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Risk and Prognosis of Secondary Rectal Cancer After Radiation Therapy for Pelvic Cancer.

ABSTRACT: Background:The relationship between pelvic radiation therapy (RT) and second primary rectal cancer (SPRC) is unclear. The aim of this study was to assess the risk and prognosis of SPRC after pelvic RT. Materials and Methods:Data for patients who had primary pelvic cancer (PPC) between 1973 and 2016 were retrieved from the Surveillance, Epidemiology, and End Results (SEER) database. Multiple primary standardized incidence ratios (SIRs) were used to assess the risk of SPRC. Five-year overall survival (OS) and rectal cancer-specific survival (RCSS) were calculated using Kaplan-Meier curves. Results:A total of 573,306 PPC patients were included, 141,225 of whom had been treated with RT. Primary cancers were located in the prostate (50.83%), bladder (24.18%), corpus uterus (16.26%), cervix (5.83%), and ovary (2.91%). A total of 1,491 patients developed SPRC. Overall, the patients who received RT were at increased risk of developing SPRC (SIR = 1.39, 95% confidence interval [CI]: 1.27-1.52). The risk of SPRC decreased in patients who did not undergo RT (SIR = 0.85, 95% CI: 0.80-0.91). The SIR for SPRC in patients who underwent external beam radiation therapy (EBRT) was 1.22 (95% CI: 1.09-1.36). The SIR for SPRC in patients who underwent a combination of EBRT and brachytherapy (EBRT-BRT) was 1.85 (95% CI: 1.60-2.14). For patients who received RT, the SIR for SPRC increased with time after a 5-year latency period from PPC diagnosis. The survival of RT-treated SPRC patients was significantly worse than that of patients with primary rectal cancer only (PRCO). Conclusions:Patients receiving pelvic RT were at an increased risk of developing SPRC. Different pelvic RT treatment modalities had different effects on the risk of SPRC. We suggest that long-term surveillance of SPRC risk is required for patients who have undergone pelvic RT, especially young patients.

SUBMITTER: Yang R

PROVIDER: S-EPMC7658675 | biostudies-literature | 2020

REPOSITORIES: biostudies-literature

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Risk and Prognosis of Secondary Rectal Cancer After Radiation Therapy for Pelvic Cancer.

Yang Runkun R Guan Xu X Liu Enrui E Wei Ran R Zhao Zhixun Z Chen Haipeng H Liu Zheng Z Yang Ming M Jiang Zheng Z Wang Xishan X

Frontiers in oncology 20201029

<h4>Background</h4>The relationship between pelvic radiation therapy (RT) and second primary rectal cancer (SPRC) is unclear. The aim of this study was to assess the risk and prognosis of SPRC after pelvic RT.<h4>Materials and methods</h4>Data for patients who had primary pelvic cancer (PPC) between 1973 and 2016 were retrieved from the Surveillance, Epidemiology, and End Results (SEER) database. Multiple primary standardized incidence ratios (SIRs) were used to assess the risk of SPRC. Five-yea ...[more]

PMID: 33194727

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Project description:BackgroundAlthough radiation therapy (RT) improves local control for rectal cancer (RC), the long-term risks from RT, including development of a secondary malignancy, are controversial. The risk and prognosis of secondary bladder cancer (SBC) in RC patients undergoing RT have not been adequately studied. Our goal is to investigate the impact of RT on the risk of developing SBC and assess their survival outcomes.MethodsThis large population-based study included RC patients as their initial primary cancer from nine registries of the Surveillance, Epidemiology and End Results (SEER) database between 1973 and 2015. The cumulative incidence of SBC was assessed by using Fine and Gray's competing risk regression. The standardized incidence ratio (SIR) was used to compare the incidence of SBC in RC survivors to the US general population. The Kaplan-Meier method was used to evaluate the 10-year overall survival (OS) and 10-year cancer specific survival (CSS) for patients with SBC.ResultsOf 74,646 RC patients, 24,522 patients were treated with surgery and RT and 50,124 patients were treated with surgery alone. The incidence of SBC was 1.85% among patients who received RT and 1.24% among patients who did not. The incidence of SBC in RC patients who received RT was higher than the US general population (SIR, 1.35; 95% CI, 1.19-1.53, P<0.05), and decreased with increasing age at diagnosis, and increased with time since diagnosis. In competing risk regression analysis, undergoing RT was associated with a higher risk of SBC (hazard ratio [HR], 1.443, 95% confidence interval [CI], 1.209-1.720; P<0.001). The results of the dynamic SIR for SBC revealed that a slightly increased risk of SBC was observed after RT in the early latency, and was significantly related to the variations of age at RC diagnosis and decreased with time progress. The 10-year OS and CSS among SBC patients after RT were comparable to SBC patients after NRT.ConclusionRadiation was associated with an increased risk of developing SBC in RC patients, and special attention should be paid to the surveillance of these patients.

Project description:The aim of this study was to estimate the radiation-related secondary cancer risks in organs during the treatment of breast cancer with different radiotherapy techniques, such as three-dimensional conformal radiotherapy (3D-CRT), intensity modulated radiotherapy (IMRT), and volumetric modulated arc therapy (VMAT). The treatment plans for 26 patients with breast cancer who received whole-breast irradiation at a dose of 50?Gy included tangential field 3D-CRT with hard-wedges (W-TF), tangential field IMRT (2F-IMRT), multiple field IMRT (6F-IMRT), and double partial arcs (VMAT). Patients were divided into three groups according to the distance between the contralateral breast (CB) and the body of the sternum. Setup error was simulated by moving the isocenter, and the dose distribution was then recalculated without changing the field fluency distribution. Based on the linear-exponential, the plateau, and the full mechanistic dose-response models, the organ equivalent dose and excess absolute risk were calculated from dose-volume histograms to estimate the secondary cancer risks in organs. Compared with 3D-CRT, IMRT and VMAT showed excellent results regarding tumor conformity and homogeneity; however, the low dose volume to organs was considerably higher in 6F-IMRT and VMAT. Secondary cancer risks for 2F-IMRT were comparable or slightly lower than for W-TF, but considerably lower than for 6F-IMRT or VMAT. After setup error simulation, there was a small increase in secondary cancer risk for 2F-IMRT and an increase of 159% and 318% for 6F-IMRT and VMAT, respectively, compared with W-TF. Although these results were obtained in most patients, they did not necessarily apply to every individual. The secondary cancer risks in the CB decreased significantly in correlation with increased distance for all alternative techniques, although they were higher in VMAT and lower in 2F-IMRT regardless of the distance. After setup error simulation, the increased changes in secondary cancer risks in the CB were comparable between 2F-IMRT, 6F-IMRT, and VMAT, suggesting that the secondary cancer risks in the CB mainly depend on radiotherapy techniques and distance, although the effect of setup error cannot be ignored. In the contralateral lung (CL), the secondary cancer risks were almost independent from distance and depended mainly on radiotherapy techniques; they were rarely affected by setup error. VMAT was associated with a higher secondary cancer risk in the CL. For the ipsilateral lung (IL), the secondary cancer risks were higher than those in other organs because the IL receives high doses to achieve tumor control, and they were relatively lower in VMAT. This warrants special consideration when estimating the secondary cancer risk to the IL. The study results suggested that the optimal radiotherapy method for breast cancer should be determined on an individual basis and according to the balance between secondary cancer risks related to anatomic diversity and setup error, which can prevent blind selection of techniques.

Project description:BackgroundWhile chemo-radiotherapy improves local control in patients with locally advanced rectal cancer, it can also increase acute hematological toxicity (HT), which leads to poor outcomes. Patients receiving bone marrow radiation have been shown to develop acute HT. However, the safety and efficacy of bone marrow sparing is undetermined. The aim of our study was to explore the feasible dosimetric constraints for pelvic bone marrow (PBM) that can be widely used in rectal cancer patients undergoing chemo-radiotherapy.Methods112 rectal cancer patients were selected and divided into the PBM sparing IMRT group (60 cases) and the non-PBM sparing IMRT group (52 cases). All patients underwent pelvic radiotherapy with concurrent capecitabine-based chemotherapy. The PBM dosimetric constraints in the PBM sparing IMRT group were set to:V10 ≤ 85%, V20 ≤ 65% and V30 ≤ 45%. An independent sample t test was applied for the dose-volume parameters, and Chi-squared analysis was applied for clinical parameters and adverse events.ResultsThe radiation dose to PBM (V5~V45, Dmean, P<0.05), PBM sub-regions (V10~V35, Dmean, P<0.05) and both femoral heads (V5~V40, Dmean, P<0.05) decreased significantly in the PBM sparing IMRT group compared with that of the non-PBM sparing IMRT group (P<0.05). There was no significant difference in any dose-volume parameters of the bladder and small bowel in either groups, and none in the planning target volume (PTV) dose homogeneity and conformity (P>0.05). For acute HT observation, the incidence of grade 3 acute HT (χ2 = 7.094, P=0.008) was significantly reduced in patients treated with PBM sparing IMRT compared with patients treated with non-PBM sparing IMRT. There was no statistical difference in the incidence of vomiting, diarrhea, fatigue, anorexia, nausea, hand-foot syndrome, cystitis, perianal pain and perianal dermatitis in patients of both groups (P >0.05).ConclusionsApplying PBM dosimetric constraints (V10 ≤ 85%, V20 ≤ 65% and V30 ≤ 45%) can significantly reduce the radiation dose to PBM. The patients treated with PBM sparing IMRT had a lower incidence of acute HT compared with those treated with non-PBM sparing IMRT. Applying the PBM dosimetric constraints proposed by our study can benefits the patients with rectal cancer undergoing capecitabine-based chemo-radiotherapy.

Project description:Background: To investigate the role of stereotactic body RT (SBRT) in decreased total peripheral lymphocyte count (TLC) in patients with early-stage lung cancer and to explore possible risk factors for RT-induced lymphopenia. Materials and Methods: We analyzed the TLCs and lymphocyte subsets of 76 patients in our prospective clinical database who received SBRT for early-stage lung cancer treatment. Relationships between clinical factors or dosimetric parameters and TLC were evaluated using Spearman's correlation analysis and Chi-square tests for continuous and categorical variables, respectively. Multivariate linear regression analysis was used to control for confounding factors. Kaplan-Meier analysis with a log-rank test and a multivariate Cox regression model were used for survival analysis. Results: Most patients (64/76, 84.2%) experienced decreased absolute lymphocyte counts following SBRT, as well as shifts in lymphocyte subset distributions. Spearman's correlation coefficients between post-SBRT TLC and the percentage of the lung and heart receiving 5 to 50 Gy (in 5 Gy increments) shown that most lung DVH parameters [V(10)-V(50)] were significantly negatively correlated with post-SBRT TLC, while only heart V(5), V(20), V(25), V(30), and V(45) were significant. Univariate analyses revealed that a lower Pre-SBRT TLC level, higher mean lung dose, longer treatment duration, and longer TBT were significantly associated with a lower Post-SBRT TLC level (all P < 0.05). Stepwise multivariate linear regression, which incorporated all of the significantly clinical variables and SBRT-related parameters in univariate analysis, revealed that lower pre -SBRT TLC (P < 0.001), higher heart V5 (P = 0.002), and longer total beam-on time (TBT) (P = 0.001) were the independent risk factors for decrease in post-SBRT TLC. Patients with lower post-SBRT TLC and longer TBT exhibited significantly inferior progression-free survival (PFS) (P < 0.001 and P = 0.013) and overall survival (P = 0.006 and P = 0.043). Conclusions: G2 and more severe lymphopenia after SBRT might be an independent prognostic factor for poorer outcome in early-stage lung cancer. Lowering heart V5 and TBT when designing SBRT plans may spare circulating lymphocytes and have the potential to further improve survival outcomes.

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Risk and Prognosis of Secondary Rectal Cancer After Radiation Therapy for Pelvic Cancer.

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Risk and Prognosis of Secondary Rectal Cancer After Radiation Therapy for Pelvic Cancer.

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