Low-complexity and low-latency equalization technique - probabilistic noise cancellation.

Both inside data centers (DCs) and in short optical links between data centers (DC campuses), intensity-modulation and direct-detection (IMDD) systems using four-level pulse amplitude modulation (PAM4) will dominate this decade due to low transceiver price and power consumption. The next DC transceiver generation based on 100 Gbaud PAM4 will require advanced digital signal processing (DSP) algorithms and more powerful forward error correction (FEC) codes. Because of bandwidth limitations, the conventional DC DSP based on a few-tap linear feed-forward equalizer (FFE) is likely to be upgraded to more complex but still low-complexity Volterra equalizers followed by a noise whitening filter and either a maximum likelihood sequence estimation (MLSE) or a maximum a posteriori probability (MAP) algorithm. However, stringent power consumption and latency requirements may limit the use of complex algorithms such as decision feedback equalizer (DFE) or MLSE/MAP in DC networks (DCN). In this paper, we introduce a low-complexity, low-latency algorithm based on a feedforward structure, yielding a performance between DFE and MLSE. We call the novel equalization algorithm probabilistic noise cancellation (PNC), since it weights noise patterns based on their probabilities in the presence of bandwidth limitations. The probabilistic weighting is efficiently exploited in correcting correlated errors caused by noise coloring in the FFE.

Experimental demonstration of advanced modulation formats for data center networks on 200 Gb/s lane rate IMDD links.

This work contributes experimental demonstrations and comprehensive comparisons of various modulation and coding techniques for 200 Gb/s intensity modulation and direct detection links including four-level pulse amplitude modulation (PAM-4), PAM-6, trellis-coded modulation (TCM) over PAM and discrete multi-tone (DMT) transmission. Both C-band Mach-Zehnder modulator and O-band electro-absorption modulated laser transmitters were examined for intra-data center applications based on state-of-the-art commercial components.

Correlation between multiple cerebral aneurysms and a rare type of segmental duplication of the middle cerebral artery.

BACKGROUND: Connection between the duplication of the middle cerebral artery (DMCA) and the presence of multiple aneurysms has been described in a small number of cases. CASE PRESENTATION: The presence of a rare type of DMCA associated with cerebral aneurysms was diagnosed in 56 year old woman after a rupture of an aneurysm on the dorsal segment of the DMCA. .. The presence of equal diameters of branches of the DMCA and anterior cerebral artery (ACA) could be recorded as trifurcation of the carotid internal artery (ICA). However, due to the anastomosis of the DMCA branches in the area of the M2 segment, the recorded anatomical change represented a segmental duplication of MCA. Three aneurysms that were directly related to the segmental DMCA were diagnosed. CONCLUSIONS: Anatomical variation by type of segmental DMCA is a rare subtype of DMCA. The presence of multiple aneurysms associated with this type of anatomical variation in MCA indicates their high hemodynamic instability.

Association between Circle of Willis Configuration and Rupture of Cerebral Aneurysms.

Background and Objectives: Intracranial hemorrhage caused by the rupture of brain aneurysms occurs in almost 10 per 100,000 people whereas the incidence of such aneurysms is significantly higher, accounting for 4-9%.Linking certain factors to cerebral aneurysm rupture could help in explaining the significantly lower incidence of their rupture compared to their presence. The aim of this study is to determine the association between the corresponding circle of Willis configurations and rupture of cerebral aneurysms. MATERIALS AND METHODS: A group of 114 patients treated operatively for aruptured cerebral aneurysm and a group of 56 autopsied subjects were involved in the study. Four basic types of the circle of Willis configurations were formed-two symmetric types A and C, and two asymmetric types B and D. RESULTS: A statistically significantly higher presence of asymmetry of the circle of Willis was determined in the group of surgically-treated subjects (p = 0.001),witha significant presence of asymmetric Type B in this group (p < 0.001). The changeson the A1 segment in the group of surgically-treated subjects showed a statistically significant presence compared to the group of autopsied subjects (p = 0.001). Analyzing the presence of symmetry of the circle of Willis between the two groups, that is, the total presence of symmetric types A and C, indicated their statistically significant presence in the group of autopsied patients (p < 0.001). CONCLUSIONS: Changes such as hypoplasia or aplasia of A1 and the resulting asymmetry of the circle of Willis directly affect the possibility of the rupture of cerebral aneurysms. Detection of the corresponding types of the circle of Willis after diagnostic examination can be the basis for the development of a protocol for monitoring such patients.

Long-lasting undetected neurocysticercosis.

Neurocysticercosis is the most common parasitic disease of the nervous system, nevertheless, it can remain undetected for a long period of time, especially if it occurs in non endemic areas and regions with low-endemicity. Inadequate diagnostic procedures and lack of clinician's dedication towards this health issue can lead to a missed diagnose. Herein, we present a case of a 51-year-old male, with a missed diagnosis of neurocysticercosis for more than two decades. A history of epilepsy had started twenty-one years earlier and was of unclear etiology. Recently, after neurological worsening and headaches, brain computed tomography and magnet resonance imaging was performed as well as Western blot immunoassay of serum and cerebrospinal fluid, surgery, and pathohistological examination of the extracted cysts. Neurocysticercosis was confirmed. Combined therapy that consisted of albendazole and prednisolone was administered for a period of four weeks. Also, antiepileptic therapy was continued. Both clinical status and brain imaging showed the apparent improvement in the patient's condition. Review of the literature was implemented in the discussion that deals with proper and adequate therapy option and outcome factors in neurocysticercosis patients. Over a long period of time, the majority of patients develop seizures as the most common symptom, which requires the administration of medications. Proper diagnostic procedures and adequate combination of surgery and conservative treatment areessential.

Nonlinearity mitigation of intensity modulation and coherent detection systems.

Coherent optical communication systems are still too expensive for metro and short reach networks in the near future. Coherent detection with an intensity modulator replacing a costly dual-polarization in-phase and quadrature modulator could offer a good trade-off between cost and performance for metro networks. The major performance limit of such systems is the nonlinearity. To the best of our knowledge, this Letter offers the first known investigation on nonlinearity of a high speed intensity modulation and coherent detection system using an integrated laser and electro-absorption modulator. Advanced nonlinearity mitigation digital signal processing (DSP) are proposed including a 2×1 multiple-input single-output complex transversal Volterra feed-forward equalizer (FFE) filter, a first proposed post-FFE noise cancellation filter taking into account both pre- and post-cursor noise correlations based on a simple autocorrelation coefficient calculation, and a maximum likelihood sequence estimator. The receiver DSP needs no carrier and phase recovery that is required by a conventional coherent receiver DSP. Results show that, compared to a simple linear FFE equalization, the proposed nonlinear DSP enables over 8 and 4 dB improvement in optical signal to noise ratio (OSNR) sensitivity at 7% overhead hard-decision feed-forward error correction (FEC) and 20% overhead soft-decision FEC threshold bit error rates (BERs), respectively, for a 56 Gb/s intensity modulation and coherent detection system. To the best of our knowledge, a record 18 dB OSNR sensitivity at a hard-decision FEC threshold BER of 3.8×10-3 is also achieved.

Spontaneous chronic subdural hematoma in elderly people - Arterial hypertension and other risk factors.

BACKGROUND: The risk factors implicated in the genesis of chronic subdural hematomas include old age, alcoholism, diabetes mellitus, arachnoid cysts, coagulopathy, anticoagulant (ACTh) and antiplatelet drugs. However, no study has reported an association between arterial hypertension (HTA) and chronic subdural hematomas. Therefore, the aim of this study was to investigate whether HTA is a risk factor for spontaneous chronic subdural hematomas (SCSDHs). METHODS: This multicenter study included patients aged over 60 years and was conducted from January 2009 to the end of 2015. One hundred and twenty-two patients with SCSDHs and 111 controls treated for other reasons with no evidence of intracranial hemorrhages on brain computed tomography were enrolled. The patients were separated into three age subgroups to provide a better insight into the role of risk factors with age. RESULTS: The average age in the SCSDH group was 74.45 ± 8.16 years, compared to 71.28 ± 6.69 years in the control group. The SCSDH group was significantly older than the control group (p = 0.0014). The patients in the 60-69 years age group diagnosed with SCSDHs had significantly higher rates of HTA (p = 0.0519), ACTh treatment (p = 0.0292) and alcoholism (p = 0.0300) than the control group. The patients in the 70-79 years age group diagnosed with SCSDHs had significantly higher rates of HTA (p = 0.0071) and ACTh treatment (p = 0.0158) than the control group. In the subgroup of patients older than 80 years, there were no statistical differences. CONCLUSION: The incidence of HTA had borderline significance in the patients aged 60-69 years with SCSDHs and statistical significance in the patients aged 70-79 years with SCSDHs. Anticoagulant therapy was the most significant risk factor. Among the patients with SCSDHs aged 60-69 years, the percentage of heavy drinkers was significantly higher than in the control group.

Partial response signaling for improved chromatic dispersion tolerance in intensity modulation optical transmissions.

We investigate partial response signaling (PRS) as a way of increasing the transmission length achievable by direct detection optical systems. The performance of the duobinary and PRS modulations is evaluated against that of conventional on-off-keying (OOK). We prove by simulation and experimentally that duobinary increases the link distance by up to 1.5 times and PRS by up to 3 times, when no signal processing is employed. The gain is preserved even when equalization is used. PRS is employed also with 4-level pulse-amplitude modulation (PAM-4) and is shown to improve the transmission distance by almost 3 times.

Single-lane 180 Gb/s DB-PAM-4-signal transmission over an 80 km DCF-free SSMF link.

We experimentally demonstrate the generation and successful transmission of a single-lane 180 Gb/s (90 GBd) duo-binary four-level pulse-amplitude modulation (DB-PAM-4) signal over an 80 km standard single-mode fiber with a net data-rate of 150 Gb/s, enabled by a dual-drive Mach-Zehnder modulator-aided dispersion pre-compensation. A net data rate of 168 Gb/s is also achievable, for ranges up to 40 km. To mitigate bandwidth limitations and error spreading, pre-coded DB-PAM-4 is used; the pre-coding provides a gain of approximately 1 dB. A Volterra filter and a maximum likelihood sequence estimator are used at the receiver side to reduce the linear and nonlinear distortions.

Cost-effective single-lane 112 Gb/s solution for mobile fronthaul and access applications.

We experimentally demonstrate the possibility of transmitting 112 Gb/s PAM-4 signals over 30-km standard single-mode fibers with commercial 20-GHz components. The impact on system performance of three different equalization schemes-feed-forward equalizer (FFE), Volterra filter (VF), and maximum likelihood sequence estimator (MLSE)-is investigated and compared. We prove that the |x| and x|x| components of the VF can efficiently reduce the chirp-induced signal skew distortion, and that an MLSE with only four states can be used to remove the error floor. In contrast, the performance of FFE is worse than that of VF with a 4-state MLSE, even when a 64-state MLSE is used.

Transmission of single lane 128 Gbit/s PAM-4 signals over an 80 km SSMF link, enabled by DDMZM aided dispersion pre-compensation.

Direct detection systems with advanced modulation schemes are of great importance in metropolitan networks, because of their low cost and low power requirements. In particular, PAM-4 has attracted considerable attention, but has significant transmission distance limitations in the C-band. To extend its reach, we used a dual drive Mach-Zehnder modulator to generate a chromatic dispersion (CD) pre-compensated signal with an extra (j-1) multiplication to align the optical carrier and the modulated optical signal; by doing so, we achieved successful 128 Gbit/s transmission over an 80 km SSMF link, the longest reported reach of single lane 100 Gbit/s PAM-4 signals over DCF-free links. Synchronized bandwidth pre-compensation was also used, to reduce the influence of bandwidth-limitations.

Single-lane 180 Gbit/s PAM-4 signal transmission over 2 km SSMF for short-reach applications.

We experimentally demonstrate the generation and transmission of a single-lane 180 Gbit/s (90 GBaud) four-level pulse-amplitude modulation (PAM-4) signal in an intensity-modulation direct-detection system with a 7.5 GHz 3 dB bandwidth. The generated signal is transmitted over a 2 km standard single-mode fiber with, to the best of our knowledge, the highest reported net data rate in the C-band: 150 Gbit/s. A net data rate of 168 Gbit/s is also reachable with 1 km reach. The PAM-4 and duobinary (DB) PAM-4 modulation schemes are compared; the obtained results show that DB-PAM-4 significantly outperforms PAM-4 in the considered strong bandwidth-constrained system. Both a feed-forward equalizer and a maximum-likelihood sequence estimator are investigated for data recovery.

Apparent diffusion coefficient in the evaluation of cerebral gliomas malignancy.

BACKGROUND/AIM: Magnetic resonance imaging (MRI) is a key modality not only for lesion diagnosis, but also to evaluate the extension, type and grade of the tumor. Advanced MRI techniques provide physiologic information that complements the anatomic information available from conventional MRI. The aim of this study was to determine whether there is a correlation between apparent diffusion coefficient (ADC) maps of intracranial glial tumors and histopathologic findings and whether ADCs can reliably distinguish low-grade from high-grade gliomas. METHODS: This retrospective study included 25 patients with MRI examination up to seven days before surgery, according to the standard protocol with the following sequences: T1WI, T2WI, FLAIR, DWI and post contrast T1WI. Data obtained from DW MRI were presented by measuring the value of ADC. The ADC map was determined by utilizing Diffusion-Perfusion (DP) Tools software. All the patients underwent surgical resection of the tumor. Histological diagnosis of tumors was determined according to the World Health Organization (WHO) classification. The ADC values were compared with the histopathologic findings according to the WHO criteria. RESULTS: The ADC values of astrocytomas grades I (0.000614 +/- 0.000032 mm2/s) were significantly higher (< 0.001) than the ADC values of anaplastic astrocytomas (0.000436 +/- 0.000016 mm2/s) and the ADC values of glioblastomas multiforme (0.000070 +/- 0.000008 mm2/s). The ADC values of astrocytomas grades II (0.000530 +/- 0.000114 mm2/s) were significantly higher (< 0.001) than the ADC values of anaplastic astrocytomas (0.000436 +/- 0.000016 mm2/s) and glioblastomas multiforme (0.000070 +/- 0.000008 mm2/s). The ADC values of anaplastic astrocy-omas (0.000436 +/- 0.000016 mm2/s) were significantly higher (< 0.001) than the ADC values of glioblastomas multiforme (0.000070 +/- 0.000008 mm2/s). The ADC values in the cystic part of the tumor for astrocytomas grades I (0.000775 +/- 0.000023 mm2/s) were significantly higher (< 0.001) than the ADC values of anaplastic astrocytomas (0.000119 +/- 0.000246 mm2/s) and glioblastomas multiforme (0.000076 +/- 0.000004 mm2/s). The ADC values astrocytomas grades II (0.000511 +/- 0.000421 mm2/s) were significantly higher (< 0.001) than the ADC values of glioblastomas multiforme (0.000076 +/- 0.000004 mm2/s). CONCLUSION: DWI with calculation of ADC maps can be regarded as a reliable useful diagnostic tool, which indirectly reflects the proliferation and malignancy of gliomas. The ADCs maps can both predict the results of histopathological tumor and distinguish between low- and high-grade gliomas, and provide significant information for presurgical planning, treatment and prognosis for patients with high-grade astrocytomas.

Adverse Effects of Pharmacological Therapy of Benign Prostatic Hyperplasia on Sexual Function in Men.

INTRODUCTION: The development of effective medications makes pharmacological therapy of BPH the dominant mode of treatment today. It improves urinary symptoms and prevents disease progression while producing side effects on male sexual function. OBJECTIVE: The aim of the study is to present the effects of BPH pharmacological treatment on the occurrence of sexually adverse effects in men: changes in sexual desire, erectile, ejaculatory and the orgasmic function. METHODS: A prospective study involving 156 BPH patients.The average age was 61.16 ± 2.97. Four groups of 39 patients each were formed.The 4 groups were administered tamsulosin (alpha-blocker), finasteride (5-alpha reductase inhibitor), combination therapy (tamsulosin and finasteride) respectively, while the control group received no treatment. PSS-QoL, IIEF and MSHQ-EjD questionnaires were used to evaluate the symptoms of voiding and sexual function. Follow-up examinations were performed 3 and 6 months into treatment. RESULTS: Voiding symptoms improved in all groups receiving therapy. The side effects on the sexual function in all these groups include significant disorders of ejaculation and the orgasmic function. Ejaculation disorders: tamsulosin (-4.38 ± 2.55; p < 0.001), combined therapy (-3.89± 2.84) and finasteride (-1.49 ± 2.52). Orgasmic function disorders: tamsulosin (-1.03 ± 1.94), combined therapy (-0.76 ± 2.07) and finasteride (-0.54 ± 1.68). Complete absence of ejaculation was experienced by 23% of patients on combined therapy, 15% on tamsulosin and 5% on finasteride. CONCLUSION: Pharmacological therapy of BPH improved voiding symptoms producing different effects on male sexual function. The main adverse effect on sexual function in men is the deterioration in ejaculation or the absence thereof. Clinical consideration of BPH should include the elements of male sexual function, patients' age, the characteristics and effects of each group of drugs.

Improvement of sexual function in men with benign prostatic hyperplasia by pharmacologic therapy.

INTRODUCTION: Benign prostatic hyperplasia (BPH) causes disorders of voiding and sexual function. Phar- macologic therapy reduces symptoms of voiding thus impacting sexual function. OBJECTIVE: To determine sex life status in men with BPH before and after pharmacologic treatment adapted to achieve satisfactory sexual function. METHODS: We studied 117 sexually active BPH patients, not previously treated for BPH. After clinical examinations, symptoms of voiding, sexual and ejaculatory function were measured using standardized IPSS, IIEF and MSHQ-EjD questionnaires. After obtaining patients' personal opinion about the importance of their sex life, therapy was chosen and possible side effects explained. Three groups of 39 patients each were formed.The first group was treated with alpha-blocker, tamsulosin, the second with 5-alpha reductase inhibitor, finasteride, while the third group was administered a combination therapy. The complete examination procedure was repeated after 3 and 6 months of therapy. RESULTS: The average age of patients was 61.34 ± 3.04 years. Eighty-seven percent reported that their sex life was important to a certain degree. Satisfaction with their sex life was reported by 47% of patients before treatment and by 67% of respondents 6 months after treatment. Questionnaire scores indicated general improvement of sexual function in all groups, which was statistically significant compared to baseline only in the group on tamsulosin alpha-blocker (2.95 ± 7.81; p = 0.028). The overall satisfaction with sex life as a component of sexual function, improved significantly in the group on the combined therapy (0.78 ± 1.81; p = 0.012). CONCLUSION: Before BPH treatment sexual function should be assessed and therapy customized to the patient's expectations. Side effects of drugs should be presented especially to patients who emphasize the importance of sex life. In the manifested stages of the disease overall satisfaction with sex life may be improved by combined therapy comprising 5-alpha reductase inhibitors and third generation alpha blockers. In earlier stages, BPH alpha blockers monotherapy may improve overall sexual function.

De novo mutation in the NOTCH3 gene causing CADASIL.

Cerebral autosomal dominant arteriopathy with subcortical infarcts and leucoencephalopathy (CADASIL) is one of the most common hereditary forms of stroke, and migraine with aura, mood disorders and dementia. CADASIL is caused by mutations of the NOTCH3 gene. This mutation is inherited as an autosomal dominant trait. Most individuals with CADASIL have a parent with the disorder. In extremely rare cases, CADASIL may occur due to a spontaneous genetic mutation that occurs for unknown reasons (de novo mutation). We report a new case of patient with de novo mutation of the NOTCH3 gene and a condition strongly suggestive of CADASIL (migraine, stroke, and white matter abnormalities), except that this patient did not have any first-degree relatives with similar symptoms.

A rare case of retroperitoneal malignant Triton tumor invading renal vein and small intestine.

INTRODUCTION: Malignant Triton tumor is a very rare malignant peripheral nerve sheath tumor with rhabdomyosarcomatous differentiation. Most of those tumors occur in patients with von Recklinghausen's disease or as a late complication of irradiation and commonly seen in the head, neck, extremities and trunk. CASE REPORT: We reported retroperitoneal malignant Triton tumor in a 57-year-old female patient. Skin lesions were not present, and there was no family history of neurofibromatosis or previous irradiation. The presented case is one of a few recorded in the specialized literature that occurs in the retroperitoneal space in sporadic form. In this case, tumor consisted of a multilobular mass was in close relation with the abdominal aorta and inferior vena cava and involved the renal vein with gross invasion of the small intestine. The patient underwent total resection of the tumor and left nefrectomy was performed. The small intestine 10 cm in length was also resected and end-to-end anastomosis was conducted. The postoperative course was uneventful and the patient was discharged from the hospital ten days after the surgery. CONCLUSION: Diagnostically, it is crucial to recognize this uncommon histological variant because malignant Triton tumor has a worse prognosis than classic malignant peripheral nerve sheath tumor does. The use of the immunohistochemistry is essential in making the correct diagnosis. Only appropriate pathological evaluation supported by immunostaining with S-100 protein and desmin confirmed the diagnosis. Aggressive surgical management treatment improves the prognosis of such cases with adjuvant radiotherapy.

Giant renal oncocytoma.

BACKGROUND: Renal onkocytoma is a distinctive benign tumor derived from epithelial cells of the distal renal tubules. These tumors are often clinically asymptomatic, diagnosed accidentally and difficult to distinguish from renal cell carcinoma. CASE REPORT: We presented a giant renal onkocytoma in a man aged 64, without any signs or symptoms of the urogenital system disorder. The preoperative diagnosis described the tumor mass of the right kidney, size 16 x 14 cm, and indicated a malignant tumor of kidney. The patient underwent radical nephrectomy. The tumor was encapsulated at the intersection with the characteristic central hyaline scar. Microscopically, it was built of uniform polygonal cells with abundant eosinophilic cytoplasm. Immunohystochemiclly, tumor cells were immunoreactive to CK AE1/AE3 and CD 117, but showed negative immunoreactivity to CK 7, RCC marker and Vimentin. CONCLUSION: Giant renal oncocytomas are rare tumors with benign clinical course. As a rule, they are discovered by accident. Clinical differentiation from malignant tumors of the kidney is not possible. They are treated surgically, mainly by radical nephrectomy. A definitive diagnosis is made only by histopathological examination of tumors using immunohistochemical marker panels.

Presence of anatomical variations of the circle of Willis in patients undergoing surgical treatment for ruptured intracranial aneurysms.

BACKGROUND/AIM: The presence of aneurysmal changes on the brain blood vessels has been subject to numerous research. This study investigated the relation between ruptured aneurysms and anatomical configuration of the Circle of Willis, with the purpose to obtain an insight into their mutual connection. METHODS: The analysis included 114 patients suffering from ruptured intracranial aneurysms. Preoperative cerebral angiography was performed and compared with the intraoperative findings in order to attain a precise insight into morphological changes occurring on the circle of Willis. RESULTS: The prevalence of asymmetrical Willis in the whole group of patients was 64%. Within the group of patients suffering from multiple aneurysms, the presence of asymmetrical Willis' circle was 75.7%. The highest incidence of the asymmetrical Circle of Willis was found among patients with aneurysmal rupture detected at the anterior comunicative artery (ACoA) site (72.7% among cases with solitary and 100% among those with multiple aneurysms). Morphological changes on the A1 segment of ACoA were observed in 50 (44%) cases, with higher incidence found on the right side (60%). When comparing location of ruptured aneurysms between genders, a statistically significant prevalence of the ruptured aneurisms on ACoA was present in men, whereas women showed higher incidence of ruptured aneurysms on interior cartid artery (ICA) site (p < 0.01). The linkage between aneurysms with hypoplasia of the A1 segment of ACA and decreasing of the angle at which segments A1 and A2 join suggests the relationship between their onset, corresponding configuration type of Willis and subsequent hemodynamic changes. CONCLUSION: High incidence of asymmetry of Willis circle in the group of patients with ruptured aneurysms imply association of asymmetrical configuration and disorder in haemodynamic relations with forming and rupture of intracranial aneurysms.

[Relation of serum prostate-specific antigen and the Gleason grade in patients with prostatic carcinoma]. / Odnos serumskog prostata specificnog antigena i Glisonovog gradusa kod bolesnika sa karcinomom prostate.

The prostatic adenocarcinoma is one of the most frequent malignant tumors of men over 50 years of age. It is distinguished by aggressive clinical course and heterogeneous multifocal histomorphologic changes. PSA is the most reliable serum marker in diagnostics and observation of prostatic carcinoma, and Gleason's system of tumor-diferentiation grading is generally accepted way of determining the histologic grade. Gleason's system is correlated with serum levels of PSA and with biological behaviour of the tumor. We presented 40 patients with verified ACP in whom the level of serum PSA, Gleason's grade and score were compared. Highly significant correlation was found between serum level of PSA and the differentiation grade of the tumor--Gleason's grade and score. Combination of PSA parameters and Gleason's score enables correct estimation of tumor's behaviour and correct therapeutic protocol.