Evaluating the effect of tumor size and sidedness on prognosis in stage 2 colon cancer: a retrospective population study

OBJECTIVE

In this study, we aimed to evaluate the effect of tumor size and tumor sidedness on prognosis in patients with stage 2 colon cancer.

PATIENTS AND METHODS

Data of 501 patients diagnosed with stage 2 colon cancer were evaluated retrospectively. It was evaluated whether the patients' age, gender, tumor differentiation, tumor node metastasis (TNM) stage, overall survival rate, and disease-free survival rate had any correlation with horizontal tumor diameter and tumor sidedness. In the ROC analysis performed to determine the cut-off value for the tumor diameter, which we think will predict survival, no significant results were obtained with maximum sensitivity and specificity. Therefore, the median value of the tumor diameter, which is 5 cm, was accepted as the cut-off value.  Kaplan-Meier method and Cox regression analysis were used for survival analysis and determination of prognostic factors.

RESULTS

When the patients were evaluated in terms of tumor localization, 189 (37.7%) patients had right colon tumors and 312 (62.3%) patients had left colon tumors. There was no statistically significant difference in terms of disease-free survival and overall survival according to tumor localization. When the patients were analyzed by dividing them into two groups according to the horizontal tumor size (<5 cm and ≥5 cm), no statistically significant difference was found between the groups in terms of disease-free survival (DFS) and overall survival (OS) p=0.085, p=0.699, respectively.

CONCLUSIONS

Our results suggest that the management of patients with stage 2 colon cancer requires a better understanding of tumor biology rather than features such as tumor size and localization.

Effect of Tb3+ doping in mixed-valence manganites and cobaltites

The magnetic ordering of four Tb³⁺-doped manganites and cobaltites, La_0.7Tb_0.1Sr_0.2MnO₃, La_0.7Tb_0.1Ca_0.2MnO₃, La_0.7Tb_0.1Sr_0.2CoO₃ and La_0.7Tb_0.1Ca_0.2CoO₃, have been studied by means of neutron diffraction and SQUID magnetometry. All the samples were prepared by sintering of sol-gel precursors and their orthorhombic or rhombohedral perovskite structures at room and low temperatures were refined. A long-range ferromagnetic (FM) order was detected at the Mn and Co sites. In addition, a small but significant ordered moment was observed at A sites of studied cobaltites, which was attributed to local Tb³⁺ moments, aligned by exchange interactions due to FM ordered Co sublattice. No or minor Tb³⁺ contribution was detected in studied manganites.

Effect of Ising-type Tb3+ ions on the low-temperature magnetism of La, Ca cobaltite

Crystal and magnetic structures of the x = 0.2 member of the La0.8-xTbxCa0.2CoO3 perovskite series have been determined from powder neutron diffraction. Enhancement of the diffraction peaks due to ferromagnetic or cluster glass ordering is observed below TC = 55 K. The moments first evolve on Co sites, and ordering of Ising-type Tb(3+) moments is induced at lower temperatures by a molecular field due to Co ions. The final magnetic configuration is collinear Fx for the cobalt subsystem, while it is canted FxCy for terbium ions. The rare-earth moments align along local Ising axes within the ab-plane of the orthorhombic Pbnm structure. The behavior in external fields up to 70-90 kOe has been probed by magnetization and heat capacity measurements. The dilute terbium ions contribute to significant coercivity and remanence that both steeply increase with decreasing temperature. A remarkable manifestation of the Tb(3+) Ising character is the observation of a low-temperature region with an anomalously large linear term of heat capacity and its field dependence. Similar behaviors are detected also for other terbium dopings x = 0.1 and 0.3.

Distribution of cations in nanosize and bulk Co-Zn ferrites

The structural and magnetic properties of Co(1-x)Zn(x)Fe2O4 ferrites (Co-Zn ferrites) are investigated in a narrow compositional range around x = 0.6, which is of interest because of applications in magnetic fluid hyperthermia. The study by x-ray and neutron diffraction, Mössbauer spectroscopy and magnetization measurements is done on nanoparticles prepared by the coprecipitation method and bulk samples sintered at high temperatures. In spite of the known preference of Zn2+ for tetrahedral (A) sites and Co2+ for octahedral [B] sites, the cations are distributed nearly evenly over the two sites of spinel structure and there is also a variable number of [B] site vacancies (see text), making cobalt ions trivalent. In particular for x = 0.6, the cationic distribution is refined to [Formula: see text] and [Formula: see text] for the 13 nm particles (T(C) = 335 K) and bulk sample (T(C) = 351 K), respectively.

Core-shell La(1-x)Sr(x)MnO3 nanoparticles as colloidal mediators for magnetic fluid hyperthermia

Core-shell nanoparticles consisting of La(0.75)Sr(0.25)MnO(3) cores covered by silica were synthesized by a procedure consisting of several steps, including the sol-gel method in the presence of citric acid and ethylene glycol, thermal and mechanical treatment, encapsulation employing tetraethoxysilane and final separation by centrifugation in order to get the required size fraction. Morphological studies revealed well-separated particles that form a stable water suspension. Magnetic studies include magnetization measurements and investigation of the ferromagnetic-superparamagnetic-paramagnetic transition. Magnetic heating experiments in 'calorimetric mode' were used to determine the heating efficiency of the particles in water suspension and further employed for biological studies of extracellular and intracellular effects analysed by tests of viability.

Silica encapsulated manganese perovskite nanoparticles for magnetically induced hyperthermia without the risk of overheating

Nanoparticles of manganese perovskite of the composition La(0.75)Sr(0.25)MnO(3) uniformly coated with silica were prepared by encapsulation of the magnetic cores (mean crystallite size 24 nm) using tetraethoxysilane followed by fractionation. The resulting hybrid particles form a stable suspension in an aqueous environment at physiological pH and possess a narrow hydrodynamic size distribution. Both calorimetric heating experiments and direct measurements of hysteresis loops in the alternating field revealed high specific power losses, further enhanced by the encapsulation procedure in the case of the coated particles. The corresponding results are discussed on the basis of complex characterization of the particles and especially detailed magnetic measurements. Moreover, the Curie temperature (335 K) of the selected magnetic cores resolves the risk of local overheating during hyperthermia treatment.