Predictors of poor cosmesis in breast cancer patients treated with adjuvant whole breast radiation therapy plus high-dose-rate interstitial brachytherapy boost after breast conservation surgery.

Purpose: To identify patient, tumor, and treatment-related factors, which predict cosmesis in breast cancer survivors treated with adjuvant whole breast irradiation (WBI) plus high-dose-rate (HDR) multicatheter interstitial brachytherapy (MIBT) boost after breast conservation surgery. Material and methods: At least 12 months after completion of radiotherapy, cosmetic outcomes were measured both objectively with BCCT.core software (using a front view digital photograph), and subjectively according to Harvard's criteria. MIBT dose fractionation regimen was 13.6 Gy/4 fractions (bid). To evaluate the correlation between cosmetic scores and dose-volume histogram (DVH) parameters, WBI and MIBT plans were retrospectively analyzed, and ipsilateral skin and breast biologically equivalent dosimetric indices were recorded (α/ß = 3 Gy). A multivariate ordinal logistic regression model was used for statistical analysis. Results: Twenty-eight consecutive patients were enrolled into this study. The median time from completion of radiation therapy to cosmesis scoring was 18 months. In evaluation with BCCT.core software, no patient was scored as excellent. Cosmesis was good in 18%, fair in 50%, and poor in 32% of patients. According to Harvard's scale, 10.5% of patients had excellent cosmesis, and 43%, 28.5%, and 18% of patients had good, fair, and poor scores, respectively. In univariate analysis, patients with higher absolute MIBT V29Gy (cc), those treated with irradiation of regional lymphatics (odds ratio ≈ 5), and patients with larger breast volumes had statistically significant lower Harvard's scores. In the multivariate model, none of the mentioned factors remained statistically significant, except for a trend for poorer cosmesis in patients with higher absolute MIBT V29Gy (p-value = 0.066). Conclusions: Based on the results of this study, MIBT breast V29Gy, regional nodal irradiation, and larger breast volumes are the potential factors, which could predict cosmesis.

The comparison of transforming growth factor beta-1 serum levels in early-stage breast cancer patients treated with external beam whole breast irradiation plus boost versus interstitial brachytherapy accelerated partial breast irradiation.

PURPOSE: Transforming growth factor beta-1 (TGF-ß1) is a profibrotic cytokine used as an early biomarker to develop radiation-induced fibrosis (RIF). This study aimed to compare TGF-ß1 serum levels in early-stage breast cancer patients treated with whole-breast radiation therapy (WBRT) plus boost versus accelerated partial breast irradiation (APBI) using multicatheter interstitial brachytherapy. METHODS AND MATERIALS: This clinical trial study was conducted on 20 women with early-stage breast cancer after breast-conserving surgery candidate for adjuvant radiotherapy in Golestan hospital, Ahvaz, in 2021. In one group APBI with high-dose-rate brachytherapy (n = 10), the other group WBRT with external beam radiation plus boost (n = 10) was performed. Serum level of TGF-ß1 was evaluated before radiotherapy, immediately after the end of radiotherapy and three months after the end of radiotherapy by Enzyme-linked immunosorbent assay technique (ELISA). RESULTS: Median serum TGF-ß1 level before radiotherapy was not significantly different between the two groups (p = 0.971). In both APBI and WBRT groups, serum TGF-ß1 levels significantly decreased immediately after radiotherapy compared to before treatment (p = 0.005 and p = 0.007, respectively); But three months after radiotherapy, serum TGF-ß1 levels increased significantly in the WBRT group (40.50 to 77.41 pg/mL; p = 0.017), while no significant change was observed in the APBI group (24.75 to 30.50 pg/mL; p = 0.332). CONCLUSIONS: Higher TGF-ß1 values in the WBRT group after radiotherapy can be used as an early and vital biomarker in this treatment, and this data may corroborate links between TGF-beta1 and fibrosis and fibrosis rates between APBI and WBRT; It also shows the preference for using the brachytherapy technique in this group of patients. However, due to the small number of samples, definitive conclusions require further prospective studies.

Evaluation of rectal volume correlation with dosimetric parameters during optimized intracavitary high-dose-rate brachytherapy in cervical cancer.

PURPOSE: Brachytherapy (BRT) is a cornerstone in cervical cancer treatment, with the ultimate goal to maximize the tumor dose while sparing organs at risk (OARs), such as rectum. Several studies evaluated the effect of rectal volume on rectal doses, but the results are inconsistent. This study aimed to evaluate the rectal volume and dose-volume histogram (DVH) relationship in high-dose-rate (HDR) brachytherapy in locally advanced cervical cancer. MATERIAL AND METHODS: Planning computed tomography of 65 patients who underwent HDR brachytherapy boost as a component of definitive radiotherapy from March 2016 to February 2018 were reviewed. OARs and target volume were re-delineated by a single physician to decrease interobserver variation. Two sets of plan were generated; in the first set, the dose was prescribed to point A with Manchester system loading pattern, while in the second set, the dose was prescribed to high-risk clinical target volume (HR-CTV) D90 with inverse planning optimization. The DVH values for rectum, sigmoid, and HR-CTV were generated and correlated with rectal or sigmoidal volume variation. RESULTS: Dose to 2cc (D2cc), 1cc (D1cc), and 0.1cc (D0.1cc) of rectum and sigmoid showed a significant decrease in optimization vs. point A planning (p < 0.0001). HR-CTV D90 coverage was significantly higher in optimization vs. point A planning (p = 0.041). Rectal volume showed a significant correlation with D2cc (rs, 0.302, p = 0.014), D1cc (rs, 0.310, p = 0.012), and D0.1cc (rs, 0.283, p = 0.02) of rectum in optimization planning. CONCLUSIONS: Larger rectal volumes are associated with higher rectal dose parameters during HDR brachytherapy using inverse planning optimization. This method spares OAR, while producing reasonable HR-CTV D90. Prospective studies are needed to find appropriate technique of rectal volume reduction.

Photoneutron Dose Estimation in GRID Therapy Using an Anthropomorphic Phantom: A Monte Carlo Study.

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.

Radiation sensitization with sodium nitrite in patients with brain metastases: a pilot randomized controlled trial.

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.

Analytical approach for determining beam profiles in water phantom of symmetric and asymmetric fields of wedged, blocked, and open photon beams.

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.