Is Robotic Assisted Colorectal Cancer Surgery Equivalent Compared to Laparoscopic Procedures during the Introduction of a Robotic Program? A Propensity-Score Matched Analysis.

BACKGROUND: Robotic surgery represents a novel approach for the treatment of colorectal cancers and has been established as an important and effective method over the last years. The aim of this work was to evaluate the effect of a robotic program on oncological findings compared to conventional laparoscopic surgery within the first three years after the introduction. METHODS: All colorectal cancer patients from two centers that either received robotic-assisted or conventional laparoscopic surgery were included in a comparative study. A propensity-score-matched analysis was used to reduce confounding differences. RESULTS: A laparoscopic resection (LR Group) was performed in 82 cases, and 93 patients were treated robotic-assisted surgery (RR Group). Patients' characteristics did not differ between groups. In right-sided resections, an intracorporeal anastomosis was significantly more often performed in the RR Group (LR Group: 5 (26.31%) vs. RR Group: 10 (76.92%), p = 0.008). Operative time was shown to be significantly shorter in the LR Group (LR Group: 200 min (150-243) vs. 204 min (174-278), p = 0.045). Conversions to open surgery did occur more often in the LR Group (LR Group: 16 (19.51%) vs. RR Group: 5 (5.38%), p = 0.004). Postoperative morbidity, the number of harvested lymph nodes, quality of resection and postoperative tumor stage did not differ between groups. CONCLUSION: In this study, we could clearly demonstrate robotic-assisted colorectal cancer surgery as effective, feasible and safe regarding postoperative morbidity and oncological findings compared to conventional laparoscopy during the introduction of a robotic system.

Are risk factors for anastomotic leakage influencing long-term oncological outcomes after low anterior resection of locally advanced rectal cancer with neoadjuvant therapy? A single-centre cohort study.

PURPOSE: Anastomotic leakage (AL) poses the most serious problem following low anterior resection in patients with rectal cancer independent of surgical approach or technique. The aim of this study was to evaluate risk factors for the occurrence of AL and how they affect the oncological long-term outcome of patients who received neoadjuvant therapy. METHODS: A single centre cohort study of 163 consecutive locally advanced rectal cancer patients (cT3, cT4, N +) that received neoadjuvant therapy followed by resection with primary anastomosis between January 1998 and December 2020 were included in this study. Short- and long-term findings were compared between patients with AL (Leakage +) and without AL (Leakage -). RESULTS: A complete follow-up was obtained from 163 patients; thereby, 33 patients (20%) developed an AL. We observed more patients with comorbidities (38% vs. 61%, p = 0.049) which developed a leakage in the course. Permanent stoma rate (36% vs. 18%, p = 0.03) was higher, and time between primary operation and stoma reversal was longer (219 days [172-309] vs. 93 days [50-182], p < 0.001) in this leakage group as well. Tumour distance lower than 6 cm from the anal verge (OR: 2.81 [95%CI: 1.08-7.29], p = 0.04) and comorbidities (OR: 2.22 [95%CI: 1.01-4.90], p = 0.049) was evaluated to be independent risk factors for developing an AL after rectal cancer surgery. Oncological outcome was not influenced by AL nor by other associated risk factors. CONCLUSION: We could clearly detect the distance of tumour from the anal verge and comorbidities independent risk factors for the occurrence of AL. Oncological findings and long-term outcome were not influenced by these particular risk factors.

Short- and Long-Term Outcome of Laparoscopic- versus Robotic-Assisted Right Colectomy: A Systematic Review and Meta-Analysis.

Background: There is a rapidly growing literature available on right hemicolectomy comparing the short- and long-term outcomes of robotic right colectomy (RRC) to that of laparoscopic right colectomy (LRC). The aim of this meta-analysis is to revise current comparative literature systematically. Methods: A systematic review of comparative studies published between 2000 to 2021 in PubMed, Scopus and Embase was performed. The primary endpoint was postoperative morbidity, mortality and long-term oncological results. Secondary endpoints consist of blood loss, conversion rates, complications, time to first flatus, hospital stay and incisional hernia rate. Results: 25 of 322 studies were considered for data extraction. A total of 16,099 individual patients who underwent RRC (n = 1842) or LRC (n = 14,257) between 2002 and 2020 were identified. Operative time was significantly shorter in the LRC group (LRC 165.31 min ± 43.08 vs. RRC 207.38 min ± 189.13, MD: −42.01 (95% CI: −51.06−32.96), p < 0.001). Blood loss was significantly lower in the RRC group (LRC 63.57 ± 35.21 vs. RRC 53.62 ± 34.02, MD: 10.03 (95% CI: 1.61−18.45), p = 0.02) as well as conversion rate (LRC 1155/11,629 vs. RRC 94/1534, OR: 1.65 (1.28−2.13), p < 0.001) and hospital stay (LRC 6.15 ± 31.77 vs. RRC 5.31 ± 1.65, MD: 0.84 (95% CI: 0.29−1.38), p = 0.003). Oncological long-term results did not differ between both groups. Conclusion: The advantages of robotic colorectal procedures were clearly demonstrated. RRC can be regarded as safe and feasible. Most of the included studies were retrospective with a limited level of evidence. Further randomized trials would be suitable.

Thoracoscopic resympathectomy for persistent or recurrent palmar hyperhidrosis: single-center experience.

BACKGROUND: In case of recurrence or persistent palmar hyperhidrosis, a sympathetic chain resection is suggested, however, many surgeons are still reluctant to offer further intervention because of the inability to predict the efficacy of such a procedure. We analyzed our large series of resympathectomy. METHODS: Substantive retrospective analysis of 39 patients underwent a resympathectomy (minimally invasive bilaterally sympathetic chain Th2-3 resection). Patients referred from other hospitals or primarily operated at our institution for recurrence or persistence palmar hyperhidrosis were included in the study group. RESULTS: No intraoperative complications were detected. Reoperation or chest tube positioning was necessary in 2 patients. Twenty-eight patients had a positive response (excellent or good results). Seven patients described a substantial, but not sufficient, reduction of the symptomatology. Four patients were very unsatisfied and regretted the operation. CONCLUSIONS: Resympathectomy is highly effective procedure for patients who have persistent or recurrent symptoms. However, the indication of the operations should be more dissuasive as possible to avoid the risk of any undesirable psychologically side effects.

Incidence and risk factors for umbilical incisional hernia after reduced port colorectal surgery (SIL + 1 additional port)-is an umbilical midline approach really a problem?

PURPOSE: Umbilical midline incisions for single incision- or reduced port laparoscopic surgery are still discussed controversially because of a higher rate of incisional hernia compared to conventional laparoscopic techniques. The aim of this study was to evaluate incidence and risk factors for incisional hernia after reduced port colorectal surgery. METHODS: A total 241 patients underwent elective reduced port colorectal surgery between 2014 and 2020. Follow-up was achieved through telephone interview or clinical examination. The study collective was examined using univariate and multivariate analysis. RESULTS: A total of 150 patients with complete follow-up were included into this study. Mean follow-up time was 36 (IQR 24-50) months. The study collective consists of 77 (51.3%) female and 73 (48.7%) male patients with an average BMI of 26 kg/m2 (IQR 23-28) and an average age of 61 (± 14). Indication for surgery was diverticulitis in 55 (36.6%) cases, colorectal cancer in 65 (43.3%) patients, and other benign reasons in 30 (20.0%) cases. An incisional hernia was observed 9 times (6.0%). Obesity (OR 5.8, 95% CI 1.5-23.1, p = 0.02) and pre-existent umbilical hernia (OR 161.0, 95% CI 23.1-1124.5, p < 0.01) were significant risk factors for incisional hernia in the univariate analysis. Furthermore, pre-existent hernia is shown to be a risk factor also in multivariate analysis. CONCLUSION: We could demonstrate that reduced port colorectal surgery using an umbilical single port access is feasible and safe with a low rate of incisional hernia. Obesity and pre-existing umbilical hernia are significant risk factors for incisional hernia.

Does intraoperative flexible endoscopy offer any benefit compared to conventional air leak testing after circular stapled left-sided laparoscopic colon surgery?

BACKGROUND: Anastomotic leakage is still a feared complication after left-sided colonic resections. Various types of "anastomotic leak testing methods" are described in current literature. In this study we evaluated the use of intraoperative flexible endoscopy in comparison to conventional air leak testing after performing a circular stapled anastomosis in left-sided laparoscopic colon surgery. METHODS: A retrospective database consisting of 130 patients with left sided colonic resections between 01/2015 and 12/2019 at our hospital was evaluated. After performing a circular stapled anastomosis flexible endoscopy was done in 69 cases, 61 patients were controlled with a conventional air leak test. Intraoperative and postoperative complications were recorded and retrospectively evaluated. RESULTS: In the flexible endoscopy group, we observed complications in 13,04%, in the conventional air leak testing group in 9.83%. Postoperative anastomotic leakage was observed in 10,14% in the flexible endoscopy group and 4.91% in the conventional air leak test group. In 10.14% a positive air leak test was seen in the flexible endoscopy group and 11.47% in the conventional air leak testing group. In those cases, we observed no postoperative complications in the first group, in the conventional group we had two anastomotic leakages and one infected haematoma. CONCLUSIONS: In the case of a positive air leak, flexible endoscopy offered a more exact detection of the leak. In those cases, no anastomotic leakage was observed postoperatively. In our opinion, flexible endoscopy should be recommended for testing the anastomosis intraoperatively in every left-sided colon surgery.

Reduced port versus open right hemicolectomy for colorectal cancer: a retrospective comparison study of two centers.

PURPOSE: The concept of complete mesocolic excision (CME) in right-sided colorectal cancer is well known for open and laparoscopic surgery. The aim of this study was to evaluate and compare perioperative and oncological outcomes of reduced port and open surgery for right-sided colorectal cancer. METHODS: One hundred forty-one patients received elective surgery for right-sided colonic cancer between January 2015 and December 2019 and were included in a retrospective database. RESULTS: We observed longer operation time in the RP-CME group (145 min vs. 119.43 min, p<0.01). Hospital stay (8 days vs. 14 days, p<0.01) and time to first intestinal passage (42 h. vs. 59 h, p<0.01) were significantly shorter in the reduced port group. Postoperative complications were more likely to be observed in the O-CME group (7.2% vs. 14.1%, p=0.28); anastomotic leakage rate was low in both groups (1.8% vs. 2.4%, p=1.00). Specimen scores (score 1= good: 93.8% vs. 91.7%, p=1.00) and average number of retrieved lymph nodes were comparable (24 vs. 23 p=0.69). In O-CME patients, we observed more advanced tumor stages (UICC III: 21.4% vs. 45.9%, p<0.01). CONCLUSION: To our knowledge, this is the first study comparing reduced port to open surgery for right-sided colorectal cancer. We could demonstrate that this technique is feasible for oncological right hemicolectomy with observation of shorter hospital stay and lower morbidity rates compared to open surgery. The oncological outcome did not differ in the present study.

Colorectal resection in endometriosis patients: correlation between histopathological findings and postoperative outcome.

INTRODUCTION: Endometriosis is associated with a high number of chronic pelvic pain and reduced quality of life. Colorectal resections in case of bowel involvement of endometriosis are associated with an unneglectable morbidity in young and healthy patients. There is no linear correlation established between the degree of symptoms and stage of endometriosis. The aim of this study was to correlate the histological findings to preoperative pain scores in colorectal resected patients with endometriosis. METHODS: Twenty-five patients who underwent laparoscopic colorectal resection for endometriosis between 2014 and 2019 were included in this retrospective study. Pain level was assessed preoperatively and postoperatively via phone call in May 2020. Histopathology was correlated to preoperative symptoms and postoperative outcome. RESULTS: Average follow-up time was 38.68 months (± 19.92). Preoperative VAS-score was 8.32 (± 1.70). We observed a significant reduction of pain level in all patients after surgery (p ≤ 0.005). Pain levels were equal regarding the presence of satellite spots and various degrees of infiltration depth. The resection margins were clear in all patients. Postoperative complications occurred in 6 cases (24%) and anastomotic leakage was observed in 3 patients (12%). Average VAS-score at time of follow-up was 1.70 (± 2.54). CONCLUSION: Our data demonstrate that adequate colorectal resection leads to reduction of pain and an increase of quality of life irrespective of histopathological findings. An experienced team is necessary to improve intraoperative outcome and to reduce postoperative morbidity in case of complication.

Reduced alpha diversity of the oral microbiome correlates with short progression-free survival in patients with relapsed/refractory multiple myeloma treated with ixazomib-based therapy (AGMT MM 1, phase II trial).

Alterations in the human microbiome have been linked to several malignant diseases. Here, we investigated the oral microbiome of 79 patients with relapsed/refractory multiple myeloma (MM) treated with ixazomib-thalidomide-dexamethasone. Increased alpha diversity (Shannon index) at the phylum level was associated with longer progression-free survival (PFS) (10.2 vs 8.5 months, P = .04), particularly in patients with very long (>75% quartile) PFS . Additionally, alpha diversity was lower in patients with progressive disease (P < .05). These findings suggest an interrelationship between the oral microbiome and outcome in patients with MM and encourage a novel direction for diagnostic and/or therapeutic strategies.

Impact of the COVID-19 pandemic on a visceral surgical department in western Austria.

BACKGROUND: The COVID-19 pandemic caused by the SARS-CoV­2 virus has strongly affected the visceral and thoracic surgery department in southern Vorarlberg in Austria, which comprises two locations: the focus hospital in Feldkirch and the regional hospital in Bludenz. METHODS: The complete lockdown lasted 6 weeks (from March 16 to April 26, 2020), after which the hospital in Bludenz started day surgery again and in Feldkirch the capacity was slowly increased. We compared how oncological and acute operations differed during those 6 weeks to the 6 weeks before lockdown. RESULTS: Our findings show a clear increase in emergency operations for acute cholecystitis (+133%) and acute appendicitis (+157%). While the acute operations increased, some oncological operations decreased, which was especially apparent for oncological colorectal resections (-66%) and oncological lung resections (-43%). CONCLUSION: This survey shows that due to the increased catchment area, more acute operations were performed and also demonstrated that we were confronted with more advanced stages of those diseases. Furthermore, cancer operations which rely on short-term peripheral diagnostics decreased considerably.

Quality of life in patients with relapsed/refractory multiple myeloma during ixazomib-thalidomide-dexamethasone induction and ixazomib maintenance therapy and comparison to the general population.

This trial evaluated quality of life (QoL) using the EORTC QLQ-C30 and the EORTC QLQ-MY20 instruments in 90 patients with relapsed/refractory multiple myeloma during induction and maintenance therapy with eight cycles of ixazomib-thalidomide-dexamethasone, followed by 12 months of ixazomib maintenance therapy. When patient's baseline QoL was compared with data of the general population, a significant impairment in health-related QoL, physical, role, and social functioning and several other dimensions, as well as more pain and fatigue, was noted. Induction therapy resulted in significant improvement of pain and worsening of neuropathy, with no significant variation of other parameters. During maintenance treatment, scores for most dimensions including health-related QoL, physical functioning and pain, improved, while for neuropathy no improvement was observed. Time to deterioration (≥10 score points) of health-related QoL, physical functioning, pain, and neuropathy was distinctly shorter than time to progression. Health-related QoL and physical functioning at baseline correlated with overall survival.

Ixazomib-Thalidomide-Dexamethasone for induction therapy followed by Ixazomib maintenance treatment in patients with relapsed/refractory multiple myeloma.

BACKGROUND: Ixazomib-revlimid-dexamethason showed significant activity in relapsed/refractory multiple myeloma (RRMM). Here, we evaluate ixazomib in combination with thalidomide and dexamethasone for induction treatment followed by ixazomib maintenance therapy in RRMM patients. METHODS: Ninety patients have been included. Ixazomib-thalidomide-dexamethasone (4 mg, day 1, 8, 15; 100 mg daily; and 40 mg weekly) was scheduled for eight cycles followed by maintenance with ixazomib for one year. RESULTS: The overall response rate was 51.1%, 23.3% achieved CR or VGPR and 10% MR resulting in a clinical benefit rate of 61.1%. In patients completing ≥2 cycles, the rates were 60.5%, 27.6% and 68.4%, respectively. Median progression-free survival (PFS) was 8.5 months in all, and 9.4 months in those completing ≥2 cycles. Response rates, PFS and overall survival (OS) were similar in patients with and without t(4;14) and/or del(17p), but PFS and OS was significantly shorter in patients with gain of 1q21. Multivariate regression analysis revealed gain of 1q21 as the most important factor associated with OS. Ixazomib maintenance resulted in an upgrade in the depth of response in 12.4% of patients. Grade 3/4 toxicities were relatively rare. CONCLUSIONS: Ixazomib-thalidomide-dexamethasone followed by ixazomib maintenance therapy is active and well tolerated in patients with RRMM. TRIAL REGISTRATION NUMBER: NCT02410694.

Impact of renal impairment on outcomes after autologous stem cell transplantation in multiple myeloma: a multi-center, retrospective cohort study.

BACKGROUND: Renal impairment (RI) is a negative prognostic factor in Multiple Myeloma (MM) and affected patients are often excluded from autologous stem cell transplantation (ASCT). However, it remains unclear whether historically inferior outcome data still hold true. METHODS: From a total of 475 eligible MM patients who had undergone ASCT between 1998 and 2016, 374 were included in this multi-centric retrospective cohort study. Renal function was determined both at the time of MM diagnosis and ASCT by estimated glomerular filtration rate (eGFR according to the MDRD formula, RI defined as eGFR < 60 ml/min/1.73m2). Patients were categorized into 3 groups: A) no RI diagnosis and ASCT, B) RI at diagnosis with normalization before ASCT and C) RI both at the time of diagnosis and ASCT. Log-rank testing was used for overall and progression-free survival (OS, PFS) analysis. CONCLUSION: While severe RI at MM diagnosis confers a risk of shorter OS, MM progression after ASCT is not affected by any stage of renal failure. It can be concluded that ASCT can be safely carried out in MM patients with mild to moderate RI and should be pro-actively considered in those with severe RI. RESULTS: When comparing all groups, no difference in OS and PFS was found (p = 0.319 and p = 0.904). After further stratification according to the degree of RI at the time of diagnosis, an OS disadvantage was detected for patients with an eGFR < 45 ml/min/m2. PFS was not affected by any RI stage.

Chemotherapy-induced thrombosis: a role for microparticles and tissue factor?

Chemotherapy is an independent risk factor of thromboembolic events in cancer patients. Various pathogenetic mechanisms have been hypothesized in the past, but until now their individual contribution to the risk of thrombosis has been hardly investigated in clinical trials. In recent years, studies increasingly suggested an association between the prothrombotic state in cancer patients and circulating tissue factor-exposing microparticles. In this review, we discuss the roles of tissue factor and microparticles with regard to chemotherapy-induced hypercoagulability.

1alpha,25-dihydroxyvitamin D3 downregulates CYP27B1 and induces CYP24A1 in colon cells.

The antimitotic and prodifferentiating 1alpha,25-dihydroxyvitamin D3 (1alpha,25-(OH)2D3), synthesized at various extrarenal sites could potentially prevent sporadic tumor development. Physiological regulation of extrarenal Vitamin D hydroxylases following tissue accumulation of 1alpha,25-(OH)2D3 is unknown. We therefore investigated basal and Vitamin D-regulated expression and activity of the synthesizing (CYP27B1) and metabolizing (CYP24A1) hydroxylase in three cell lines derived from the colon, and compared this to cells from the prostate and mammary gland. Our results show that all cells, irrespective of origin and differentiation, express CYP27B1 mRNA, whereas basal CYP24A1 mRNA is highly expressed only in undifferentiated cells. Treatment with 1alpha,25-(OH)2D3 diminishes CYP27B1 and Vitamin D receptor mRNA expression, but elevates CYP24A1 mRNA to equal levels in all cells. As shown by HPLC, CYP27B1 is active only if basal 24-hydroxylation is not maximally functional. In turn, accumulation of 1alpha,25-(OH)2D3 will induce 24-hydroxylation. We conclude that, although extrarenal and renal metabolic pathways for Vitamin D are similar, malignancy of tumor cells determines extent of Vitamin D catabolism.

A 24-phenylsulfone analog of vitamin D inhibits 1alpha,25-dihydroxyvitamin D(3) degradation in vitamin D metabolism-competent cells.

The antimitotic, prodifferentiating, and proapoptotic steroid hormone, 1alpha,25-dihydroxyvitamin D(3) [1alpha,25-(OH)(2)D(3)], at supraphysiological levels has potential for tumor therapy. However, epithelial cells from tumor-prone organs such as colon, prostate, and breast express not only the vitamin D receptor, but also vitamin D hydroxylases. In contrast to normal cells, malignant cells have high basal levels of the hydroxylase 25-hydroxyvitamin D(3)-24-hydroxylase (CYP24) and, in addition, have the potential to induce CYP24 in response to 1alpha,25-(OH)(2)D(3). Because 24-hydroxylation by CYP24 would rapidly degrade the steroid hormone in the course of therapy, the enzyme activity in tumor cells should be inhibited. We demonstrate that a 24-phenylsulfone analog of 1alpha,25-(OH)(2)D(3), KRC-24SO(2)Ph-1 (S-4a), rapidly and potently inhibits 24-hydroxylase activity in human tumor cells derived from colon, prostate, and mammary gland. Although enzymatic inhibition is a consequence of direct interaction, S-4a as a vitamin D analog apparently binds to the vitamin D receptor and induces CYP24 mRNA, which, however, is not translated into increased enzymatic activity. 25-Hydroxyvitamin D(3)-1alpha-hydroxylase expression is not affected at all by S-4a. When both 1alpha,25-(OH)(2)D(3) and S-4a are added to the cell culture, transcription of CYP24 is increased, possibly because of an increase in the half-life of the hormone. The colon cell line COGA-13 has very high levels of CYP24 and is, therefore, resistant to the action of vitamin D. Yet, S-4a imparts antimitotic activity to 1alpha,25-(OH)(2)D(3) and may therefore constitute a therapeutic to stimulate the antiproliferative potential of vitamin D-based antitumor activity.

Genistein and 17beta-estradiol, but not equol, regulate vitamin D synthesis in human colon and breast cancer cells.

Extrarenal synthesis of the active vitamin D metabolite 1,25-dihydroxyvitamin-D3 (1,25-D) has been observed in cells derived from human organs prone to sporadic cancer incidence. Enhancement of the synthesizing hydroxylase CYP27B1 and reduction of the catabolic CYP24 could support local accumulation of the antimitotic steroid, thus preventing formation of tumors of e.g., colon and breast. By applying quantitative RT-PCR and HPLC it was observed that in colon-(Caco-2) and breast-(MCF-7) derived cells, 17beta-estradiol and genistein induced CYP27B1 but reduced CYP24 activity, while equol was inactive. Mammary cells express both estrogen receptors (ER) a and beta, while colon cells express mainly ERbeta, possibly explaining why MCF-7 cells were more affected. These results indicate a potential, new approach for cancer prevention by counteraction of the 1,25-D-driven negative feedback, i.e., down-regulation of CYP27B1 and up-regulation of CYP24, which prevents its own local accumulation. However, mammary cells may be more susceptible to this than colonocytes.

The Vitamin D endocrine system of the gut--its possible role in colorectal cancer prevention.

While Vitamin D insufficiency in the US and European population is rising, epidemiological studies suggest an inverse correlation between low serum levels of 25-hydroxyvitamin D(3) (25-OH-D(3)) and colorectal cancer incidence. The antimitotic, prodifferentiating and proapoptotic active metabolite 1alpha,25-dihydroxyvitamin D(3) (1,25-(OH)(2)-D(3)) is synthesized also by colonocytes, since these possess Vitamin D synthesizing (CYP27B1) and catabolic (CYP24) hydroxylases similar to the kidney. Early during colon tumor progression, expression of CYP27B1 and of the Vitamin D receptor increases, suggesting an autocrine/paracrine growth control in colon tissue as a physiological restriction against tumor progression. However, in human adenocarcinomas expression of the catabolic CYP24 is also enhanced when compared with adjacent normal mucosa. Therefore, to maintain colonic accumulation of 1,25-(OH)(2)-D(3) its catabolism needs to be restricted. Our studies in mice show that low nutritional calcium causes hyperproliferation of colon crypts and significant elevation of CYP24 expression, which can be completely abrogated by soy feeding. We suggest that phytoestrogens in soy, known to be estrogen receptor modulators, are responsible for decreased CYP24 expression. These results and our observation that 17beta-estradiol can elevate CYP27B1 expression in rectal tissue of postmenopausal women, may underlie the observed protective effect of estrogens against colorectal cancer in females.

Epigenetic regulation of vitamin D hydroxylase expression and activity in normal and malignant human prostate cells.

It was previously suggested that the 25-Vitamin-D3-1alpha-hydroxylase (CYP27B1) is downregulated during human prostate tumor pathogenesis while the catabolic 25-Vitamin-D3-24-hydroxylase (CYP24) expression is increased. The latter could lead to resistance against the antimitotic, pro-differentiating activity of 1,25-dihydroxycholecalciferol. Our hypothesis was that regulation of Vitamin D hydroxylase expression during prostate tumor progression might be under epigenetic control. We demonstrate by real time RT-PCR that PNT-2 human normal prostate cells indeed possess CYP27B1, but are practically devoid of CYP24 mRNA, whereas DU-145 cancer cells have constitutive expression of CYP24, and very low levels of CYP27B1 mRNA. Treatment of PNT-2 cells with the methylation inhibitor 5-aza-2'-deoxycytidine together with the deacetylation inhibitor trichostatin A resulted in elevation of both CYP27B1 and CYP24 mRNA expression demonstrating that even in normal human prostate cells expression of Vitamin D hydroxylases may be under epigenetic control. In the DU-145 malignant cell line trichostatin A together with 5-aza-2'-deoxycytidine increased CYP27B1 mRNA expression to a smaller extent than in normal cells, however this resulted in a highly significant increase in 1alpha-hydroxylation capacity. This demonstrates for the first time that synthesis of 1,25-dihydroxycholecalciferol in human prostate tumors could be reinitiated by epigenetic regulators.