Outcomes after stereotactic body radiotherapy for lung tumors, with emphasis on comparison of primary lung cancer and metastatic lung tumors

BACKGROUND: The goal of this study was to determine the prognostic factors associated with an improved overall outcome after stereotactic body radiotherapy (SBRT) for primary lung cancer and metastatic lung tumors. METHODS: A total of 229 lung tumors in 201 patients were included in the study. SBRT of 45 Gy in 3 fractions, 48 Gy in 4 fractions, 60 Gy in 8 fractions or 60 Gy in 15 fractions was typically used to treat 172 primary lungs cancer in 164 patients and 57 metastatic lung tumors in 37 patients between January 2001 and December 2011. Prognostic factors for local control (LC) and overall survival (OS) were analyzed using a Cox proportional hazards model. RESULTS: The median biologically effective dose was 105.6 Gy based on alpha/beta = 10 (BED10). The median follow-up period was 41.9 months. The 3-year LC and OS rates were 72.5% and 60.9%, and the 5-year LC and OS rates were 67.8% and 38.1%, respectively. Radiation pneumonitis of grades 2, 3 and 5 occurred in 22 petients, 6 patients and 1 patient, respectively. Multivariate analyses revealed that tumor origin (primary lung cancer or metastatic lung tumor, p < 0.001), tumor diameter (p = 0.005), BED10 (p = 0.029) and date of treatment (p = 0.011) were significant independent predictors for LC and that gender (p = 0.012), tumor origin (p = 0.001) and tumor diameter (p < 0.001) were significant independent predictors for OS. CONCLUSIONS: SBRT resulted in good LC and tolerable treatment-related toxicities. Tumor origin and tumor diameter are significant independent predictors for both overall survival and local control

Focal dose escalation using FDG-PET-guided intensity-modulated radiation therapy boost for postoperative local recurrent rectal cancer: a planning study with comparison of DVH and NTCP

<p>Abstract</p> <p>Background</p> <p>To evaluate the safety of focal dose escalation to regions with standardized uptake value (SUV) >2.0 using intensity-modulated radiation therapy (IMRT) by comparison of radiotherapy plans using dose-volume histograms (DVHs) and normal tissue complication probability (NTCP) for postoperative local recurrent rectal cancer</p> <p>Methods</p> <p>First, we performed conventional radiotherapy with 40 Gy/20 fr. (CRT 40 Gy) for 12 patients with postoperative local recurrent rectal cancer, and then we performed FDG-PET/CT radiotherapy planning for those patients. We defined the regions with SUV > 2.0 as biological target volume (BTV) and made three boost plans for each patient: 1) CRT boost plan, 2) IMRT without dose-painting boost plan, and 3) IMRT with dose-painting boost plan. The total boost dose was 20 Gy. In IMRT with dose-painting boost plan, we increased the dose for BTV+5 mm by 30% of the prescribed dose. We added CRT boost plan to CRT 40 Gy (<it>summed plan 1</it>), IMRT without dose-painting boost plan to CRT 40 Gy (<it>summed plan 2</it>) and IMRT with dose-painting boost plan to CRT 40 Gy (<it>summed plan 3</it>), and we compared those plans using DVHs and NTCP.</p> <p>Results</p> <p>D_meanof PTV-PET and that of PTV-CT were 26.5 Gy and 21.3 Gy, respectively. V₅₀of small bowel PRV in <it>summed plan 1 </it>was significantly higher than those in other plans ((<it>summed plan 1 </it>vs. <it>summed plan 2 </it>vs. <it>summed plan 3</it>: 47.11 ± 45.33 cm³vs. 40.63 ± 39.13 cm³vs. 41.25 ± 39.96 cm³(p < 0.01, respectively)). There were no significant differences in V₃₀, V₄₀, V₆₀, D_meanor NTCP of small bowel PRV.</p> <p>Conclusions</p> <p>FDG-PET-guided IMRT can facilitate focal dose-escalation to regions with SUV above 2.0 for postoperative local recurrent rectal cancer.</p

Proof-of-Concept Comparative Dosimetric Analysis of Coplaner Horizontal-Port Carbon-Ion Radiotherapy in the Head and Neck

Purpose/Objective(s)Carbon-ion radiotherapy (CIRT) may offer improved treatment of radioresistant disease in complex anatomy, such as in head and neck (H&N) cancer. Nonetheless, center cost remains prohibitive. A compact center implementing only horizontal ports has been theorized; coplaner irradiation may improve target coverage. As proof of concept, horizontal+coplaner (H+C) treatment was dosimetrically compared in variously located, complex H&N cases, to evaluate feasibility of this approach.Materials/Methods3 previously-treated patients with adenoid cystic carcinoma (ACC) (L. maxillary sinus, R. parotid, upper R. sinus), 1 with R. nasal angiosarcoma, and 1 with R. parotid adenocarcinoma, were selected. A H+C plan was developed on identical CIRT software per standard. Prescription dose was maintained (64-70.4 Gy (RBE)). Bed roll of +/-30 degrees and off-medial transcranial irradiation were employed to improve targeting and organ at risk (OAR) protection. OAR limits included a Dmax 40 Gy (RBE) with V40 20% for optic nerves and chiasm and Dmax 30 Gy (RBE) for brain stem. Individual dose-volume histograms (DVH) were qualitatively compared.ResultsPTV and GTV coverage varied <1% in all cases, with comparable DVHs. Stem dose was below Dmax 30 Gy (RBE) in all patients, with reduced H+C dose noted in the upper R. sinus and L maxillary sinus ACC patients (Dmax 6.8 vs 14.7 Gy (RBE) and 1.3 vs 17.8 Gy (RBE), respectively). H+C unilateral optic nerve dose was above the Dmax limit of 40 Gy (RBE) in the upper R sinus and L maxillary sinus ACC cases as well (40.4 vs 37.0 Gy (RBE) and 45.7 vs 46.2 Gy (RBE), respectively). In the latter case, left H+C optic nerve V40 dose exceeded the 20% limit, at 21.6% vs 3.6% standard. In the former, the upper sinus location increased bilateral eye irradiation: V10 rose from 57% and 0% to 100% each, with Dmax increased to 51.7 from 47 Gy (RBE) in the right, and 30.9 from 8 Gy (RBE) in the left. The sarcoma case experienced increased H+C chiasm Dmax to 28.7 from 1.8 Gy (RBE), below the 40 Gy (RBE) limit. H+C irradiation raised all V5, V10, and V20 brain dosages, with averages of 16.2 vs 2.2%, 10.9 vs 1.5%, and 2.8 vs 0.8%, respectively. Maximums of 25%, 20%, and 7% were noted in the right parotid ACC.ConclusionAdequate CIRT dose delivery with protection of key OARs in complex H&N cancer appears feasible using only a horizontal port with coplaner approach. Dose increase could be seen in optic nerves and eyes when near or obstructing tumor from the port, highlighting disease location and anatomical limitations of treating solely within the horizontal plane. Increased brain dosage was noted in all cases. The impact of low-dose high-LET CIRT on neural tissue requires further exploration prior to deployment of a coplaner approach. Potentials such as sitting-up immobilization for anteroposterior delivery may mitigate the limitations seen here. A larger cohort analysis is in progress.The American Society for Radiation Oncology (ASTRO) Annual meeting 202

Proof-of-Concept Comparative Dosimetric Analysis of Coplanar Horizontal-Port Carbon-Ion Radiotherapy in the Head and Neck

- Adequate CIRT dose delivery with protection of key OARs in complex H&N cancer appears feasible with the horizontal + coplanar approach. - Dose increase in optic nerves and eyes when near or obstructing tumor from the port were noted. - Increased brain dosage was noted in all cases. The impact of low-dose high-LET CIRT on neural tissue requires further exploration. - Potentials such as sitting-up immobilization for anteroposterior delivery may mitigate the limitations seen here. A larger cohort analysis is in progress.American Society for Radiation Oncology (ASTRO) Annual meeting 202

The Role of Particle Therapy in Adenoid Cystic Carcinoma and Mucosal Melanoma of the Head and Neck

Particle irradiation is suitable for resistant histologies owing to a combination of improved dose delivery with potential radiobiologic advantages in high linear energy transfer radiation. Within the head and neck, adenoid cystic carcinoma and mucosal melanoma are two such histologies, being radioresistant and lying closely proximal to critical structures. Here, we review the use of particle irradiation for adenoid cystic carcinoma and mucosal melanoma of the head and neck

Adaptation of stochastic microdosimetric kinetic model to hypoxia for hypo-fractionated multi-ion therapy treatment planning.

For hypo-fractionated multi-ion therapy (HFMIT), the stochastic microdosimetric kinetic (SMK) model had been developed to estimate the biological effectiveness of radiation beams with wide linear energy transfer (LET) and dose ranges. The HFMIT will be applied to radioresistant tumors with oxygen-deficient regions. The response of cells to radiation is strongly dependent on the oxygen condition in addition to radiation type, LET and absorbed dose. This study presents an adaptation of the SMK model to account for oxygen-pressure dependent cell responses, and develops the oxygen-effect-incorporated stochastic microdosimetric kinetic (OSMK) model. In the model, following assumptions were made: the numbers of radiation-induced lesions (double-strand breaks and clustered DNA damages) are reduced due to lack of oxygen, and the numbers of oxygen-mediated lesions are reduced for radiation with high LET. The model parameters were determined by fitting survival data under aerobic and anoxic conditions for human salivary gland tumor cells and V79 cells exposed to helium-, carbon-, and neon-ion beams over the LET range of 18.5-654.0 keV/μm. The OSMK model provided good agreement with the experimental survival data of the cells with determination coefficients > 0.9. In terms of oxygen enhancement ratio, the OSMK model reproduced the experimental data behavior, including slight dependence on particle type at the same LET. The OSMK model was then implemented into the in-house treatment planning software for the HFMIT to validate its applicability in clinical practice. A treatment plan with helium- and neon-ion beams was made for a pancreatic cancer case assuming an oxygen-deficient region within the tumor. The biological optimization based on the OSMK model preferentially placed the neon-ion beam to the hypoxic region, while it placed both helium- and neon-ion beams to the surrounding normoxic region. The OSMK model offered the accuracy and usability required for hypoxia-based biological optimization in HFMIT treatment planning