Context:The colorectal cancer (CRC) is the most common malignancy between men and women. CRC has considerable morbidity and mortality, with more than 1000,000 new cases and 500,000 annual deaths. Regional lymph nodes are most common sites of metastasis from colon cancer. Lymph node involvement is an essential factor in enabling the accurate evaluation of prognosis in CRC patients.Aims:In this study, we focused on the frequency of CRC and involved lymph nodes and adequacy of lymph node dissection in patients who referred to the Oncology and Radiotherapy Department of Golestan Hospital in Ahvaz City located in South-West Iran.Setting and Design:We conducted a retrospective study among patients receiving surgical treatment for CRC in the Department of Oncology and Radiotherapy of Golestan Hospital in Ahvaz City located in South-West Iran between 2001 and 2010.Methods and Materials:All patients who underwent resection for CRC by open or laparoscopic approaches were included in the study. Data were collected from patients’ medical records.Statistical Analysis Used:Statistical data were analyzed using SPSS 21.Results:A total of 585 cases with CRC aged from16 to 89 years with mean age of 53-year-old were studied. Average number of dissected nodes was 8 lymph nodes, and lymph nodes were not found in pathology specimen of 61 cases (10.4%). In 199 patients (34.01%), number of dissected lymph nodes was 12 or more and in 386 patients (65.98%), number of dissected lymph nodes was <12.Conclusion:This study revealed a large amount of patients that had been under over treatment with radiotherapy and the following inability. Lack of removal of sufficient tissue by the surgeon during surgery or an inadequate sample check by a pathologist might lead to an inability to correct staging of the disease as well as the inability to determine the treatment program of the patients and over treatment with radiotherapy and chemotherapy.

Nowadays, in most radiotherapy departments, the commercial treatment planning systems (TPS) used to calculate dose distributions needs to be verified; therefore, quick, easy‐to‐use, and low‐cost dose distribution algorithms are desirable to test and verify the performance of the TPS. In this paper, we put forth an analytical method to calculate the phantom scatter contribution and depth dose on the central axis based on the equivalent square concept. Then, this method was generalized to calculate the profiles at any depth and for several field shapes — regular or irregular fields—under symmetry and asymmetry photon beam conditions. Varian 2100 C/D and Siemens Primus Plus linacs with 6 and 18 MV photon beam were used for irradiations. Percentage depth doses (PDDs) were measured for a large number of square fields for both energies and for 45° wedge, which were employed to obtain the profiles in any depth. To assess the accuracy of the calculated profiles, several profile measurements were carried out for some treatment fields. The calculated and measured profiles were compared by gamma‐index calculation. All γ–index calculations were based on a 3% dose criterion and a 3 mm dose‐to‐agreement (DTA) acceptance criterion. The γ values were less than 1 at most points. However, the maximum γ observed was about 1.10 in the penumbra region in most fields and in the central area for the asymmetric fields. This analytical approach provides a generally quick and fairly accurate algorithm to calculate dose distribution for some treatment fields in conventional radiotherapy.PACS number: 87.10.Ca

Background:In the past, GRID therapy was used as a treatment modality for the treatment of bulky and deeply seated tumors with orthovoltage beams. Now and with the introduction of megavoltage beams to radiotherapy, some of the radiotherapy institutes use GRID therapy with megavoltage photons for the palliative treatment of bulky tumors. Since GRID can be a barrier for weakening the photoneutrons produced in the head of medical linear accelerators (LINAC), as well as a secondary source for producing photoneutrons, therefore, in terms of radiation protection, it is important to evaluate the GRID effect on photoneutron dose to the patients.Methods:In this study, using the Monte Carlo code MCNPX, a full model of a LINAC was simulated and verified. The neutron source strength of the LINAC (Q), the distributions of flux (φ), and ambient dose equivalent (H*[10]) of neutrons were calculated on the treatment table in both cases of with/without the GRID. Finally, absorbed dose and dose equivalent of neutrons in some of the tissues/organs of MIRD phantom were computed with/without the GRID.Results:Our results indicate that the GRID increases the production of the photoneutrons in the LINAC head only by 0.3%. The calculations in the MIRD phantom show that neutron dose in the organs/tissues covered by the GRID is on average by 48% lower than conventional radiotherapy. In addition, in the uncovered organs (by the GRID), this amount is reduced to 25%.Conclusion:Based on the findings of this study, in GRID therapy technique compared to conventional radiotherapy, the neutron dose in the tissues/organs of the body is dramatically reduced. Therefore, there will be no concern about the GRID effect on the increase of unwanted neutron dose, and consequently the risk of secondary cancer.

Systemic administration of nitrite anion seems to be a practical way to produce local burst of nitric oxide, a hypoxic cell radiosensitizer in solid tumors. This randomized controlled pilot study assessed radiologic objective response rate (ORR) in patients suffered from brain metastases treated by whole-brain radiotherapy (WBRT) concurrent with intravenous infusion of sodium nitrite versus WBRT alone. Twenty patients were randomized into the following groups: Ten patients treated by WBRT (30 Gy in ten fractions over 2 weeks) concomitant with 2-hour intravenous infusion of sodium nitrite (267 µg/kg/h) before each fraction of radiation (WBRT + SN arm) and ten patients received the same schedule of WBRT, alone (control arm). ORR was measured according to response evaluation criteria in solid tumors (RECIST version 1.1). There were four radiologic objective responses in WBRT + SN arm compared with three in the control group without significant statistical difference (P = 1.00). In contrast, age ≤ 65 years (P = 0.05) and presence of extra-cranial metastases (P = 0.01) were predictor factors of ORR. In conclusion, intravenous infusion of sodium nitrite with this dose and schedule to patients with brain metastases concurrent with radiotherapy did not show any major benefit in terms of radiologic response.

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