Renatas Tikuišis

Dr. Renatas Tikuišis


Research Focus & Metrics

Academic Career Length

7Years (2020-Present)

(Calculated once Scilit publication data is synced: current year − year of first publication + 1)

Representative Publications

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11 February 2020 in Medicina
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JDJanina Didžiapetrienė
Janina Didžiapetrienė
BKBirutė Kazbarienė
Birutė Kazbarienė
RTRenatas Tikuišis
Renatas Tikuišis
Audrius DulskasAudrius Dulskas
Audrius Dulskas
DDDaiva Dabkevičienė
Daiva Dabkevičienė
VOValerijus Ostapenko
Valerijus Ostapenko
Background and Objectives: The purpose of this study is to evaluate the level of oxidative stress before and after breast cancer surgery. Materials and Methods: Malondialdehyde (MDA) level was tested using a thiobarbituric acid (TBA) assay based on the release of a color complex due to TBA reaction with MDA. The glutathione S-transferase (GST) activity was evaluated by enzymatic conjugation of reduced glutathione (GSH) with 1-chloro-2,4-dinitrobenzene. The level of total glutathione (reduced GSH and oxidized GSSG) was detected using a recycling system by 5,5-dithiobis(2-nitrobenzoic acid). The levels of the indices were determined in the serum of 52 patients before surgery, two hours and five days after surgery, and in 42 healthy women. Results: In the patients over 50 years old the level of MDA was higher after surgery in comparison with before surgery, and GST activity was lower in comparison with the control. The GSH + GSSG level in both ages groups after surgery was lower than in the control. Significant differences of MDA level were detected in patients with stage III after surgery compared to the control. The level of GSH + GSSG was significantly lower in the patients with I–III stages compared to the control. Conclusion: The most expressed changes demonstrate the significance of MDA as a marker to evaluate oxidative stress in breast cancer patients. The degree of oxidative stress depends on the patient’s age and stage of disease. (1) Malondialdehyde can be used as an oxidative stress marker; (2) A higher stage of the disease and older age correspond to a higher rise of malondialdehyde, suggesting more intensive oxidative stress.

9 November 2021 in Healthcare
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DDDaiva Dabkeviciene
Daiva Dabkeviciene
IVIeva Vincerzevskiene
Ieva Vincerzevskiene
VUVincas Urbonas
Vincas Urbonas
JVJonas Venius
Jonas Venius
Audrius DulskasAudrius Dulskas
Audrius Dulskas
SJSonata Jarmalaite
Sonata Jarmalaite
The pandemic spread of the COVID-19 virus significantly affected daily life, but the highest pressure was piled on the health care system. Our aim was to evaluate an impact of COVID-19 pandemic management measures on cancer services at the National Cancer Institute (NCI) of Lithuania. We assessed the time period from 1 February 2020 to 31 December 2020 and compared it to the same period of 2019. Data for our analysis were extracted from the NCI Hospital Information System (HIS) and the National Health Insurance Fund (NHIF). Contingency table analysis and ANOVA were performed. The COVID-19 pandemic negatively affected the cancer services provided by NCI. Reductions in diagnostic radiology (−16%) and endoscopy (−29%) procedures were accompanied by a decreased number of patients with ongoing medical (−30%), radiation (−6%) or surgical (−10%) treatment. The changes in the number of newly diagnosed cancer patients were dependent on tumor type and disease stage, showing a rise in advanced disease at diagnosis already during the early period of the first lockdown. The extent of out-patient consultations (−14%) and disease follow-up visits (−16%) was also affected by the pandemic, and only referrals to psychological/psychiatric counselling were increased. Additionally, the COVID-19 pandemic had an impact on the structure of cancer services by fostering the application of modified systemic anticancer therapy or hypofractionated radiotherapy. The most dramatic drop occurred in the number of patients participating in cancer prevention programs; the loss was 25% for colon cancer and 62% for breast cancer screening. Marked restriction in access to preventive cancer screening and overall reduction of the whole spectrum of cancer services may negatively affect cancer survival measures in the nearest future.

20 August 2021 in Journal of Clinical Medicine
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PBPaulius Bosas
Paulius Bosas
GZGintaras Zaleskis
Gintaras Zaleskis
DDDaiva Dabkevičiene
Daiva Dabkevičiene
NDNeringa Dobrovolskiene
Neringa Dobrovolskiene
AMAgata Mlynska
Agata Mlynska
FJFeliksas Jankevičius
Feliksas Jankevičius
Background: Prostate cancer (PCa) is known to exhibit a wide spectrum of aggressiveness and relatively high immunogenicity. The aim of this study was to examine the effect of tumor excision on immunophenotype rearrangements in peripheral blood and to elucidate if it is associated with biochemical recurrence (BCR) in high risk (HR) and low risk (LR) patients. Methods: Radical prostatectomy (RP) was performed on 108 PCa stage pT2–pT3 patients. Preoperative vs. postoperative (one and three months) immunophenotype profile (T- and B-cell subsets, MDSC, NK, and T reg populations) was compared in peripheral blood of LR and HR groups. Results: The BCR-free survival difference was significant between the HR and LR groups. Postoperative PSA decay rate, defined as ePSA, was significantly slower in the HR group and predicted BCR at cut-off level ePSA = −2.0% d−1 (AUC = 0.85 (95% CI, 0.78–0.90). Three months following tumor excision, the LR group exhibited a recovery of natural killer CD3 − CD16+ CD56+ cells, from 232 cells/µL to 317 cells/µL (p < 0.05), which was not detectable in the HR group. Prostatectomy also resulted in an increased CD8+ population in the LR group, mostly due to CD8+ CD69+ compartment (from 186 cells/µL before surgery to 196 cells/µL three months after, p < 001). The CD8+ CD69+ subset increase without total T cell increase was present in the HR group (p < 0.001). Tumor excision resulted in a myeloid-derived suppressor cell (MDSC) number increase from 12.4 cells/µL to 16.2 cells/µL in the HR group, and no change was detectable in LR patients (p = 0.12). An immune signature of postoperative recovery was more likely to occur in patients undergoing laparoscopic radical prostatectomy (LRP). Open RP (ORP) was associated with increased MDSC numbers (p = 0.002), whereas LRP was characterized by an immunity sparing profile, with no change in MDSC subset (p = 0.16). Conclusion: Tumor excision in prostate cancer patients results in two distinct patterns of immunophenotype rearrangement. The low-risk group is highly responsive, revealing postoperative restoration of T cells, NK cells, and CD8+ CD69+ numbers and the absence of suppressor MDSC increase. The high-risk group presented a limited response, accompanied by a suppressor MDSC increase and CD8+ CD69+ increase. The laparoscopic approach, unlike ORP, did not result in an MDSC increase in the postoperative period.

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NSNarimantas Evaldas Samalavicius
Narimantas Evaldas Samalavicius
ZKZygimantas Kuliesius
Zygimantas Kuliesius
Robertas Stasys SamalavičiusRobertas Stasys Samalavičius
Robertas Stasys Samalavičius
RTRenatas Tikuišis
Renatas Tikuišis
ESEdgaras Smolskas
Edgaras Smolskas
Audrius DulskasAudrius Dulskas
Audrius Dulskas
The aim of this study was to report overall experience, perioperative and long-term survival results in a single tertiary referral center in Lithuania with hand assisted laparoscopic surgery (HALS) for colorectal cancer. A prospectively maintained database included 467 patients who underwent HALS for left-sided colon and rectal cancer, from April 2006 to October 2016. All those operations were performed by three consultant surgeons and nine surgical residents, in all cases assisted by one of the same consultant surgeons. There were 230 (49.25%) females, with an average age of 64 ± 9.7 years (range, 26–91 years). The procedures performed included 170 (36.4%) anterior rectal resections with partial mesorectal excision, 160 (34.26%) sigmoid colectomies, 81 (17.35%) left hemicolectomies, 45 (9.64%) low anterior rectal resections with total mesorectal excision, and 11 (2.25%) other procedures. Stage I colorectal cancer was found in 140 (29.98%) patients, 139 (29.76%) stage II, 152 (32.55%) stage III and 36 (7.71%) stage IV. There were five conversions to open surgery (1.1%). The mean postoperative hospital stay was 6.9 ± 3.4 days (range, 1–30 days). In total, 33 (7.06%) patients developed postoperative complications. The most common complications were small bowel obstruction (n = 6), anastomotic leakage (n = 5), intraabdominal abscess (n = 4) and dysuria (n = 4). There were two postoperative deaths (0.43%). Overall, 5-year survival for all TNM stages was 85.7%, 93.2% for stage I, 88.5% for stage II and 76.3% for stage III. Hand assisted colorectal surgery for left-sided colon and rectal cancer in a single tertiary referral center was feasible and safe, having all the advantages of minimally invasive surgery, with good perioperative parameters, adequate oncological quality and excellent survival.