CLINICOPATHOLOGICAL RETROSPECTIVE ANALYSIS OF THYMOMA IN SERBIA: SINGLE CENTER EXPERIENCE KLINIĈKO-PATOLOŠKA RETROSPEKTIVNA ANALIZA TIMOMA U SRBIJI: ISKUSTVO JEDNOG CENTRA

Background/Aim. Thymoma is the most common mediastinal tumor. The treatment procedures are based on the results from the research of retrospective studies because they 3 are not frequent tumors. The objective of this work was to define common clinical features, therapeutic aspects, survival and recurence free survival. Methods. This study was performed in the Clinic for Pulmonology, Clinical Centre of Serbia, Belgrade from January 1993 to December 2013. We analyzed 62 patients of pathohistologically proven thymoma. The results were obtaind from medical history, physical exam, chest X-ray and/or computed tomography, and an operational finding or a report of a diagnostic procedure. The World Health Organization classifies thymoma on the basis of pathohistological findings. Thymoma are staged according to the Masaoka-Koga staging system. Results. There were more female (54,8%) patients. Patients were mostly in the seventh decade of life. One third (29%) of the patients were asymptomatic. Cough was the dominant symptom. Myasthenia gravis was the most common paraneoplastic syndrome (12.9%). Solitary tumour was the most common in our patients(61.3%), as well as the tumours larger than 5 cm (52.5%), and noninvasive thymomas (52.5%). The majority of patients (40%) were in the stage I of the disease. The operative approach has been conducted in most of the patients (88.7%). A statistically significant difference in survival was in women, patients with solitary tumor, non-invasive thymomas, patients in the stage I of the disease, and those who were operated. The dimension of the tumor mass is approaching the conventional level of significance. Conclusion. The obtained results confirm that according to the survival rate analyses, statistically significant survival rate predictors are gender, presence of solitary tumor mass, tumor invasiveness, clinical stage of the disease and the carried out operation.


Introduction
Thymomas are not so common mediastinal tumors.They are developing from epithelial thymic cells and present 0.2-1.5% of all malignancies 1 .On one hand they are very rare, but on the other hand they present 20% of all mediastinal masses and up to 50% of all anterior mediastinal masses 2 .Average incidence of thymomas is 0.15 per 100,000 persons/year.
The disease is usually developed locally but metastases are most often found on the pleura, pericardium, or diaphragm 3,4 .The World Health Organization (WHO) classifies thymmoma on the basis of pathohistological (PH) findings which differs thymomas from thymic carcinomas.This classification was made in 1999 and updated in 2003.Thymomas are subdivided into five main types (called A, AB, B1, B2, B3) and a few less frequent other types based upon the morphology of the epithelial tumor cells and on the proportion of the non-tumoral lymphocytic component, which may indicate an aggressiveness of the tumor.The greatest probability of a good outcome have type A, and decreases going to type B3 5,6 .Staging of the thymomas is based on the Masaoka -Koga system (1994) which was adapted in 2011 by the International Thymic Malignancy Interest Group (ITMIG) 7 .
Clinical presentation of thymomas can be asymptomatic, with the symptoms of local spread of the tumor and within paraneoplastic syndromes.Autoimmunity is a very frequent clinical feature 8 , especially myasthenia gravis (MG) which is present in 30% of patients, but also other autoimmune diseases can be seen 9,10,11,12 .Treatment options for this patients are: operational approach, radiotherapy (RT), chemotherapy and the best supportive care (BSC), and/or with the combinations of this regimens 13 depending on the location of the disease, stage of the thymoma and due to general condition of the patient, as well as the presence of comorbidities.
Here we retrospectively analyzed the clinical presentation and overall survival in patients with histologically confirmed thymoma diagnosed during an 20-year period in our institution.

Methods
This retrospective study was performed in the Clinic for Pulmonology, Clinical Centre of Serbia, Belgrade from January 1993 to December 2013.We analyzed 62 patients who were hospitalized and treated in our hospital.All the cases with thymoma confirmed by the pathohistological (PH) analysis of tissue obtained during surgery or by fine needle aspiration biopsy (FNAB).Thymoma are classified according to the WHO histopathological classification and staged on the basis of the Masaoka-Koga staging system.The results were obtained from medical history, physical exam, chest X-ray and/or computed tomography, and an operational finding or a report of a diagnostic procedure with a PH proof of thymoma.We analyzed the potential gender, age and smoking influence on thymoma and whether it affects the survival rate in thymoma patients.We analyzed the incidence of paraneoplastic disorders, paying particular attention to myasthenia gravis, comorbidities in thymoma patients and the presence of certain symptoms and their duration before establishing the diagnosis.The overall survival rate was analyzed in thymoma patients compared to tumor size, tumor spread and invasiveness of the disease, its clinical stage and PH findings as well as the survival rate related to the therapy approaches, i.e.
whether they underwent the surgical approaches, especially if the radical operation or incomplete resection (palliative surgical approach) was done, and survival in relation to other methods of treatment when the operation was not possible to be carried out.We also studied thymoma relaps in patients who had complete surgical resection related to the possible influence of smoking, clinical stage of the disease and PH findings to the relapse of the disease.Results are presented as count (percent), mean±standard deviation or median, depending on data type.Log rank test was performed to assess significant predictors of survival.Survival was presented using medians or means with confidence intervals if appropriate.Due to a small sample size, Cox regression was performed using Forward method.Also, due to high difference between means and medians, some results are presented as medians without confidence interval.All data were analyzed using SPSS 20.0 (IBM corp.)statistical software.All p values less than 0.05 were considered significant.Certain parameters do not have the calculated confidence interval due to small sample.Nevertheless, due to big difference between arithmetic middle and median survival we determined for median.The Institutional Ethics Committee approved the study.
The average age was 55.7±13.0 years (ranging from 21 to 75 years).The highest percentage of patents is in their 70-s, 20 (32.3%), and the next group are the patients in their 60 -s,17 (27.4%).The basic characteristics of the patients are shown in Table 1.The clinical presentation of thymoma varied.Nearly one third (29%) of the patients had no symptoms and rest of the patients had minimum symptom (Figure 1): the dominant one being cough in 24 (38.7 %) patients followed by general weakness and chest pain, the same as in 22 (35.5%)patients.Polyneuropathia as paraneoplastic syndrome was present in 1(1.6%) patient, while myasthenia gravis was present in 8 (12,9%) pts, 5 of whom were women (62.5%).The duration of symptoms prior to diagnosis of thymoma varies from 1 month to more than one year.The majority of the patients (nearly half, or 46.7%) had symptoms with a duration of 6 months, while a duration of one month and a duration of more than one year were approximately alike: 12 patients (or 26.7%) and 11 patients (or 25%), respectively.Comorbidities were recorded in nearly half of the patients 30 (48.4%) pts, mainly in women 21 (70%) pts.The most common was arterial hypertension in 13(43.3%)pts, 4 (13.3%)pts had hyperplasia of the thyroid gland.Two patients (6,6%) experienced the following diseases: bronchiectasis, angina pectoris, and cardiac arrhythmia.Other diseases (such as degenerative spinal diseases and alcoholism) were in individual cases.Secondary malignancies were in 4 (13.3%)pts, and all were previously cured by a radical operational approach.A solitary finding was more frequent radiographic presentation in our patients (61.3%), while atypical lesions (21%) pts and metastatic process (17.7%) were less present ( the type B1 thymoma.All were smokers except one patient, with the 1-year survival rate despite chemotherapy and RT treatment after relapse of the disease.One patient had a relapse after one year, he was a smoker with preoperative stage II, type B3 thymoma.The operation was carried out again as well as chemotherapy and RT, with the 5-year survival rate.Two patients had a relapse of the disease after five years.The relapse of the disease occurred in two patients after 5 years, one patient was a smoker with preoperative stage III, type B3 thymoma and the 10-year survival rate, while the other patient was a nonsmoker, initially stage II of the disease, with type A thymoma, with the 5-year survival rate.
Significant predictors of survival according to the Cox regression analysis are presented in table 5. Gender and clinical stage were significant predictor of longer survival.

Discussion
According to published data, thymomas are heterogeneous group of unfrequent thoracic tumors, with evidence of annual incidence from 1.3 to 3.2 per million 14 .The thymoma incidence is probably related to genetic risk factors because they are more common in Blacks and Asians/Pacific Islanders than in Whites and Hispanic 15 .There is little information about thymoma in the region of the Balkans including our country and Southern Europe too.Thymoma is the most common in the middle age and seventies patients, while in children and joung adults it is very rare 16,17 .Our study is one of the largest about thymoma cases in the Southeast Europe, and so far no similar studies have been conducted in the region.We found that there were more female than male patients (gender ratio 1.2 : 1) with thymoma, mostly in the seventies, but approximately the same number of patients was in the sixth decade of life too, about 30% each, which is confirmed by papers from different regions 5,14 , but there are a studies with different findings.Weis et al. 18 gave the results of the study which was focused on 4221 thymomas diagnosed between 1983 and 2012 with WHO histotype information from the ITMIG database presented with the aim to recognize the most important clinical features and to improve the options for treatment, due to rarity of the disease and lack of information from single centres.
According to this results, gender factor is not important (49% male and 51% female patients).Type A and AB patients were much older than type B1-3 patients.Concerning symptoms before the diagnosis was in our study, nearly half of the patients (46,7%), came for an examination in the period of the first 6 months from the appearance of symptoms, while the duration of symptoms of one month and more than one year were approximately alike, 26.7 and 25% respectively.Quick establishing of diagnosis is most probably due to obvious clinical symptoms which shown the existence of the tumor.Almost one third of the patients in our study were asymptomatic.Coughing dominated in more than one third of patients, followed by general weakness and chest pain in 35.5% of patients, while a small number of patients (4.8%) had dysphagia, and only one patient had both stridor and hoarseness, which shows that in most of the patients the disease was not in an advanced stage.Other complaints included nonspecific symptoms such as weight loss, fever, sweating, as well as hemoptysis and cardiac arrhythmia.Our experience is consistent with literature data.Chest pain, cough and dyspnoea are frequent symptoms of local compression on mediastinal structures, as well as hoarsness due to pressure on recurrent laryngeal nerve or phrenic nerve palsy, superior vena cava obstruction may be present too.
Presentation with pericardial or pleural effusions, as a signe of metastatic disease, is indicative of a poor prognosis.Our research does not differ from the analysis of the other centres in which it is stated that one third to one half of patients are diagnosed by incidence because they were asymptomatic and one third present with local symptoms 8 .In 40% of patients it is present paraneoplastic syndrome, such as a systemic and neurologic syndromes 19,20 .Above mentioned syndromes myasthenia gravis (MG) is well studied due to its frequence as it appears in 30-50% of patients, on the other hand 10-15% of MG patients are diagnosed with thymoma.Five percent of thymoma patients with MG can have several paraneoplastic syndrome 19 .In contrast, MG was less frequently observed among our patients(12.9%.).MG was more frequent among women, and only one patient of them had polyneuropathy.Neurological symptoms existed in just over half of our patients with paraneoplastic syndrome.Comorbidities were recorded in half (48,4%) of the patients, and mainly in women (70%).The most common was arterial hypertension (43.3% of the patients), and it can not be characterized as a predisponing disease or condition.Other chronic illnesses, such as hyperplasia of the thyroid gland, angina pectoris, and cardiac arrhythmia, were observed in fewer cases, while degenerative spinal diseases and alcoholism were represented in even smaller numbers.Diseases that represent a risk factor for the occurrence of malignant lung disease were present in two patients (6,6%) who had chronic obstructive disease.Secondary malignancies were found in 4 patients (13.3%) in our study, these patients have previously been cured of breast cancer (Ca), carcinoma of urinary bladder, skin Ca and uterine Ca.Some studies 21 conducted in single centers have shown that thymoma patients are under a high risk for cancer (lung, thyroid, prostate, lymphomas, sarcomas and leukemias etc), probably because of genetic risk factors or immune disorders.Besides this, environmental risk factors, as well as therapy for thymoma (as chemo/radiotherapy) are responsible for occurrence of the disease 22,23 .The influence of smoking history, secondary malignancies, particularly those caused by viruses as EBV on the occurrence of thymoma have not been clearly proven jet 24 .In our study, FNAB was performed as the invasive diagnostic procedure in a certain proportion of the patients (12.9%).That was a small number of patients who could not be operated due to extensive disease or because of the presence of comorbidities that represented a risk factor for the operation, which is in line with the attitudes in the literature 7 .In order to establish diagnosis of thymic tumors it is neccesary clinical examination, radiologic and PH findings.
Computed tomography (CT) scan is used to suspect the disease and to check up the patients during the treatment regimens 25 .MRI is very useful in pre-operative preparation in order to detect possible infiltration of the heart and great vessels 26 .PET scan is used to differ benign from malignant lesions.Cyto-histological diagnosis by biopsy is performed only if the tumor is unresectable 27,28 .Radiographic findings in our research showed that solitary tumors in the chest were more frequent, in two-thirds (61.3%) of the patients, than the other radiographic findings.Massive tumors larger than 5 cm were the most commonly present, occurring in more than half of the patients (58,1%).On the contrary, atypical lesions and metastatic process were significantly less present (21% and 17.7% of the patients respectively).All the patients had pathological findings on radiography.
pts had incomplete resection.In non-operated patients, other treatment modalities were applied: in 3.2% of patients, chemotherapy and RT were administered, and 4.8% of patients received BSC.Thymomas are rare tumors, so that for a long time there were no recommendations or guidelines for the treatment of these diseases, which is an explanation for the small amount of applied neoadjuvant/adjuvant chemotherapy and/or RT, as well as our patient series was analyzed for a period of 20 years since 1993.A statistically significant difference in survival was in patients who were operated compared to those who were not operated in our research, but there were no statistically significant differences in relation to whether the operation was radical compared to palliative.However, survival was longer in RO patients and the results are in agreement with studies conducted in other centers.16% of the RO patients experience relapse, of whom one woman is still alive.She was initially in stage II, with PH type A. Chemo and RT continued after the relapse of the disease and she has 10-year survival rate.In other patients, recurrence free survival was from 6 months in 4 patients to 5 years, with a survival time of 240 months.The survival rate after RO for thymoma is great.In the most comprehensive retrospective research of thymectomy for thymoma, 92% of patients had RO.The survival rate at both 5 and 10 years for stage I thymoma was 100%.Patients in stage II of the disease did nearly as well, with 5 year and 10 year survival rates of 98%.However, stage III patients exhibited a much lower survival rate compared to stage I and II patients, with 5-year survival rates of 89% and 10-year survival rates of 78%.Patients in stage IV manifested alike tendencies, approximately 5 year survival rates of 71% and 10 year survival rates of 47%.This shows that even patients with extensive disease can rich long-term survival rate that are not common in other malignancies 30 .If RO can not be accomplished at the time of surgery (either initially or after neoadjuvant chemotherapy), patients should undergo maximum debulking followed by postoperative chemotherapy/RT 46 .The operational approach has another important role: even in unresectable cases, explorative thoracotomy is recommended for establishing the diagnosis of thymoma, in terms to precisely define diagnosis and prevent disease dissemination due to invasive diagnostic procedures as fine needle aspiration biopsy.Due to the fact that usually the nature of this tumors is not aggressive in majority of the cases, even for the patients who were operated, the prolonged follow up is advisable, the authors are consistent in this statement.Locoregional recurrence is the most frequent one 47,48,49 but it can often be seen (≤92.0%) on the pleura 50,51 .Weis et al 18 noticed that the progression free survival is better in early stages and in type A and AB (recurrence rates, 1-2%) compared to B1 to B3 thymomas (2-7%).Whenever a relapse occurs, it is advised to retry the operation, followed by adjuvant therapy as RT or chemiotherapy or both, depending on stage of the disease 52 .Our study analyzed a small heterogeneous group of patients whose age ranges from 21 to 61 years, which have diverse smoking habits.
They differ in relation to the presence of comorbidity.All the PH findings and clinical stages of the disease were manifested in this patients.Given this small group of respondents, based on these findings, a general conclusion can not be drawn about the predisposing factors on the onset of disease relapse.However, according to conducted multicentre examinations, allows us to conclude: radicality of the operation, early stage of the disease and A~AB PH findings are the aspects that can influence better survival 38,41,42 .
The approach of chemotherapy in this chemosensitive tumors is quite complex.It can be applied in non-operative patients with extensive disease or with comorbidities wich prevent surgical approach, alone or combined with RT.In patients who are primarily non-operative, chemotherapy can decrease disease and thus a patient can become operative.In postoperative approach, chemothetrapy is administrated as adjuvant treatment together or without RT with the intention of preventing recurrence of the disease.Platinum based regimens are recommended.Some researches give advantage to antracyclines based regimens, and carboplatin/paclitaxel options in B3/C thymoma 53 .The patients with the advanced stage of the disease have benefits from postoperative RT (PORT) 54 .Although, findings are contradictory such as Boothe et al. that found that patients with thymic carcinoma and thymoma type A and AB have better results 55 .When the patient is not considered to be operative, RT is suggested along with chemotherapy 56 , where multidisciplinary atitude is needed.As thymoma patients have long term good prognosis, lung parenchyma and heart have to be protected during the RT.Recently, there has been an expansion of knowledge related to the molecular biology of thymoma, and this has led both, to the discovery of numerous significant mutations and to the consideration of therapeutic options related to thymoma genetics 57 as it is called personalized medicine.One of the most encouraging and recent treatment strategies, so-called checkpoint blockade, has been shown to block immunosuppression by using inhibitors against particular checkpoint receptors.There are a number of reports of favorable systemic responses to immunotherapy treatment 58 .If multiple studies justify the application of molecular therapy and immunotherapy in patients with thymomas, and these drugs are included in the treatment of these patients, it is likely that longer survival will be achieved while improving the quality of life of the patients, since the therapy is better tolerated and has less adverse effects.Final resolutions, according to our results, can not be made because we had a small and very heterogeneous group of patients with thymoma over a long, two-decade time interval in which attitudes to treatment approach were changed and supplemented, until finally played a major role in developing of the 8th edition of the TNM of thoracic malignancies (Table 7), which has been officially accepted by the Union of the international cancer control(UICC) and American joint committee of cancer (AJCC) and globally implemented in 2017, but the AJCC has delayed its implementation until 2018 59 .The new TNM staging (Table 7) may help to formalize resectability criteria 60 .The retrospective nature is one of the factors which influences the results of our research.In order to make important conclusions, which would improve the treatment of the patients, it is necessary to conduct the study in the countries of the region, ie the Balkans, as a multicentre study, and with cooperation with worldwide countries and thus to integrate findings.Further projects should intensify genomic explorations and establish data base for this patients.

Conclusion
Predictive factors of better survival in patients with thymoma in our study are early stage of the disease, non-invasive thymoma, younger age and operative treatment approaches.There is a need for further analysis of the dimension of the tumor mass as a predictive factor.
Timely detection of the disease with providing a timely therapy will prolong the overall survival of these patients, prolong the recurrence free survival and increase the number of cures.
the pericardium (partial or full-thickness)T3Direct invasion of the lung, the brachiocephalic vein, the superior vena cava, the chest wall, the phrenic nerve and/or hilar (extrapericardial) pulmonary vessels T4 Direct invasion of the aorta, arch vessels, the main pulmonary artery, the myocardium, the trachea or the oesophagus

Table 2
). Massive tumor, larger than 5 cm, verified by radiographic findings or /and during surgery, were the most commonly present in 58.1% of the patients.Noninvasive thymomas were the most common in 52.5% patients.A majority of the patients were in the stage I of the disease (46.5%), while This is the reason why the diagnosis is often established late, hence radical operation (RO) can not be implemented on time.Fukui et al. 29proved that the size of the tumor is one of the crucial prognostic factors in the prediction of better survival.In our analysis it was noted that the noninvasive thymomas were the most common, in half (52.5%) of the patients, while the invasive process in fatty tissue was observed in 18% of the patients, and metastatic disease in 29.5% patients.Recent researches proved rising occurence of metastases (MT) in the United States.For example, 17 cases were diagnosed in 1973, while in 2008, 90 cases were registered in the SEER database.Matthew et al. discovered that male population is more subject to the disease 30 .This is explained by Engels et al 15 who realised the influence of occupational exposure.Authors reported the presence of pleural and/or pericardial metastasis in 6.8% of all thymoma cases.Stage of the disease is one of the the main prognostic factors in thymoma patients, as an indicator of operability that represents a therapeutic approach with the highest probability of healing.Kaufman et al described that the ability to do RO for early stage disease is almost 100%, while in the third and fourth stages of the disease, the RO rate fluctuated considerably, what differs in the studies conducted due to the different location and degree of invasion of these tumors, as well as the difference in the strategic approaches to RO treatment of the medical centers 30 .Our analysis showed that a majority of the patients, nearly one half, were in stage I, while a remarkable variability in the proportion of stages, as specified by the Masaoka-Koga staging system, was noticed in stage II, III and IV.Vincenzo et al have found 31 that roughly 40% of thymomas are discovered while in the first stage, while 25% each are in the second and third stages, 10% at stage IVa and 1%-2% at stage IVb.Invasion into mediastinal tissue (in stages II and III) occurs in 50% of thymomas.Pleural invasion is the most widespread, followed by pulmonary and pericardial invasion.About 30% of these cases involve the innominate vein or superior vena cava and 20% involve the phrenic nerve.Our Overall, almost two thirds of patients with thymoma had 10 years survival rate, and most of this patients were in stage I, as expected by literary data.Patients in stage I had the best survival rate in all of these categories (1-,2-,5-,10-years survival) as compared to other stages of the disease, which is in accordance with other centers studies.Statistically significantly longer survival was found in women compared to men.There was no statistically significant difference in survival compared to age, but longer survival was observed in patients under the age of 55.There was no statistically significant difference in survival in smokers compared to non-smokers.There is no precise data in the literature about smoking habits 33 .The presence of MG was not statistically significant in survival, but patients without MG had a better survival rate in comparison with those who had MG.Symptoms of MG help to detect the disease early, and that is way that the prognosis is better 37 .A statistically significant difference in survival was in patients who had a solitary tumor in the chest in our study, compared to atypical presentations of thymomas and metastatic disease, and in our analysis, the impact of tumor size was not of statistical significance to survival.But dimension of the tumor mass is approaching the conventional level of significance.This analysis did not differ from the literature data.Patients in our study with non-invasive thymomas had a analysis of PH findings shows that the most frequently present was type B1, followed by type A and type AB (equally represented in nearly a third of the patients), and finally types B3 and B2 were least represented.Margaritora et al. 32performed an analysis of 317 patients with thymomas, but some of them had a thymic carcinoma too, and discovered that the B2 variety of tumors were the most often noticed (in 57.5% of the cases), followed by the B1 variety (19.2% of the cases) and finally the AB variety (9.5% of the cases).Weis at al 18 in multicentre analysis proposed that difference was due to geography; the rate of occurrence of the type A thymoma is roughly the same in Europe as in the United States lower (90% in stages I-II).This result was similar to patients with a PH finding of AB when compared to thymomas of type B1 to B3 (38% of type B3 thymomas were in stage III).The median overall survival OS (Table3) in patients with thymoma was 204 months.Our results did not show an important connection between immunological disorders and secondary malignancies and survival, but some reaserch have shown that types A and AB thymoma have a low association with MG, whereas types B1 and B2 are more likely to be associated with MG, and thus may contribute to prognosis.Okumura et al 34 claimed that type A thymomas and type C carcinomas were not found in cases with MG, while types AB, B1, B2, and B3 were found in 6.8%, 40%, 55.6%, and 10% of the cases, respectively.In previously published studies, the impact of MG on the prognosis for thymoma is disputed.Initial studies seemed to indicate that the presence of MG signaled a poor prognosis.The latest publications appear to show that existence of MG may either not have an effect on the prognosis, or that these thymoma patients might have a more favorable prognosis35.The results of a study carried out byWang et al. in 2016suggest that MG has a positive impact on the long-term outcomes of thymoma 36 .Filosso et al. pointedto a link between MG and the early Masaoka stage.statistically significant better survival versus invasive in fat tissue and metastatic tumors.Patients in stage I had the best survival rate and the difference was statistically significant compared to patients in stages II, III, and IV.It is confirmed by our work that the Masaoka~Koga stage is the best prognostic predictor of survival . Correlation between the WHO classification and stage at diagnosis can best explain clinical features and prognostic factors of thymoma6,43,44.There was no statistically significant difference in survival in our study in relation to PH findings, although longer survival was registered in patients with thymoma type B versus AB and type A. Although it is still debatable, it has been concluded that the stage of the disease shows better outcome, inspite of the fact that many authors, including Carillo et al underlined that PH findings can also predict the survival rate: starting from type A to B3, prognostic factors are getting worse.Patients with the early stage of the disease are good candidates for RO, but this also depends on patient`s general condition and the presence of potential comorbidities 45 .As for treatment, in the group of patients analyzed in our Clinic, the most common was the operative approach (88.7% of patients),with the majority of patients (90.9%) completely operated, and 10.1%

Table 1 .
Basic characteristics of 62 patients with thymoma *Results are presented as number of patients (N) and percent (%) arithmetic mean (mean) and standard deviation (SD) Figure 1.Symptoms distribution in 62 patients with thymoma

Table 2 .
Clinical characteristics of 62 patients with thymoma

Table 4 .
Survival of 62 patients with thymoma, according to the different characteristics

Table 5 .
Significant predictors of survival, according to the Cox regression analysis