3D MRI-based evaluation of the 2D brachytherapy planning in patients with advanced cervical cancer: An analysis of the delivered dose.

PURPOSE: To analyze the dose distribution achieved during 2D radiography-based brachytherapy (BRT) planning, by using a 3D MRI-based BRT replanning evaluation, in patients with advanced cervical carcinoma, treated with definitive concomitant chemoradiation (CCRT). METHODS: The curative CCRT was applied to 30 patients with advanced cervical carcinoma. For each patient, 2D radiography-based planning and a 3D MRI-based BRT replanning were performed. Applying the same source positions and dwell times in both planning methods, it was possible to use the MRI replanning to evaluate the dose distribution, maximum organs at risk (OAR) doses and target volume coverage, that was obtained during 2D BRT planning. RESULTS: A statistically significant difference for bladder and rectum maximum doses, between 2D planning (Bmax, Rmax) and 3D replanning (D0.1ccm, D1ccm, D2ccm) was found, except between Bmax and bladder D2ccm dose (p=0.07), and Rmax and rectal D2ccm dose in the group of patients with symmetrical rectum position regarding the applicator system (p=0.47). MRI evaluation of the HR-CTV volume, according to the 2D planning achieved dose distribution, revealed total EQD2 HR-CTV doses: D90 (107.15±22.06 Gy) and D100 (80.66±14.58 Gy). CONCLUSION: 2D radiography-based BRT planning can provide a good estimation for the bladder and rectum 3D D2ccm dose with a significant statistical difference for the doses in the smaller OAR volumes (D0.1ccm, D1ccm). Inability to visualize tumor tissue during 2D BRT planning provides no option in tailoring the dose distribution to the tumor volume and patient anatomy, leading to potential under/over-treatment in some patients.

Implementation of intensity-modulated radiotherapy and comparison with three-dimensional conformal radiotherapy in the postoperative treatment of cervical cancer.

PURPOSE: Within implementation of intensity-modulated radiotherapy (IMRT) in the postoperative irradiation of cervical cancer we evaluated and compared IMRT and three-dimensional conformal radiotherapy (3DCRT) dosimetric parameters for target volumes and organs at risk (OAR). METHODS: We randomized 95 patients with cervical cancer, UICC stage I-III, in groups depending of the type of external beam postoperative radiotherapy. Forty-five patients were treated with IMRT and 50 with 3DCRT. All patients underwent brachytherapy, and according to risk factors some of the patients had concomitant cisplatin chemotherapy. The study was done in a period of three years from December 2015. Analysis of dosimetric parameters for target volume coverage and OARs was performed. RESULTS: IMRT plans showed better conformity compared to 3DCRT plans, represented with homogenity index and conformity index, with higher maximum dose (PTV105 and D2). Both plans achieved adequate planning target volume coverage described with PTV95. Statistically significant difference between groups was found for bladder, rectum and bowel high dose regions: bladder V45 (p=0.000), rectum V40 (p=0.043) and V45 (p=0.000), bowel V45 (p=0.000), and bone marrow dosimetric parameters V20-V45; all were better in IMRT plans. Significant difference was found for volume of patient body normal tissue receiving dose of 20Gy, which was higher in IMRT. CONCLUSION: IMRT is a highly conformal technique. Satisfactory target volume coverage was achieved with both techniques, with better sparing of OARs in the IMRT group. With this technique improvement, we expect better quality of life in cervical cancer patients with good prognosis.

Acute toxicity of postoperative intensity-modulated radiotherapy and three-dimensional conformal radiotherapy for cervical cancer: The role of concomitant chemotherapy.

PURPOSE: The toxicity of postoperative radiotherapy for cervical cancer affects patients' quality of life. We evaluated acute toxicity in postoperative intensity-modulated radiotherapy (IMRT) and three-dimensional conformal radiotherapy (3DCRT) as well as the influence of dosimetric parameters and concomitant chemotherapy. METHODS: A total of 45 patients with early operable cervical cancer underwent postoperative IMRT with 40-45 Gy. The control group of 50 patients was treated with 3DCRT. Brachytherapy and concomitant cisplatin chemotherapy were performed in all patients according to pathologic and histologic findings. The patients were monitored for acute gastrointestinal, urological and hematological toxicity classified according to the RTOG acute radiation morbidity scoring criteria. We also analyzed the influence of dosimetric parameters on acute toxicity. RESULTS: Significant differences were found in overall acute toxicity (p=0.018), acute genitourinary toxicity (p=0.029), anemia (p=0.043) and neutropenia (p=0.027) but not in acute gastrointestinal toxicity between the IMRT and 3DCRT groups. In all patients, regarding chemotherapy administration, differences were found between the chemoradiotherapy and radiotherapy group as far as overall acute toxicity (CHRT vs RT; p=0.011) and hematological toxicity were concerned (p=0.001). Patients with ≥3 cycles of chemotherapy showed increased hematologic toxicity. In the IMRT group according to the administration of chemotherapy (chemoradiotherapy vs radiotherapy), statistically significant difference for leukopenia (p=0.009) was found and in the 3DCRT group for anemia (p=0.021) and neutropenia (p=0.029). According to chemotherapy administration (chemoradiotherapy vs radiotherapy), a statistically significant difference in leukopenia (p=0.009) was found in the IMRT group while in the 3DCRT group the differences were in anemia (p=0.021) and neutropenia (p=0.029). CONCLUSION: IMRT is associated with lower acute toxicity and better dosimetric parameters in organs at risk (OAR) compared to 3DCRT. Higher hematological toxicity occurred when concomitant chemotherapy was performed, regardless of RT technique. Further reduction of toxicity is expected with protocol and technical improvement and research of gene-related toxicity.