The Tumor-Stroma Ratio Is An Independent Predictor For Survival In Nasopharyngeal Cancer

Background and PurposeNasopharyngeal cancer (NPC) is one of the most common malignant tumor in southern China, and is one of the most common malignant tumor of head and neck in Southeast Asia and Northern Africa. According to epidemiological survey data, Guangdong、Guangx、Zhuang Autonomous Region、Hunan、Fujian and Jiangxi are areas of a high incidence of nasopharyngeal cancer in the world. The incidence of nasopharyngeal cancer, male to female ratio is 2-3:1, most patients are in the 40-50 years old age. Genetic factors, virus infection and environmental factors are related to the occurrence of nasopharyngeal cancer. The TNM staging system is an important basis for judging the prognosis and guiding the treatment of nasopharyngeal cancer, but it was found that patients in the same clinical staging with the same treatment scheme, the prognosis is different. It suggests that biological differences existing in nasopharyngeal cancer. The TNM clinical staging system is based on the anatomical information and is not sufficient to predict prognosis in patients with nasopharyngeal cancer. With the same clinical staging of nasopharyngeal cancer, patients often have different clinical development process, so it can be expected that there may be some other prognostic factors to provide help for a more precise prognosis. Every nasopharyngeal cancer patients can get individualized treatment programs and greatly improve the prognosis of the patients. Now with the progress in the study of tumor molecular biology, many of the biological markers may predicting the prognosis of nasopharyngeal cancer and used to guide the clinical treatment have been found. In the past, the treatment of malignant tumor is mainly according to the TNM staging system. The medical mode is changed from evidence based medicine to individual medicine mode basing on the gene phenotyp. The individual treatment is given to the patients with breast cancer、lung cancer according to the different gene expression.Tumor-stroma ratio (TSR) is the proportion of stromal tissue surrounding tumor cells to the tumor cells. It has been proved to be a independent prognostic factor in many solid tumors such as colon cancer, non small cell lung cancer, breast cancer and esophageal squamous cell cancer. Stroma-rich tumors were associated with poor prognosis and an increased risk of relapse. As we know, tumor tissue is composed of both carcinoma cells and stroma cells recruited from normal tissue. Maintenance of both normal epithelial tissues and their malignant counterparts is supported by the host tissue stroma. In normal tissue, the stroma may actually act as a barrier in tumor genesis by constraining tumor cell proliferation. Although most host cells in the stroma possess certain tumor-suppressing abilities, the stroma will change during malignancy and eventually promote growth, invasion, and metastasis. In tumor tissue, however, stroma components could facilitate the process of tumor progression. The tumor stroma mainly consists of the basement membrane, fibroblasts, extracellular matrix (ECM), immune cells, and vasculature. The majority of studies have focused on events that occur within cancer cells. Other studies have addressed the microenvironment of tumor cells supporting tumor progression. It has been found that the lymphoid stroma characteristically found in undifferentiated NPC is a prerequisite for the development of this tumor. During recent years, the crosstalk between the cancer cells and the tumor stroma, which is highly responsible for the progression of tumors and their metastasis, has been increasingly revealed. Tumor interstitial changes including tumor associated fibroblasts (CAFS) play a crucial role in promoting tumor progression.The aim of this study was to evaluate the prognostic value of the TSR in nasopharyngeal cancer (NPC). Patients and MethodsWe analyzed 93 consecutive patients with biopsy-proven, previously untreated stages I-IVa NPC between January 2004 and December 2007. Patients with distant metastasis at presentation were excluded. All patients underwent fiberoptic nasopharyngoscopy and biopsy for pathological diagnosis. The initial staging evaluation included a clinical examination and computed tomography (CT) and/or magnetic resonance imaging (MRI) of the head and neck, chest radiography, abdominal sonography or CT, and a complete blood count with differential count and biochemical profile. Staging of NPC was based on the TNM system of the American Joint Committee on Cancer (AJCC),6th edition. There were 28 (28.2%) female and 65 (71.8%) male patients. The median age of the patients was 46 years (range 19-76 years).6 patients were diagnosed with keratinizing squamous cell carcinoma (WHO type Ⅰ),37 patients with non-keratinizing differentiated carcinoma (WHO type Ila), and 50 patients with non-keratinizing undifferentiated carcinoma (WHO type Ⅱb). The numbers of patients with stage Ⅰ, Ⅱ, Ⅲ, and Ⅳa disease were 4,20,44, and 25 respectively.63 patients underwent concurrent or adjuvant chemotherapy. All patients received radiotherapy with or without chemotherapy.Routine hematoxylin and eosin (H&E)-stained slides of the NPC tumor from pathology archives were microscopically analyzed for the presence of stroma involvement. In case of tumor heterogeneity, stroma-rich areas were considered to be of worse prognostic value and therefore deemed decisive. In general, areas rich in stroma were found near the site of deepest microscopic infiltration. The surrounding stroma tissue not containing tumor cells was considered not to be connected with the tumor. Using a 4×objective, the most invasive area of the tumor slide was selected. Subsequently, using a 10× objective, the fields where both stroma and tumor were present and tumor cells were visualized on all sides were scored per 10-fold percentage. The assessment was done on the basis of the analysis of at least 1 microscopic field. The estimate was then recorded as the TSR. With this protocol, tumor sections were independently assessed by 2 investigators. A third pathologist’s decision was decisive when the 2 observers disagreed. The cut-off of the TSR was taken as 50%, as described before. The TSR was defined as stroma poor (with a proportion of stroma of< 50%) or stroma rich (with a proportion of stroma of^ 50%).They were treated with radiotherapy either in conventional 2-dimensional radiotherapy (2D-RT) or 3-dimensional conformal radiotherapy (3D-CRT) or intensity-modulated radiotherapy (IMRT). The numbers of patients receiving conventional 2D-RT,3D-CRT, and IMRT were 38,18, and 37, respectively. Conventional radiotherapy(1) posture and position fixingSupine position, flat rack, the head is placed in the appropriate pillow, using 3D laser light position, so that the patient horizontal plane parallel to the bed, the body of the sagittal plane perpendicular to the surface of bed, special attention should be paid to the midline neck and body in a straight line, when necessary, can adjust the position in the simulated machine until to meet the conditions. Immobilization by U type thermoplastic mask can be fixed.(2) The conventional radiotherapy simulation locationThe faciocervical portals on the both sides of the horizontal isocenter irradiation, determine the irradiation field before and after, the upper, lower bounds and field center perspective. Method:first in perspective will field center moved to the body midline, and then the frame to 90 degrees, will be moved to the position of the center of the nasopharyngeal cavity, will be "well" word line open to the desired size of irradiation field. The lower bound is generally hyoid level or lower bound adjustment according to lymph node, shoot positioning sheet (GA=90 degrees, HA=0 degrees, center unchanged), shooting the other side of the positioning piece of wild, also on the mask mark field center, recording the field depth. Finally, the frame back to zero, mark field center on the mask, record lift bed height.The neck clavicle using source skin distance vertical irradiation technology, the upper bound and lower bound of lower face and neck wild collinear, along the lower edge of clavicle walking, both sides located in the medial margin of the acromioclavicular joint to avoid the acromioclavicular joint, will shoot nodal line and 1/2 is arranged in the center of the body center of wild wild long, shooting a positioning sheet (GA=0 degrees, HA=0 degrees), and mark the field center. The amplification coefficient of radiography best fixed, in order to reach a tacit understanding with the die chamber. 3-dimensional conformal radiotherapy and intensity-modulated radiotherapy(1) position and fixed by the supine position, select the head pillow suitable (B or C pillow), fixed cover for neck shoulder heat surface, hands holding body side, and the patient’s name, the number of hospitalized, the head pillow type record on the mask.(2) CT simulation in machine center CT simulation to determine the scanning, and in three dimensional laser light, projection will center on the skin (a front, sides) labeled with a metal point, in order to be able to identify the image on CT scan.(3) CT scan directly with enhanced continuous scanning, slice thickness 3mm, scan range from the top of the head to the subclavian 3 cm range, and will get the influence of information through the network system to plan system workstation for patient information registration, data for image reconstruction in workstation and confirm.(4)The delineation of target and organs at risk target delineation preferably with MRI image data, in order to minimize the error in the position of target delineation.(5)Dose prescription and requirements stated in the radiotherapy planning for single selection, treatment indications and complications of radiotherapy treatment, target area, endanger the organ dose prescription dose.(6) Design, field calculation and optimization meet the prescribed dose requirements and minimize the segment number, shorten the time of irradiation.(7) Treatment plan verification shall not execute untested treatment plan.(8)Confirm the treatment plan requires two physical person sign and competent physician signature recognition.(9)Treatment and treatment verification First treatment requirements of physical teacher and doctor in charge in position, and other inspection and simulation of perturbation center positioning CT as center image alignment, began treatment is correct when. For the first 3 times a day taken verification like once, then once a week, to ensure that the error of IMRT treatment remained in an acceptable range. The radiation dose and chemotherapyThe total median dose was 72 Gy/7-8 weeks (range:70-76 Gy) administered to the nasopharygeal and the positive neck region using megavoltage radiation. The dose administered to the risk neck region was 50-60 Gy/5-6 weeks. Early-stage patients were treated with radiotherapy alone. Patients with stage III-IVa disease received concurrent or adjuvant chemotherapy including cisplatin and 5-fluorouracil. The patients received 2-6 cycles of chemotherapy depending on the response and tolerance. The chemotherapy consisted of cisplatin 25 mg/m2 on days 1-3 and 5-fluorouracil 500 mg/m2 on days 1-5, repeated every 21 days. Those patients with local recurrence or/and distant metastasis received re-irradiation or/and chemotherapy. Follow-UpPatients were evaluated for tumor response, disease-free survival (DFS), and overall survival (OS). Tumor response was assessed according to the WHO criteria. All patients had a regular follow-up schedule every 3 months during the first year after radiation therapy and 6 months thereafter. Physical examination, complete blood count, and blood chemistry were performed at each visit, along with head and neck CT or MRI, chest radiography, abdominal sonography, and whole-body bone scan every 6 months. A biopsy was performed when residual disease or recurrence was suspected. The median follow-up time for surviving patients was 67 months. ResultsThe response rate of the stroma-poor group and the stroma-rich group was similar. The adavers reaction in both groups was similar. The 5-year overall survival (OS) and disease-free survival (DFS) rates were 66.67%and 54.91%, respectively, in the stroma-poor group and 40.48% and 33.33%, respectively, in the stroma-rich group. Both the 5-year OS and DFS rates in the stroma-poor group were significantly better than those in the stroma-rich group (p< 0.05). In a multivariate analysis, the TSR was identified as a highly significant prognostic factor for the 5-year OS (hazard ratio (HR) 1.999; p= 0.030) and the 5-year DFS (HR 1.925; p= 0.042). In the Cox univariate and multivariate analyses of the 5-year OS, the HRs of the TSR were 1.979 (95% CI 1.103-3.5515; p= 0.022) and 2.069 (95% CI 1.153-3.713; p= 0.015), respectively. As for DFS, the HRs were 1.999 (95% CI 1.068-3.744; p= 0.030) and 1.925 (95% CI 1.024-3.620; p= 0.042). In the Cox univariate model, TSR, T stage, N stage, UICC stage, and chemotherapy were significantly related to the 5-year OS and DFS. the TSR was an independent prognostic variable for the 5-year OS and DFS. In the multivariate analysis, the TSR was an independent prognostic variable for the 5-year OS with an HR of 2.069 (95% CI 1.153-3.713; p= 0.015) (table 2) and DFS with an HR of 1.925 (95% CI 1.024-3.620; p= 0.042), independent of other clinicopathological parameters.Conclusion1 Recent curative effect The complete remission rate (CR) of the stroma-poor group and the stroma-rich group had no difference, the clinical remission rate (CR+PR) had no difference too.2 Toxicity The acute skin reaction, mucosa reaction and blood toxicity had no obvious difference between the stroma-poor group and the stroma-rich group.3 The long term effect The 5 years OS and DFS was better in the tumor stroma poor group than the stroma-rich group. Survival curves of the two groups had significant difference. In the analysis of single factor and multi variables Cox, TSR is an independent prognostic factor apart from other clinical pathological parameters.4 Stroma-rich tumors were associated with poor prognosis which may serve as a new prognostic histological characteristic in NPC.