensity-modulated radiotherapy

Background

The prognostic values of staging parameters require continual re-assessment amid changes in diagnostic and therapeutic methods. This study aimed to identify the prognostic factors and failure patterns of non-metastatic nasopharyngeal carcinoma (NPC) in the intensity-modulated radiotherapy (IMRT) era.

Methods

We reviewed the data from 749 patients with newly diagnosed, biopsy-proven, non-metastatic NPC in our cancer center (South China, an NPC endemic area) between January 2003 and December 2007. All patients underwent magnetic resonance imaging (MRI) before receiving IMRT. The actuarial survival rates were estimated using the Kaplan–Meier method, and survival curves were compared using the log-rank test. Multivariate analyses with the Cox proportional hazards model were used to test for the independent prognostic factors by backward eliminating insignificant explanatory variables.

Results

The 5-year occurrence rates of local failure, regional failure, locoregional failure, and distant failure were 5.4, 3.0, 7.4, and 17.4%, respectively. The 5-year survival rates were as follows: local relapse-free survival, 94.6%; nodal relapse-free survival, 97.0%; distant metastasis-free survival, 82.6%; disease-free survival, 75.1%; and overall survival, 82.0%. Multivariate Cox regression analysis revealed that orbit involvement was the only significant prognostic factor for local failure (P = 0.011). Parapharyngeal tumor extension, retropharyngeal lymph node involvement, and the laterality, longest diameter, and Ho’s location of the cervical lymph nodes were significant prognostic factors for both distant failure and disease failure (all P < 0.05). Intracranial extension had significant prognostic value for distant failure (P = 0.040).

Conclusions

The key failure pattern for NPC was distant metastasis in the IMRT era. With changes in diagnostic and therapeutic technologies as well as treatment modalities, the significant prognostic parameters for local control have also been altered substantially.

Ethanolic Extracts of Pluchea indica Induce Apoptosis and Antiproliferation Effects in Human Nasopharyngeal Carcinoma Cells

Pluchea indica is used in traditional medicine for the treatment of lumbago, ulcer, tuberculosis and inflammation. The anti-cancer activities and the underlying molecular mechanisms of the ethanolic extracts of P. indica root (PIRE) were characterized in the present study. PIRE strongly inhibited the viability of the human nasopharyngeal carcinoma cells (NPC-TW 01 and NPC-TW 04) in a time- and dose-dependent manner. Migration of cancer cells was also suppressed by PIRE. In addition, PIRE significantly increased the occurrence of the cells in sub-G1 phase and the extent of DNA fragmentation in a dose-dependent manner, which indicates that PIRE significantly increased apoptosis in NPC cells. The apoptotic process triggered by PIRE involved up-regulation of pro-apoptotic Bax protein and down-regulation of anti-apoptotic Bcl-2 protein, consequently increasing the ratios of Bax/Bcl-2 protein levels. Moreover, the p53 protein was up-regulated by PIRE in a concentration-dependent manner. Therefore, PIRE could induce the apoptosis-signaling pathway in NPC cells by activation of p53 and by regulation of apoptosis-related proteins.

MRI-detected skull-base invasion: prognostic value and therapeutic implication in intensity-modulated radiotherapy treatment for nasopharyngeal carcinoma

PURPOSE

With advances in imaging and radiotherapy, the prognostic value of skull-base invasion in nasopharyngeal carcinoma (NPC) needs to be reassessed. We aimed to define a classification system and evaluate the prognostic value of the classification of magnetic resonance imaging (MRI)-detected skull-base invasion in NPC treated with intensity-modulated radiotherapy (IMRT).

PATIENTS AND MATERIALS

We retrospectively reviewed 749 patients who underwent MRI and were subsequently histologically diagnosed with nondisseminated NPC and treated with IMRT.

RESULTS

MRI-detected skull-base invasion was not found to be an independent prognostic factor for overall survival (OS), distant metastasis-free survival (DMFS), local relapse-free survival (LRFS), or disease-free survival (DFS; p > 0.05 for all). Skull-base invasion was classified according to the incidence of each site (type I sites inside pharyngobasilar fascia and clivus vs. type II sites outside pharyngobasilar fascia). The 5-year OS, DMFS, LRFS, and DFS rates in the classification of skull-base invasion in NPC were 83 vs. 67 %, 85 vs.75 %, 95 vs. 88 %, and 76 vs. 62 %, respectively (p < 0.05 for all). Multivariate analysis indicated the classification of skull-base invasion was an independent prognostic factor.

CONCLUSION

MRI-detected skull-base invasion is not an independent prognostic factor in patients with NPC treated with IMRT. However, classification according to the site of invasion has prognostic value. Therefore, patients with various subclassifications of stage T3 disease may receive treatment with different intensities; however, further studies are warranted to prove this.

Comparison of TNM staging systems for nasopharyngeal carcinoma, and proposal of a new staging system

BACKGROUND

There are few systematic evaluations regarding the sixth and seventh editions of the UICC/AJCC TNM Staging System (TNM6th, TNM7th) and Chinese 2008 Staging System (TNMc2008) for nasopharyngeal carcinoma (NPC).

METHODS

We classified 2333 patients into intensity-modulated radiotherapy (IMRT) cohort (n=941) and conventional radiotherapy (CRT) cohort (n=1392). Tumour staging defined by TNM6th, TNM7th and TNMc2008 was compared based on Akaike information criterion (AIC) and Harrell's concordance index (c-index).

RESULTS

For T-classification, TNM6th (AIC=2585.367; c-index=0.6390385) had superior prognostic value to TNM7th (AIC=2593.242; c-index=0.6226889) and TNMc2008 (AIC=2593.998; c-index=0.6237146) in the IMRT cohort, whereas TNMc2008 was superior (AIC=5999.054; c-index=0.623547) in the CRT cohort. For N-classification, TNMc2008 had the highest prognostic value in both cohorts (AIC=2577.726, c-index=0.6297874; AIC=5956.339, c-index=0.6533576). Similar results were obtained when patients were stratified by chemotherapy types, age and gender. Using staging models in the IMRT cohort, we failed to identify better stage migrations than TNM6th T-classification and TNMc2008 N-classification. We therefore proposed to combine these categories; resultantly, stage groups of the proposed staging system showed superior prognostic value over TNM6th, TNM7th and TNMc2008.

CONCLUSION

TNM6th T-classification and TNMc2008 N-classification have superior prognostic value in the IMRT era. By combining them with slight modifications, TNM criteria can be unified and its prognostic value be improved.

MRI signal changes in the skull base bone after endoscopic nasopharyngectomy for recurrent NPC: a serial study of 9 patients

PURPOSE

This study was focused on the serial changes in magnetic resonance images (MRI) of the skull-base bone that occur after endoscopic nasopharyngectomy in patients with local recurrent nasopharyngeal carcinoma (rNPC).

MATERIALS AND METHODS

Nine patients with histologically proven rNPC were enrolled in this study. Two experienced radiologists independently reviewed all presurgical and postsurgical MR images for each patient.

RESULTS

At 36 sites on the skull base, the MRI signal underwent a change after surgery, which took the form of a heterogeneous pattern of hypointense regions with moderate contrast enhancement on T1WI. The onset of changes ranged between 2 weeks and 3 months after surgery. For 21 of the sites, the changes subsided over the course of follow-up, while in 6 they remained stable. At 9 sites, the alteration MRI signal became more pronounced with time. Changes were more common on the homolateral side of the skull base with respect to the recurrent tumor (P<0.05). The skull-base bone adjacent to the resection boundary had a higher incidence of signal change than nonadjacent areas (P<0.05).

CONCLUSIONS

MRI changes in the skull base bone, having a number of distinguishing characteristics, appear to be a common sequel to endoscopic nasopharyngectomy for rNPC.

Patterns of regional lymph node metastasis of nasopharyngeal carcinoma: a meta-analysis of clinical evidence

BACKGROUND

The characteristics of cervical lymphatic metastasis in nasopharyngeal carcinoma (NPC) are not completely understood. As such, radiotherapy to the entire lymphatic of the neck bilaterally has been empirically practiced even in early stage disease, although not supported by clinical evidence. We studied the pattern and probability of nodal metastasis through a meta-analysis of published evidences, with an aim to establish an evidence-based guideline for selecting and delineation of clinical target volume of neck lymphatics for conformation radiation for NPC.

METHODS

A literature search yielded an initial 411 original articles, and 13 studies with 2920 NPC cases staged via MRI were included in this analysis. The occurrence of nodal metastasis was calculated and analyzed according to the respective regional nodal levels.

RESULTS

85% of NPC cases presented with lymphadenopathy. The most commonly involved regions include retropharyngeal (69%) and level II lymph nodes (70%). The overall probability of levels III, IV, and V nodal involvement are 45%, 11%, and 27%, respectively. Low-risk node groups included the supraclavicular, levels IA/IB and VI nodes, and parotid nodes with involvement rates at 3%, 0%, 3%, 0%, and 1%, respectively. Nodal metastases followed an orderly pattern and the probability of "skip" metastasis between levels varied between 0.5-7.9%.

CONCLUSIONS

Lymph node metastasis in NPC follows a predictable and orderly pattern. The rarity of metastasis in certain nodal groups and "skip" metastasis suggest that reduced treatment volume is feasible in conformal radiotherapy for NPC.

The seventh edition of the UICC/AJCC staging system for nasopharyngeal carcinoma is prognostically useful for patients treated with intensity-modulated radiotherapy from an endemic area in China

PURPOSE

To evaluate the 7th edition of the International Union against Cancer/American Joint Committee on Cancer (UICC/AJCC) staging system for nasopharyngeal carcinoma (NPC) in patients treated with intensity-modulated radiotherapy.

METHODS AND MATERIALS

We performed a retrospective data review from 512 patients with biopsy-proven, nonmetastatic NPC in our cancer center (South China) between January 2003 and December 2006.

RESULTS

The local relapse-free survival rates (LRFS) and disease failure-free survival rates (DFS) in the 6th edition system T1 and T2a stages were not significantly different (P=0.629 and P=0.820), while the LRFS and DFS of T1 and T2 using the 7th edition system were significantly different (P=0.019 and P=0.009). The LRFS and DFS between T2 and T3 in the 7th edition systems were lack of significance (P=0.874 and P=0.589). The total difference in distant metastasis-free survival rate and DFS between N0 and N3 was slightly larger using the 7th edition system than the 6th edition. The nodal dimension of a cervical lymph node was not a significant prognostic factor.

CONCLUSIONS

We observed a better segregation of survival curves by using the 7th edition system. It seems reasonable to downstage T3 as T2 and reject nodal greatest dimension from the N-staging system in the future revised edition.

Effect of patient-related delay in diagnosis on the extent of disease and prognosis in nasopharyngeal carcinoma

BACKGROUND

The reasons causing the patient-related delay in diagnosis (PRDD) and the effects of PRDD on the extent of disease and prognosis in the nasopharyngeal carcinoma (NPC) remain uncertain. The aim of this study was to investigate the status of PRDD and evaluate the relationship between PRDD and prognostic factors of NPC.

METHODS

The data of 216 patients with NPC, from 2002 to 2006, were analyzed retrospectively with respect to patient age, gender, smoking status, education experience, living area, and symptoms. PRDD was recorded as the time from initial symptoms to the first visit to a medical doctor. The extent of disease was determined by TNM staging according to the International Union Against Cancer classification in 1997.

RESULTS

PRDD of the analyzed cases ranged from half a month to 24 months, with a mean delay in diagnosis of 5.6 months. Senior residents and low education population tended to have longer PRDD (p < 0.05). There was a significant correlation between PRDD and the degree of invasion, clinical stage of NPC (p < 0.05).

CONCLUSION

Senior residents and low education population tend to have longer PRDD. Delay in diagnosis correlates with the degree of invasion and stage of NPC.

Expression and clinical significance of epidermal growth factor receptor and type 1 insulin-like growth factor receptor in nasopharyngeal carcinoma

OBJECTIVES

Epidermal growth factor (EGF) and type 1 insulin-like growth factor (IGF-1) receptors play an important role in the growth and apoptosis of nasopharyngeal carcinoma (NPC). They were separately found to be associated with prognosis in patients with NPC. To date, their expression correlation and clinicopathologic significance have never been specifically addressed in NPC.

METHODS

Seventy-five patients with NPC and 21 noncancerous nasopharyngeal epithelial samples were accrued between 1998 and 2006 in a single hospital. The expressions of EGF and IGF-1 receptors were detected by immunohistochemical staining in the 75 NPC samples and the 21 noncancerous samples. Furthermore, the messenger RNA and protein expressions were assessed by real-time quantitative polymerase chain reaction and the Western blot technique, respectively, in NPC cell lines and normal nasopharyngeal epithelial cells.

RESULTS

The 5-year survival rates, assessed by the Kaplan-Meier method, were 71.4% and 66.6% in the EGF and IGF-1 receptor protein-negative groups, respectively, whereas they were only 28.6% and 33.3% in the receptor protein-positive groups. The levels of these two proteins significantly correlated with each other, and the overexpression rates of EGF and IGF-1 receptors were 65.3% and 56% in nasopharyngeal samples, respectively. Furthermore, both protein expressions were significantly higher in NPC patients with cervical lymph node or distant metastasis than in NPC patients without lymph node or distant metastasis. Recurrence more often appears in cases positive for both proteins than in cases negative for both proteins. The expression levels of the receptor messenger RNA and proteins were higher in several NPC cell lines than in normal nasopharyngeal epithelial cells.

CONCLUSIONS

These findings demonstrate that both receptor proteins may play an important role in the invasion, metastasis, and recurrence of NPC. Both receptors are valuable markers for assessing the prognosis of NPC. Their expression at such high frequencies provides the basis of combined targeted therapy with specific pharmacologic inhibitors to enhance the effects of radiotherapy and chemotherapy.