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The successes of neoadjuvant therapy for locally advanced rectal cancer, which can sometimes achieve significant tumor regression, suggests that the performance of total mesorectumectomy in certain categories of such patients may be excessive. The rapid development of minimally invasive surgical technologies designed to limit the trauma due to the intervention, reduce the risk of postoperative complications, improve the quality of life and increase the proportion of sphincter-preserving operations, initiated several studies investigating the results of local excision of irradiated tumors of rectal cancer. This review article considers the published results of such studies, the problems, and prospects of this surgical strategy. The search of scientific literature was carried out using the PubMed database.

Objective: to determine the predicting factors for the effectiveness of neoadjuvant treatment in colorectal cancer based on the analysis of overall and relapse-free survival, as well as the possibility of multiparametric magnetic resonance imaging (MRI) in stratifying patients into groups with favorable and unfavorable clinical course.Materials and methods. 112 patients who received preoperative chemoradiotherapy (n = 85) and chemoradiotherapy supplemented with neoadjuvant polychemotherapy (n = 27) followed by surgery were enrolled in retrospective study. To determine the most significant predicting factors and criteria for evaluating the effectiveness of treatment that affect overall and relapse-free survival, Kaplan–Meier estimator and Cox regression were used.Results. The relapse-free survival was significantly affected by the presence or absence of extramural venous invasion according to MRI (mrEMVI) (p = 0.0001), circumferential resection margin status according to pathomorphological data (pCRM) (p = 0.031), change in volume of tumor (mrVolumetric analysis) (p = 0.015), tumor regression grade according to MRI (mrTRG) (p = 0.017) and pathomorphological data (pTRG) (p = 0.038). Independent predictors of overall survival were: extramural venous invasion according to MRI (mrEMVI) (p = 0.0001), posttreatment N staging (p = 0.047) and tumor regression grade according to MRI (mrTRG) (p = 0.059). Based on the most significant MR criteria, a mathematical model was developed to predict the risk of relapse after neoadjuvant treatment.Conclusions. MRI allows stratifying patients into groups with a favorable and unfavorable prognosis at the preoperative stage and optimizing the management of patients after surgery taking into account pathomorphological data.

In this article are reviewed the most recent diagnostic methods for patients with probable and verified rectal cancer, in different stages of treatment. The importance of high quality visualization of rectal cancer, opportunities of magnetic resonance imaging in primary diagnosis and restaging of the disease after neoadjuvant chemotherapy, optimal examination methods and interpretation of images in routine are discussed.

Currently, combination therapy, including preoperative irradiation of the tumor and areas of regional lymphatic drainage, has become the standard for the treatment of patients with locally advanced rectal cancer. Methods for evaluating neoadjuvant therapy response are increasingly being introduced into the practice of specialized medical centers. However, the prognostic value of tumor regression grade remains unclear. The results of numerous studies presented in modern literature are contradictory, and their comparative analysis is extremely difficult because of the abundance of post-radiation regression classifications used. This review article reflects the current views on the role and ways of assessing the therapeutic pathomorphosis of rectal cancer after radiotherapy/chemoradiotherapy.

Extralevator abdominal-perineal extirpation of the rectum causes a vast perineal wound, which requires to be closed. The article considers different approaches to perineal wound repair including primary closure, mesh reconstruction and muscular flap reconstruction.

Photometric studies of the dwarf nova V503 Cygni have been conducted for 29 nights at the Crimean Astrophysical Observatory and at the Terskol Observatory during 2010. We detected none of the socalled “negative” superhumps observed previously in the quiet state and in ordinary (short) outbursts [1]. Instead, during the ordinary outbursts and in a superoutburst and for some time after its termination, we recorded “positive” superhumps. At other times outside the outbursts we have for the first time detected oscillations in the brightness at the orbital period of 0.077760(3) days that have not been observed photometrically before.

The results of surgical treatment of 169 patients with R0 combined resections performed in the period from 2000 to 2005 due to advanced stomach cancer were analyzed. The postoperative morbidity rate was 31,4 ± 3,3%, postoperative mortality rate was- 7,1 ± 1,0%. The overall 5-year survival rate was 24,1 ± 3,1%, median of survival was 16 months. The categories of patients with R0 resections which have not improved the treatment long-term results were identified. This requires a differentiated surgical treatment for patients with advanced stomach cancer

We analyze photometry of the dwarf nova MN Dra carried out using various instruments at four observatories on 18 nights between May 20 and June 28, 2009. The observations cover a variety of activity states of the system: a superoutburst, three normal outbursts, and quiescence. Analysis of the system’s light curve during the superoutburst decline reveals positive superhumps that recur, on average, with a period of 0.105 days and are due to the direct apsidal precession of the accretion disk. These are observed until the end of the superoutburst, but their period decreases at a rate of −24.5 × 10−5 of the period per period. Both the positive-superhump period and its derivative are in good agreement with estimates made during previous superoutbursts. At the brightness minimum and in normal outbursts, MN Dra displays brightness variations with a period of 0.096 days, whose amplitude is much larger during the brightness minimum (0.8m–1.5m) than during normal outbursts (0.1m–0.2m). We suggest that these brightness variations could be negative superhumps due to nodal precession of the oblique accretion disk.

Continuing the project described by Kato et al. (2009, PASJ 61, S395, arXiv:0905.1757), we collected times of superhump maxima for 51 SU UMa-type dwarf novae mainly observed during the 2010-2011 season. Although most of the new data for systems with short superhump periods basically confirmed the findings by Kato et al. (2009) and Kato et al. (2010, PASJ 62, 1525, arXiv:1009.5444), the long-period system GX Cas showed an exceptionally large positive period derivative. An analysis of public Kepler data of V344 Lyr and V1504 Cyg yielded less striking stage transitions. In V344 Lyr, there was prominent secondary component growing during the late stage of superoutbursts, and the component persisted at least for two more cycles of successive normal outbursts. We also investigated the superoutbursts of two conspicuous eclipsing objects: HT Cas and the WZ Sge-type object SDSS J080434.20+510349.2. Strong beat phenomena were detected in both objects, and late-stage superhumps in the latter object had an almost constant luminosity during the repeated rebrightenings. The WZ Sge-type object SDSS J133941.11+484727.5 showed a phase reversal around the rapid fading from the superoutburst. The object showed a prominent beat phenomenon even after the end of the superoutburst. A pilot study of superhump amplitudes indicated that the amplitudes of superhumps are strongly correlated with orbital periods, and the dependence on the inclination is weak in systems with inclinations smaller than 80 deg., Comment: 87 pages, 92 figures, Accepted for publication in PASJ, correction in the author list and text

We carried out the photometric observations of the SU UMa-type dwarf nova ER UMa during 2011 and 2012, which showed the existence of persistent negative superhumps even during the superoutburst. We performed two-dimensional period analysis of its light curves by using a method called "least absolute shrinkage and selection operator" (Lasso) and "phase dispersion minimization" (PDM) analysis, and we found that the period of negative superhumps systematically changed between a superoutburst and the next superoutburst. The trend of the period change can beinterpreted as reflecting the change of the disk radius. This change of the disk radius is in good agreement with the predicted change of the disk radius by the thermal-tidal instability (TTI) model. The normal outbursts within a supercycle showed a general trend that the rising rate to maximum becomes slower as the next superoutburst approaches. The change can be interpreted as the consequence of the increased gas-stream flow onto the inner region of the disk as the result of the tilted disk. Some of the superoutbursts were found to be triggered by a precursor normal outburst when the positive superhumps appeared to develop. The positive and negative superhumps co-existed during the superoutburst. The positive superhumps were prominent only during four or five days after the supermaximum, while the signal of the negative superhumps became strong after the middle phase of the superoutburst plateau. A simple combination of the positive and negative superhumps was found to be insufficient in reproducing the complex profile variation. We were able to detect the developing phase of positive superhumps (stage A superhumps) for the first time in ER UMa-type dwarf novae. Using the period of stage A superhumps, we obtained a mass ratio of 0.100(15), which indicates that ER UMa is on the ordinary evolutional track of CVs., PASJ accepted

Continuing the project described by Kato et al. (2009a, arXiv:0905.1757), we collected times of superhump maxima for SU UMa-type dwarf novae mainly observed during the 2012-2013 season. We found three objects (V444 Peg, CSS J203937 and MASTER J212624) having strongly positive period derivatives despite the long orbital period (Porb). By using the period of growing stage (stage A) superhumps, we obtained mass ratios for six objects. We characterized nine new WZ Sge-type dwarf novae. We made a pilot survey of the decline rate of slowly fading part of SU UMa-type and WZ Sge-type outbursts. The decline time scale was found to generally follow the expected Porb^(1/4) dependence and WZ Sge-type outbursts also generally follow this trend. There are some objects which show slower decline rates, and we consider these objects good candidates for period bouncers. We also studied unusual behavior in some objects, including BK Lyn which made a transition from an ER UMa-type state to the novalike (standstill) state in 2013 and unusually frequent occurrence of superoutbursts in NY Ser and CR Boo. We applied least absolute shrinkage and selection operator (Lasso) power spectral analysis, which has been proven to be very effective in analyzing the Kepler data, to ground-based photometry of BK Lyn and detected the dramatic disappearance of the signal of negative superhumps in 2013. We suggested that the mass-transfer rates did not vary strongly between the ER UMa-type state and novalike state in BK Lyn, and this transition was less likely caused by a systematic variation of the mass-transfer rate., 83 pages, 95 figures, accepted for publication in PASJ

Continuing the project described by Kato et al. (2009, arXiv:0905.1757), we studied 86 SU UMa-type dwarf novae. We confirmed the general trends such as the relation between period derivatives and orbital periods. There are some systems showing positive period derivatives despite the long orbital periods. We observed the 2011 outburst of the WZ Sge-type dwarf nova BW Scl, and recorded an O-C diagram similar to those of previously known WZ Sge-type dwarf novae. The WZ Sge-type dwarf nova OT J184228.1+483742 showed an unusual pattern of double outbursts composed of an outburst with early superhumps and one with ordinary superhumps. We propose an interpretation that a very small growth rate of the 3:1 resonance due to an extremely low mass-ratio led to a quenching of the superoutburst before the ordinary superhumps appeared. We studied ER UMa-type dwarf novae and found that V1159 Ori showed positive superhumps similar to ER UMa in the 1990s. The recently recognized ER UMa-type object BK Lyn dominantly showed negative superhumps, and its behavior was very similar to the present-day state of ER UMa. The pattern of period variations in AM CVn-type objects were very similar to short-period hydrogen-rich SU UMa-type dwarf novae, making them helium analogue of hydrogen-rich SU UMa-type dwarf novae. SBS 1108+574, a peculiar hydrogen-rich dwarf nova below the period minimum, showed a very similar pattern of period variations to those of short-period SU UMa-type dwarf novae. The mass-ratio derived from the detected orbital period suggests that this secondary is a somewhat evolved star whose hydrogen envelope was mostly stripped during the mass-exchange. CC Scl, MASTER OT J072948.66+593824.4 and OT J173516.9+154708 showed only low-amplitude superhumps with complex profiles. These superhumps are likely a combination of closely separated two periods., Comment: 81 pages, 92 figures, PASJ in press, correction in the author list and text

We report on a discovery of “negative” superhumps during the 2011 January superoutburst of ER UMa. During the superoutburst, which started on 2011 January 16, we detected negative superhumps having a period of 0.062242(9) d, shorter than its orbital period by 2.2%. No evidence of a positive superhump was detected during this observation. This finding indicates that the disk exhibited retrograde precession during this superoutburst, contrary to all other known cases of superoutbursts. The duration of this superoutburst was shorter than those of ordinary superoutbursts, and the interval of its normal outbursts was longer than those of ordinary normal outbursts of ER UMa. We suggest the possibility that such unusual outburst properties are likely to be a result of a disk tilt, which is supposed to be a cause of negative superhumps; the tilted disk could prevent the disk from being filled with materials in the outmost region, which is supposed to be responsible for long-duration superoutbursts in ER UMa-type dwarf novae. This discovery signifies the importance of the classical prograde precession in sustaining long-duration superoutbursts. Furthermore, the presence of pronounced negative superhumps in this system with a high mass-transfer rate supports the hypothesis that hydrodynamical lift is the cause of the disk tilt.